WO2021131910A1

WO2021131910A1 - Carbonaceous material, manufacturing method therefor, and electrode material for electrical double layer capacitor

Info

Publication number: WO2021131910A1
Application number: PCT/JP2020/046776
Authority: WO
Inventors: 人見　充則; 松下　稔; 裕之西浪; 光▲徳▼ 西田; 山田　隆之
Original assignee: 株式会社クラレ
Priority date: 2019-12-25
Filing date: 2020-12-15
Publication date: 2021-07-01
Also published as: JPWO2021131910A1; JP7545418B2

Abstract

The present invention relates to a carbonaceous material that has a BET specific surface area according to a nitrogen adsorption method of 1750 m2/g to 2100 m2/g, and satisfies any one of the following conditions (1), (2), and (3). (1) The pore volume as calculated by the HK method on the basis of an adsorption isotherm according to a nitrogen adsorption method is 0.76 cm3/g to 0.91 cm3/g, the powder electrical conductivity is 13 S/cm to 22 S/cm, the surface functional group quantity is 0.22 meq/g to 0.29 meq/g, and the hydrogen content is 0.41 mass% or less. (2) The pore volume as calculated by the NLDFT method on the basis of an adsorption/desorption isotherm according to a carbon dioxide adsorption/desorption method is 0.37 cm3/g to 0.41 cm3/g, the surface functional group quantity is 0.22 meq/g to 0.29 meq/g, and the hydrogen content is 0.41 mass% or less. (3) The pore volume (A) as calculated by the HK method on the basis of an adsorption isotherm according to a water vapor adsorption method is 0.48 cm3/g to 0.64 cm3/g, the pore volume (B), as calculated by the HK method on the basis of the adsorption isotherm according to the water vapor adsorption method, of pores that are 1.2 nm or smaller in diameter is 0.14 cm3/g to 0.30 cm3/g, and the ratio of the pore volume (B) to the pore volume (A) is 25% to 59%.

Description

Carbon material and its manufacturing method, electrode material for electric double layer capacitors

The present invention relates to a carbonaceous material, a method for producing the same, and an electrode material for an electric double layer capacitor containing the carbonaceous material.

An electric double layer capacitor, which is one of the electrochemical devices, uses a capacity (electric double layer capacity) obtained only by physical ion adsorption / desorption without a chemical reaction, and therefore has an output compared to a battery. Excellent in characteristics and life characteristics. In recent years, due to the excellent characteristics of such electric double layer capacitors and the urgent countermeasures against environmental problems, they have been installed in electric vehicles (EV) and hybrid vehicles (HV) as auxiliary power sources and regenerative energy storage applications. It is also attracting attention. Such electric double layer capacitors for automobiles are required not only to have a higher energy density, but also to have high durability and safety under severe usage conditions (for example, in a severe temperature environment) as compared with consumer applications. Has been done.

In response to such demands, various methods for improving the durability of electric double layer capacitors have been studied. For example, Patent Document 1 aims to suppress the generation of gas by controlling the amount of oxygen in the skeleton in addition to the surface functional groups existing on the surface of activated carbon, and to improve the durability of the electric double layer capacitor. , A method of crushing and classifying activated carbon obtained by activation treatment and then heat-treating it at a high temperature is disclosed.

International Publication No. 2018/2000769 Pamphlet

As described in Patent Document 1, controlling the amount of functional groups on the surface of activated carbon and the amount of oxygen in the skeleton has a certain effect on reducing the amount of gas generated during charging and discharging in the electric double layer capacitor. However, even if the amount of functional groups on the surface of activated carbon, which is the electrode material, and the amount of oxygen in the skeleton are appropriately controlled, it is difficult to suppress the generation of gas over time, and the capacity retention rate changes as the amount of gas generated changes. There is a limit to the improvement of the durability of the electric double layer capacitor by controlling only the amount of functional groups on the surface of activated carbon and the amount of oxygen in the skeleton.

The present invention provides a carbonaceous material suitable as an electrode material for an electric double layer capacitor, which is excellent in suppressing gas generation during charging and discharging and can realize a high capacity retention rate for a long period of time, a method for producing the same, and the carbonaceous material. It is an object of the present invention to provide an electrode for an electric double layer capacitor using a material.

The present inventors have arrived at the present invention as a result of repeated detailed studies on carbonaceous materials and methods for producing the same in order to solve the above problems.
That is, the present invention includes the following preferred embodiments.
[1] The BET specific surface area by the nitrogen adsorption method is 1750 m ² / g or more and 2100 m ² / g or less, and the following (1), (2) and (3):
(1) The pore volume calculated by the HK method based on the adsorption isotherm by the nitrogen adsorption method is 0.76 cm ³ / g or more and 0.91 cm ³ / g or less, and the powder conductivity is 13 S / cm or more and 22 S / It is cm or less, the surface functional group content is 0.22 meq / g or more and 0.29 meq / g or less, and the hydrogen content is 0.41 mass% or less;
(2) The pore volume calculated by the NLDFT method based on the adsorption isotherm by the carbon dioxide adsorption / desorption method is 0.37 cm ³ / g or more and 0.41 cm ³ / g or less, and the surface functional group amount is 0.22 meq. / G or more and 0.29 meq / g or less, and the hydrogen content is 0.41% by mass or less;
(3) a pore volume calculated by the HK method based on adsorption isotherm by steam adsorption method (A) is not more than 0.48 cm ³ / g or more 0.64 cm ³ / g, the adsorption isotherm by steam adsorption method Based on this, the pore volume (B) with a pore diameter of 1.2 nm or less calculated by the HK method is 0.14 cm ³ / g or more and 0.30 cm ³ / g or less, and the pore volume (B) with respect to the pore volume (A). ) Is a carbonaceous material that satisfies any of the conditions of 25% or more and 59% or less.
[2] The carbonaceous material according to the above [1], which satisfies the condition (2) or (3) and has a powder conductivity of 13 S / cm or more and 22 S / cm or less.
[3] The carbonaceous material according to the above [1] or [2], which satisfies the condition (3) and has a surface functional group amount of 0.22 meq / g or more and 0.29 meq / g or less.
[4] The carbonaceous material according to any one of [1] to [3] above, which satisfies the condition (3) and has a hydrogen content of 0.41% by mass or less.
[5] pore size 4nm or more of the pore volume as measured by the BJH method is not more than 0.07 cm ³ / g or more 0.18 cm ³ / g, carbon according to any one of [1] to [4] Quality material.
[6] The carbonaceous material according to any one of [1] to [5] above, wherein the alkali metal content is 40 ppm or less.
[7] The carbonaceous material according to any one of [1] to [6] above, wherein the carbonaceous material is derived from a carbon precursor derived from coconut shell.
[8] An electrode material for an electric double layer capacitor containing the carbonaceous material according to any one of the above [1] to [7].
[9] After carbonizing the carbon precursor, the activated carbon obtained by activating the carbon precursor is alkaline-washed in an alkaline solution, and
The method for producing a carbonaceous material according to any one of [1] to [7] above, which comprises a step of acid-cleaning the activated carbon after alkaline cleaning and then heat-treating at 1100 ° C. or higher and 1300 ° C. or lower.

According to the present invention, a carbonaceous material suitable as an electrode material for an electric double layer capacitor, which has an excellent effect of suppressing gas generation during charging and discharging and can realize a high capacity retention rate for a long period of time, a method for producing the same, and the above. An electrode for an electric double layer capacitor using a carbonaceous material can be provided.

It is a figure which shows the sheet-shaped electrode composition. It is a figure which shows the current collector (etched aluminum foil) coated with a conductive adhesive. It is a figure which shows the polar electrode which bonded the sheet-like electrode composition and the current collector, and ultrasonically welded the aluminum tab. It is a figure which shows the bag-shaped exterior sheet. It is a figure which shows the electrochemical device. It is a graph which shows the capacity retention rate change rate in an Example and a comparative example. It is a graph which shows the gas generation amount change rate in an Example and a comparative example.

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without impairing the gist of the present invention.

<Carbonate material>
The carbonaceous material of the present invention has a BET specific surface area of 1750 m ² / g or more and 2100 m ² / g or less by the nitrogen adsorption method, and a pore volume calculated by the HK method based on the adsorption isotherm by the nitrogen adsorption method is 0. 76cm ³ / g or more 0.91cm and a ³ / g or less, the powder conductivity is less 13S / cm or more 22S / cm, the amount of surface functional groups are located below 0.22 meq / g or more 0.29meq / g Moreover, the hydrogen content is 0.41% by volume or less.

The BET specific surface area (hereinafter, also referred to as “BET specific surface area”) of the carbonaceous material of the present invention by the nitrogen adsorption method is 1750 m ² / g or more, preferably 1800 m ² / g or more, and more preferably 1850 m ² / g or more. Is. When the BET specific surface area is ^{less than 1750 m 2} / g, the capacitance per unit mass becomes small, and the capacity retention rate tends to decrease. In addition, since the average pore diameter is relatively small, the resistance that is thought to be due to the diffusion resistance of non-aqueous electrolyte ions in the pores tends to increase during charging and discharging under a large current. On the other hand, BET specific surface area of the carbonaceous material of the present invention is not more than 2100 m ² / g, preferably at most 2050m ² / g. When the BET specific surface area ^{exceeds 2100 m 2} / g, the number of micropores in the carbonaceous material tends to increase, the amount of gas generated itself tends to increase, and gas tends to be generated over time. As a result, the capacity retention rate tends to decrease when used in an electric double layer capacitor. Further, the bulk density of the obtained electrode tends to decrease, and the capacitance per unit volume tends to decrease, and the performance may decrease when used in an electric double layer capacitor.
In the present invention, the BET specific surface area can be calculated by the nitrogen adsorption method, for example, by the method described in Examples described later.

Conventionally, as an effective means for increasing the initial capacitance of an electric double layer capacitor, it is known to provide fine pores in a carbonaceous material to increase the pore volume. On the other hand, water is easily adsorbed and exists in the micropores. Such water is often strongly adhered to the micropores, and it is difficult to completely remove such water even after a sufficient drying step when forming an electrode from a carbonaceous material, for example. For this reason, a small amount of water remaining in the micropores flows out into the electrolytic solution over time, or the water itself decomposes, so that gas is likely to be generated, and electricity is generated as the amount of gas generated changes. The capacity of the double layer capacitor tends to decrease.
The carbonaceous material of the present invention mainly controls the pore volume of the micropore region to a specific range, and has physical characteristics (for example, powder conduction) that serve as an appropriate index according to the measurement / calculation method of the pore volume. By controlling the rate, amount of surface functional group, etc.) in combination with the control of the pore volume, it is possible to secure a high initial capacity of the electric double layer capacitor and reduce the presence of fine pores to which moisture easily adheres. Therefore, the amount of gas generated is unlikely to change over time, and a high capacity retention rate can be achieved over a long period of time.

In one aspect of the present invention, the carbonaceous material of the present invention has the above BET specific surface area and has a pore volume of 0.76 cm ³ / g calculated by the HK method based on the adsorption isotherm by the nitrogen adsorption method. More than 0.91 cm ³ / g or less, powder conductivity of 13 S / cm or more and 22 S / cm or less, surface functional group amount of 0.22 meq / g or more and 0.29 meq / g or less, hydrogen content Is 0.41% by volume or less. Hereinafter, the carbonaceous material of the said aspect is referred to as a carbonaceous material of the first aspect of the present invention. Further, in the present specification, when the carbonaceous material of the present invention is simply referred to, in principle, the first aspect and the second and third aspects described later shall be collectively referred to.

The pore volume (hereinafter, also referred to as "pore volume (N)") of the micropore region, which is calculated by the HK method based on the adsorption isotherm by the nitrogen adsorption method, is within the range of ^{0.76 cm 3 / g or more.} By controlling, the specific surface area is increased to secure a high initial capacity of the electric double layer capacitor, ^{and by controlling the range to 0.91 cm 3} / g or less, the presence of fine pores to which moisture easily adheres is eliminated. By reducing the amount of gas generated, the amount of gas generated is less likely to change with time, and a carbonaceous material capable of achieving a high capacity retention rate for a long period of time can be obtained. In order to obtain the effect of suppressing gas generation over a long period of time and a higher capacity retention rate, the pore volume (N) in the carbonaceous material of the first aspect of the present invention is preferably 0.78 cm ³ / g or more. It is preferably 0.80 cm ³ / g or more, more preferably 0.82 cm ³ / g or more, and preferably 0.90 cm ³ / g or less, more preferably 0.89 cm ³ / g or less, still more preferably 0. .88 cm ³ / g or less.
Here, the HK method is a calculation method generally used for analysis of micropores (pores of less than 2 nm), and is a method proposed by Horvast Kawazoe et al. In the present invention, the pore volume (N) can be calculated by applying the HK method to the nitrogen adsorption isotherm measured by the nitrogen adsorption method.

The powder conductivity of the carbonaceous material of the first aspect of the present invention is 13 S / cm or more and 22 S / cm or less. When the powder conductivity is not more than the above upper limit value, excessive development of the carbon crystal structure of the carbonaceous material can be suppressed, and the shrinkage of the pores of the carbonaceous material can be suppressed, so that the initial stage per weight can be suppressed. The capacitance increases. Further, when the powder conductivity is equal to or higher than the above lower limit value, the carbon crystal structure of the carbonaceous material is in a sufficiently developed state and the crystallinity is increased, so that the electrical conductivity of the carbon itself is improved. It is possible to suppress an increase in resistance due to current leakage during charging and discharging, and it is possible to improve the capacity retention rate. In order to further enhance the above effect, the powder conductivity is preferably 13.5 S / cm or more, more preferably 14 S / cm or more, and preferably 21.5 S / cm or less.
In the present invention, the powder conductivity of the carbonaceous material can be measured by measuring the powder resistance at a load of 12 kN, and can be calculated, for example, according to the method described in Examples described later.

In the carbonaceous material of the first aspect of the present invention, the amount of surface functional groups is 0.22 meq / g or more and 0.29 meq / g or less. When the amount of surface functional groups (acidic functional groups) present on the surface of the carbonaceous material is not more than the above upper limit, gas generation in the electric double layer capacitor can be suppressed more effectively, and the capacity of the electric double layer capacitor is maintained. The rate can be expected to improve. Therefore, from the viewpoint of the durability of the electric double layer capacitor, particularly the reduction of the amount of gas generated and the improvement of the capacity retention rate, the smaller the surface functional group amount of the carbonaceous material is, the better, preferably 0.28 meq / g or less. .. On the other hand, if the amount of surface functional groups is too small, the moldability of the electrode tends to be low. Therefore, the lower limit of the amount of surface functional groups is preferably 0.23 meq / g or more, more preferably 0.24 meq / g or more. is there.
In the present invention, the surface functional group mainly means an acidic functional group containing oxygen and adsorbing a basic substance, and examples thereof include a hydroxyl group, a carboxyl group, a carbonyl group, and a lactone group. The amount of these surface functional groups can be measured, for example, according to the method described in Examples described later.

The hydrogen content in the carbonaceous material of the first aspect of the present invention is 0.41% by mass or less. When the hydrogen content in the carbonaceous material is not more than the above upper limit, the carbon crystal structure is in a sufficiently developed state and the crystallinity tends to be high. Therefore, the hydrogen content in the carbonaceous material is preferably 0.40% by mass or less, more preferably 0.35% by mass or less, still more preferably 0.30% by mass or less. The lower the hydrogen content in the carbonaceous material, the higher the crystallinity tends to be, and when used as an electrode material for an electric double layer capacitor, the capacity retention rate is likely to be improved. Therefore, the lower the hydrogen content in the carbonaceous material is, the more preferable it is, and the lower limit thereof is not particularly limited, but from the viewpoint of production efficiency, it is usually 0.05% by mass or more, preferably 0.10% by mass. That is all.
In the present invention, the hydrogen content of the carbonaceous material can be measured, for example, according to the method described in Examples described later.

In another aspect of the present invention, the carbonaceous material of the present invention has the above BET specific surface area, and the pore volume calculated by the NLDFT method based on the adsorption isotherm by the carbon dioxide adsorption / desorption method is 0. It is .37 cm ³ / g or more and 0.41 cm ³ / g or less, the surface functional group amount is 0.22 meq / g or more and 0.29 meq / g or less, and the hydrogen content is 0.41 mass% or less. Hereinafter, the carbonaceous material of the said aspect is referred to as a carbonaceous material of the second aspect of the present invention.

Pore volume mainly in the micropore region calculated by the NLDFT method (Non Localized Density Functional Theory) based on the adsorption isotherm by the carbon dioxide adsorption / desorption method (hereinafter, "pores"). By controlling the volume (C) to ^{a range of 0.37 cm 3} / g or more, the specific surface area is increased to ensure a high initial capacity of the electric double layer capacitor, and 0.41 cm ³ / g. By controlling to the following range, it is possible to reduce the presence of micropores to which moisture easily adheres, so that the amount of gas generated is less likely to change over time, and a carbonaceous material that can achieve a high capacity retention rate over a long period of time can be obtained. Obtainable. By using the carbon dioxide adsorption / desorption method, micropores of a smaller size (for example, 0.31 to 1) that are difficult to detect when the nitrogen adsorption method, which is widely used in the past, is used to measure the pore volume in a carbonaceous material. The presence of .47 nm pores) can be confirmed. By controlling the presence of such small-sized micropores in which water easily adheres and it is difficult to remove the water, a high initial capacity and capacity retention rate can be achieved when used as an electrode material. Moreover, it is possible to obtain a carbonaceous material having an excellent effect of suppressing gas generation for a long period of time. The pore volume (C) in the carbonaceous material of the second aspect of the present invention is preferably 0.40 cm ³ / g or less, more preferably 0.39 cm ³ / g or less.
The measurement and calculation of the pore volume (C) by the NLDFT method based on the adsorption isotherm by the carbon dioxide adsorption / desorption method can be performed, for example, according to the method described in Examples.

In the carbonaceous material of the second aspect of the present invention, the amount of surface functional groups is 0.22 meq / g or more and 0.29 meq / g or less. When the amount of surface functional groups (acidic functional groups) is not more than the above upper limit, gas generation in the electric double layer capacitor can be suppressed more effectively, and the capacity retention rate of the electric double layer capacitor can be expected to be improved. If the amount of surface functional groups is too small, the moldability of the electrode tends to be low. The preferable range of the amount of surface functional groups (acidic functional groups) in the carbonaceous material of the second aspect of the present invention is the same as the preferable range of the amount of surface functional groups in the carbonic material of the first aspect described above. ..

The hydrogen content in the carbonaceous material of the second aspect of the present invention is 0.41% by mass or less. When the hydrogen content in the carbonaceous material is not more than the above upper limit, the carbon crystal structure tends to be sufficiently developed and the crystallinity tends to be high, and the lower the hydrogen content is, the higher the crystallinity tends to be. When used as an electrode material for electric double layer capacitors, it tends to improve the capacity retention rate. The preferred range of hydrogen content in the carbonaceous material of the second aspect of the present invention is the same as the preferred range of hydrogen content in the carbonaceous material of the first aspect described above.

The powder conductivity of the carbonaceous material according to the second aspect of the present invention is preferably 13 S / cm or more and 22 S / cm or less. When the powder conductivity is not more than the above upper limit value, excessive development of the carbon crystal structure of the carbonaceous material can be suppressed, and the shrinkage of the pores of the carbonaceous material can be suppressed, so that the initial stage per weight can be suppressed. When the capacitance tends to increase and the powder conductivity is equal to or higher than the above lower limit, the carbon crystal structure of the carbonaceous material is in a sufficiently developed state and the crystallinity increases, so that the electrical conductivity of the carbon itself becomes high. By improving the above, it is possible to suppress an increase in resistance due to current leakage during charging and discharging, and it is possible to improve the capacity retention rate. The more preferable range of the powder conductivity in the carbonaceous material of the second aspect of the present invention is the same as the preferable range of the powder conductivity in the carbonic material of the first aspect described above.

In another aspect of the present invention, the carbonaceous material of the present invention has the above BET specific surface area, and the pore volume (A) calculated by the HK method based on the adsorption isotherm by the water vapor adsorption method is 0. .48Cm ³ / g or more 0.64cm and a ³ / g or less, pore size 1.2nm or less of the pore volume calculated by HK method based on adsorption isotherm by steam adsorption method (B) is 0.14 cm ³ / It is g or more and 0.30 cm ³ / g or less, and the ratio of the pore volume (B) to the pore volume (A) is 25% or more and 59% or less. Hereinafter, the carbonaceous material of the said aspect is referred to as a carbonaceous material of the third aspect of the present invention.

The pore volume (hereinafter, also referred to as "pore volume (A)") of the micropore region, which is calculated by the HK method based on the adsorption isotherm by the water vapor adsorption method, is within the range of ^{0.48 cm 3 / g or more.} By controlling, the specific surface area is increased to secure a high initial capacity of the electric double layer capacitor, ^{and by controlling the range to 0.64 cm 3} / g or less, the presence of fine pores to which water easily adheres is eliminated. By reducing the amount of gas generated, the amount of gas generated is less likely to change over time, and a carbonaceous material capable of achieving a high capacity retention rate for a long period of time can be obtained. By using the water vapor adsorption method, very small pores (for example, 0.31 to 1.) that are difficult to detect when the nitrogen adsorption method, which is widely used in the past, is used to measure the pore volume in carbonaceous materials. The presence of 94 nm pores) can be confirmed. By controlling the presence of such small-sized micropores in which water easily adheres and it is difficult to remove the water, a high initial capacity and capacity retention rate can be achieved when used as an electrode material. Moreover, it is possible to obtain a carbonaceous material having an excellent effect of suppressing gas generation for a long period of time. The pore volume of the carbonaceous material of the third aspect of the present invention (A) is preferably 0.49cm ³ / g or more, more preferably 0.50 cm ³ / g or more, more preferably 0.54 cm ³ / g It is more preferably 0.62 cm ³ / g or less, and more preferably 0.60 cm ³ / g or less.
The measurement and calculation of the pore volume by the HK method based on the adsorption isotherm by the water vapor adsorption method can be performed, for example, according to the method described in Examples.

In the carbonaceous material of the third aspect of the present invention, the pore volume having a pore diameter of 1.2 nm or less calculated by the HK method based on the adsorption isotherm by the water vapor adsorption method (hereinafter, also referred to as “pore volume (B)”). Is 0.14 cm ³ / g or more and 0.30 cm ³ / g or less. Since the pore volume (B) with a pore diameter of 1.2 nm or less detected by the water vapor adsorption method is 0.14 cm ³ / g or more, it is easy to secure a sufficient initial capacity when used as an electrode material, and When it is 0.30 cm ³ / g or less, the presence of extremely small micropores in which water easily adheres and it is difficult to remove the water is reduced, and gas generation over time can be effectively suppressed. This makes it possible to obtain a carbonaceous material capable of achieving a high capacity retention rate for a long period of time. In the carbonaceous material of the third aspect of the present invention, the pore volume (B) is preferably 0.15 cm ³ / g or more, and preferably not more than 0.29 cm ³ / g, more preferably 0.28cm ^{It is 3} / g or less.

In the carbonaceous material of the third aspect of the present invention, the ratio of the pore volume (B) to the pore volume (A) [(B) / (A) × 100] is 25% or more and 59% or less. When the ratio of the pore volume (B) to the pore volume (A) is in the above range, the fine pores in which water that can cause gas generation is easily adsorbed are reduced, while the high initial capacity required as an electrode material is high. Since there are appropriate pores that are advantageous for ensuring the capacity retention rate, the electrode density is improved and the pore volume is increased, which is important for achieving a high initial capacity when used as an electrode material. As a result, it becomes easier to achieve both suppression of gas generation over time due to moisture adsorbed on the micropores. In the carbonaceous material of the third aspect of the present invention, the ratio of the pore volume (B) to the pore volume (A) is preferably 55% or less, more preferably 50% or less, still more preferably 45% or less, particularly. It is preferably 43% or less.

The powder conductivity of the tricarbonate material of the present invention is preferably 13 S / cm or more and 22 S / cm or less. When the powder conductivity is not more than the above upper limit value, excessive development of the carbon crystal structure of the carbonaceous material can be suppressed, and the shrinkage of the pores of the carbonaceous material can be suppressed, so that the initial stage per weight can be suppressed. When the capacitance tends to increase and the powder conductivity is equal to or higher than the above lower limit, the carbon crystal structure of the carbonaceous material is in a sufficiently developed state and the crystallinity increases, so that the electrical conductivity of the carbon itself becomes high. By improving the above, it is possible to suppress an increase in resistance due to current leakage during charging and discharging, and it is possible to improve the capacity retention rate. The more preferable range of the powder conductivity in the carbonaceous material of the third aspect of the present invention is the same as the preferable range of the powder conductivity in the carbonic material of the first aspect described above.

In the carbonaceous material of the third aspect of the present invention, the amount of surface functional groups is preferably 0.22 meq / g or more and 0.29 meq / g or less. When the amount of surface functional groups (acidic functional groups) is not more than the above upper limit, gas generation in the electric double layer capacitor can be suppressed more effectively, and the capacity retention rate of the electric double layer capacitor can be expected to be improved. If the amount of surface functional groups is too small, the moldability of the electrode tends to be low. The preferable range of the amount of surface functional groups (acidic functional groups) in the carbonaceous material of the third aspect of the present invention is the same as the preferable range of the amount of surface functional groups in the carbonic material of the first aspect described above. ..

The hydrogen content in the carbonaceous material according to the third aspect of the present invention is preferably 0.41% by mass or less. When the hydrogen content in the carbonaceous material is not more than the above upper limit, the carbon crystal structure tends to be sufficiently developed and the crystallinity tends to be high, and the lower the hydrogen content is, the higher the crystallinity tends to be. When used as an electrode material for electric double layer capacitors, it tends to improve the capacity retention rate. The preferable range of the hydrogen content in the carbonaceous material of the third aspect of the present invention is the same as the preferable range of the hydrogen content in the carbonaceous material of the first aspect described above.

In the carbonaceous materials of the first aspect, the second aspect and the third aspect of the present invention, the pore volume having a pore diameter of 4 nm or more measured by the BJH method (hereinafter, also referred to as “pore volume (BJH)”) is , preferably 0.07 cm ³ / g or more, more preferably 0.08 cm ³ / g or more, more preferably 0.09 cm ³ / g or more, and preferably not more than 0.18 cm ³ / g, more preferably It is 0.17 cm ³ / g or less, more preferably 0.16 cm ³ / g or less. When the pore volume (BJH) with a pore diameter of 4 nm or more is not more than the above lower limit value, a carbonaceous material having relatively few fine pores, which causes gas generation when used in an electric double layer capacitor, is relatively easy to adhere to. This leads to an improvement in the capacity retention rate and durability of the electric double layer capacitor. On the other hand, when the pore volume (BJH) having a pore diameter of 4 nm or more is not more than the above upper limit value, a high initial capacitance can be secured, the bulk density of the electrode is improved, and the capacitance per unit volume is increased. It tends to be higher.
Here, the BJH method is a calculation method generally used for analysis of mesopores (pores of 2 nm or more and 50 nm or less), like the CI method and the DH method, and is a method proposed by Barrett, Joiner, Hallenda et al. Is. In the present invention, the pore volume can be calculated by applying the BJH method to the nitrogen adsorption isotherm measured by the nitrogen adsorption method.

The alkali metal content of the carbonaceous materials of the first, second and third aspects of the present invention is preferably 40 ppm or less, more preferably 35 ppm or less, still more preferably 30 ppm or less. Examples of the alkali metal species that can be contained in the carbonaceous material include lithium, sodium, potassium and cesium. In particular, since sodium and potassium are generally present in relatively large amounts in carbonaceous materials, controlling their contents is advantageous for improving the quality of carbonaceous materials. When a plurality of types of alkali metals are contained, the content of each alkali metal is preferably not more than the above upper limit value, and the total content of all alkali metals is more preferably not more than the above upper limit value. When the alkali metal content is not more than the above upper limit, the alkali metal element is less likely to be eluted into the electrolytic solution, and a short circuit due to reprecipitation is less likely to occur. Further, since the pores of the carbonaceous material are less likely to be clogged by the alkali metal, the charge / discharge capacity tends to increase. The lower limit of the alkali metal content of the carbonaceous material of the present invention is not particularly limited, and the smaller it is, the more preferable, but it is usually 1 ppm or more, for example, 3 ppm or more. The alkali metal content of the carbonaceous material can be adjusted to the above amount by, for example, alkaline cleaning or acid cleaning in the method for producing a carbonaceous material of the present invention described later. The alkali metal content of the carbonaceous material of the present invention can be measured, for example, by the method described in Examples described later.

<Manufacturing method of carbonaceous material>
The carbonaceous materials of the first aspect, the second aspect and the third aspect of the present invention are, for example, for example.
A step of carbonizing the carbon precursor and then activating the activated carbon to perform alkaline cleaning in an alkaline solution (hereinafter, also referred to as "alkaline cleaning step"), and
A step of acid-cleaning the activated carbon after alkaline cleaning and then heat-treating at 1100 ° C. or higher and 1300 ° C. or lower (hereinafter, also referred to as "heat treatment step").
It can be manufactured by a method including.

Further, in addition to the above steps, the above manufacturing method may be used, for example.
(I) A step of acid cleaning and then deoxidizing in an oxidizing gas atmosphere at 500 to 1000 ° C. (hereinafter, also referred to as "deoxidizing step").
(Ii) A step of activating a carbon precursor as a raw material to obtain activated carbon (hereinafter, also referred to as "activation step"), and / or (iii) a step of crushing and / or classifying an activated carbon and / or a carbonaceous material. It may be included.

The carbon precursor used as a raw material for the carbonaceous material of the present invention is not particularly limited as long as it forms activated carbon by activating after carbonization, and is a plant-derived carbon precursor, a mineral-derived carbon precursor, or a natural carbon precursor. It can be widely selected from a carbon precursor derived from a material, a carbon precursor derived from a synthetic material, and the like. From the viewpoint of reducing harmful impurities, protecting the environment and from a commercial point of view, the carbonaceous material of the present invention is preferably based on a carbon precursor derived from a plant, in other words, the carbonaceous material of the present invention. It is preferable that the carbon precursor used as the raw material of the material is derived from a plant.

Examples of mineral-derived carbon precursors include petroleum-based and carbon-based pitches and coke. Examples of carbon precursors derived from natural materials include natural fibers such as cotton and hemp, regenerated fibers such as rayon and viscose rayon, and carbides of semi-synthetic fibers such as acetate and triacetate. Examples of carbon precursors derived from synthetic materials include polyamide-based materials such as nylon, polyvinyl alcohol-based materials such as vinylon, polyacrylonitrile-based materials such as acrylic, polyolefin-based materials such as polyethylene and polypropylene, polyurethane, phenol-based resins, and vinyl chloride-based resins. Examples include carbides.

The plant-derived carbon precursor is not particularly limited, but for example, wood, charcoal, rice husks, coconut husks, palm husks and other fruit husks, coffee beans, tea leaves, sugar cane, fruits (for example, mandarin oranges, bananas), straw, etc. Examples include, but are not limited to, rice husks, hardwoods, conifers, and bamboo. This example includes waste after use for its intended purpose (eg, used tea leaves) or some plant material (eg, banana or tangerine peel). These plant raw materials may be used alone or in combination of two or more. Among these plant raw materials, coconut husks are preferable because they are easily available and carbonaceous materials having various properties can be produced.

The coconut shell is not particularly limited, and examples thereof include coconut husks such as palm palm (oil palm), coconut palm, salak, and lodoicea. These coconut shells may be used alone or in combination of two or more. Coconut and palm husks, which are biomass wastes generated in large quantities after the palm is used as a food, detergent raw material, biodiesel oil raw material, etc., are particularly preferable from the viewpoint of availability.

It is possible to obtain it in the form of char (palm shell char) by temporarily firing the coconut shell, and it is preferable to use this as a raw material. Here, the char is generally a powdery solid rich in carbon that is produced without melting and softening when coal is heated, but here, the carbon content that is produced by heating an organic substance without melting and softening. It also refers to a powdery solid that is rich in carbon. The method for producing char from coconut shell is not particularly limited, and the char can be produced using a method known in the art. For example, the coconut shell as a raw material contains, for example, an inert gas such as nitrogen, carbon dioxide, helium, argon, carbon monoxide or fuel exhaust gas, a mixed gas of these inert gases, or these inert gases as main components. It can be produced by firing (carbonizing treatment) at a temperature of about 400 to 800 ° C. in an atmosphere of a mixed gas with another gas.

<Activation process>
The coconut shell-derived activated carbon, which is a suitable raw material for producing the carbonaceous material of the present invention, can be obtained, for example, by activating the carbonized precursor or coconut shell char. The activation treatment is a treatment in which pores are formed on the surface of the carbon precursor and converted into a porous carbonaceous substance, whereby activated carbon having a large specific surface area and pore volume can be obtained. When the carbon precursor is used as it is without the activation treatment, the specific surface area and pore volume of the obtained carbonaceous substance are not sufficient, and when used as the electrode material, a sufficiently high initial capacity is secured. Becomes difficult. The activation treatment can be carried out by a method general in the art, and there are mainly two types of treatment methods, a gas activation treatment and a chemical activation treatment.

As a gas activation treatment, for example, a method of heating a carbon precursor in the presence of water vapor, carbon dioxide, air, oxygen, combustion gas, or a mixed gas thereof is known. Further, as the drug activation treatment, for example, an activator such as zinc chloride, calcium chloride, phosphoric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide is mixed with a carbon precursor and is inactive. A method of heating in a gas atmosphere is known. In the present invention, it is preferable to use the gas activation treatment because the drug activation requires a step of removing the residual drug and the production method becomes complicated.

When steam activation is adopted as the gas activation treatment, it is preferable to use a mixture of an inert gas and steam similar to that used in the carbonization treatment from the viewpoint of efficiently advancing the activation. The partial pressure is preferably in the range of 10 to 60%. When the partial pressure of water vapor is 10% or more, the activation is likely to proceed sufficiently, and when it is 60% or less, the rapid activation reaction is suppressed and the reaction is easy to control.

The total amount of the activating gas supplied in the steam activation is preferably 50 to 10000 parts by mass or more, more preferably 100 to 5000 parts by mass or more, and further preferably 200 to 3000 parts by mass or more with respect to 100 parts by mass of the carbon precursor. is there. When the total amount of the activated gas to be supplied is within the above range, the activation reaction can proceed more efficiently.

The specific surface area and pore volume of activated carbon can be controlled by changing the activation treatment method of the carbon precursor and its conditions. For example, when activated carbon is obtained by steam activation treatment, it can be controlled by the gas used, the heating temperature, the time, and the like. In the steam activation treatment, the specific surface area and pore diameter of the obtained activated carbon tend to decrease when the heating temperature is low, and tend to increase when the heating temperature is high. In the present invention, when activated carbon is obtained by steam activation treatment, its heating temperature (activation temperature) depends on the type of gas used, but is usually 700 to 1100 ° C, preferably 800 to 1000 ° C. Further, the heating time and the heating rate are not particularly limited, and may be appropriately determined according to the heating temperature, the desired specific surface area of activated carbon, and the like.

The BET specific surface area and pore volume of the activated carbon obtained by the activation treatment can be appropriately adjusted depending on the conditions of the activation treatment and the like. By appropriately adjusting the BET specific surface area and pore volume of the activated carbon, the BET specific surface area and pore volume of the carbonaceous material obtained through the subsequent alkaline cleaning step and heat treatment step can be used as the carbonaceous material of the present invention. It becomes easier to control within an appropriate range.

The activation treatment may be performed once or more than once, if necessary, in order to obtain the desired specific surface area and pore volume. When the activation treatment is carried out twice or more, for example, a step of washing the activated carbon after the first activation (hereinafter, also referred to as “primary activation”) with an acid may be included. By performing acid cleaning after the primary activation, impurities such as alkali metals and alkaline earth metals contained in the carbonaceous material can be reduced or removed, and excessive development of the pore diameter due to the activation treatment can be suppressed. it can. In addition, by removing impurities after the primary activation and then performing further activation (hereinafter, also referred to as "secondary activation"), it is possible to prevent the number of mesopores that tend to reduce the capacitance per volume from becoming too large. can do. By performing the secondary activation, the alkali concentration in the alkaline cleaning and the temperature during the alkaline cleaning and / or the heat treatment may be lowered, which may be advantageous in terms of workability, energy efficiency and the like.

The acid cleaning after the primary activation can be performed by immersing the activated carbon after the primary activation in a cleaning liquid containing an acid or the like. After the acid washing, the activated carbon is secondarily activated by washing it thoroughly with ion-exchanged water to remove the residual acid, drying it, and then activating it again.

The conditions for acid cleaning after activation are not particularly limited, and the type, concentration, cleaning temperature, cleaning time, etc. of the acid to be used may be appropriately determined, and are the same as those in the acid cleaning step after alkaline cleaning, which will be described later. Similar conditions and the like can be adopted. Further, the conditions for the second and subsequent activations are not particularly limited, and as in the case of the primary activation, the heating temperature, heating time, etc. may be appropriately determined according to the desired specific surface area, pore volume, etc. of the activated carbon. ..

<Alkaline cleaning process>
The method for producing a carbonaceous material of the present invention includes a step of washing the activated carbon after activation with an alkaline solution. In the alkaline cleaning step, the activated carbon is washed with an alkaline cleaning solution to remove metal components dissolved in alkali and non-immobilized carbon (hydrocarbons) present in a trace amount in order to improve the carbon purity of the activated carbon. This is the process of. In addition, impurities such as silicon element contained in activated carbon can be removed by alkaline cleaning. As a result, when used as an electrode for an electric double layer capacitor, the number of active points that react with the electrolytic solution is reduced, and the decomposition reaction of the electrolytic solution can be suppressed, so that the amount of gas generated during charging and discharging is more effective. Can be reduced to. The alkaline cleaning step can be performed by immersing the activated carbon obtained after activation in an alkaline cleaning solution, reacting the activated carbon after activation with an alkali in a gas phase, etc., but the process is simplified, operability, and cost are reduced. From the viewpoint, the method of immersing in an alkaline cleaning solution is preferable.

Examples of the alkaline substance that can be used in the alkaline cleaning solution include alkali metal hydroxides, and examples of the alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. Of these, sodium hydroxide is preferable from the viewpoint of process operability and cost. These alkaline substances may be used alone or in combination of two or more. The solvent for dissolving the alkaline substance is not particularly limited, but water is preferable.

The concentration of the alkaline substance in the cleaning liquid is not particularly limited, and may be appropriately adjusted according to the type of alkaline substance used, the cleaning temperature and time, the ratio of the liquid amount to the amount of activated carbon, and the like. The alkali concentration of the cleaning liquid is preferably 0.001 mol / l or more and 10 mol / l or less, and more preferably 0.01 mol / l or more and 2 mol / l or less. When the alkali cleaning concentration is within the above range, trace hydrocarbons and metals are removed, and the residual amount of alkali metal can be reduced.

The pH of the cleaning solution for alkaline cleaning is not particularly limited and may be appropriately adjusted according to the type of cleaning solution used, etc., but is usually 10 or more, preferably 12 or more.

The temperature at which the alkaline cleaning is performed is not particularly limited, and may be appropriately determined according to the type of alkaline substance used, the alkaline concentration, the alkaline cleaning method, the alkaline cleaning time, and the like. For example, the cleaning temperature with an alkaline cleaning solution may be, for example, 5 ° C. or higher, preferably 10 ° C. or higher, and more preferably 20 ° C. or higher. Further, for example, it may be 110 ° C. or lower, preferably 100 ° C. or lower, more preferably 98 ° C. or lower, and further preferably 95 ° C. or lower. When the temperature of the alkaline cleaning solution is within the above range, it becomes easy to remove trace amounts of hydrocarbons and metals.

The alkaline cleaning time is not particularly limited, and may be appropriately determined according to the type of alkaline substance used, the alkaline concentration, the alkaline cleaning method, the alkaline cleaning temperature, and the like. The alkaline cleaning time is usually 5 minutes or more, preferably 10 minutes or more, and more preferably 15 minutes or more. Further, for example, it may be 300 minutes or less, preferably 180 minutes or less, and more preferably 120 minutes or less. When the alkaline cleaning time is within the above range, it becomes easy to remove trace amounts of hydrocarbons and metals.

When performing alkaline cleaning by immersing activated carbon in an alkaline cleaning solution, the method is to immerse the activated carbon in the cleaning solution placed in the cleaning container for a predetermined time, and then remove all or part of the cleaning solution. The method may be a method in which a new cleaning liquid is newly added and immersion-drainage is repeated, or a method in which activated carbon is immersed in a new cleaning liquid continuously supplied into the cleaning container for a predetermined time.

The ratio of the alkaline cleaning solution to the activated carbon for alkaline cleaning may be appropriately determined according to the type of alkaline substance used, the alkaline concentration, the alkaline cleaning temperature, the time, and the like. For example, the mass of the activated carbon to be immersed is usually 3 to 50% by mass, preferably 5 to 30% by mass, based on the mass of the cleaning liquid. Within the above range, impurities eluted in the cleaning liquid are less likely to precipitate from the cleaning liquid, reattachment to the activated carbon is likely to be suppressed, and volumetric efficiency is appropriate, which is desirable from the viewpoint of economy.

The atmosphere for performing alkaline cleaning is not particularly limited, and may be, for example, an atmospheric atmosphere or an atmosphere of an inert gas such as nitrogen gas.

After alkaline cleaning of activated carbon, the activated carbon may be washed with water in order to remove the residual cleaning liquid.

<Acid cleaning process>
The method for producing a carbonaceous material of the present invention includes washing the activated carbon after alkaline washing with an acid, preferably an acidic solution. By acid-cleaning the activated carbon after alkaline cleaning, impurities such as metal components contained in the activated carbon can be reduced and removed. The acid cleaning after the alkaline cleaning can be performed by immersing the activated carbon after the alkaline cleaning in a cleaning liquid containing an acid. In the pickling step, the raw material activated carbon may be washed with an acid (for example, hydrochloric acid) and then washed with water, or the pickling and pickling may be combined as appropriate, such as repeating pickling and washing.

The acid cleaning solution includes inorganic acids such as hydrochloric acid, sulfuric acid and nitrate, saturated carboxylic acids such as formic acid, acetic acid, propionic acid, oxalic acid and tartaric acid and citric acid, and organic carboxylic acids such as benzoic acid and terephthalic acid. It is preferable to use an acid, and above all, cleaning with hydrochloric acid which does not oxidize the activated carbon is more preferable. When hydrochloric acid is used as the acid cleaning solution, the concentration of hydrochloric acid is preferably 0.1 to 3.0%, more preferably 0.3 to 1.0%. If the hydrochloric acid concentration is too low, it is necessary to increase the number of picklings in order to remove impurities. On the contrary, if the hydrochloric acid concentration is too high, the amount of residual hydrochloric acid increases. The process can be performed, which is preferable from the viewpoint of productivity.

The liquid temperature for pickling or washing with water is not particularly limited, but is preferably 0 to 98 ° C, more preferably 10 to 95 ° C, and even more preferably 15 to 90 ° C. When the temperature of the cleaning liquid when immersing the raw material activated carbon is within the above range, it is desirable that the cleaning can be carried out in a practical time and while suppressing the load on the apparatus.

The atmosphere for acid cleaning is not particularly limited, and may be, for example, an atmospheric atmosphere or an atmosphere of an inert gas such as nitrogen gas.

<Deoxidizing process>
The method for producing a carbonaceous material of the present invention may include a deoxidizing step for removing an acid (for example, hydrochloric acid or the like) derived from an acid cleaning solution remaining in the activated carbon after acid cleaning. The deoxidizing step can be performed, for example, by heating the activated carbon after acid cleaning for a short time in an oxidizing gas atmosphere and bringing the activated carbon into contact with the oxidizing gas for a short time to remove residual acid.

Examples of the oxidizing gas include oxygen, water vapor, carbon dioxide, and combustion gas obtained by burning kerosene and propane. These oxidizing gases may be mixed and used, or diluted with an inert gas and used. Of these, a combustion gas obtained by burning kerosene or propane, and a gas obtained by adding steam to the combustion gas are more preferable because they can also be used as a heat source. The concentration of the oxidizing gas may be appropriately determined depending on the type of gas used, but is usually 1 to 40% when steam is added, and preferably 2% or more when carbon dioxide gas is added.

The treatment temperature for bringing the oxidizing gas into contact with the activated carbon is preferably 500 to 1000 ° C, more preferably 650 to 850 ° C. When it is within the above temperature range, the deoxidizing step can be carried out without significantly changing the pore structure of the activated carbon, which is preferable. The time for contact with the oxidizing gas varies depending on the contact temperature, but is usually about 30 minutes to 3 hours.

<Heat treatment process>
The method for producing a carbonaceous material of the present invention includes a heat treatment step. By heat-treating the acid-cleaned activated carbon after the alkali-cleaning step, the carbon structure can be developed and the surface functional groups can be reduced. The heat treatment temperature is preferably 1100 ° C. or higher and 1300 ° C. or lower. If the heat treatment temperature is too low, the development of the carbon structure becomes insufficient, and the surface functional groups cannot be sufficiently removed. Therefore, in the present invention, the heat treatment temperature is more preferably 1100 ° C. or higher, further preferably 1150 ° C. or higher, and particularly preferably 1200 ° C. or higher. If it is too high, the surface functional groups will decrease, but sufficient capacity will not be obtained due to the decrease in the specific surface area due to the shrinkage of the pores of the activated carbon and the decrease in the edge surface of the activated carbon. In the method for producing a carbonaceous material of the present invention, by heat-treating activated carbon from which alkali metals and the like have been removed through an alkaline cleaning step, shrinkage of micropores is easily promoted and moisture that can cause gas generation is likely to occur. It is possible to reduce the fine pores that are easily adsorbed by the gas, and by heating within the above specific temperature range, the pores that are advantageous for ensuring the high initial capacity and capacity retention rate required for the electrode material. It is considered that the gas generation can be suppressed, and the formation and distribution of micropores that can function in a well-balanced manner in improving the initial capacity and the capacity retention rate can be realized.

The heat treatment time may be appropriately determined according to the heat treatment temperature, heating method, equipment used, etc., and is usually 0.1 to 10 hours, preferably 0.3 hours or more, and more preferably 0.5 hours or more. Also, it is preferably 8 hours or less, more preferably 5 hours or less. By selecting and adjusting the heat treatment temperature and time within the above range, the BET specific surface area, pore volume, powder conductivity, surface functional group amount, etc. of the obtained carbonaceous material can be controlled.

It is preferable that the heat treatment is performed under an inert gas condition or in a gas atmosphere generated from activated carbon by blocking oxygen or air. Examples of the inert gas used for the heat treatment include nitrogen gas, argon gas, helium gas and the like. Only one of these gases may be used alone, or two or more of these gases may be used as a mixed gas.

As the furnace used for the heat treatment, for example, various types of furnaces such as a rotary kiln, a fluidized layer furnace, a fixed layer furnace, a mobile layer furnace, and a mobile bed furnace can be used, and raw materials are continuously input and products are taken out continuously. It can be applied to both continuous furnaces and intermittent batch furnaces. As the heating means, there is no problem as long as it can be heated to a predetermined temperature, and electric heating, gas combustion type heating, high frequency induction heating, energization heating and the like can be applied. Further, these heating means may be used alone or in combination.

<Crushing process>
The method for producing a carbonaceous material of the present invention may include a pulverization step. The pulverization step is a step for controlling the shape and particle size of the finally obtained carbonaceous material to a desired shape and particle size. The pulverization step may be performed at any stage of the carbonaceous material as long as a carbonaceous material having a desired shape and particle size is finally obtained. The particle size of the carbonaceous material of the present invention is not particularly limited, but when used in an electric double layer capacitor application, the carbonaceous material is crushed so that the average particle size is preferably 1 to 15 μm, more preferably 2 to 10 μm. It is preferable to do so.

The crusher used for crushing is not particularly limited, and for example, a known crusher such as a cone crusher, a double roll crusher, a disc crusher, a rotary crusher, a ball mill, a centrifugal roll mill, a ring roll mill, a centrifugal ball mill, or a jet mill can be used. , Can be used alone or in combination.

<Classification process>
The method for producing a carbonaceous material of the present invention may include a classification step. By removing small particles and large particles in the activated carbon by classification, it is possible to control the particle size of the carbonaceous material and obtain a carbonaceous material having a narrow particle size distribution width. By removing such fine particles, it is possible to reduce the amount of binder in the electrode configuration. The classification method is not particularly limited, and examples thereof include classification using a sieve, wet classification, and dry classification. Examples of the wet classifier include classifiers that utilize principles such as gravity classification, inertial classification, hydraulic classification, and centrifugal classification. Examples of the dry classifier include classifiers that utilize principles such as sedimentation classification, mechanical classification, and centrifugal classification. From the viewpoint of economy, it is preferable to use a dry classifier.

It is also possible to carry out crushing and classification using one device. For example, pulverization and classification can be carried out using a jet mill having a dry classification function. Further, a device in which the crusher and the classifier are independent can be used. In this case, crushing and classification can be performed continuously, but crushing and classification can also be performed discontinuously.

<Electrode material for electric double layer capacitors>
The carbonaceous materials of the first aspect, the second aspect and the third aspect of the present invention can be suitably used as polar materials for various battery devices, respectively. In particular, it is suitable as an electrode material for electric double layer capacitors, and by using the carbonaceous material of the present invention, the amount of gas generated during charging and discharging is low, and the amount of gas generated does not change over a long period of time. , It is possible to manufacture an electric double layer capacitor capable of maintaining a high capacity for a long period of time. Therefore, in one embodiment of the present invention, it is possible to provide an electrode material for an electric double layer capacitor, which comprises the carbonaceous material of the present invention. Using this electrode material for electric double layer capacitors, it is also possible to provide electrodes for electric double layer capacitors and electric double layer capacitors.

The electrode material for electric double layer capacitors of the present invention can be produced from the carbonaceous material of the present invention. For example, the electrode material of the present invention can be obtained by kneading the carbonaceous material of the present invention with components such as a conductivity-imparting agent, a binder, and a solvent, and coating and drying the kneaded product. Further, a paste is prepared by adding a solvent to the electrode material, the paste is applied to a current collector plate such as an aluminum foil, the solvent is dried and removed, and the paste is placed in a mold and press-molded. , Electrodes for electric double layer capacitors can be manufactured.

As the conductivity-imparting agent used for the electrode material, for example, acetylene black, ketjen black and the like can be used. As the binder, for example, a fluorine-based polymer compound such as polytetrafluoroethylene or polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, petroleum pitch, phenol resin and the like can be used. Examples of the solvent include water, alcohols such as methanol and ethanol, saturated hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene, xylene and mesityrene, ketones such as acetone and ethylmethylketone, and acetic acid. Esters such as methyl and ethyl acetate, amides such as N, N-dimethylformamide and N, N-diethylformamide, cyclic amides such as N-methylpyrrolidone and N-ethylpyrrolidone can be used.

Further, an electric double layer capacitor can be manufactured by using the above electric double layer electrode. An electric double layer capacitor generally has an electrode, an electrolytic solution, and a separator as its main components, and has a structure in which a separator is arranged between a pair of electrodes. Examples of the electrolytic solution include an electrolytic solution in which an amidine salt is dissolved in an organic solvent such as propylene carbonate, ethylene carbonate, and methyl ethyl carbonate, an electrolytic solution in which a quaternary ammonium salt of perchloric acid is dissolved, and quaternary ammonium and lithium. Examples thereof include an electrolytic solution in which an alkali metal tetrafluoroborate and a hexafluorophosphate are dissolved, and an electrolytic solution in which a quaternary phosphonium salt is dissolved. Examples of the separator include non-woven fabrics, cloths, and micropore films containing cellulose, glass fibers, or polyolefins such as polyethylene and polypropylene as main components. Electric double layer capacitors can be manufactured, for example, by arranging these main configurations in a manner conventionally common in the art.

In the electric double layer capacitor containing the carbonaceous material of the present invention, the size of the pores and the amount of micropores existing on the surface of the carbonaceous material are controlled, and the water content generated over time due to the micropores is controlled. In addition to suppressing decomposition and outflow into the electrolytic solution, the amount of surface functional groups is reduced, so that the reactivity with the electrolytic solution is low, and the effect of suppressing gas generation during charging and discharging is high. As a result, high durability, particularly capacity retention rate, can be realized, and excellent capacitor performance can be exhibited even after long-term use.

Hereinafter, the present invention will be described in more detail based on Examples, but the following Examples do not limit the present invention. Each physical property value in Examples and Comparative Examples was measured by the following method.

The physical property values in the examples were measured according to the method described below.

<Contents of sodium element and potassium element>
The contents of sodium element and potassium element were measured by the following methods. First, a calibration curve for the sodium element and potassium element contents is prepared from a standard solution having a known concentration. Then, the crushed measurement sample was dried at 115 ° C. for 3 hours, 0.1 g was placed in a decomposition vessel, 10 ml of nitric acid was added and mixed, and then the sample was sampled using a microwave sample pretreatment device (“MARS6” manufactured by CEM). Was dissolved. The solution was taken out, and the solution was prepared by measuring it into 25 ml, and then analyzed by an ICP emission spectrophotometer (“ICPE-9820” manufactured by Shimadzu Corporation). Each concentration was determined from the obtained value and the calibration curve prepared earlier, the content of each element was determined from the following formula, and the total amount thereof was taken as the alkali metal amount.

<Powder conductivity>
The conductivity of the carbonaceous material was measured using the powder resistivity measurement unit "MCP-PD51" manufactured by Mitsubishi Chemical Analytech Co., Ltd. For the measurement of conductivity, a sample having an amount of the activated carbon pellet having a thickness of 3.5 to 4.5 mm when a load of 12 kN was applied was used, and the conductivity of the activated carbon pellet under a load of 12 kN was measured. ..

<Amount of surface functional groups>
The amount of surface functional groups is H.I. P. Boehm, Advan. Catal. , 1966, 16, 179, etc., and measured by a known hydrochloric acid titration method. Specifically, a 0.1 N ethanol solution was prepared as a measurement solution using sodium ethoxide manufactured by High Purity Chemical Laboratory Co., Ltd. To 25 ml of this measurement solution, 0.5 g of a carbonaceous material as a sample was added, and the mixture was stirred at 25 ° C. for 24 hours. After stirring, the measurement solution and the carbonaceous material are separated by centrifugation, 10 ml of the measurement solution is collected, and the pH is 4.0 with 0.1 N hydrochloric acid using "888 Titration" manufactured by Metrohm of Switzerland. Neutralization titration was performed as the titration end point, and sample titration was determined. On the other hand, a blank test was carried out with a solution containing no sample, the amount of blank test titration was also determined, and the amount of surface functional groups was calculated by the following formula.
Surface functional group amount (meq / g) =
{Blank test titration (mL) -Sample titration (mL)} x 0.1 x f (hydrochloric acid factor) /
Carbon material used Weight (g) x 25 (mL) / 10 (mL)

<Nitrogen adsorption isotherm>
Using BELSORP-MAX manufactured by Microtrac Bell Co., Ltd., the carbonaceous material as a sample is heated at 300 ° C. for 5 hours under reduced pressure (vacuum degree: 0.1 kPa or less), and then the carbonaceous material at 77 K. Nitrogen adsorption isotherm was measured.

<Pore volume of 4 nm or more (BJH)>
With respect to the obtained nitrogen adsorption isotherm, the pore volume of the pores having a pore diameter of 4 nm or more calculated in the range of _{relative pressure P / P 0 = 0.99 or less was determined by using the BJH method.} In the analysis by the BJH method, the reference t-curve "NGCB-BEL.t" provided by Microtrack Bell Co., Ltd. was used for the analysis.

<BET specific surface area>
The obtained nitrogen adsorption isotherm was analyzed by the multipoint method by the BET formula, and the specific surface area was calculated from the straight line in the region of the _{relative pressure P / P 0 = 0.01 to 0.1 of the obtained curve.}

<Pore volume (N) by HK method>
The obtained nitrogen adsorption isotherm was analyzed by the HK method. The analysis conditions were 28.010 for the adsorbate molecular weight, 0.808 g / cm ³ for the adsorbate density, a straight line for the file data interpolation method, and N2-C (77K) for the parameter setting. It was HKS.

<Pore volume (C) by carbon dioxide desorption method>
By measuring the adsorption and desorption of carbon dioxide at 273K at a relative pressure (p / p0) from 0.00075 to 0.030 using a gas adsorption measuring device (AUTOSORB-iQ MP-XR manufactured by Quantachrome). Carbon dioxide adsorption and desorption isotherms were obtained.
For the carbon dioxide adsorption isotherm obtained by the above method, "CO2 at 273K on carbon (NLDFT model)" was applied as a calculation model and analyzed by the NLDFT method to obtain the pore size distribution, and the total pore volume was obtained. Was calculated.

<Pore volume (A) by water vapor adsorption method>
Adsorption isotherm by measuring the adsorption of water vapor at 298K at a relative pressure (p / p0) from 0.00 to 1.00 using a gas adsorption measuring device (AUTOSORB-iQ MP-XR manufactured by Quantachrome). Got a line.
For the water vapor adsorption isotherm obtained by the above method, the pore size distribution was analyzed by the HK method, the pore size distribution was obtained, and the total pore volume was calculated.

<Pore volume (B) by water vapor adsorption method>
For the water vapor adsorption isotherm obtained by the above method, the pore diameter distribution was analyzed by the HK method, the pore diameter distribution was obtained, and the pore volume of the pores having a pore diameter of 1.2 nm or less was calculated.

From the values of the pore volume (A) and the pore volume (B) calculated above, the ratio of the pore volume (B) to the pore volume (A) was calculated.

<Particle size distribution>
The particle size of the carbonaceous material was measured by a laser diffraction measurement method. That is, the carbonaceous material to be measured was put into ion-exchanged water together with a surfactant, and ultrasonic vibration was applied using BRANSONIC M2800-J manufactured by EMERSON to prepare a uniform dispersion liquid, and Microtrack Bell Co., Ltd. It was measured by the transmission method using the Microtrac MT3200 manufactured by the same manufacturer. The carbonaceous material concentration of the uniform dispersion was adjusted so that it was within the measurement concentration range displayed by the device. Further, as the surfactant used for the purpose of uniform dispersion, "polyoxyethylene (10) octylphenyl ether (Triton X-100)" manufactured by Fuji Film Wako Pure Chemical Industries, Ltd. was used. The surfactant was added in an appropriate amount that can be uniformly dispersed and does not generate bubbles or the like that affect the measurement. The analysis conditions are shown below.

(Analysis conditions)
Number of measurements: 1 measurement time: 30 seconds Distribution display: Volume particle size classification: Standard calculation mode: MT3000
Solvent name: WATER
Upper limit of measurement: 1408 μm, lower limit of measurement: 0.243 μm
Residual ratio: 0.00
Passage ratio: 0.00
Residual ratio setting: Invalid particle permeability: Transmitted particle refractive index: 1.81
Particle shape: Non-spherical solvent Refractive index: 1.333
DV value: 0.0150-0.0500
Transmittance (TR): 0.750 to 0.920
Flow velocity: 50%

Hereinafter, in this embodiment, the average particle size of the carbonaceous material indicates the value of the particle size at a volume fraction of 50% in the volume fraction integrated particle size distribution display.

<Hydrogen content>
Elemental analysis was performed using an elemental analyzer EMGA-930 manufactured by HORIBA, Ltd.
The detection method of the device is hydrogen: inert gas melting-non-dispersion infrared absorption method (NDIR). As a pretreatment, 20 mg of a sample whose water content was measured at 250 ° C. for about 10 minutes was taken in a Ni capsule and an elemental element was detected. The measurement was performed after degassing in the analyzer for 30 seconds. The test was analyzed with 3 samples, and the average value was used as the analysis value.

1. 1. Experimental Example for Carbonated Material of First Aspect <Example 1>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon having a surface area of 2117 m ² / g and a pore volume by the HK method: 0.92 cm ³ / g was obtained. The obtained activated charcoal was washed with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) at 25 ° C. for 30 minutes, and then with ion-exchanged water to remove residual base. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and nitrogen gas + steam (water vapor partial pressure). 3%) Under an atmosphere, deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, 1100-1220 ° C.; 2 ° C./min, held at 1220 ° C. for 30 minutes), finely pulverize to an average particle size of 6 μm and carbonaceous material for capacitor electrodes. Obtained the material. For the obtained carbonaceous material, measure and calculate BET specific surface area, HK pore volume (N), powder conductivity, surface functional group amount, hydrogen content, pore volume (BJH) of 4 nm or more, and alkali metal amount. did. The results are shown in Table 1.

<Example 2>
The alkaline and acid-cleaning activated carbon obtained in Example 1 was placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. Heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 30 minutes), and then finely pulverized to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 3>
The alkaline and acid-cleaning activated carbon obtained in Example 1 were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min, 1100 to 1220 ° C.; 2 ° C./min, held at 1220 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 4>
The alkaline and acid-cleaning activated carbon obtained in Example 1 was placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. After heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 60 minutes), finely pulverize to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 5>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon is secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%), and has a BET specific surface area of 1912 m ² / g and a pore volume by the HK method: 0.83 cm ³ / g. Next activated activated carbon was obtained. The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, held at 1100 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 6>
The alkaline and acid-cleaning activated carbon obtained in Example 5 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 7>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon having a surface area of 2117 m ² / g and a pore volume by the HK method: 0.92 cm ³ / g was obtained. The obtained activated charcoal was alkaline-washed at 100 ° C. for 30 minutes with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluent: ion-exchanged water), and then ion-exchanged water was used to remove residual bases. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat, and under a nitrogen stream, 1150 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to After heat treatment at 1100 ° C; 2.5 ° C / min, 1100 to 1150 ° C; 2 ° C / min, held at 1150 ° C for 60 minutes), finely pulverized to an average particle size of 6 μm and carbon for the capacitor electrode. Obtained quality material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Example 8>
The alkaline and acid-cleaning activated carbon obtained in Example 7 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min, 1100-1200 ° C.; 2 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 1>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon having a surface area of 2117 m ² / g and a pore volume by the HK method: 0.92 cm ³ / g was obtained. The obtained activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and nitrogen gas. A carbonaceous material for capacitor electrodes is deoxidized at 700 ° C. under a + water vapor (water vapor partial pressure 3%) atmosphere to remove residual acid, and then finely pulverized to an average particle size of 6 μm. Got The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 2>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon is secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%), and has a BET specific surface area of 1912 m ² / g and a pore volume by the HK method: 0.83 cm ³ / g. Next activated activated carbon was obtained. The obtained secondary activated activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried. After that, deoxidation treatment was carried out for 60 minutes at 700 ° C. under a stream of nitrogen + water vapor (water vapor partial pressure 3%) to remove the residual acid, and then finely pulverized to a particle size of 6 μm for the capacitor electrode. A carbonaceous material was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 3>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon is secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%), and has a BET specific surface area of 1912 m ² / g and a pore volume by the HK method: 0.83 cm ³ / g. Next activated activated carbon was obtained. The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. This was finely pulverized so as to have a particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 4>
The alkaline and acid-cleaning activated carbon obtained in Comparative Example 3 was subjected to 1000 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1000 ° C.; After heat treatment at 2.5 ° C./min and 1000 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 5>
The same char as in Comparative Example 1 was activated at 900 ° C. using propane combustion gas + steam (partial pressure of steam: 25%), had a BET specific surface area of 1886 m ² / g, and had a pore volume by the HK method: 0.78 cm ³ / g of activated carbon was obtained. The obtained activated charcoal is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen gas. Under a + water vapor (water vapor partial pressure 3%) atmosphere, a deoxidizing treatment was carried out at 700 ° C. to remove residual acid to obtain an acid-cleaning activated charcoal. Then, it was finely pulverized so that the average particle size was 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 6>
The same char as in Comparative Example 1 was first activated at 850 ° C. using propane combustion gas + steam (partial pressure of steam: 25%) to obtain a primary activated carbon having ^{a BET specific surface area of 1185 m 2 / g.} .. Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon is secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%), and has a BET specific surface area of 2117 m ² / g and a pore volume of 0.92 cm ³ / g by the HK method. Next activated activated carbon was obtained. The obtained activated carbon is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen. Under the atmosphere of gas + water vapor (water vapor partial pressure 3%), deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain pickled activated carbon. The obtained acid-cleaning activated carbon was placed in a magnetic boat and placed at 1000 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1000 ° C.; 2) under a nitrogen stream. After heat treatment at 5.5 ° C./min and 1000 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 7>
The acid-cleaning activated carbon obtained in Comparative Example 6 was placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 900 ° C.) under a nitrogen stream. After heat treatment at 1100 ° C.; 2.5 ° C./min, held at 1100 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 8>
The acid-cleaning activated carbon obtained in Comparative Example 6 was placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 900 ° C.) under a nitrogen stream. After heat treatment at 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

<Preparation of test electrodes>
The carbonaceous material (electrode active material for electric double layer capacitors), conductive auxiliary material, and binder, which are the electrode components, are dried under reduced pressure for 16 hours or more in advance at 120 ° C. and reduced pressure (0.1 kPa or less) before use. did.

The carbonaceous material, conductive auxiliary material and binder were weighed at 0.81 g, 0.09 g, and 0.1 g, respectively, and kneaded. As the conductive auxiliary material, conductive carbon black "Denka Black Granules" manufactured by Denka Co., Ltd. is used, and as the binder, polytetrafluoroethylene "6J" manufactured by Mitsui DuPont Fluorochemical Co., Ltd. is used. did. After kneading, in order to further homogenize, the pieces were cut into flakes of 1 mm square or less, and ^{a pressure of 400 kg / cm 2} was applied with a coin molding machine to obtain a coin-shaped secondary molded product. The obtained secondary molded product is formed into a sheet having a thickness of 160 μm ± 5% (8 μm) by a roll press, and then cut into a predetermined size (30 mm × 30 mm) to form an electrode composition as shown in FIG. 1 was produced. Then, the obtained electrode composition 1 was dried at 120 ° C. under a reduced pressure atmosphere for 16 hours or more, and then the mass, sheet thickness and dimensions were measured and used for the following measurements.

<Preparation of measurement electrode cell>
As shown in FIG. 2, the etching aluminum foil 3 manufactured by Hosen Co., Ltd. is coated with the conductive adhesive 2 "HITASOL GA-703" manufactured by Hitachi Kasei Kogyo Co., Ltd. so that the thickness at the time of coating is 100 μm. did. Next, as shown in FIG. 3, the etched aluminum foil 3 coated with the conductive adhesive 2 and the previously cut sheet-shaped electrode composition 1 were adhered to each other. Further, a tab 4 with an aluminum sealant 5 manufactured by Hosen Co., Ltd. was welded to the etched aluminum foil 3 using an ultrasonic welding machine. After welding, it was vacuum dried at 120 ° C. to obtain a polar electrode 6 provided with an aluminum current collector.

As shown in FIG. 4, an aluminum laminated resin sheet manufactured by Hosen Co., Ltd. is cut into a rectangle (length 200 mm × width 60 mm), folded in half, and one side ((1) in FIG. 4) is thermocompression bonded. A bag-shaped exterior sheet 7 having the remaining two sides open was prepared. A laminated body in which two of the above polar electrodes 6 were laminated was produced via a cellulose separator "TF-40" (not shown) manufactured by Nippon Kodoshi Kogyo Co., Ltd. This laminated body was inserted into the exterior sheet 7, and one side ((2) in FIG. 5) in contact with the tab 4 was thermocompression bonded to fix the polar electrode 6. Then, after vacuum drying at 120 ° C. under a reduced pressure atmosphere for 16 hours or more, the electrolytic solution was injected in a dry box with an argon atmosphere (dew point −90 ° C. or lower). As the electrolytic solution, an acetonitrile solution of 1.0 mol / L tetraethylammonium tetrafluoroborate manufactured by Kishida Scientific Co., Ltd. was used. After impregnating the laminate with the electrolytic solution in the exterior sheet 7, the remaining one side ((3) in FIG. 5) of the exterior sheet 7 was thermocompression bonded to prepare the electric double layer capacitor 8 shown in FIG. ..

<Capacitance measurement>
The obtained electric double layer capacitor 8 is charged with a constant current of 50 mA per electrode surface surface at −30 ° C. up to a maximum voltage of 3.0 V using “CAPACITOR TESTER PFX2411” manufactured by Kikusui Electronics Co., Ltd. It was supplementarily charged at 3.0 V for 30 minutes under a constant voltage, and after the supplementary charge was completed, it was discharged at 25 mA. The obtained discharge curve data was calculated by the energy conversion method and used as the capacitance (F). Specifically, after charging, the battery was discharged until the voltage became zero, and the capacitance (F) was calculated from the discharged energy discharged at this time. Then, the capacitance (F / cc) divided by the electrode volume was obtained.

<Durability test>
In the durability test, the measurement electrode cell described above is held in a constant temperature bath at 60 ° C. for an arbitrary time while applying a voltage of 3.0 V, and then the capacitance is measured at −30 ° C. in the same manner as above. Was done. The arbitrary holding time was 0, 25, 200, 400, 600 hours. In addition, the capacity retention rate was calculated according to the following formula. The holding time of 0 hours was defined as before the durability test, and the holding time of 600 hours was defined as after the durability test. The results are shown in Table 2.

The slope obtained from the relationship between the capacity retention rate at each time obtained by the capacitance measurement of the durability time of 200 hours, 400 hours, and 600 hours and the durability time was defined as the capacity retention rate change rate. The results are shown in Table 2 and FIG.

<Measurement of gas generation>
After the capacitance measurement described above, the dry weight of the measurement electrode cell and the mass in water are measured, the cell volume is obtained from the generated buoyancy and water density, and the gas volume calculated from the change in cell volume before and after the durability test. The amount was calculated by correcting the temperature difference at the time of measurement. That is, the amount of gas generated was calculated according to the following formula. In the formula, the cell mass A represents the cell mass (g) in air, and the cell mass W represents the cell mass (g) in water.
Gas generation amount (cc) =
{(Cell mass A after endurance test-Cell mass W after endurance test)
-(Cell mass A before endurance test-Cell mass W before endurance test)} /
(273 + measured temperature after endurance test (° C)) / (273 + measured temperature before endurance test (° C))
The value obtained by further dividing the above gas generation amount by the mass of the carbonaceous material constituting the electrode composition was defined as the gas generation amount (cc / g) per carbonic material mass. The results are shown in Table 3.

Further, as with the capacity retention rate, the gas generation amount change rate was obtained from the gas generation amount at each endurance time of 200 hours, 400 hours, and 600 hours. The results are shown in Table 3 and FIG.

In Examples 1 to 4, 7 and 8, by combining alkaline cleaning and high-temperature heat treatment, the specific surface area, the pore volume by the HK method, the powder conductivity, the surface functional group amount, and the hydrogen content are the first of the present invention. It was confirmed that the electrode material can be an electrode material that falls within the range specified in the embodiment, has a high capacity retention rate at a durability time of 600 hours, and has a low gas generation amount, capacity retention rate change rate, and gas generation amount change rate. ..

In Examples 5 and 6 in which alkaline cleaning and high-temperature heat treatment were performed on the activated carbon subjected to two-stage activation, even if the alkali concentration, the temperature during alkaline cleaning, and the high-temperature heat treatment temperature were lower than those in Examples 1 to 4, the carbonaceous properties were obtained. An electrode material having a material property value within the range of the first aspect of the present invention, a high capacity retention rate at a durability of 600 hours, and a low gas generation amount, capacity retention rate change rate, and gas generation amount change rate. Was confirmed.

When alkaline cleaning and high-temperature heat treatment are not performed (Comparative Examples 1 and 2), all the physical property values according to the first aspect of the present invention are satisfied even if the same activated activated carbon used in Example 1 or 5 is used. It was confirmed that the carbonaceous material to be produced could not be obtained, and that the obtained carbonaceous material had a low capacity retention rate at a durability of 600 hours, and a high gas generation amount, capacity retention rate change rate, and gas generation amount change rate. Was done.

In Comparative Example 3 in which only alkaline cleaning was performed using the same activated activated carbon as in Comparative Example 2, a carbonaceous material satisfying all the physical property values according to the first aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. Although the amount of gas generated was low, it was confirmed that the capacity retention rate at the endurance time of 600 hours was low, and the capacity retention rate change rate and the gas generation amount change rate were high.

In Comparative Example 4 in which the activated carbon obtained in Comparative Example 3 was heat-treated at 1000 ° C. under a nitrogen stream, a carbonaceous material satisfying all the physical property values according to the first aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. In the material, it was confirmed that the amount of gas generated at the endurance time of 600 hours was low and the rate of change in the amount of gas generated was low, but the capacity retention rate was low and the rate of change in the capacity retention rate was high.

In Comparative Example 5 using activated carbon having a low degree of activation and not subjected to alkaline washing and high-temperature heat treatment, a carbonaceous material satisfying all the physical property values according to the first aspect of the present invention could not be obtained and was obtained. It was confirmed that in the carbonaceous material, the capacity retention rate at the endurance time of 600 hours was low, and the gas generation amount, the capacity retention rate change rate, and the gas generation amount change rate were high.

In Comparative Examples 6 to 8 in which the activated carbon of Comparative Example 2 was heat-treated at 1000 ° C., 1100 ° C. or 1200 ° C. without performing alkaline cleaning, the carbonaceous material satisfying all the physical property values according to the first aspect of the present invention. It was confirmed that it was not possible to obtain a product that satisfied all of the capacity retention rate, the capacity retention rate change rate, the gas generation amount, and the gas generation amount change rate.

2. Experimental Example for Carbonated Material of Second Aspect <Example 9>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was washed with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) at 25 ° C. for 30 minutes, and then with ion-exchanged water to remove residual base. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and nitrogen gas + steam (water vapor partial pressure). 3%) Under an atmosphere, deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, 1100-1220 ° C.; 2 ° C./min, held at 1220 ° C. for 30 minutes), finely pulverize to an average particle size of 6 μm and carbonaceous material for capacitor electrodes. Obtained the material. For the obtained carbonaceous material, the BET specific surface area, carbon dioxide adsorption pore volume (C), powder conductivity, surface functional group amount, hydrogen content, pore volume (BJH) of 4 nm or more, and alkali metal amount were measured.・ Calculated. The results are shown in Table 4.

<Example 10>
The alkaline and acid-cleaning activated carbon obtained in Example 9 was placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. Heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 30 minutes), and then finely pulverized to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 11>
The alkaline and acid-cleaning activated carbon obtained in Example 9 were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min, 1100 to 1220 ° C.; 2 ° C./min, held at 1220 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 12>
The alkaline and acid-cleaning activated carbon obtained in Example 9 was placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. After heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 60 minutes), finely pulverize to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 13>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, held at 1100 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 14>
The alkaline and acid-cleaning activated carbon obtained in Example 13 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 15>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was alkaline-washed at 100 ° C. for 30 minutes with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluent: ion-exchanged water), and then ion-exchanged water was used to remove residual bases. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat, and under a nitrogen stream, 1150 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to After heat treatment at 1100 ° C; 2.5 ° C / min, 1100 to 1150 ° C; 2 ° C / min, held at 1150 ° C for 60 minutes), finely pulverized to an average particle size of 6 μm and carbon for the capacitor electrode. Obtained quality material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Example 16>
The alkaline and acid-cleaning activated carbon obtained in Example 15 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min; 1100 to 1200 ° C.; 2 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 9>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and nitrogen gas. A carbonaceous material for capacitor electrodes is deoxidized at 700 ° C. under a + water vapor (water vapor partial pressure 3%) atmosphere to remove residual acid, and then finely pulverized to an average particle size of 6 μm. Got The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 10>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried. After that, deoxidation treatment was carried out for 60 minutes at 700 ° C. under a stream of nitrogen + water vapor (water vapor partial pressure 3%) to remove the residual acid, and then finely pulverized to a particle size of 6 μm for the capacitor electrode. A carbonaceous material was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 11>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. This was finely pulverized so as to have a particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 12>
The alkaline and acid-cleaning activated carbon obtained in Comparative Example 11 was subjected to 1000 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1000 ° C.; After heat treatment at 2.5 ° C./min and 1000 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 13>
The same char as in Comparative Example 9 was activated at 900 ° C. using propane combustion gas + steam (partial pressure of steam: 25%) to obtain activated carbon having ^{a specific surface area of 1886 m 2 / g.} The obtained activated charcoal is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen gas. Under a + water vapor (water vapor partial pressure 3%) atmosphere, a deoxidizing treatment was carried out at 700 ° C. to remove residual acid to obtain an acid-cleaning activated charcoal. Then, it was finely pulverized so that the average particle size was 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 14>
The same char as in Comparative Example 9 was first activated at 850 ° C. using propane combustion gas + steam (partial pressure of steam: 25%) to obtain a primary activated carbon having ^{a BET specific surface area of 1185 m 2 / g.} .. Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 2117 m 2 / g.} The obtained activated carbon is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen. Under the atmosphere of gas + water vapor (water vapor partial pressure 3%), deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain pickled activated carbon. The obtained acid-cleaning activated carbon was placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100 ° C.; 2) under a nitrogen stream. After heat treatment at 5.5 ° C./min and 1100 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

<Comparative Example 15>
The acid-cleaning activated carbon obtained in Comparative Example 14 was placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 900 ° C.) under a nitrogen stream. After heat treatment at 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 9. The results are shown in Table 4.

Using the carbonaceous materials of Examples 9 to 16 and Comparative Examples 9 to 15, an electric double layer capacitor for testing was prepared in the same manner as in Example 1, and capacitance measurement and durability test were performed. , The amount of gas generated was measured, and the rate of change in the amount of gas generated was calculated. The results are shown in Tables 5 and 6.

In Examples 9 to 12, 15 and 16, the specific surface area, the pore volume by the carbon dioxide adsorption / desorption method, the surface functional group amount and the hydrogen content are determined by combining alkaline cleaning and high temperature heat treatment in the second aspect of the present invention. It was confirmed that the electrode material can be an electrode material that falls within the specified range, has a high capacity retention rate at a durability time of 600 hours, and has a low gas generation amount, capacity retention rate change rate, and gas generation amount change rate.

In Examples 13 and 14 in which alkaline cleaning and high-temperature heat treatment were performed on the activated carbon subjected to two-stage activation, even if the alkali concentration, the temperature during alkaline cleaning, and the high-temperature heat treatment temperature were lower than those in Examples 9 to 12, the carbonaceous properties were obtained. Each physical property value of the material is within the range of the second aspect of the present invention, and the electrode material can be an electrode material having a high capacity retention rate at a durability time of 600 hours and a low gas generation amount, capacity retention rate change rate, and gas generation amount change rate. It was confirmed that.

When alkaline cleaning and high-temperature heat treatment are not performed (Comparative Examples 9 and 10), even if the same activated carbon used in Example 9 or 13 is used, all the physical property values according to the second aspect of the present invention are satisfied. It was confirmed that the carbonaceous material to be produced could not be obtained, and that the obtained carbonaceous material had a low capacity retention rate at a durability of 600 hours, and a high gas generation amount, capacity retention rate change rate, and gas generation amount change rate. Was done.

In Comparative Example 11 in which only alkaline cleaning was performed using the same activated activated carbon as in Comparative Example 10, a carbonaceous material satisfying all the physical property values according to the second aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. Although the amount of gas generated was low, it was confirmed that the capacity retention rate at the endurance time of 600 hours was low, and the capacity retention rate change rate and the gas generation amount change rate were high.

In Comparative Example 12 in which the activated carbon obtained in Comparative Example 11 was heat-treated at 1000 ° C. under a nitrogen stream, a carbonaceous material satisfying all the physical property values according to the second aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. In the material, it was confirmed that the amount of gas generated at the endurance time of 600 hours was low and the rate of change in the amount of gas generated was low, but the capacity retention rate was low and the rate of change in the capacity retention rate was high.

In Comparative Example 13 using activated carbon having a low degree of activation and not subjected to alkaline washing and high-temperature heat treatment, a carbonaceous material satisfying all the physical property values according to the second aspect of the present invention could not be obtained and was obtained. It was confirmed that in the carbonaceous material, the capacity retention rate at the endurance time of 600 hours was low, and the gas generation amount, the capacity retention rate change rate, and the gas generation amount change rate were high.

In Comparative Examples 14 and 15 which were heat-treated at 1100 ° C. or 1200 ° C. without performing alkaline cleaning using the activated carbon of Comparative Example 10, a carbonaceous material satisfying all the physical property values according to the second aspect of the present invention was obtained. It was confirmed that it was not possible to obtain a product that satisfied all of the capacity retention rate, the capacity retention rate change rate, the gas generation amount, and the gas generation amount change rate.

3. 3. Experimental Example for Carbonated Material of Third Aspect <Example 17>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was washed with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) at 25 ° C. for 30 minutes, and then with ion-exchanged water to remove residual base. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and nitrogen gas + steam (water vapor partial pressure). 3%) Under an atmosphere, deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, 1100-1220 ° C.; 2 ° C./min, held at 1220 ° C. for 30 minutes), finely pulverize to an average particle size of 6 μm and carbonaceous material for capacitor electrodes. Obtained the material. Regarding the obtained carbonaceous material, the ratio of (B) to the pore volume (A), (B) and (A) by the steam adsorption method, powder conductivity, surface functional group amount, hydrogen content, pores of 4 nm or more. The volume (BJH) and the amount of alkali metal were measured and calculated. The results are shown in Table 7.

<Example 18>
The alkaline and acid-cleaning activated carbon obtained in Example 17 were placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. Heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 30 minutes), and then finely pulverized to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 19>
The alkaline and acid-cleaning activated carbon obtained in Example 17 were placed in a magnetic boat and placed at 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min, 1100 to 1220 ° C.; 2 ° C./min, held at 1220 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 20>
The alkaline and acid-cleaning activated carbon obtained in Example 17 were placed in a magnetic boat, covered, and heated to 1220 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./) under a nitrogen stream. After heat treatment at 900 ° C to 1100 ° C; 2.5 ° C / min, 1100 to 1220 ° C; 2 ° C / min, held at 1220 ° C for 60 minutes), finely pulverize to an average particle size of 6 μm. A carbonaceous material for the capacitor electrode was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 21>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100) under a nitrogen stream. After heat treatment at ° C.; 2.5 ° C./min, held at 1100 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 22>
The alkaline and acid-cleaning activated carbon obtained in Example 21 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 23>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was alkaline-washed at 100 ° C. for 30 minutes with an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluent: ion-exchanged water), and then ion-exchanged water was used to remove residual bases. Washed thoroughly with water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + water vapor (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. Further, the obtained alkali and acid-cleaning activated carbon were placed in a magnetic boat, and under a nitrogen stream, 1150 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to After heat treatment at 1100 ° C; 2.5 ° C / min, 1100 to 1150 ° C; 2 ° C / min, held at 1150 ° C for 60 minutes), finely pulverized to an average particle size of 6 μm and carbon for the capacitor electrode. Obtained quality material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Example 24>
The alkaline and acid-cleaning activated carbon obtained in Example 23 were placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900) under a nitrogen stream. After heat treatment at ° C. to 1100 ° C.; 2.5 ° C./min; 1100 to 1200 ° C.; 2 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverize to an average particle size of 6 μm for capacitor electrodes. Obtained a carbonaceous material. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 16>
Char (specific surface area: 370 m ² / g) made from coconut husks from the Philippines is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. Activated carbon with a surface area of 2117 m ² / g was obtained. The obtained activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and nitrogen gas. A carbonaceous material for capacitor electrodes is deoxidized at 700 ° C. under a + water vapor (water vapor partial pressure 3%) atmosphere to remove residual acid, and then finely pulverized to an average particle size of 6 μm. Got The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative example 17>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried. After that, deoxidation treatment was carried out for 60 minutes at 700 ° C. under a stream of nitrogen + water vapor (water vapor partial pressure 3%) to remove the residual acid, and then finely pulverized to a particle size of 6 μm for the capacitor electrode. A carbonaceous material was obtained. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 18>
Char (specific surface area: 370 m ² / g) made from Philippine coconut husks is first activated at 850 ° C using propane combustion gas + steam (partial pressure of steam: 25%) to achieve a BET ratio. A primary activated carbon having a surface area of 1185 m ^{2 / g was obtained.} Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 1912 m 2 / g.} The obtained secondary activated activated charcoal was alkaline-washed at 100 ° C. for 30 minutes using an aqueous sodium hydroxide solution (concentration: 1 mol / l, diluted solution: ion-exchanged water) to remove residual bases. It was thoroughly washed with ion-exchanged water. Next, pickle with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly wash with ion-exchanged water, dry, and then nitrogen + steam (water vapor partial pressure). 3%) Deoxidation treatment was carried out at 700 ° C. under an air stream for 60 minutes to remove residual acid to obtain alkali and pickled activated charcoal. This was finely pulverized so as to have a particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 19>
The alkaline and acid-cleaning activated carbon obtained in Comparative Example 18 was subjected to 1000 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1000 ° C.; After heat treatment at 2.5 ° C./min and 1000 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 20>
The same char as in Comparative Example 16 was activated at 900 ° C. using propane combustion gas + steam (partial pressure of steam: 25%) to obtain activated carbon having ^{a BET specific surface area of 1886 m 2 / g.} The obtained activated charcoal is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen gas. Under a + water vapor (water vapor partial pressure 3%) atmosphere, a deoxidizing treatment was carried out at 700 ° C. to remove residual acid to obtain an acid-cleaning activated charcoal. Then, it was finely pulverized so that the average particle size was 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 21>
The same char as in Comparative Example 16 was first activated at 850 ° C. using propane combustion gas + steam (partial pressure of steam: 25%) to obtain a primary activated carbon having ^{a BET specific surface area of 1185 m 2 / g.} .. Then, it was washed with hydrochloric acid (concentration: 0.5N, diluted solution: ion-exchanged water) at a temperature of 85 ° C. for 30 minutes, and then sufficiently washed with ion-exchanged water and dried to remove residual acid. , A primary cleaning activated charcoal having a potassium element content of 150 ppm was obtained. This primary cleaning activated carbon was secondarily activated at 950 ° C. using propane combustion gas (partial pressure of water vapor 15%) to obtain a secondary activated carbon having ^{a BET specific surface area of 2117 m 2 / g.} The obtained activated carbon is pickled with hydrochloric acid (concentration: 1 mol / l, diluent: ion-exchanged water) at a temperature of 100 ° C. for 30 minutes, thoroughly washed with ion-exchanged water, dried, and then nitrogen. Under the atmosphere of gas + water vapor (water vapor partial pressure 3%), deoxidation treatment was carried out at 700 ° C. to remove residual acid to obtain pickled activated carbon. The obtained acid-cleaning activated carbon was placed in a magnetic boat and placed at 1100 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 1100 ° C.; 2) under a nitrogen stream. After heat treatment at 5.5 ° C./min and 1100 ° C. for 60 minutes), the mixture was finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

<Comparative Example 22>
The acid-cleaning activated carbon obtained in Comparative Example 21 was placed in a magnetic boat and placed at 1200 ° C. (heating rate: room temperature to 600 ° C.; 10 ° C./min, 600 to 900 ° C.; 5 ° C./min, 900 ° C. to 900 ° C.) under a nitrogen stream. After heat treatment at 1200 ° C.; 2.5 ° C./min, held at 1200 ° C. for 60 minutes), finely pulverized to an average particle size of 6 μm to obtain a carbonaceous material for a capacitor electrode. The physical characteristics of the obtained carbonaceous material were measured and calculated in the same manner as in Example 17. The results are shown in Table 7.

Using the carbonaceous materials of Examples 17 to 24 and Comparative Examples 16 to 22, electric double layer capacitors for testing were prepared in the same manner as in Example 1, and capacitance measurement, durability test, and durability test were performed. , The amount of gas generated was measured, and the rate of change in the amount of gas generated was calculated. The results are shown in Tables 8 and 9.

In Examples 17 to 20, 23 and 24, the specific surface area, the pore volume (A) by the steam adsorption method, the pore volume (B) and the pore volume (A) were (a) by combining alkaline washing and high temperature heat treatment. The ratio of B) falls within the range specified in the third aspect of the present invention, the capacity retention rate at a durability time of 600 hours is high, and the gas generation amount, the capacity retention rate change rate, and the gas generation amount change rate are high. It was confirmed that it can be a low electrode material.

In Examples 21 and 22 in which alkaline cleaning and high-temperature heat treatment were performed on the activated carbon subjected to two-stage activation, even if the alkali concentration, the temperature during alkaline cleaning, and the high-temperature heat treatment temperature were lower than those in Examples 17 to 20, the carbonaceous material was used. An electrode material having a material property value within the range of the third aspect of the present invention, a high capacity retention rate at a durability of 600 hours, and a low gas generation amount, capacity retention rate change rate, and gas generation amount change rate. Was confirmed.

When alkaline cleaning and high-temperature heat treatment are not performed (Comparative Examples 16 and 17), all the physical property values according to the third aspect of the present invention are satisfied even if the same activated activated carbon used in Example 17 or 21 is used. It was confirmed that the carbonaceous material to be produced could not be obtained, and that the obtained carbonaceous material had a low capacity retention rate at a durability of 600 hours, and a high gas generation amount, capacity retention rate change rate, and gas generation amount change rate. Was done.

In Comparative Example 18 in which only alkaline cleaning was performed using the same activated activated carbon as in Comparative Example 17, a carbonaceous material satisfying all the physical property values according to the third aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. Although the amount of gas generated was low, it was confirmed that the capacity retention rate at the endurance time of 600 hours was low, and the capacity retention rate change rate and the gas generation amount change rate were high.

In Comparative Example 19 in which the activated carbon obtained in Comparative Example 18 was heat-treated at 1000 ° C. under a nitrogen stream, a carbonaceous material satisfying all the physical property values according to the third aspect of the present invention could not be obtained, and the obtained carbonaceous material could not be obtained. In the material, it was confirmed that the amount of gas generated at the endurance time of 600 hours was low and the rate of change in the amount of gas generated was low, but the capacity retention rate was low and the rate of change in the capacity retention rate was high.

In Comparative Example 20 using activated carbon having a low degree of activation and not subjected to alkaline washing and high-temperature heat treatment, a carbonaceous material satisfying all the physical property values according to the third aspect of the present invention could not be obtained and can be obtained. It was confirmed that in the carbonaceous material, the capacity retention rate at the endurance time of 600 hours was low, and the gas generation amount, the capacity retention rate change rate, and the gas generation amount change rate were high.

In Comparative Examples 21 and 22 which were heat-treated at 1100 ° C. or 1200 ° C. without performing alkaline washing using the activated carbon of Comparative Example 17, a carbonaceous material satisfying all the physical property values according to the third aspect of the present invention was obtained. It was confirmed that it was not possible to obtain a product that satisfied all of the capacity retention rate, the capacity retention rate change rate, the gas generation amount, and the gas generation amount change rate.

1 Electrode composition 2 Conductive adhesive 3 Etched aluminum foil 4 Tabs 5 Sealant 6-minute polar electrode 7 Bag-shaped exterior sheet 8 Electric double layer capacitor (1) Thermocompression bonded side (2) One side where tabs touch (3) Bag The remaining side of the exterior sheet

Claims

The BET specific surface area by the nitrogen adsorption method is 1750 m 2 / g or more and 2100 m 2 / g or less, and the following (1), (2) and (3):
(1) The pore volume calculated by the HK method based on the adsorption isotherm by the nitrogen adsorption method is 0.76 cm 3 / g or more and 0.91 cm 3 / g or less, and the powder conductivity is 13 S / cm or more and 22 S / It is cm or less, the surface functional group content is 0.22 meq / g or more and 0.29 meq / g or less, and the hydrogen content is 0.41 mass% or less;
(2) The pore volume calculated by the NLDFT method based on the adsorption isotherm by the carbon dioxide adsorption / desorption method is 0.37 cm 3 / g or more and 0.41 cm 3 / g or less, and the surface functional group amount is 0.22 meq. / G or more and 0.29 meq / g or less, and the hydrogen content is 0.41% by mass or less;
(3) a pore volume calculated by the HK method based on adsorption isotherm by steam adsorption method (A) is not more than 0.48 cm 3 / g or more 0.64 cm 3 / g, the adsorption isotherm by steam adsorption method Based on this, the pore volume (B) with a pore diameter of 1.2 nm or less calculated by the HK method is 0.14 cm 3 / g or more and 0.30 cm 3 / g or less, and the pore volume (B) with respect to the pore volume (A). ) Is a carbonaceous material that satisfies any of the conditions of 25% or more and 59% or less.
The carbonaceous material according to claim 1, which satisfies the condition (2) or (3) and has a powder conductivity of 13 S / cm or more and 22 S / cm or less.
The carbonaceous material according to claim 1 or 2, which satisfies the condition (3) and has a surface functional group amount of 0.22 meq / g or more and 0.29 meq / g or less.
The carbonaceous material according to any one of claims 1 to 3, which satisfies the condition (3) and has a hydrogen content of 0.41% by mass or less.
Pore size 4nm or more of the pore volume as measured by the BJH method is not more than 0.07 cm 3 / g or more 0.18 cm 3 / g, the carbonaceous material according to any one of claims 1 to 4.
The carbonaceous material according to any one of claims 1 to 5, wherein the alkali metal content is 40 ppm or less.
The carbonaceous material according to any one of claims 1 to 6, wherein the carbonaceous material is derived from a carbon precursor derived from coconut shell.
An electrode material for an electric double layer capacitor containing the carbonaceous material according to any one of claims 1 to 7.
After carbonizing the carbon precursor, the activated carbon obtained by activating it is alkaline-washed in an alkaline solution, and
The method for producing a carbonaceous material according to any one of claims 1 to 7, further comprising a step of acid-cleaning the activated carbon after alkaline cleaning and then heat-treating at 1100 ° C. or higher and 1300 ° C. or lower.