JP4724390B2 - Negative electrode carbon material for lithium ion secondary battery and method for producing the same - Google Patents

Description

  The present invention relates to a negative electrode carbon material for a lithium ion secondary battery and a method for producing the same. More specifically, the present invention relates to a negative electrode carbon material for a lithium ion secondary battery that uses a rice starch portion as a raw material and is more excellent in raw material cost reduction effect, and a method for producing the same.

  In the present specification, the rice starch portion refers to a portion of endosperm containing a large amount of starch particles, which is a starch portion derived from rice and is referred to as middle white rice cake or upper white rice cake.

JP 2001-266850 A

  Patent Document 1 discloses a technique of using rice bran as a raw material for a negative electrode carbon material for a lithium ion secondary battery.

  Rice bran is rice seed, and brown rice is obtained by removing rice husk from this rice bran. The brown rice tissue consists of pericarp, seed coat, embryo and endosperm, and the endosperm consists of an outer paste layer and an inner starch storage tissue. Also, the pericarp and seed coat are also called red coral. From the outside, the mass ratio of each tissue of brown rice is 5-7% for red cocoons, 2-3% for embryos, and 90-93% for endosperm.

  The surface layer portion of brown rice having a rice polishing ratio L of 100-91% is the red rice layer, the outer part of the endosperm having a rice polishing ratio L of 91-81% is the sapio layer, and the inner part of the endosperm having a rice polishing ratio L of 81-66% Is sometimes called a birch layer.

  Generally, in the process of brown rice polishing, the degree of rice polishing can be expressed by the rice polishing ratio L. The polished rice ratio L refers to the ratio of the white rice mass to the brown rice mass (Formula 1).

(Formula 1) Rice polishing ratio L (%) = (white rice mass ÷ brown rice mass) × 100

  The milling ratio is the ratio of the grinding mass to the brown rice mass (Formula 2).

(Formula 2) Polishing rate (%) = (grinding mass ÷ brown rice mass) × 100

  The brown rice mass is the sum of the white rice mass and the grinding mass (Formula 3).

(Formula 3) White rice mass + grinding mass = brown rice mass

  Therefore, the following relationship is always established for the degree of brown rice polishing (Formula 4).

(Formula 4) Milling ratio L (%) + Milling ratio (%) = 100 (%)

  The rice polishing ratio L of the rice that is eaten as rice is generally about 92 to 90%. For sake brewing, white rice having a rice polishing ratio L of 70 to 50% is usually used. If the rice polishing ratio L is lowered, the quality of the sake is generally improved. The portion where the rice polishing ratio L is 90 to 70% (milling rate 10 to 30%) is called middle white rice cake, and the portion 70 to 50% (milling rate 30 to 50%) is called upper white rice cake.

  In Patent Document 1, as can be seen from the removal of the oil from the rice bran, the part of the pericarp and seed coat of the rice bran, that is, the part commonly referred to as red rice bran, is used as a raw material and is baked with a thermosetting resin. Carbon material. Here, the rice bran residue from which the oil has been removed is mixed with a phenol resin, which is a thermosetting resin, and the mixture is baked.

  However, in the case of the embodiment disclosed in Patent Document 1, a process for removing oil from rice bran is necessary, otherwise a large amount of volatiles other than moisture floats and adheres to the furnace during firing, causing malodor It is not practical. The cost burden of electric furnace maintenance after firing is also a problem. Furthermore, although phenol resin is used, the price is higher than that of rice bran, and the merit of cost reduction by using rice bran which is one of plant residues cannot be enjoyed.

  As for the use of rice bran, middle white rice cake and upper white rice cake are also used for feed and confectionery raw materials, but further development of effective use is desired.

  Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and the problem to be solved by the present invention is that lithium having a performance equal to or better than that of a conventional product using rice white birch or white birch effectively. A negative electrode carbon material for lithium ion secondary batteries, which is a negative electrode carbon material for ion secondary batteries, which solves the problem of bad odor during firing and the problem of electric furnace maintenance and can be manufactured at a lower cost by improving the manufacturing cost. To provide materials.

  As a result of intensive studies, the present inventors have acquired a rice starch portion from brown rice and firing it to solve the problem of bad odor during firing and the problem of electric furnace maintenance, and are equivalent to conventional products. The inventors have found that a negative electrode carbon material for lithium ion secondary batteries having the above performance can be produced at low cost, and completed the present invention.

  That is, the negative electrode carbon material for a lithium ion secondary battery of the present invention is characterized in that it is obtained by baking a rice starch portion from which pericarp and seed coat are removed from brown rice.

  In the starch storage tissue of endosperm, which is a starch part derived from rice, normally, about 50 to 80 starch particles are densely packed in one amyloplast. Rice starch particles are about 6 to 10 μm in diameter for amyloplasts with a relatively large major axis of about 40 μm, and about 1 μm in diameter for small amyloplasts. That is, the size of rice starch particles is generally 10 μm or less, which is considerably smaller than starches derived from other plants. Therefore, the specific surface area as the negative electrode carbon material for a lithium ion secondary battery can be increased by reducing the carbon particle diameter (primary particle diameter) after firing.

  It is preferable that the rice starch part is middle white rice cake or upper white rice cake when brown rice is polished, and the powder X-ray (CuKα) diffraction pattern of the negative electrode carbon material for lithium ion secondary battery is compared with 2θ = 40-50 °. It is preferable to have a broad peak and a sharper peak at 2θ = 42 to 44 °. In the case of having this sharp peak at 2θ = 42 to 44 °, when a lithium ion secondary battery is configured using this negative electrode carbon material, the first charge / discharge efficiency is improved and better performance is exhibited. It was. In order to easily distinguish this sharp peak from noise, the ratio A / B of the sharp peak intensity A to the broad peak intensity B is preferably 1.2 or more, and 1.4 or more. It is more preferable that The half-width of the broad peak is preferably 3.5 to 5.5 °, and the half-width of the sharp peak is preferably 0.30 to 0.45 °.

  The negative electrode carbon material for a lithium ion secondary battery of the present invention uses a starch portion made of starch particles smaller than other plant-derived starch as a raw material, and after firing, a negative electrode for a lithium ion secondary battery The fine particles constituting the carbon material can be made smaller, the distance between the particles can be shortened, and the fine structure can be made denser. It is considered that the fine structure formed a (110) plane and formed a sharp peak at 42 to 44 °. If the fine particles after firing can be made small and the distance between the particles can be made into a dense structure, a negative electrode for a lithium ion secondary battery can be formed with a thinner carbon material when a network structure such as hard carbon is formed. be able to. Further, when comparing negative electrodes having the same volume, a high capacity can be expected because the fine structure of the carbon material increases the network structure and the volume of voids into which lithium ions can easily enter.

  In the negative electrode carbon material for lithium ion secondary battery of the present invention, since a portion containing a large amount of starch particles is used, the structure after firing is finer than that obtained by adding phenol resin to red rice cake, and battery characteristics. Will be improved. In addition, it is advantageous in terms of production cost as compared with a carbon material produced from petroleum pitch.

  Moreover, the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention includes a first step of removing the pericarp and seed coat from brown rice to obtain a rice starch portion, and a second step of baking the rice starch portion. , Provided. Since the pericarp and seed coat are removed in the first step, there is no oil in the rice starch portion baked in the second step, and a large amount of volatile matter does not float. For example, in the rice milling process for sake production, it is possible to use the first step of obtaining medium white lees or upper white lees as a by-product simply by selecting the pericarp and seed coat and other rice starch parts from the rice bran. Thereby, raw material cost can be reduced significantly. In the second step, the rice starch portion can be fired to obtain a negative electrode carbon material for a lithium ion secondary battery having a dense network structure excellent in lithium ion retention. Firing in the second step can be performed in an inert gas such as nitrogen gas or argon gas.

  The first step preferably includes a step of further removing the paste powder layer after removing the pericarp and seed coat from the brown rice. Medium white cocoons contain some paste layers and endosperm. An upper white rice cake containing only endosperm is preferable in terms of homogenization and refinement of the structure of the negative electrode carbon material obtained after firing. However, the cost of obtaining the white birch is higher for the white birch and the white birch. Whether the white birch or the white birch is used as a raw material or a mixture of both depends on the balance with cost.

  Further, the first step is a step of obtaining a rice starch portion corresponding to the middle white rice bran or the upper white rice bran when the brown rice is polished, and the second step is a rice starch portion corresponding to the middle white rice bran or the upper white rice bran. It is preferable that the process of baking is included. At this time, the rice starch portion is in the form of powder, and the first step can be a step of removing the pericarp and seed coat from the brown rice to obtain a powdery rice starch portion. By forming the rice starch portion of this into a pellet and firing this pellet-shaped rice starch portion, it becomes easy to fire uniformly in a short time.

  In the method for producing a negative electrode carbon material for a lithium ion secondary battery according to the present invention, the first step is to remove the skin and seed coat corresponding to at least a polishing ratio of less than 7% (exceeding a polishing ratio of 93%) to a polishing ratio of 7% to 65 % Rice starch portion corresponding to within the range, it is preferable that the second step is a step of firing the rice starch portion, the first step is at least less than 9% milling rate (over 91% rice milling rate) More preferably, the pericarp and seed coat corresponding to the above are removed to obtain a rice starch portion corresponding to a whitening ratio of 9% to 65%, and the second step is a step of baking the rice starch portion.

  Furthermore, in the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention, the first step is to remove the skin, seed coat and paste powder layer corresponding to at least a milling ratio of less than 12% (more than a milling ratio of 88%). It is particularly preferable that a rice starch portion corresponding to a whitening ratio of 12% to 65% is obtained, and the first step is a step of firing the rice starch portion.

  The lower limit of the refining rate of the rice starch portion to be obtained must be at least 7% in order to remove the peel and seed coat from brown rice, and more than 9% in order to remove the peel and seed coat from brown rice more completely It is particularly preferably 12% or more for removing the paste powder layer and homogenizing and refining the structure of the resulting carbide. The upper limit of the milling rate of the rice starch portion to be obtained is preferably 65% or less because rice breaks when trying to polish the milling rate exceeding 65%, and more preferably 60% or less to obtain it at a low price. % Or less is particularly preferable.

  In the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention, the first step is preferably a step of obtaining koji produced as a by-product in the rice milling process of sake production. When milling to a polishing rate of 35%, a rice starch portion with a milling rate of 65% or less can be used as a baking raw material in the second step. When polishing to a polishing rate of 40%, a milling rate of 60% or less The rice starch portion can be used as the baking raw material in the second step. When the rice polishing ratio is polished to 50%, the rice starch portion having a polishing ratio of 50% or less can be used as the baking raw material in the second step. In the case of polishing rice to a proportion of 65%, a rice starch portion having a polishing ratio of 35% or less can be used as a baking raw material in the second step.

  In the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention, the second step is a pre-baking step of pre-baking the rice starch portion to obtain a pre-fired product, and crushing the pre-fired product into a pulverized product It is preferable to include a pulverization step of performing the main calcination of the pulverized product at a temperature higher than the temperature of the preliminary calcination step. By carrying out the second step in this way, it is possible to obtain a negative electrode carbon material for a lithium ion secondary battery that can be fired more uniformly and has good powder characteristics. In the pulverization step, for example, the calcined product is pulverized into a pulverized product having an average particle size of 5 to 40 μm.

  In the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention, the second step can be, for example, a step of baking the rice starch portion at 500 to 2700 ° C. for 0.5 to 50 hours. In the second step, the preliminary baking step is preferably a step of baking the rice starch portion at 500 to 1000 ° C. for 0.5 to 10 hours, and the main baking step is baking the pulverized product at 700 to 1600 ° C. for 0.5 to 50 hours. It is preferable that it is a process. The firing step is more preferably a step of firing the pulverized product at 1100 to 1400 ° C, and particularly preferably a step of firing at 1200 to 1300 ° C.

  The negative electrode carbon material for a lithium ion secondary battery of the present invention is calcined at a firing temperature of 1100 to 1400 ° C. for 0.5 to 50 hours, and the powder X-ray (CuKα) diffractogram of the negative electrode carbon material for a lithium ion secondary battery of the present invention It can have a relatively broad peak at 2θ = 40 to 50 ° and a sharper peak at 2θ = 42 to 44 °.

  According to the method for producing a negative electrode carbon material for a lithium ion secondary battery of the present invention, since the pericarp and seed coat are removed from the brown rice, volatiles are less likely to float during the baking operation, and workability is excellent. Since the starch part derived from rice obtained as a by-product such as manufacturing is used, the raw material cost can be reduced, and the workability and cost can be improved compared with the case of baking the mixture of red rice bran and phenol resin, which is a conventional technique. . Since the skin part has been removed, the performance of the obtained negative electrode carbon material for lithium ion secondary batteries can be equal to or higher than that of conventional products, and the starch part derived from rice obtained as a by-product of sake production etc. Since it is used, raw material costs can be reduced, and the seed coat part of brown rice has been removed, so that volatiles are less likely to float during the baking operation, and workability is excellent, and the total of negative electrode carbon materials for lithium ion secondary batteries Manufacturing costs can be greatly reduced.

  Further, in the method for producing a negative electrode carbon material for a lithium ion secondary battery according to the present invention, a rice starch portion having relatively small starch particles is used. Therefore, a starch portion derived from another plant is baked to obtain a lithium ion secondary battery. Compared with the case of the negative electrode carbon material for use, the fine structure of the negative electrode carbon material for the lithium ion secondary battery after firing can be made smaller and denser, and the secondary battery can be configured as a thin and small negative electrode. As a result, the charge / discharge capacity per unit volume can be increased.

  In addition, the red rice bran portion of the rice bran tends to undergo component fluctuations depending on the production area of the brown rice used, climate change, harvest time, etc., whereas the quality control of the obtained negative electrode carbon material for lithium ion secondary batteries is difficult. In the method for producing a negative electrode carbon material for a lithium ion secondary battery according to the present invention, since the red rice bran portion is removed from the rice bran, the component variation derived from the raw material is small and quality control is easy.

  Embodiments of the present invention will be described below.

(Examples 1 to 13)
(Rice starch part acquisition process)
600 kg of brown rice was polished with a Chiyoda type brewing machine (HS-15 CNC) over 28 hours to a polished rice with a polishing ratio L = 50%. At this time, the red coral layer (L = 100-91%) and the sapio layer (L = 91-85%) are removed, and the powder corresponding to the medium white coral (L = 85-75%, whitening ratio 15-25%) About 60 kg of body-shaped rice starch portion was obtained (Examples 1 and 2). Similarly, the red rice bran layer and the sapio layer (L = 100-80%) are removed, and the powdery rice starch portion corresponding to the medium white rice cake (L = 80-70%, whitening rate 20-30%) is obtained. Obtained (Example 3). The red rice bran layer and the sapio layer (L = 100-90%) were removed, and a powdery rice starch portion corresponding to the medium white rice cake (L = 90-70%, whitening ratio 10-30%) was obtained (implementation) Examples 4-9). In the same manner, powdery rice starch portions corresponding to upper white rice bran (L = 65-50%, whitening ratio 35-50%) were obtained (Examples 10 and 11). Powdered rice starch portions corresponding to medium white rice cake and upper white rice cake (L = 85-50%, whitening rate 15-50%) were obtained (Examples 12 and 13). Each of these rice starch parts was sprayed with water at a mass ratio of about 5%, mixed and stirred, and formed into pellets of 3mmφ × 3mm with a granulator (desk pelleter, F20 / 330 type). Dry at -80 ° C for 5 minutes.

(Baking process)
Each pellet-shaped rice starch site | part obtained was provisionally baked in a rotary kiln in nitrogen gas at 450 to 900 ° C. for 0.4 to 9 hours. Next, the calcined product is pulverized into a pulverized product having an average particle size of 20 to 30 μm, and the pulverized product is put into a crucible and subjected to main calcination at 650 to 2700 ° C. for 0.45 to 48 hours. A negative electrode carbon material for a battery was obtained. These conditions are summarized in Table 1.

  Among these, about the negative electrode carbon material (Example 1) for lithium ion secondary batteries obtained by carrying out this baking at 1200 degreeC and 5 hours, the result of an X-ray-diffraction figure is shown in FIG. The X-ray source was CuKα (40 kV, 30 mA), the divergence slit width was 1/2 deg, the scattering slit width was 1/2 deg, the light receiving slit was 0.15 mm, and a Kβ filter was used to measure in a scanning range of 10 to 90 °. The horizontal axis of the obtained X-ray diffraction diagram is 2θ (°), and the vertical axis is the detection intensity (cps). It can be seen that there is a relatively broad peak at 2θ = 40 to 50 ° and a sharper peak at 2θ = 42 to 44 °. More specifically, the half width of a relatively broad peak at 2θ = 40 to 50 ° (peak top is 2θ = 44 °) was 4.6 °, and the peak height was 24 cps. The half width of the sharper peak at 2θ = 42 to 44 ° (peak top is 2θ = 42.9 °) was 0.36 °, and the peak height was 46 cps. The ratio of the sharp peak intensity to the broad peak intensity was 1.92.

  In addition, the negative electrode carbon materials for lithium ion secondary batteries of Examples 2, 3, 10, and 12 also have a relatively broad peak at 2θ = 40 to 50 ° and 2θ = 42 to 44 ° as in Example 1. And a sharper peak. However, the negative electrode carbon materials for lithium ion secondary batteries of Examples 4 to 9, 11, and 13 had a relatively broad peak at 2θ = 40 to 50 °, but at 2θ = 42 to 44 °. The half width of a peak is less than 0.30 °, or the ratio A / B of the intensity A of this peak to the intensity B of a broad peak is less than 1.2, and cannot be distinguished from noise (Table 2). ). The X-ray diffraction pattern of the negative electrode carbon material of Example 8 is shown in FIG.

  In Table 1, the negative electrode carbon material for a lithium ion secondary battery of Example 7 that was calcined at 2700 ° C. has a graphite structure. Other negative electrode carbon materials for lithium ion secondary batteries have an amorphous hard carbon structure.

Next, using these negative electrode carbon materials for lithium ion secondary batteries, secondary batteries using lithium manganate LiMn ₂ O ₄ as a positive electrode active material were prepared in the following manner.

(Preparation of negative electrode)
The negative electrode carbon material for a lithium ion secondary battery and polyvinylidene fluoride (binder) were uniformly mixed in a N: methylpyrrolidinone solvent at a mass ratio of 91: 9. This mixture was applied on both sides of a 14 μm thick copper foil (negative electrode current collector) to a thickness of about 80 μm, and then dried to prepare a sheet-like negative electrode. This negative electrode was cut out to 14.8 cm × 13.0 cm.

(Preparation of positive electrode)
Commercially available lithium manganate LiMn ₂ O ₄ (positive electrode active material, average particle size 10 μm), acetylene black (conductive agent) and polyvinylidene fluoride (binder) in a mass ratio of 89: 6: 5 N -Mixed with pyrrolidone. This mixture was applied to both sides of a 15 μm thick aluminum sheet (positive electrode current collector) so as to have a thickness of about 130 μm, and then dried to produce a sheet-like positive electrode. This positive electrode was cut into 14.3 cm × 12.9 cm.

(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved at a concentration of 1 mol / L in a solvent in which EC (Ethylene carbonate) and DMC (Dimethyl carbonate) were mixed at a mass ratio of 50:50 to prepare a non-aqueous electrolyte.

(Separator)
A commercially available porous stretched polypropylene sheet (manufactured by Ube Industries, Ltd., UP3025) was used as a separator. This separator was cut into 14.8 cm × 12.8 cm.

(Battery assembly)
A laminate in which the separator was sandwiched between the positive electrode and the negative electrode was used as the basic configuration of the test battery. This was immersed in the non-aqueous electrolyte prepared above for 10 minutes to impregnate the porous stretched polypropylene sheet with the non-aqueous electrolyte, and a lithium ion secondary battery was assembled. Lead wires were attached to the positive and negative electrode current collectors, and a charge / discharge cycle test was conducted at a constant current at 30 ° C. In the charge / discharge test, the initial charge / discharge capacity was measured at a charge end voltage of 4.2 V, a discharge end voltage of 2.9 V, and a charge / discharge current density of 1 mA / cm ² . These results are shown in Table 2 together with the results of initial charge / discharge efficiency (initial efficiency = initial discharge capacity / initial charge capacity × 100 (%)). The initial charge / discharge efficiency of the negative electrode carbon material for a lithium ion secondary battery of the present invention is equivalent to (△) or superior to that of a conventional product (◎, ○), and relatively relatively 2θ = 40 to 50 °. The charge / discharge performance of the negative electrode carbon material for a lithium ion secondary battery having a broad peak and a sharper peak at 2θ = 42 to 44 ° was particularly excellent (◎).

(Comparative Examples 1-3)
Acquire the red cocoon layer part (L = 99.5-94%, whitening ratio 0.5-6%), add phenol resin, and refer to JP-A-2001-266850 to make 75% by mass of red cocoon layer. 25% by mass of phenol resin was mixed. In the same manner as in Example 1, the pelletized raw material was calcined in a rotary kiln at 800 to 900 ° C. for 6 hours in nitrogen gas. Next, the calcined product is pulverized into a pulverized product having an average particle diameter of 20 to 30 μm, and the pulverized product is put into a crucible and subjected to main firing at 900 to 1550 ° C. for 5 to 10 hours. Battery negative electrode carbon materials were obtained (Table 1). A lithium ion secondary battery was assembled in the same manner as in Example 1, and charge / discharge performance was evaluated. The evaluation results are shown in Table 2.

(Comparative Examples 4-6)
In the milling process of brown rice, the red rice bran (Comparative Example 4), the medium white rice bran (Comparative Example 5), and the upper white rice bran (Comparative Example 6) corresponding to the pericarp and seed coat were used as samples to try firing in an electric furnace. It was. About 50 g of each sample was tested under conditions of 1600 ° C. and 2 h in an Ar gas atmosphere. In Akamine (Comparative Example 4), a large amount of volatilization exceeding 10% by mass of the sample was placed on the top plate inside the electric furnace. Adherent material was attached, and a bad odor during baking was strong. In the middle birch (Comparative Example 5) and the upper white birch (Comparative Example 6), the adhesion of volatile substances on the top plate inside the electric furnace was less than 2% by mass. In Comparative Example 4, including the low recovery rate and the time for maintenance of the electric furnace, it took five times or more time and labor to obtain the same amount of fired material as that of Nakashiragi (Comparative Example 5).

FIG. 1 is an X-ray diffraction pattern of a negative electrode carbon material for a lithium ion secondary battery of Example 1 according to the present invention. FIG. 2 is an X-ray diffraction pattern of the negative electrode carbon material of Example 8.

Claims (9)

A negative electrode carbon material for a lithium ion secondary battery, which is obtained by firing a middle white rice cake or an upper white rice cake obtained by polishing brown rice from which fruit skin and seed coat have been removed. 2. The negative electrode carbon material for a lithium ion secondary battery according to claim 1 , wherein a powder X-ray (CuKα) diffractogram of the negative electrode carbon material for a lithium ion secondary battery is relatively broad at 2θ = 40 to 50 °. And a sharper peak at 2θ = 42 to 44 °, a negative electrode carbon material for a lithium ion secondary battery. 3. The negative electrode carbon material for a lithium ion secondary battery according to claim 2 , wherein a ratio A / B of the sharp peak intensity A to the broad peak intensity B is 1.2 or more. 4. The lithium ion secondary battery according to claim 2 , wherein the half-value width of the broad peak is 3.5 to 5.5 °, and the half-value width of the sharp peak is 0.30 to 0.45 °. 5. Negative electrode carbon material. The first step of removing the pericarp and seed coat from the brown rice to obtain a rice starch portion corresponding to the middle white rice bran or the upper white rice bran when polishing the brown rice, and the second step of firing the rice starch portion. A method for producing a negative electrode carbon material for a lithium ion secondary battery. 6. The method for producing a negative electrode carbon material for a lithium ion secondary battery according to claim 5 , wherein the first step further includes a step of removing the paste powder layer after removing the peel and seed coat from the brown rice. 7. The method for producing a negative electrode carbon material for a lithium ion secondary battery according to claim 5 , wherein the first step obtains a rice starch portion corresponding to a polishing rate of 7% to 65%. . The second step is a pre-baking step of pre-baking a rice starch portion corresponding to the middle white rice bran or upper white rice bran to obtain a pre-baked product, a pulverizing step of pulverizing the pre-baked product into a pulverized product, and the pulverized product. A method for producing a negative electrode carbon material for a lithium ion secondary battery according to any one of claims 5 to 7 , comprising a main firing step of performing a main firing at a temperature higher than the temperature of the temporary firing step. . The pre-baking step is a step of baking the rice starch portion corresponding to the white birch or upper white birch at 500 to 1000 ° C. for 0.5 to 10 hours, and the main baking step is 0.5 to 50 hours at 700 to 1600 ° C. The method for producing a negative electrode carbon material for a lithium ion secondary battery according to claim 8 , wherein the method is a firing step.

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