JPH09283178A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which has such a construction as enhancing battery capacity by heightening energy density. SOLUTION: A nonaqueous electrolyte secondary battery is formed by containing an electrode element 20 which is formed by layering a positive electrode 2 and a negative electrode 1 via a separator 3 and winding the same into spiral in a cylindrical battery case 5, and by filling nonaqueous electrolyte into the same. By setting the outer diameter dimension of the electrode element 20 to 0.8 to 1.3 times of the inner diameter dimension of the battery case 5, the expansions of respective electrodes 1, 2 produced by initial charge are regulated. In order to make the inner pressure of the battery case proper, it is favorable that the ratio of the maximum value of the outer dimension of the battery case and the minimum value of the outer dimension is also made to be proper.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a battery case,
The present invention relates to a non-aqueous electrolyte secondary battery that accommodates an electrode element in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween.

[0002]

2. Description of the Related Art As portable electronic devices have become smaller and lighter and have higher performance, power supplies to be used have been required to have smaller size, higher capacity, higher energy density and higher reliability. For this reason, secondary batteries have been spotlighted as a portable power source that can meet such demands, and active research and development have been conducted to obtain higher energy density.

Among them, a lithium ion secondary battery using a non-aqueous electrolyte has a higher energy density than an aqueous electrolyte battery such as a lead battery or a nickel cadmium battery. As an actual lithium-ion secondary battery, a cylindrical battery in which a long-shaped electrode is spirally wound and housed in a cylindrical battery case, one in which folded electrodes and rectangular electrodes are laminated, Further, a rectangular battery in which a long electrode wound in an elliptical shape is housed in a rectangular battery case can be given.

[0004] In such a non-aqueous electrolyte secondary battery, as a cathode material, lithium composite alloy oxide LiCoO ₂ made have been in practical use, this LiCoO ₂ is
It is characterized in that lithium is extracted during charge and the crystal lattice expands, and during discharge lithium is inserted and the crystal lattice contracts.

On the other hand, as a negative electrode material, a carbon material capable of inserting and extracting lithium has been put into practical use. This carbon material includes a non-graphitizable carbon material obtained by heat-treating an organic material at a relatively low temperature and an easily graphitizable carbon material. Recently, an artificial graphite material obtained by heat-treating an easily graphitizable carbon material at a higher temperature and However, natural graphite materials obtained by removing impurities from materials produced as ores have also come to be used.

[0006]

By the way, in the negative electrode made of the carbon material as described above, lithium is inserted at the time of charging and the crystal lattice expands at the time of discharging, similarly to the process of forming the lithium graphite intercalation compound. Lithium is extracted and the crystal lattice contracts. In particular, since the graphitizable carbon material and the graphite material have a small (002) plane spacing obtained by an X-ray diffraction method, a large expansion / contraction of the crystal lattice occurs as lithium is inserted / extracted between layers due to charge / discharge.

Therefore, such a carbon material is used as the negative electrode,
In a non-aqueous electrolyte secondary battery using LiCoO ₂ as the positive electrode, the expansion of the positive electrode and the negative electrode that occurs at the time of initial charging is very large, which causes the electrode to be distorted and the Coulombic efficiency to decrease. This is because when the electrode expands / contracts due to charging / discharging, the stress deteriorates the binding property between the particles of the active material, and the active material falls off from the electrode, resulting in a decrease in electrical conductivity. This is probably because the internal resistance becomes high. When the internal resistance of the battery increases, the active material that can participate in charging / discharging decreases and the charging / discharging capacity per unit weight of the active material decreases. In addition, the load characteristic is deteriorated due to the increase of the internal resistance, the battery cannot be discharged even if it is charged, and the substantial battery capacity is reduced. Therefore, in the non-aqueous electrolyte secondary battery as described above, the charge / discharge capacity per unit weight of the active material is low, and the active material filled in the battery cannot be fully utilized.

When a non-graphitizable carbon material is used for the negative electrode, the change in the electrode structure of the negative electrode is small, but the same problem occurs due to the large expansion of the positive electrode.

Therefore, it is an object of the present invention to provide a non-aqueous electrolyte secondary battery having a structure in which the battery capacity can be improved by increasing the energy density.

[0010]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to achieve the above-mentioned object, the size of the electrode element and the size of the battery case accommodating the electrode element are optimized to achieve the initial charging. It has been found that the change in electrode size caused by the above is suppressed and the battery capacity can be increased.

That is, according to the present invention, an electrode element in which a positive electrode and a negative electrode are laminated via a separator is housed in a battery case, and a non-aqueous electrolytic solution is prepared by injecting a non-aqueous electrolytic solution. In the secondary battery, the outer dimension of the electrode element is 0.8 to 1.5 times the inner dimension of the battery case before the electrode element is housed in the battery case.

[0012] Here, the electrode element is formed by winding a long electrode in a spiral shape into a columnar shape, and when the battery case is a cylindrical type, the outer diameter of the electrode element is equal to that of the battery. It is preferable that it is 0.8 to 1.3 times the inner diameter of the case. Further, the electrode element is a rectangular parallelepiped formed by laminating a plurality of rectangular electrodes, and when the battery case is rectangular, the electrode element stacking direction in the electrode element (that is, with respect to the surface on which each electrode extends) Direction orthogonal to each other)
It is preferable that the outer dimension is 0.95 to 1.5 times the inner dimension corresponding to the stacking direction in the battery case.

By thus optimizing the size of the electrode element and the size of the battery case accommodating the electrode element, expansion of the electrode caused by initial charging can be restricted. And, because of this, since the binding property between the particles of the active material is favorably maintained,
The increase of the internal resistance of the battery is suppressed, and the utilization rate of the active material can be increased. In addition, a sufficient capacity can be obtained even in the discharge after the initial charge.

If the ratio of the outer dimension of the electrode element to the inner dimension of the battery case is larger than the above range, it becomes difficult to insert the electrode element into the battery case, and in the worst case, the electrode element is destroyed. On the contrary, if the ratio of the outer dimension of the electrode element to the inner dimension of the battery case is smaller than the above range,
The expansion of the electrode element due to charging cannot be regulated sufficiently. If the outer dimension of the electrode element is larger than the inner dimension of the battery case, make the inner dimension near the opening of the battery case larger than the inner dimension of the bottom of the battery case, and insert the electrode element. Then, the vicinity of the opening of the battery case may be processed so that the inner size becomes equal to the inner size at the bottom of the battery case.

As described above, in the present invention, the size of the electrode element and the size of the battery case accommodating the electrode element are optimized so that the expansion of the electrode caused by the initial charge is regulated. Therefore, the battery case of the completed non-aqueous electrolyte secondary battery receives a predetermined pressure from the inside thereof, the side surface orthogonal to the stacking direction of the electrodes of the electrode element bulges outward, and the outer dimension is large. Tends to become. However, in the part of the side surface of the battery case near the bottom, the outer dimensions are almost fixed by the outer circumference of the bottom part, and in the part of the side surface of the battery case near the opening for inserting the electrode element. However, since this opening is later sealed by the battery lid, the change in the outer dimension is small. Therefore, the greater the pressure that the battery case receives from the inside or the smaller the hardness of the battery case, the greater the difference between the maximum value of the outer dimensions of the battery case and the minimum value of the outer dimensions.

Therefore, in the non-aqueous electrolyte secondary battery as described above, in order to optimize the internal pressure of the battery case, the ratio between the maximum value of the outer dimension of the battery case and the minimum value of the outer dimension is also set. It is suitable and suitable. Specifically, the maximum value of the outer dimensions of the battery case is 1.01 to 1 ... with respect to the minimum value of the outer dimensions after the electrode element is housed in the battery case.
It is preferably 35 times.

Here, the electrode element is formed by winding a long electrode in a spiral shape into a columnar shape, and when the battery case is cylindrical, the maximum outer diameter of the battery case is It is preferable that the minimum value of the outer diameter is 1.01 to 1.14 times. Further, when the electrode element is a rectangular parallelepiped formed by laminating a plurality of rectangular electrodes, and the battery case is rectangular, the maximum value of the outer dimension corresponding to the electrode stacking direction in the battery case is It is preferable to be 1.04 to 1.35 times the minimum size.

This makes it possible to improve the capacity per battery volume. When the ratio of the maximum value of the outer dimension to the minimum value of the outer dimension of the battery case is larger than the above range, the battery capacity increases, but the capacity per battery volume does not always increase. Is greatly distorted, which causes a problem in designing a device that uses the non-aqueous electrolyte secondary battery as a power source. On the contrary, when the ratio of the maximum value of the outer dimension to the minimum value of the outer dimension of the battery case is smaller than the above range, the battery case receives almost no pressure due to the expansion of the electrode element, so that Will also be smaller.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described below with reference to the drawings.

First Embodiment Here, the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery as shown in FIG.

In this non-aqueous electrolyte secondary battery, a spirally wound electrode element 20 formed by stacking a negative electrode 1 and a positive electrode 2 with a separator 3 in between is wound into a cylindrical battery case 5. It is housed inside.

Here, the above-mentioned negative electrode 1 is a coating film containing negative electrode active material powder and a binder on both surfaces of the negative electrode current collector 10 (hereinafter referred to as negative electrode active material-containing coating film) 15. The positive electrode 2 has a coating film containing positive electrode active material powder and a binder on both surfaces of the positive electrode current collector 11 (hereinafter,
It is referred to as a positive electrode active material-containing coating film. ) 16 is formed.

As the positive electrode active material used for the positive electrode 2,
A substance that can reversibly insert and remove lithium ions is used. For example, TiS ₂ , MoS ₂ , V ₂ O ₅ , V
₆ O ₁₃ , MnO _{2 and the} like can be used, but they are preferable because they contain a sufficient amount of lithium and have the general formula LiM _x O _y.
(However, M is Co, Ni, Mn, Fe, Al, V, Ti
Represents at least one selected from The composite metal oxide composed of lithium and a transition metal represented by the above) or an intercalation compound containing Li is suitable. A conductive agent is generally added to the positive electrode active material used in powder form in order to ensure electron conduction with the current collector. The conductive agent is not particularly limited, but metal powder, carbon powder, or the like is used. For example, pyrolytic carbon such as carbon black, and graphitized products thereof, artificial or natural scaly graphite powder, carbon fibers and carbon powders such as graphitized products are preferred. Also, a mixture of these carbons can be used.

As the negative electrode active material used for the negative electrode 1, lithium metal or lithium metal and Al, P
An alloy of b, In and the like can be used. Further, by using a carbon material capable of inserting and extracting lithium as the negative electrode active material, it is possible to obtain a battery having further excellent cycle life. As the carbon material for the negative electrode,
Although not particularly limited, those obtained by thermal decomposition or calcining carbonization of various organic compounds (so-called non-graphitizable carbon materials), these graphitized products, and naturally occurring natural graphite can also be used. In the form, a non-graphitizable carbon material is used.

The non-graphitizable carbon material has a large charge / discharge capacity per weight and is excellent in cycle characteristics. Examples of the organic material as a starting material include phenol resins, acrylic resins, vinyl halide resins, polyimide resins, polyamideimide resins, polyamide resins, polyacetylene, conjugated resins such as polyparaphenylene, cellulose and its derivatives, and any organic compounds. Molecular compounds can be used. In addition, condensed polycyclic hydrocarbon compounds such as naphthalene, phenanthrene, anthracene, triphenylene, pyrene, perylene, pentaphene and pentacene, derivatives thereof (for example, carboxylic acids thereof, carboxylic acid anhydrides, carboxylic acid imides and the like), It is also possible to use various pitches containing a mixture as a main component, acenaphthylene, indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine, phenanthridine and the like, and derivatives thereof.

Further, furan resin composed of furfuryl alcohol or furfural homopolymer or copolymer is particularly preferably used as a starting material. Specific examples thereof include polymers composed of furfural + phenol, furfuryl alcohol + dimethylol urea, furfuryl alcohol, furfuryl alcohol + formaldehyde, furfuryl alcohol + furfural, furfural + ketones and the like. The carbonaceous materials obtained by carbonizing these furan resins have a (002) plane spacing of 0.370 nm or more, a true density of less than 1.70 g / cm ³ , and a differential thermal analysis of 700 ° C. or more in an air stream. It has no exothermic peak and exhibits very good characteristics as a negative electrode material for batteries.

The temperature for firing these organic materials is
Depends on the starting material, usually 500-2000 ° C
It is said.

Alternatively, a petroleum pitch having a hydrogen / carbon atom ratio of 0.6 to 0.8 is used as a starting material, a functional group containing oxygen is introduced into the petroleum pitch, and so-called oxygen cross-linking is performed to obtain an oxygen content of 10 to 20% by weight. %, The carbonaceous material obtained by firing the precursor, as well as the carbonaceous material obtained from the furan resin, shows very good characteristics as a negative electrode material of a battery.
Petroleum pitch is distilled (vacuum distillation, atmospheric distillation, steam distillation), thermal polycondensation, extraction, chemical polycondensation from tars, asphalt, etc. obtained by high-temperature pyrolysis of coal tar, ethylene bottom oil, crude oil, etc. It can be obtained by an operation such as. Further, the specific means for introducing a functional group containing oxygen into these petroleum pitches is not limited, but for example, nitric acid, mixed acid, sulfuric acid, a wet method using an aqueous solution of hypochlorous acid, or an oxidizing gas (air, Oxygen) dry method, further sulfur, ammonium sulfate, ammonium persulfate,
A reaction with a solid reagent such as ferric chloride is used. When oxygen is introduced into the petroleum pitch by such a method,
The final carbonaceous material is obtained in the solid state without melting during the carbonization process (400 ° C. or higher), which is similar to the process of forming non-graphitizable carbon.

When a carbonaceous material is obtained by using these organic materials, for example, after carbonizing at 300 to 700 ° C. in a nitrogen stream, the temperature rising rate is 1 to 20 ° C. per minute in the nitrogen stream, and the reached temperature is 900 to The firing may be performed under the conditions of 1300 ° C. and a holding time of 0 to 5 hours at the ultimate temperature. Of course, the carbonization operation may be omitted in some cases.

Further, a carbonaceous material having a large doping amount with respect to lithium by adding a phosphorus compound or a boron compound when carbonizing the above-mentioned furan resin, petroleum pitch or the like can also be used. Examples of the phosphorus compound include phosphorus oxides such as phosphorus pentoxide and oxo acids such as orthophosphoric acid and salts thereof. However, from the viewpoint of ease of handling, it is preferable to use phosphorus oxide and phosphoric acid. is there. The amount of the phosphorus compound to be added is 0.2 to 30% by weight, preferably 0.5 to 15% by weight in terms of phosphorus based on the organic material or the carbonaceous material, and the proportion of phosphorus remaining in the negative electrode material is 0. 0.2 to 9.0% by weight, preferably 0.1.
3 to 5% by weight. Further, as the boron compound, boron oxide or boric acid can be added in the form of an aqueous solution. The amount of the boron compound to be added is 0.2 to 30% by weight, preferably 0.5 to 15% by weight, in terms of boro, with respect to the organic material or the carbonaceous material, and the proportion of boron remaining in the negative electrode material is 0. 2 to 9.0% by weight, preferably 0.3 to 5% by weight.

In addition, the negative electrode active material powder as described above or the positive electrode active material powder as described above is used for each current collector 10,
When it is held at No. 11, it is mixed with a binder or a solvent and applied as a paint. The binder used here is usually used as a binder in a non-aqueous electrolyte battery of this type. Any of those used can be used. For example, polytetrafluoroethylene (PTF
E), polyvinylidene fluoride (PVDF), fluororesins such as fluororubber, styrene butadiene rubber, styrene butadiene latex, carboxymethyl cellulose (C
An organic polymer such as MC) is used. PVD among them
Since F has high chemical stability and high productivity due to good slurry properties, it is often used as a binder for non-aqueous electrolyte batteries.

The negative electrode current collector 10 has a thickness of 5 to 5.
20 μm copper foil, stainless steel foil, nickel foil, etc. can be used. On the other hand, the positive electrode current collector 11 has a thickness of 10 to 40.
Aluminum foil, stainless steel foil, nickel foil or the like having a thickness of μm can be used. Note that any of the current collectors 10 and 11 is not limited to the foil shape, and a mesh shape or a mesh shape made of expanded metal or the like can be used.

Further, the separator 3 to be interposed between the negative electrode 1 and the positive electrode 2 as described above is not particularly limited, and examples thereof include woven cloth, non-woven cloth, and synthetic resin microporous film. When a thin electrode having a large area is used, a synthetic resin microporous film, particularly a polyolefin microporous film is preferably used. Specifically, a microporous membrane made of polyethylene and polypropylene, or a microporous membrane obtained by combining these is used.

The negative electrode 1, the separator 3 and the positive electrode 2 as described above are superposed in this order and wound around the center pin 14 to form a spiral electrode element 20.

A cylindrical case made of iron, nickel, stainless steel, aluminum or the like is used as the battery case 5 in which the spiral electrode element 20 is housed. If electrochemical corrosion occurs in the non-aqueous electrolyte during battery operation, appropriate plating or the like may be performed. Also,
As the hardness of the battery case 5 increases, each electrode 1
Although the expansion of No. 2 can be suppressed, if the hardness is too high, the workability deteriorates and it becomes difficult to industrially manufacture, and thus it is preferable that the material is formed of a material having an appropriate hardness.

When accommodating the spiral-shaped electrode element 20 in the battery case 5, the insulating plates 4 are arranged on both upper and lower surfaces thereof, and the negative electrode lead 12 led out from the negative electrode current collector 10 is placed in the battery case. 5, a positive electrode lead 13 electrically connected to the bottom of the positive electrode current collector 5 and led out from the positive electrode current collector 11.
Are electrically connected to the battery lid 7 via the safety valve device 8.

A non-aqueous electrolytic solution prepared by dissolving an electrolyte in an organic solvent is injected into the battery case 5, and the battery lid 7 is crimped via an insulating sealing gasket 6 coated with asphalt. It is fixed.

Here, as the electrolyte contained in the non-aqueous electrolyte, any electrolyte can be used as long as it is used in this type of battery. For example, in addition to LiPF ₆ , LiCl
O ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB
(C ₆ H ₅ ) ₄ , LiCl, LiBr, LiSO ₃ CH
₃ , LiSO ₃ CF ₃ , LiN (SO ₂ CF ₃ ) ₂ , L
iC (SO ₂ CF _{3) 3} and the like.

The organic solvent is not particularly limited,
It is preferable to use a solvent having a relatively high dielectric constant such as ethylene carbonate as a main solvent, and to which a plurality of low-viscosity solvents are added. As the high dielectric constant solvent, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, sulfolanes, butyrolactones, valerolactones and the like are preferably used. As the low-viscosity solvent, symmetrical or asymmetrical chain carbonic acid ester such as diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate and methyl propyl carbonate is preferably used, and two or more low-viscosity solvents are mixed and used. Also gives good results. In particular, when a graphite material is used as the negative electrode active material powder, a compound having a structure in which hydrogen of ethylene carbonate is replaced with a halogen element is suitable as the main solvent of the organic solvent, in addition to ethylene carbonate.

Further, a part of this main solvent is used as a small amount of the second solvent.
Good characteristics can also be obtained by substituting the component solvents. As the second component solvent, propylene carbonate, butylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,3-dimethoxypropane, diethyl ether, γ-butyrolactone, valerolactone, tetrahydrofuran, 2 -Methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,
3-dioxolane, sulfolane, methylsulfolane and the like can be used, and the addition amount thereof is preferably less than 10% by volume.

Further, with respect to the above-mentioned main solvent or a mixed solvent of the main solvent and the second component solvent,
The solvent may be added to improve the conductivity, suppress the decomposition of ethylene carbonate, improve the low temperature characteristics, and reduce the reactivity with lithium metal to improve the safety. As the solvent of the third component, symmetrical or asymmetrical chain ester carbonate such as diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate is preferably used. These third
The mixing ratio of the solvent of the components is, by volume ratio, (main solvent or mixed solvent of main solvent and second component solvent): (third component) = 1
It is preferable to be 5:85 to 40:60, and it is 18:82.
It is more preferable to be set to 35:65. The solvent of the third component may be a mixed solvent of diethyl carbonate and dimethyl carbonate. This mixing ratio is preferably a volume ratio of (dimethyl carbonate) / (diethyl carbonate) = 1: 9 to 8: 2. In addition, the mixing ratio of this mixed solvent and the main solvent or the mixed solvent of the main solvent and the second component solvent is (volume ratio of mixed solvent of diethyl carbonate and dimethyl carbonate): (main solvent or main solvent and Mixed solvent with second component solvent) = 3:
10 to 9:10 is preferable, and 5:10 to 8: 1.
0 is more preferable.

In the present embodiment, the outer diameter of the spiral electrode element 20 described above is determined by the battery case 5.
The inner diameter of the electrode element 20 to the battery case 5
It is 0.8 to 1.3 times that before it is stored.

By thus optimizing the size of the electrode element 20 and the size of the battery case 5 accommodating the same, expansion of the electrode electrodes 1 and 2 caused by initial charging can be restricted.
And, because of this, since the binding property between the respective active material powders is favorably maintained, the increase in the internal resistance of the battery is suppressed,
The utilization rate of the active material can be increased. In addition, a sufficient capacity can be obtained even in the discharge after the initial charge.

Further, in the present embodiment, the maximum value of the outer diameter of the battery case 5 is 1.
It is set to 01 to 1.14 times.

In this way, if the ratio between the maximum value of the outer dimensions of the battery case 5 and the minimum value of the outer dimensions is also optimized, the internal pressure of the battery case 5 can be optimized, and the internal pressure per battery volume can be adjusted. It is also possible to improve the capacity.

Second Embodiment In the present embodiment, a material having the same structure as that of the first embodiment will be described except that the negative electrode active material used for the negative electrode 1 is graphite.

Graphites are preferable for obtaining a high capacity battery because they have a high true density and an improved electrode filling property. As the usable graphite material, the true specific gravity needs to be 2.10 g / cm ³ or more, and 2.18 g / cm ³ or more is more preferable in order to obtain higher negative electrode mixture filling property. preferable. In order to obtain such a true specific gravity, the plane spacing of the (002) plane obtained by the X-ray diffraction method is 0.335 nm to
Must be 0.34 nm, 0.335 nm
More preferably, it is about 0.337 nm. The crystallite thickness in the C-axis direction is preferably 16.0 nm or more, more preferably 300 nm or more.

Further, the graphite material practically used as the negative electrode active material has a bulk specific gravity of 0.4 g / cm ³ or more determined by JIS-K1469. Since the graphite material having a large bulk specific gravity is dispersed relatively uniformly in the negative electrode mixture, the cycle characteristics are improved in the non-aqueous electrolyte secondary battery using the same. Further, when the average shape parameter (X) representing the flatness of the graphite material particle shape is set to x ≦ 125, the cycle characteristics are further improved. Furthermore, if the specific surface area of the graphite material is 9 m ² / g or less, the number of submicron fine particles attached to the graphite particles is reduced, which leads to an increase in bulk density.

In the particle size distribution obtained by the laser diffraction method, the cumulative 10% particle size is 3 μm or more, the cumulative 50% particle size is 10 μm or more, and the cumulative 90%.
By using graphite powder having a% particle size of 70 μm or less, a safe and reliable non-aqueous electrolyte secondary battery can be obtained. Particles with a small particle size have a large specific surface area, but by limiting this content rate, it is possible to suppress abnormal heat generation such as overcharging due to particles with a large specific surface area, and to limit the content rate of particles with a large particle size. As a result, it is possible to suppress an internal short circuit due to the expansion of particles at the time of initial charging, and it is possible to obtain a practical non-aqueous electrolyte secondary battery having high safety and reliability. Furthermore, by using graphite powder having an average breaking strength of particles of 6.0 kgf / mm ² or more, many pores for containing the non-aqueous electrolyte battery can be present in the electrode, and the load can be increased. A non-aqueous electrolyte secondary battery having excellent characteristics can be obtained.

The laser Raman spectroscopy is a measurement method in which the information on the vibration of the crystal structure of the carbon material is reflected with high sensitivity, but the G value obtained from the Raman spectrum is effective for evaluating microscopic structural defects. It is one of the indicators.
The G value is represented by the ratio of the area intensity of the Raman band derived from the complete graphite structure to the area intensity of the Raman band derived from the amorphous structure in the carbon material, and the G value is preferably 2.5 or more. 2.1 g / cm ³ when G value is less than 2.5
The true specific gravity may not be obtained.

To artificially produce graphite having the above-mentioned characteristics, coal or pitch can be used as a starting material. As pitch, tars obtained by high-temperature thermal decomposition of coal tar, ethylene bottom oil, crude oil, etc., distillation from asphalt, etc. (vacuum distillation, atmospheric distillation, steam distillation), thermal polycondensation, extraction, chemical polycondensation, etc. In addition to those obtained by operation, there are pitches generated during carbonization of wood. Further, as the starting material for the pitch, there are polyvinyl chloride resin, polyvinyl acetate, polyvinyl butyrate, 3,5-dimethylphenol resin and the like.

These coals and pitches exist in a liquid state at a maximum temperature of about 400 ° C. during carbonization, and when kept at that temperature, the aromatic rings are condensed and polycyclic to be in a laminated orientation, and then 500 ° C. At a temperature above about a certain degree, a solid carbon precursor, that is, a semi-coke is formed. Such a process is called a liquid layer carbonization process, and is a typical process of forming graphitizable carbon.

In addition, condensed polycyclic hydrocarbon compounds such as naphthalene, phenanthrene, anthracene, triphenylene, pyrene, perylene, pentaphene and pentacene, derivatives thereof (for example, carboxylic acids thereof, carboxylic acid anhydrides, carboxylic acid imides, etc.), A mixture of each compound, a condensed heterocyclic compound such as acenaphthylene, indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine and phenanthridine, and derivatives thereof can also be used as a starting material.

To produce desired artificial graphite from the above starting materials, for example, in an inert gas stream such as nitrogen,
After carbonization at 300 to 700 ° C., in an inert gas stream, the temperature rising rate is 1 to 100 ° C. per minute, and the reached temperature is 900 to 1500.
Calcination is carried out under the conditions of holding time at 0 ° C. and reaching temperature for about 0 to 30 hours, and further heat treatment at 2000 ° C. or higher, preferably 2500 ° C. or higher. Of course, in some cases, the carbonization and calcination operations may be omitted. The carbon material or graphite material that has been heat-treated at a high temperature is crushed and classified to be used as a negative electrode material. This crushing may be performed before or after carbonization, calcination, high-temperature heat treatment, or at a temperature raising process. Good.

In addition, in the non-aqueous electrolyte secondary battery according to the present embodiment, the first embodiment is different except that the material of the negative electrode active material is different.
The embodiment has the same configuration as that of the first embodiment, and the outer diameter of the spiral electrode element 20 is smaller than the inner diameter of the battery case 5 before the electrode element 20 is housed in the battery case 5. In this state, it is 0.8 to 1.3 times. In addition, the maximum value of the outer diameter of the battery case 5 is
It is 1.01 to 1.14 times.

Therefore, the expansion of the electrode electrodes 1 and 2 caused by the initial charge can be regulated, and the binding property between the electrode active material powders can be maintained well, so that the internal resistance of the battery can be increased. It is suppressed, and the utilization rate of the active material can be increased. In addition, a sufficient capacity can be obtained even in the discharge after the initial charge. Furthermore, the internal pressure of the battery case 5 can be optimized, and the capacity per battery volume can be improved.

Third Embodiment In the present embodiment, the present invention is applied to a prismatic non-aqueous electrolyte secondary battery as shown in FIG.

This non-aqueous electrolyte secondary battery has a rectangular battery case in which a rectangular parallelepiped electrode element 40 formed by laminating a plurality of rectangular negative electrodes 21 and rectangular positive electrodes 22 with a separator 23 in between is a rectangular battery case. It is housed in 25.

Here, the above-mentioned negative electrode 21 has a coating film (hereinafter referred to as a negative electrode active material-containing coating film) 35 containing the negative electrode active material powder and a binder on both surfaces of the negative electrode current collector 30. The positive electrode 22 is formed with a coating film (hereinafter referred to as a positive electrode active material-containing coating film) 36 containing a positive electrode active material powder and a binder on both surfaces of the positive electrode current collector 31. It will be done. In addition,
The same materials as those shown in the first embodiment can be used as the materials for forming the respective pole electrodes 21, 22.

A plurality of the negative electrode 21, the separator 23, and the positive electrode 22 as described above are laminated in this order to form a rectangular parallelepiped electrode element 40.

As the battery case 25 for housing the electrode element 40, a rectangular case made of the same material as that shown in the first embodiment is used.

Then, the electrode element 4 is placed in the battery case 25.
When storing 0, the insulating plate 24 is disposed on the bottom surface thereof, and the negative electrode lead 32 led out from the negative electrode current collector 30 is electrically connected to a negative electrode terminal (not shown) provided on the battery lid 27, The positive electrode lead 33 led out from the positive electrode current collector 31 is also electrically connected to the positive electrode terminal 37 provided on the battery lid 27.

In the battery case 25, a non-aqueous electrolytic solution prepared by dissolving an electrolyte in an organic solvent is injected,
The battery lid 27 is fixed to the battery case 25 by laser welding.

Here, the electrolyte contained in the non-aqueous electrolyte,
As the organic solvent, those shown in the first embodiment can be similarly used.

Further, in the present embodiment, the electrode stacking direction in the electrode element 40 (that is, each electrode 21,
The direction orthogonal to the plane in which 22 extends. It is indicated by x in FIG. The outer dimension of) is 0.95 to 1.5 times the inner dimension of the battery case 25 corresponding to the stacking direction x before the electrode element 40 is housed in the battery case 25. .

By thus optimizing the size of the electrode element 40 and the size of the battery case 25 accommodating the electrode element 40, expansion of the electrode electrodes 21 and 22 caused by initial charging can be restricted. As a result, the binding property between the active material powders is maintained well, so that the increase in the internal resistance of the battery is suppressed and the utilization rate of the active material can be increased. In addition, a sufficient capacity can be obtained even in the discharge after the initial charge.

Further, in the present embodiment, the maximum value of the outer dimension corresponding to the stacking direction x in the battery case 25 is 1.04 to 1.35 times the minimum value of the outer dimension. There is.

In this way, if the ratio between the maximum value of the outer dimensions of the battery case 25 and the minimum value of the outer dimensions is also optimized,
The internal pressure of the battery case 25 can be optimized, and the capacity per battery volume can be improved.

When the battery case 25 has a rectangular shape as in the present embodiment, its flatness (the dimension corresponding to the stacking direction x) / (the dimension in the direction orthogonal to the stacking direction x) The larger the value, the greater the above-mentioned effect.
This is because, generally, as the flatness ratio increases, the area of the wide side surface of the battery case 25 increases, and the internal pressure of the battery tends to concentrate there.

Fourth Embodiment In the present embodiment, description will be given of one having the same configuration as that of the third embodiment except that the negative electrode active material used for the negative electrode 21 is graphite.

Graphites are preferred for obtaining a high capacity battery because they have a high true density and an improved electrode filling property. As the graphites, any of those shown in the second embodiment can be used.

The non-aqueous electrolyte secondary battery according to this embodiment has the same structure as that of the third embodiment except that the material of the negative electrode active material is different. The outer dimension of the electrode of the element 40 in the stacking direction x is compared with the inner dimension of the battery case 25 corresponding to the stacking direction x,
It is 0.95 to 1.5 times that before the electrode element 40 is housed in the battery case 25. Further, the maximum value of the outer dimension corresponding to the stacking direction x in the battery case 25 is 1.04 to 1.35 times the minimum value of the outer dimension.

Therefore, the expansion of the electrode electrodes 21 and 22 caused by the initial charge can be regulated, and the binding property between the electrode active material powders can be maintained well, which increases the internal resistance of the battery. It is suppressed, and the utilization rate of the active material can be increased. In addition, a sufficient capacity can be obtained even in the discharge after the initial charge. Furthermore, the internal pressure of the battery case 25 can be optimized, and the capacity per battery volume can be improved.

Although the embodiments of the non-aqueous electrolyte secondary battery to which the present invention is applied have been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and the gist of the present invention is not limited thereto. Modifications and changes can be appropriately made without departing from the above.

For example, when the outer dimensions of the electrode elements 20 and 40 are larger than the inner dimensions of the battery cases 5 and 25, the inner dimensions near the openings of the battery cases 5 and 25 are set to the bottom portions of the battery cases 5 and 25, etc. It may be larger than the inner dimension of. That is, as shown in the upper part of FIG. 3, in the battery case 25 of the rectangular nonaqueous electrolyte secondary battery, the inner dimension b in the vicinity of the opening 25b is made larger than the inner dimension a in the bottom 25a and the like. Then, after inserting the electrode element 40, the vicinity of the opening 25b may be processed so that the inner dimension b becomes equal to the inner dimension a in the bottom portion 25a and the like as shown in the lower part of FIG. .

[0076]

EXAMPLES Here, a non-aqueous electrolyte secondary battery as shown in the above-described embodiment was actually manufactured and its characteristics were evaluated.

Example 1 In this example, the non-aqueous electrolyte secondary battery shown in the first embodiment was produced.

Specifically, first, 10 to 20% by weight of a functional group containing oxygen is introduced into petroleum pitch to effect oxygen crosslinking, and then the mixture is fired at 1000 ° C. in an inert gas stream to prevent graphitization. A carbon material was obtained. About this non-graphitizable carbon material,
As a result of powder X-ray diffraction measurement, the spacing between (002) planes was 0.376 nm. The true specific gravity was measured by the pycnometer method and found to be 1.58 g / cm ³ . Then, this non-graphitizable carbon material was pulverized to obtain a powder having an average particle diameter of 10 μm, to obtain a negative electrode active material powder.

Subsequently, 90% by weight of the above-mentioned negative electrode active material powder
And polyvinylidene fluoride (PVDF) 1 as a binder
0% by weight was mixed to obtain a negative electrode mixture, which was dispersed in a solvent N-methylpyrrolidone (NMP) to prepare a slurry.

Then, the above-mentioned slurry is applied to the surface of the negative electrode current collector 10 made of a strip-shaped copper foil having a thickness of 10 μm,
After drying, the negative electrode 1 was prepared by compression molding to form the negative electrode active material-containing coating film 15.

Further, 0.5 mol of lithium carbon and 1 mol of carbon cobalt were mixed and baked in air at 900 ° C. for 5 hours and then crushed to obtain LiCo having an average particle diameter of 15 μm.
A positive electrode active material powder consisting of O ₂ powder was obtained. Note that this L
As a result of X-ray diffraction measurement of iCoO ₂ powder, J
It was in good agreement with the LiCoO ₂ peak registered in the CPDS file. Subsequently, 91% by weight of the positive electrode active material powder described above, 6% by weight of graphite as a conductive agent, and 3% by weight of PVDF as a binder were mixed to obtain a positive electrode mixture, which was dispersed in NMP to prepare a slurry.

Then, the above-mentioned slurry is applied to the surface of the positive electrode current collector 11 made of a strip-shaped aluminum foil having a thickness of 20 μm, dried and then compression molded to form the positive electrode active material-containing coating film 16. Thus, the positive electrode 2 was produced.

Next, a separator 3 made of a microporous polypropylene film having a thickness of 25 μm was prepared, and the separator 3, the positive electrode 2, the separator 3 and the negative electrode 1 were laminated in this order and then wound, and the outermost peripheral portion was formed. A spiral electrode element 20 was manufactured by fixing with a tape. In addition, this electrode element 2
The outer diameter of 0 was 17.14 mm.

Then, the electrode element 20 described above is attached to the outer diameter 18
mm, the height was 65 mm, the inner diameter was 17.38 mm, and the can thickness was 0.31 mm. The insulating plates 4 were arranged above and below the electrode element 20, and the positive electrode lead 13 was welded to the battery lid 7 and the negative electrode lead 12 was welded to the bottom surface of the battery case 5. Then, in the battery case 5, 50% by volume of propylene carbonate, 1,2-
After injecting an organic electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l in a mixed solvent of 50% by volume of dimethoxyethane, the battery case 7 was fixed by caulking the battery case 5 through the sealing gasket 6. The non-aqueous electrolyte secondary battery was completed.

In the non-aqueous electrolyte secondary battery thus manufactured, the electrode element 20 is inserted into the battery case 5 before (electrode outer diameter dimension) / (battery case 5 inner diameter). Dimension) = 0.986. Further, during charging / discharging, (maximum outer dimension of battery case 5) / (minimum outer dimension) was 1.04. This non-aqueous electrolyte secondary battery will be referred to as a sample battery of Example 1.

Example 2 In this example, the non-aqueous electrolyte secondary battery shown in the second embodiment was produced.

Specifically, first, 30% by weight of coal tar pitch as a binder was added to 100% by weight of coal coke as a filler, mixed at about 100 ° C., and then compression molded by a press. A precursor of a carbon molded body was obtained. The pitch impregnation / firing process of impregnating the carbon material molded body obtained by heat-treating this precursor at 1000 ° C or lower with the binder pitch melted at 200 ° C or lower and heat-treating at 1000 ° C or lower is repeated several times. It was Then, this carbon molded body was heat-treated at 2600 ° C. in an inert atmosphere, then pulverized and classified to obtain a graphite material powder. This graphite material powder has a true density of 2.23 g / cm ³ , a bulk specific gravity of 0.83 g / cm ³ , and an average shape parameter x of 1.
0, specific surface area 4.4 m ² / g, average particle size 31.2 μ
m, the cumulative 10% particle size was 12.3 μm, the cumulative 50% particle size was 29.5 μm, and the cumulative 90% particle size was 53.7 μm. Then, a spiral electrode element 20 was produced in the same manner as in Example 1 except that this graphite material powder was used as the negative electrode active material powder. The outer diameter of the electrode element 20 was 17.14 mm, as in Example 1.

Thereafter, the above-mentioned electrode element 20 is used in the first embodiment.
Same as, outer diameter 18mm, height 65mm, inner diameter 1
The non-aqueous electrolyte secondary battery was completed by being housed in a cylindrical battery case 5 having a thickness of 7.38 mm and a can thickness of 0.31 mm.

Also in this non-aqueous electrolyte secondary battery, before the electrode element 20 was inserted into the battery case 5, (outer diameter dimension of the electrode element 20) / (inner diameter dimension of the battery case 5) = 0.
It was 986. Further, at the time of charging / discharging, (maximum outer dimension of battery case 5) / (minimum outer dimension) was 1.13. This non-aqueous electrolyte secondary battery is a sample battery of Example 2.

Example 3 In this example, the non-aqueous electrolyte secondary battery shown in the third embodiment was produced.

Specifically, first, a negative electrode active material powder made of a non-graphitizable carbon material was prepared in the same manner as in Example 1, and a slurry using this was made into a strip-shaped copper foil having a thickness of 10 μm. After coating on both surfaces, drying, compression molding, and cutting, a rectangular negative electrode 21 was produced.

Further, in the same manner as in Example 1, a slurry containing the positive electrode active material powder was applied to both sides of a strip-shaped aluminum foil having a thickness of 20 μm, dried and compression-molded, and then cut into a rectangular shape. The positive electrode 22 was produced.

Next, the above-mentioned negative electrode 21 and positive electrode 2
2 is laminated in multiple layers with a separator 23 made of a microporous polypropylene film interposed therebetween to form a rectangular parallelepiped electrode element 4
0 was produced. The outer dimension of the electrode element 40 in the stacking direction x was 7.54 mm.

The above-mentioned electrode element 40 has an outer dimension (thickness) of 7.5 mm corresponding to the laminating direction x, an outer dimension (width) orthogonal to the laminating direction x, and a height of 48 mm, corresponding to the laminating direction x. The battery was housed in a rectangular battery case 25 having an inner size of 7.05 mm. An insulating plate 24 is provided below the electrode element 40, and the positive electrode lead 33 and the negative electrode lead 3 are provided.
2 was welded to the terminals on the battery lid 27, respectively. Then
Propylene carbonate 50 in the battery case 25
After injecting an organic electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l in a mixed solvent of 50% by volume of dimethyl carbonate and 50% by volume of dimethyl carbonate, the battery lid 27 was fixed to the battery case 25 by laser welding, and non-aqueous electrolysis was performed. A liquid secondary battery was completed.

In the non-aqueous electrolyte secondary battery thus manufactured, the electrode element 40 was inserted into the battery case 25 before (the outer dimension of the electrode element 40 in the stacking direction x) /
(Internal dimensions corresponding to the stacking direction x of the battery case 25) =
It was 1.07. During charging / discharging, (the battery case 25
The maximum value of the outer dimension corresponding to the stacking direction x) / (the minimum value of the outer dimension) = 1.17. This non-aqueous electrolyte secondary battery is a sample battery of Example 3.

Example 4 In this example, the non-aqueous electrolyte secondary battery shown in the fourth embodiment was produced.

Specifically, first, a negative electrode active material powder made of graphite material powder was prepared in the same manner as in Example 2, and a slurry using this was applied to both sides of a strip-shaped copper foil having a thickness of 10 μm. Then, after drying, compression molding, and cutting, a rectangular negative electrode 21 was produced.

Further, a rectangular positive electrode 22 was prepared in the same manner as in Example 3, and these negative electrode 21 and positive electrode 2 were formed.
A large number of layers of 2 were laminated with the separator 23 in between to form a rectangular parallelepiped electrode element 40. The outer dimension of the electrode element 40 in the stacking direction x was 7.54 mm.

Thereafter, as in Example 3, the outer dimension (thickness) of 7.5 mm corresponding to the laminating direction x, the outer dimension (width) orthogonal to the laminating direction x, and the height of 48 mm corresponded to the laminating direction x. Square battery case 2 with internal dimensions of 7.05 mm
The above-mentioned electrode element 40 was housed in 5 to complete the non-aqueous electrolyte secondary battery.

Also in this non-aqueous electrolyte secondary battery, in the state before the electrode element 40 is inserted into the battery case 25, (the outer dimension of the electrode element 40 in the stacking direction x) / (the stacking direction x of the battery case 25) Corresponding internal dimension) = 1.07. Further, during charging / discharging, (maximum value of outer dimension corresponding to stacking direction x of battery case 25) / (minimum value of outer dimension) = 1.22
Met. This non-aqueous electrolyte secondary battery is a sample battery of Example 4.

Evaluation of Characteristics Hereinafter, characteristics such as battery capacity and non-defective rate of the non-aqueous electrolyte secondary battery produced as described above will be evaluated.

First, a non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 and Example 2 except that the inner diameter of the battery case 5 was variously changed. Further, except that the internal dimensions of the battery case 25 corresponding to the stacking direction x are variously changed,
Non-aqueous electrolyte secondary batteries were produced in the same manner as in Example 3 and Example 4.

Regarding the non-aqueous electrolyte secondary battery thus produced, (outer diameter of electrode element 20) / (inner diameter of battery case 5) or (outer diameter of electrode element 40 in the stacking direction x) (Dimension) / (internal dimension corresponding to the stacking direction x of the battery case 25) was calculated, and the initial capacity and the non-defective rate were examined, respectively.

Here, the initial capacity was measured with a constant current of 700 mA discharged to 2.75 V. Also,
The non-defective rate is 4 at a charging current of 1A and a maximum charging voltage of 4.2V.
The battery is charged at a constant current and a constant voltage for a period of time, then left in an open circuit state, and after 12 hours, the battery voltage is measured to calculate the percentage of batteries (non-defective products) in which the voltage drop is suppressed to a small level. For these measurements, 50 batteries having the same structure were prepared.

The results are shown in Tables 1 to 4 and FIGS. 4 to 7. In addition, Table 1 and FIG. 4 show the results for the non-aqueous electrolyte secondary battery having the same configuration as in Example 1 except that the inner diameter of the battery case 5 was different. Table 2 and FIG. The results are shown for the non-aqueous electrolyte secondary battery having the same configuration as in Example 2 except that the inner diameter of the battery case 5 is different. In addition, Table 3 and FIG. 6 show the results for the non-aqueous electrolyte secondary battery having the same configuration as in Example 3 except that the inner dimension corresponding to the stacking direction x of the battery case 25 is different. 4 and FIG. 7 show the results for the non-aqueous electrolyte secondary battery having the same configuration as that of Example 4 except that the inner dimensions of the battery case 25 corresponding to the stacking direction x are different.

[0106]

[Table 1]

[0107]

[Table 2]

[0108]

[Table 3]

[0109]

[Table 4]

From Tables 1 to 4 and FIGS. 4 to 7, (outer diameter of electrode element 20) / (inner diameter of battery case 5) or (outer dimension of electrode element 40 in stacking direction x) / (battery) It can be seen that if the inner dimension (corresponding to the stacking direction x) of the case 25 is too large or too small, the initial capacity will decrease. Further, (the outer diameter of the electrode element 20) / (the inner diameter of the battery case 5) or (the outer dimension of the electrode element 40 in the stacking direction x) / (the inner dimension corresponding to the stacking direction x of the battery case 25) is large. It can be seen that if it is too much, the non-defective rate decreases.

From Tables 1, 2 and 4 and 5, in the cylindrical non-aqueous electrolyte secondary battery, (outer diameter of electrode element 20) / (inner diameter of battery case 5) is 0.8 to It can be seen that when the range is 1.3, both the initial capacity and the yield rate are excellent. Also, from Tables 3 and 4 and FIGS.
In the rectangular non-aqueous electrolyte secondary battery, (electrode element 40
Outer dimension in the stacking direction x) / (inner dimension corresponding to the stacking direction x of the battery case 25) is in the range of 0.95 to 1.5, whereby both the initial capacity and the non-defective rate are excellent. I understand.

A large initial capacity was obtained by setting the outer dimensions of the electrode elements 20, 40 and the inner dimensions of the battery cases 5, 25 accommodating the electrode elements within the above-mentioned ranges, because the expansion of the electrodes caused by the initial charge was obtained. This is because the regulation was able to maintain the binding property between the particles of the active material in a good state, suppress the increase in the internal resistance of the battery, and increase the utilization rate of the active material. Further, by setting the outer dimensions of the electrode elements 20, 40 and the inner dimensions of the battery cases 5, 25 accommodating the electrode elements within the above range, a good non-defective rate can be achieved.
This is because the electrode elements 20 and 40 were prevented from being broken when the 0 and 40 were inserted into the battery cases 5 and 25.

Further, regarding the non-aqueous electrolyte secondary battery evaluated as having excellent initial capacity and good product rate as described above, the maximum outer diameter of the battery case 5 during charging / discharging was confirmed. Value) / (minimum value of the outer diameter), or (maximum value of outer dimension corresponding to the stacking direction x of the battery case 25) /
(Minimum value of the outer dimension) was calculated, and the capacity per battery volume, that is, the capacity density was examined.

The results are shown in Tables 5 to 8 and FIGS. 8 to 11.
Shown in Table 5 and FIG. 8 show the results for the non-aqueous electrolyte secondary battery having the same configuration as that of Example 1 except that the inner diameter of the battery case 5 was different, and Table 6 and FIG.
Shows the results for the non-aqueous electrolyte secondary battery having the same configuration as in Example 2 except that the inner diameter of the battery case 5 was different. Further, in Table 7 and FIG.
The results for the non-aqueous electrolyte secondary battery having the same configuration as in Example 3 except that the internal dimensions corresponding to the stacking direction x are different are shown in Table 8 and FIG. Example 4 except that the inner dimension corresponding to x is different
The results for a non-aqueous electrolyte secondary battery having the same configuration as the above are shown.

[0115]

[Table 5]

[0116]

[Table 6]

[0117]

[Table 7]

[0118]

[Table 8]

From Tables 5 to 8 and FIGS. 8 to 11, (maximum outer diameter of battery case 5) / (minimum outer diameter) or (stacking direction x of battery case 25). Even if (maximum value of outer dimension) / (minimum value of outer dimension) is too large,
It can be seen that the capacity density tends to decrease even if it is too small.

From Tables 5 and 6 and FIGS. 8 and 9, in the cylindrical non-aqueous electrolyte secondary battery, (maximum outer diameter of battery case 5) / (minimum outer diameter) 1.01-1.1
It can be seen that by setting the range to 4, a high capacity density can be obtained. From Tables 7 and 8 and FIGS. 10 and 11, in the rectangular non-aqueous electrolyte secondary battery, (maximum outer dimension corresponding to the stacking direction x of the battery case 25) / (minimum outer dimension) It can be seen that a high capacity density can be obtained by setting the value) in the range of 1.04 to 1.35.

[0121]

As is apparent from the above description, when the present invention is applied, the expansion of the electrode caused by the initial charge can be regulated, and the binding property between the particles of the active material can be maintained satisfactorily. The utilization rate of substances can be increased. For this reason,
A non-aqueous electrolyte secondary battery having high energy density and large initial capacity can be obtained.

Further, since the non-defective product rate is also excellent, the non-aqueous electrolyte secondary battery has high performance and high reliability and productivity.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a cylindrical non-aqueous electrolyte secondary battery.

FIG. 2 is a schematic cross-sectional view showing a configuration example of a prismatic non-aqueous electrolyte secondary battery.

FIG. 3 is an explanatory diagram showing a configuration of a battery case for allowing an electrode element larger than the inner dimension of the battery case to be inserted.

FIG. 4 shows a cylindrical non-aqueous electrolyte secondary battery having a negative electrode using a non-graphitizable material (outer diameter of electrode element) /
FIG. 6 is a characteristic diagram showing a relationship between (inner diameter of battery case) and initial capacity and non-defective rate.

FIG. 5 shows the relationship between (outer diameter of electrode element) / (inner diameter of battery case) and initial capacity and non-defective rate for a cylindrical non-aqueous electrolyte secondary battery having a negative electrode using a graphite material. It is a characteristic view to show.

FIG. 6 shows an angular non-aqueous electrolyte secondary battery having a negative electrode using a non-graphitizable material (outer dimension in the stacking direction of electrode elements) / (inner dimension corresponding to the stacking direction in the battery case).
FIG. 6 is a characteristic diagram showing the relationship between the initial capacity and the yield rate.

FIG. 7 shows a rectangular non-aqueous electrolyte secondary battery having a negative electrode using a graphite material, in which (outer dimension of electrode element in stacking direction) / (inner dimension corresponding to stacking direction of battery case):
FIG. 9 is a characteristic diagram showing a relationship between an initial capacity and a non-defective rate.

FIG. 8 shows a cylindrical non-aqueous electrolyte secondary battery having a negative electrode using a non-graphitizable material, (maximum outer diameter of battery case) / (minimum outer diameter) and capacity density. It is a characteristic view which shows the relationship with.

FIG. 9 shows the relationship between (maximum value of outer diameter of battery case) / (minimum value of outer diameter) and capacity density of a cylindrical non-aqueous electrolyte secondary battery having a negative electrode using a graphite material. It is a characteristic view which shows a relationship.

FIG. 10 shows the maximum non-aqueous electrolyte secondary battery having a negative electrode using a non-graphitizable material (maximum outer dimension corresponding to the stacking direction of battery cases) / (minimum outer dimension). )
FIG. 6 is a characteristic diagram showing the relationship between the capacitance density and the capacitance density.

FIG. 11 shows a rectangular non-aqueous electrolyte secondary battery having a negative electrode using a graphite material, with (maximum outer dimension corresponding to the stacking direction of battery cases) / (minimum outer dimension) ,
It is a characteristic view which shows the relationship with capacity density.

[Explanation of symbols]

1,21 Negative electrode, 2,22 Positive electrode, 3,2
3 Separator, 5,25 Battery case, 20, 4
0 electrode element

Claims (6)

[Claims] 1. A non-aqueous electrolyte secondary battery in which an electrode element in which a positive electrode and a negative electrode are laminated via a separator is housed in a battery case and a non-aqueous electrolyte is injected. The outer dimension of the electrode element is 0.8 to 1.5 times the inner dimension of the battery case before the electrode element is housed in the battery case. Non-aqueous electrolyte battery. 2. The electrode element is formed by winding a long electrode in a spiral shape into a columnar shape, and when the battery case is cylindrical, the outer diameter of the electrode element is The non-aqueous electrolyte secondary battery according to claim 1, wherein the size of the inner diameter of the battery case is 0.8 to 1.3 times. 3. The electrode element is a rectangular parallelepiped formed by stacking a plurality of rectangular electrodes, and when the battery case is rectangular, the outer dimension of the electrode element in the electrode stacking direction is:
The non-aqueous electrolyte secondary battery according to claim 1, wherein the inner dimension corresponding to the stacking direction in the battery case is 0.95 to 1.5 times. 4. The maximum outer dimension of the battery case is 1.01 to 1.35 times the minimum outer dimension of the battery case after the electrode element is housed in the battery case. The non-aqueous electrolyte secondary battery according to claim 1, wherein 5. The maximum value of the outer diameter of the battery case is obtained when the electrode element is a cylindrical electrode formed by winding a long electrode in a spiral shape, and the battery case is a cylindrical type. Is 1.01 to 1.14 times the minimum value of the outer diameter, The non-aqueous electrolyte secondary battery according to claim 3, wherein 6. The electrode element is a rectangular parallelepiped formed by stacking a plurality of rectangular electrodes, and when the battery case is rectangular, an outer dimension corresponding to a stacking direction of the electrodes in the battery case. The maximum value of 1.0 is 1.0 with respect to the minimum value of the outer dimension.
4. The non-aqueous electrolyte secondary battery according to claim 3, wherein the ratio is 4 to 1.35 times.