JP2000294243A - Carbon powder for lithium secondary battery negative electrode, manufacture therefor, negative electrode for lithium secondary battery and lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance capacity, and to improve a cycle characteristic and a rapid charge/discharge characteristic by performing isotropic pressurizing processing on carbon powder. SOLUTION: When performing isotropic pressurizing processing on carbon powder, bulk density and fluidity are improved, a fluctuation in density of a negative electrode manufactured by using this carbon powder is reduced, and adhesion to a negative electrode current collector is improved. Pressure of this pressurizing processing is desirably set to a range of 50 to 2000 kgf/cm2. The obtained carbon powder is desirably graphite powder on which an interlayer distance d(002) of a crystal is not more than 3.38 Å, the C axis directional crystallite size Lc(002) is not less than 500 Å, the average particle size is 10 to 100 μm, the specific surface area is not more than 8 m2/g, the aspect ratio is 1.1 to 5, a true specific gravity is not less than 2.2 and bulk density is not less than 0.3 g/cm3. The carbon powder as a raw material is not particularly limited, and natural graphite, artificial graphite, amorphous carbon and low temperature processing carbon are cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a carbon powder for a negative electrode of a lithium secondary battery, a carbon powder for a negative electrode of a lithium secondary battery prepared by the method, and a negative electrode for a lithium secondary battery using the carbon powder. And a lithium secondary battery using the negative electrode. More specifically, the present invention relates to a lithium secondary battery having high capacity and excellent cycle characteristics suitable for use in portable devices, electric vehicles, and electric power storage, a negative electrode for obtaining the same, a carbon powder for the negative electrode, and a method for producing the same. .

[0002]

2. Description of the Related Art Conventional negative electrode materials for lithium secondary batteries include:
Examples thereof include natural graphite particles, artificial graphite particles obtained by graphitizing coke, organic polymer materials, artificial graphite particles obtained by graphitizing pitch and the like, and graphite particles obtained by pulverizing these. These graphite particles are mixed with an organic binder and an organic solvent to form a graphite paste, the graphite paste is applied to the surface of a copper foil, the solvent is dried, and used as a negative electrode for a lithium secondary battery. I have. For example, as shown in JP-B-62-23433, the use of graphite for the negative electrode solves the problem of content short-circuit due to lithium dendrite, thereby improving cycle characteristics.

However, natural graphite in which graphite crystals are developed has a weaker bonding force between the layers of the crystal in the C-axis direction than the bonding in the plane direction of the crystals. So-called scale-like graphite particles having a large ratio are obtained. Scale-like graphite has a large aspect ratio,
When an electrode is produced by kneading with a binder and applying the mixture to a current collector, the scale-like graphite particles are oriented in the plane direction of the current collector, and as a result, the charge / discharge capacity and rapid charge / discharge characteristics are liable to be reduced. In addition, there is a problem that the inside of the electrode is broken due to the expansion and contraction in the C-axis direction caused by the repeated insertion and extraction of lithium into and from the graphite crystal, and the cycle characteristics are degraded.

On the other hand, artificial graphite obtained by calcining coke, pitch, organic materials, etc. at 2000 ° C. or higher can have a relatively small aspect ratio as compared with natural graphite, but the graphite crystal is poorly developed. Low charge / discharge capacity. Therefore, there is a demand for a carbon material for a negative electrode capable of producing a lithium secondary battery having a high capacity and improved cycle characteristics, rapid charge / discharge characteristics, and the like.

[0005]

SUMMARY OF THE INVENTION The present invention has a high capacity,
An object of the present invention is to provide a method for producing a carbon material for a lithium secondary battery negative electrode having excellent cycle characteristics and rapid charge / discharge characteristics. Another object of the present invention is to provide a carbon material for a negative electrode of a lithium secondary battery having a high capacity and excellent in cycle characteristics and rapid charge / discharge characteristics. Another object of the present invention is to provide a negative electrode for a lithium secondary battery having excellent adhesion between a current collector and a negative electrode mixture, high capacity, and excellent cycle characteristics and rapid charge / discharge characteristics.
Further, the present invention provides a lithium secondary battery having a high capacity and excellent cycle characteristics and rapid charge / discharge characteristics.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing carbon powder for a negative electrode of a lithium secondary battery, which comprises subjecting carbon powder to isotropic pressure treatment. The present invention also relates to a method for producing carbon powder for a negative electrode of a lithium secondary battery, wherein the pressing pressure in the pressure treatment is 50 to 2000 kgf / cm ² . The present invention also relates to a carbon powder for a negative electrode of a lithium secondary battery obtained by the above-mentioned production method.

Further, the present invention provides a method of manufacturing a semiconductor device, comprising the steps of:
2) is 3.38 ° or less, and the crystallite size Lc in the C-axis direction is
(002) is 500 ° or more, average particle size is 10 to 100 μm
m, specific surface area is 8 m ² / g or less, aspect ratio is 1.1 ~
5. The present invention relates to a carbon powder for a negative electrode of a lithium secondary battery, which is a graphite powder having a bulk density of 0.3 g / cm ³ or more and obtained by the above-mentioned production method.

[0008] The present invention also relates to a carbon powder produced by the above-mentioned production method or a negative electrode for a lithium secondary battery containing the carbon powder. Furthermore, the present invention relates to a lithium secondary battery having the above-mentioned negative electrode and a positive electrode containing a lithium compound.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing carbon powder for a negative electrode of a lithium secondary battery according to the present invention is characterized in that the carbon powder is subjected to isotropic pressure treatment. Here, the isotropic pressure treatment is
This is not a pressurization only from a specific direction (anisotropic pressurization process) like a pressurization from one direction, but a generally known process of pressurizing from all directions. As described above, when the carbon powder is subjected to the isotropic pressure treatment, the bulk density and the fluidity of the obtained lithium secondary battery negative electrode carbon powder are improved, and the density variation of the lithium secondary battery negative electrode to be produced is small and Adhesion with the negative electrode current collector is improved. As a result, the cycle characteristics of the obtained lithium secondary battery can be improved.

In order to improve the bulk density of the carbon powder, anisotropic pressing, such as uniaxial pressing or roll pressing, which presses in one direction, other than isotropic pressing, is used as a pressing method. If this is done, there is a problem that the rapid charge / discharge characteristics of the obtained lithium secondary battery deteriorate.

The method of the isotropic pressure treatment of the carbon powder is not particularly limited as long as it can be isotropically pressed.
For example, pressure treatment such as isostatic pressing using carbon powder in a container such as a rubber mold and using water as a pressurizing medium or isostatic pressing using air or other gas as a pressurizing medium can be performed. No.

[0012] The pressure of the pressurized medium of isotropic pressure treatment of carbon powder, preferably in the range of 50~2000kgf / cm ^2, more preferably be in the range of 200~2000kgf / cm ^2, 500~1800kgf / It is more preferable that the range is cm ² . If the pressure is less than 50 kgf / cm ² , the effect of improving the cycle characteristics of the obtained lithium secondary battery tends to be small. When the pressure exceeds 2000 kgf / cm ² , the specific surface area of the obtained carbon material for a negative electrode of a lithium secondary battery increases, and as a result, the irreversible capacity in the first cycle of the obtained lithium secondary battery tends to increase. It is in.

When the carbon powder is subjected to isotropic pressure treatment as described above, the particles tend to agglomerate. Therefore, it is preferable to perform a treatment such as crushing and sieving after the isotropic pressure treatment.
When the particles do not agglomerate, the particles need not be disintegrated.

Although the cycle characteristics and the like can be greatly improved by the above method, the carbon powder for a negative electrode of a lithium secondary battery produced in this manner has a crystal interlayer distance d (002) of 3. 38 ° or less, crystallite size Lc (002) in the C-axis direction is 500 ° or more, and average particle size is 10 to
100 μm, specific surface area 8 m ² / g or less, aspect ratio 1.1-5, true specific gravity 2.2 or more, bulk density 0.3 g / g
A graphite powder of cm ³ or more is preferable because a lithium secondary battery having high capacity and excellent in rapid charge / discharge characteristics and cycle characteristics can be obtained.

Here, the interlayer distance d (002) of the crystal is a value calculated from the measurement of wide-angle X-ray diffraction of the carbon powder for a negative electrode of a lithium secondary battery. When this value exceeds 3.38 °, the discharge capacity becomes small. Tend. The lower limit of d (002) is not particularly limited, but is usually 3.35 ° or more. Also,
The crystallite size Lc (002) in the C-axis direction is also a value calculated from the measurement of wide-angle X-ray diffraction. If this value is less than 500 °, the discharge capacity tends to be small. Lc (002)
The upper limit is not particularly limited, but is usually set to 10,000 ° or less.

On the other hand, if the aspect ratio is less than 1.1, the contact area between the particles tends to decrease, so that the conductivity tends to decrease. On the other hand, when the aspect ratio is larger than 5, the rapid charge / discharge characteristics tend to decrease. The aspect ratio is A / B, where A is the length in the major axis direction of the carbon powder for the negative electrode of the lithium secondary battery and B is the length in the minor axis direction.
It is represented by In the present invention, the aspect ratio is determined by enlarging the carbon powder for a negative electrode of a lithium secondary battery with a microscope,
The number of particles was selected, A / B was measured, and the average was taken.

Further, when the specific surface area of the carbon powder for a negative electrode of a lithium secondary battery exceeds 8 m ² / g, the irreversible capacity of the lithium secondary battery obtained in the first cycle becomes large, the energy density is small, and There is a tendency for many binders to be required when making. More preferably, the specific surface area is 1 m ² / g or more. The specific surface area can be measured by a known method such as a BET method (nitrogen gas adsorption method).

If the bulk density of the carbon powder for a negative electrode of a lithium secondary battery is less than 0.3 g / cm ³ , a large amount of a binder is likely to be required when manufacturing the negative electrode, and as a result, the lithium secondary The energy density of the battery decreases. Although the upper limit of the bulk density is not particularly limited, it is usually 1.5 g / cm ³ or less. To measure the bulk density, a measuring cylinder having a capacity of 100 cm ³ was slanted, and 100 cm ³ of sample powder was gradually poured into the measuring cylinder using a spoon. After the measuring cylinder was plugged, the measuring cylinder was dropped 50 times from a height of 5 cm. It can be calculated from the weight and volume of the sample powder after the drop.

The true specific gravity is usually 2.3 or less.
The average particle size of the obtained carbon powder for a negative electrode of a lithium secondary battery is preferably 10 to 100 μm, and 10 to 50 μm.
m is more preferred. The average particle size in the present invention can be measured by a laser diffraction type particle size distribution meter.

Further, when a graphite powder having the above-mentioned characteristics is used as the carbon powder before the isotropic pressure treatment, a lithium secondary battery having a high capacity, particularly excellent in rapid charge / discharge characteristics and cycle characteristics is used. Is preferred. The carbon powder before performing the above isotropic pressure treatment is not particularly limited, and natural graphite, artificial graphite obtained by graphitizing coke, organic polymer material, artificial graphite obtained by graphitizing pitch, etc. Carbon, low-temperature-treated carbon and the like, but preferably artificial graphite, among which, a graphitizable aggregate or a mixture of graphite and a graphitizable binder and a graphitization catalyst, and produced through a firing and pulverization process Are preferred. By mixing graphitizable aggregates or graphite with a graphitizable binder, the aspect ratio of the resulting carbon powder can be reduced, thereby improving the rapid charge / discharge characteristics of the lithium secondary battery produced. Can be done.

Examples of the graphitizable aggregate include coke powder and resin carbide. Graphitizable binders include pitch, tar, thermosetting resin,
An organic material such as a thermoplastic resin may be used. Further, by adding the graphitization catalyst, the crystal of the obtained carbon powder is easily developed, and the discharge capacity of the obtained lithium secondary battery can be improved.

As the graphitization catalyst, Ti, Si, Fe,
Metals such as Ni and B or oxides or carbides thereof are preferred. The graphitization catalyst is preferably added when the aggregate and the binder are mixed, and mixed at the same time. The mixing temperature is preferably a temperature at which the graphitizable binder softens and melts. The temperature varies depending on the material used, but is preferably in the range of 50 to 350 ° C. When the graphitizable binder is made into a solution with a solvent or the like, the graphitizing catalyst may be mixed at room temperature.

Next, a graphitizable aggregate or a mixture of graphite, a graphitizable binder and a graphitizing catalyst is mixed with 2%
It is preferable to graphitize by firing at a temperature of 500 ° C. or higher. In the present invention, before the mixture is graphitized at a temperature of 2500 ° C. or higher, pulverization and molding are performed, and
It may be fired at a temperature of about 1300 ° C. Also,
After firing at a temperature of about 700 to 1300 ° C., pulverizing,
After adjusting the particle size, the powder may be baked at a temperature of 2500 ° C. or more to graphitize. The firing temperature at the time of graphitization is 2500 in terms of crystallinity and discharge capacity of the obtained negative electrode carbon material.
C. or higher, more preferably 2800 C. or higher, even more preferably 3000 C. or higher. The atmosphere during firing is not particularly limited as long as it is not easily oxidized,
For example, a self-volatile gas atmosphere, a nitrogen atmosphere, an argon atmosphere, a vacuum or the like can be given.

Next, the powder is pulverized to adjust the particle size to obtain a carbon powder. The pulverization method is not particularly limited, and an impact pulverization method such as a jet mill, a hammer mill, and a pin mill can be used. The average particle size of the pulverized carbon powder is preferably 10 to 100 μm. In addition, when pulverized before graphitization and the particle size is adjusted, it is not necessary to pulverize after graphitization.

The carbon powder produced as described above is subjected to isotropic pressure treatment to obtain a carbon powder for a negative electrode of a lithium secondary battery suitable for a lithium secondary battery having excellent cycle characteristics and rapid charge / discharge characteristics. be able to.

The carbon powder for a negative electrode of a lithium secondary battery according to the present invention may be kneaded with an organic binder and a solvent to form a paste-like negative electrode mixture, which may be formed into a sheet-like or pellet-like shape. it can. As the organic binder, for example, polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber,
Butyl rubber, a polymer compound having a high ionic conductivity, or the like can be used.

As the high molecular compound having a high ionic conductivity, polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphasphazene, polyacrylonitrile and the like can be used. The mixing ratio of the carbon powder and the organic binder is preferably 1 to 20 parts by weight based on 100 parts by weight of the carbon powder.

The solvent is not particularly restricted but includes N-methyl-2-pyrrolidone, dimethylformamide, isopropanol and the like. The amount of the solvent is not particularly limited.
The carbon powder is kneaded with an organic binder and a solvent, and after adjusting the viscosity, applied to a current collector, and integrated with the current collector to form a negative electrode. As the current collector, for example, a metal current collector such as a foil of nickel, copper or the like, or a mesh can be used. In addition, the integration can be performed by a molding method such as a roll, a press, or the like, and these molding methods may be combined to be integrated.

The negative electrode thus obtained is used together with the positive electrode containing a lithium compound in the lithium secondary battery of the present invention. The lithium secondary battery can be obtained, for example, by arranging a positive electrode and a negative electrode to face each other with a separator interposed therebetween, and injecting an electrolytic solution. The lithium secondary battery of the present invention has high capacity, excellent cycle characteristics, and excellent rapid charge / discharge characteristics, as compared with a conventional lithium secondary battery using carbon powder for the negative electrode.

The positive electrode of the lithium secondary battery of the present invention contains a lithium compound, but the material is not particularly limited.
For example, LiNiO ₂ , LiCoO ₂ , LiMn ₂ O _{4 and the} like can be used alone or in combination. The lithium secondary battery according to the present invention generally contains an electrolyte containing a lithium compound together with a positive electrode and a negative electrode. As the electrolyte, Li
ClO ₄ , LiPF ₆ , LiAsF, LiBF ₄ , LiS
A so-called organic electrolytic solution in which a lithium salt such as O ₃ CF ₄ is dissolved in a non-aqueous solvent such as ethylene carbonate, diethyl carbonate, dimethoxyethane, dimethyl carbonate, methyl ethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, etc .; So-called polymer electrolytes can be used.

As the separator, for example, a nonwoven fabric, cloth, microporous film, or a combination thereof containing polyolefin such as polyethylene and polypropylene as a main component can be used. Note that when the positive electrode and the negative electrode of the lithium secondary battery to be manufactured do not directly contact during use, the separator may not be used.

FIG. 1 shows a partial cross-sectional front view of an example of a cylindrical lithium secondary battery. The cylindrical lithium secondary battery shown in FIG. 1 is obtained by winding a positive electrode 1 processed into a thin plate and a negative electrode 2 processed in the same manner via a separator 3 such as a polyethylene microporous membrane. This is inserted into a battery can 7 made of metal or the like, and sealed. The positive electrode 1 is connected to a positive electrode cover 6 via a positive electrode tab 4, and the negative electrode 2 is connected to a battery bottom via a negative electrode tab 5. The positive cover 6 is a gasket 8
To the battery can (positive electrode can) 7.

[0033]

Embodiments of the present invention will be described below. Example 1 [Preparation of carbon powder for pressure treatment] 50 parts by weight of coke powder having an average particle size of 15 µm, 15 parts by weight of pitch, 20 parts by weight of coal tar, and 10 parts by weight of silicon carbide were heated at 230 ° C.
For 1 hour. The mixture is then averaged with a particle size of 25.
It was pulverized to a size of μm, and the pulverized product was put into a mold and press-formed to form a rectangular parallelepiped. After heat-treating this compact at 1000 ° C., it was further heat-treated at 3000 ° C. to obtain a graphite compact.
The graphite compact was further pulverized to obtain a carbon powder.

[Preparation of Carbon Powder for Negative Electrode of Lithium Secondary Battery] The carbon powder obtained as described above is filled in a rubber container and sealed, and then the rubber container is pressurized with a hydrostatic press machine under the pressure of a pressurized medium. An isotropic pressure treatment was performed at 1500 kgf / cm ² . Then, the mixture was pulverized with a cutter mill to obtain carbon powder for a negative electrode of a lithium secondary battery. The bulk density, average particle size, specific surface area, d (0
02), Lc (002), and aspect ratio are shown in Table 1.

Next, a negative electrode and a lithium secondary battery were manufactured using the obtained carbon powder for a negative electrode. The lithium secondary battery of the present invention shown in FIG. 1 was manufactured as follows. 88% by weight of LiCoO ₂ is used as a positive electrode active material, 7% by weight of flake graphite having an average particle diameter of 2 μm is used as a conductive agent, and polyvinylidene fluoride (PVDF) 5 is used as a binder.
% N-methyl-2-pyrrolidone was added thereto and mixed to prepare a positive electrode mixture paste. Similarly, as a negative electrode active material, 10% by weight of PVDF was added as a binder to the negative electrode carbon material prepared by the above method, and N-methyl-2-pyrrolidone was added thereto, followed by mixing. The paste was adjusted.

The positive electrode mixture was applied to both sides of a 25-μm-thick aluminum foil, and then vacuum-dried at 120 ° C. for 1 hour. Then, the electrode was pressure-formed by a roll press, and further formed into a size having a width of 40 mm and a length of 285 mm. This was cut out to produce a positive electrode. However, the positive electrode mixture was not applied to both ends of the positive electrode at a length of 10 mm, and the aluminum foil was exposed. A positive electrode tab was pressure-bonded to one of these parts by ultrasonic bonding.

On the other hand, the negative electrode mixture was applied to both sides of a copper foil having a thickness of 10 μm, and then vacuum dried at 120 ° C. for 1 hour. After vacuum drying, the electrode was pressure-formed by a roll press, and cut into a size of 40 mm in width and 290 mm in length to produce a negative electrode. Like the positive electrode, the negative electrode mixture was not applied to the 10 mm long portions of both ends of the negative electrode, and the copper foil was exposed,
A negative electrode tab was pressure-bonded to one of the two by ultrasonic bonding.

As the separator, a polyethylene microporous membrane having a thickness of 25 μm and a width of 44 mm was used. A positive electrode, a separator, a negative electrode, and a separator were superimposed in this order and wound to form an electrode group. This was inserted into an AA size battery can, the negative electrode tab was welded to the bottom of the can, and a throttle portion for caulking the positive electrode lid was provided. An electrolyte obtained by dissolving lithium hexafluorophosphate at 1 mol / liter in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 2 was injected into the battery can, and then the positive electrode tab was welded to the positive electrode cover. The battery was produced by caulking the positive electrode lid.

Using this battery, the charge and discharge characteristics were evaluated. The charging condition of the manufactured lithium secondary battery is as follows.
After charging at 0 mA with a constant current to a battery voltage of 4.2 V, the battery was charged at a constant voltage of 4.2 V until the current reached 30 mA. Table 2 shows the discharge capacity when the battery was discharged at a constant current at a current of 300 mA until the battery voltage reached 2.8 V. In addition, current 30
Table 2 shows the discharge capacity retention ratio when the battery was discharged at a constant current until the battery voltage reached 2.8 V at a current of 900 mA with respect to the discharge capacity at 0 mA. At a current of 300 mA, the battery voltage is 4.2 V.
After charging the battery with a constant current up to
A cycle of constant voltage charging until the current reaches 0 mA and constant current discharging until the battery voltage reaches 2.8 V at a current of 300 mA is performed for 300 cycles.
Table 2 shows the discharge capacity retention ratio when the discharge was repeated for 500 times and 500 times.

Example 2 and Example 3 In Example 1, the pressure of the pressurized medium by the hydrostatic press was changed to 600 kgf / cm ² (Example 2) and 1000 kgf / cm ^2.
Except that the pressure was changed to kgf / cm ² (Example 3), the carbon powder was subjected to isotropic pressure treatment in exactly the same manner, and the obtained carbon powder was used in the same manner as in Example 1 to obtain a lithium secondary battery. Was prepared, and the charge / discharge characteristics were evaluated. Table 1 shows the bulk density, average particle size, specific surface area, d (002), Lc (002), and aspect ratio of the carbon powder. Table 2 shows the results of the evaluation of the charge / discharge characteristics evaluated in the same manner as in Example 1.

Comparative Example 1 A lithium secondary battery was produced in the same manner as in Example 1 except that the carbon powder prepared in Example 1 was not subjected to isotropic pressure treatment and was used as it was as a carbon powder for a negative electrode of a lithium secondary battery. Was prepared, and the charge / discharge characteristics were evaluated. Table 1 shows the bulk density, average particle size, specific surface area, d (002), Lc (002), and aspect ratio of the carbon powder. Table 2 shows the results of the evaluation of the charge / discharge characteristics evaluated in the same manner as in Example 1.

Comparative Example 2 A carbon powder produced in the same manner as in Example 1 was filled in a mold and subjected to a uniaxial press to apply a pressure of 1500 kgf / cm ² from above in a fixed direction. A negative electrode carbon powder for a lithium secondary battery was produced in the same manner as in Example 1. Table 1 shows the bulk density, average particle size, specific surface area, d (002), Lc (002), and aspect ratio of the obtained carbon powder for a lithium secondary battery negative electrode. Table 2 shows the results of the evaluation of the charge / discharge characteristics evaluated in the same manner as in Example 1.

[0043]

[Table 1]

[0044]

[Table 2]

As is clear from Table 2, the carbon powder for a negative electrode of a lithium secondary battery of the present invention is suitable as a lithium secondary battery having a high capacity, excellent cycle characteristics and rapid charge / discharge characteristics. Was.

[0046]

According to the production method of the present invention, a carbon material for a negative electrode of a lithium secondary battery having a high capacity and excellent in cycle characteristics and rapid charge / discharge characteristics can be obtained. Further, the carbon material for a negative electrode of a secondary battery of the present invention has high capacity and excellent cycle characteristics and rapid charge / discharge characteristics. Further, the negative electrode for a lithium secondary battery of the present invention has excellent adhesion between the current collector and the negative electrode mixture, has high capacity, and has excellent cycle characteristics and rapid charge / discharge characteristics. Further, the lithium secondary battery of the present invention has a high capacity,
It has excellent cycle characteristics and rapid charge / discharge characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a lithium secondary battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Positive electrode tab 5 Negative electrode tab 6 Positive electrode cover 7 Battery can 8 Gasket

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Fujita 3-3-1 Ayukawacho, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (72) Kazuo Yamada 3-chome Ayukawacho, Hitachi City, Ibaraki Prefecture No. 1 F-term in Hitachi Chemical Co., Ltd. Yamazaki Plant (reference) 4G046 CA06 CA07 CB00 CB02 CB09 CC03 5H003 AA02 AA04 BA05 BB01 BC01 BC06 BD00 BD01 BD02 BD03 BD05 5H014 AA01 BB05 EE08 HH00 HH01 HH06 HH08

Claims (6)

[Claims] 1. A method for producing a carbon powder for a negative electrode of a lithium secondary battery, wherein the carbon powder is subjected to isotropic pressure treatment. 2. The pressing pressure of the pressure treatment is 50 to 2000.
The method for producing a carbon powder for a negative electrode of a lithium secondary battery according to claim 1, wherein the weight is kgf / cm ² . 3. A carbon powder for a negative electrode of a lithium secondary battery obtained by the production method according to claim 1. 4. The interlayer distance d (002) of the crystal is 3.38.
Å Hereinafter, the crystallite size Lc (002) in the C-axis direction is 50
0 ° or more, average particle size of 10 to 100 μm, specific surface area of 8
m ² / g or less, aspect ratio of 1.1 to 5, bulk density of 0.
4. The carbon powder for a negative electrode of a lithium secondary battery according to claim 3, which is a graphite powder of ³ g / cm ³ or more. 5. A negative electrode for a lithium secondary battery comprising the carbon powder prepared by the method according to claim 1 or 2 or the carbon powder according to claim 3 or 4. 6. A lithium secondary battery comprising the negative electrode according to claim 5 and a positive electrode containing a lithium compound.