JP3361510B2 - Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a negative electrode for a lithium secondary battery, a method for producing the same, and a lithium secondary battery. More specifically, it is suitable for use in portable devices, electric vehicles, electric power storage, etc., and has excellent charge / discharge characteristics, cycle characteristics, etc., a lithium secondary battery, a negative electrode for the lithium secondary battery to obtain the lithium secondary battery, and the production thereof. Concerning the law.

[0002]

2. Description of the Related Art Conventional negative electrodes for lithium secondary batteries include, for example, natural graphite particles, artificial graphite particles obtained by graphitizing coke,
There are those using organic polymer materials, artificial graphite particles obtained by graphitizing pitch and the like, graphite particles obtained by crushing these, spherical particles obtained by graphitizing mesocarbon micro beads.
These graphite particles are used as a negative electrode for a lithium secondary battery by mixing an organic binder and an organic solvent to form a graphite paste, applying the graphite paste on the surface of a copper foil, and drying the solvent. . For example, Japanese Patent Publication No. 62-23433
As disclosed in the publication, the use of graphite for the negative electrode solves the problem of internal short circuit due to dendrite of lithium and improves cycle characteristics.

However, natural graphite having developed graphite crystals and artificial graphite particles obtained by graphitizing coke have a weaker bonding force between the layers of the crystals in the c-axis direction than the bonding in the plane directions of the crystals. As a result, the bonds between the graphite layers are broken, resulting in so-called scale-like graphite particles having a large aspect ratio. Since the scale-like graphite particles have a large aspect ratio, the scale-like graphite particles are oriented in the plane direction of the current collector when kneaded with the binder and applied to the current collector to prepare an electrode, and as a result, In addition to the problem that the internal characteristics of the electrode are destroyed due to the strain in the c-axis direction caused by the repeated insertion and extraction of lithium in the graphite crystal, the cycle characteristics are deteriorated.
When the negative electrode density is 1.5 g / cm ³ or more, lithium is less likely to be absorbed and released in the negative electrode graphite, and there is a problem that rapid charge / discharge characteristics and discharge capacity are sharply reduced. The lithium secondary battery can be expected to increase the energy density per volume by increasing the negative electrode density. Therefore, in order to improve the energy density per volume of the lithium secondary battery, there is a demand for a negative electrode that causes less decrease in discharge capacity when the negative electrode density is increased.

[0004]

The invention according to claim 1 provides a negative electrode for a lithium secondary battery suitable for a high capacity lithium secondary battery. The invention according to claims 2 and 3 provides a negative electrode for a lithium secondary battery, which has a high capacity and is suitable for a lithium secondary battery having excellent rapid charge / discharge characteristics and cycle characteristics. The invention according to claim 4 provides a method for producing a negative electrode for a lithium secondary battery, which is suitable for a lithium secondary battery having high capacity and excellent rapid charge / discharge characteristics and cycle characteristics. The invention according to claim 5 provides a lithium secondary battery having high capacity and excellent in rapid charge / discharge characteristics and cycle characteristics.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a negative electrode for a lithium secondary battery in which a mixture of graphite particles and an organic binder and a current collector are integrated with each other. And the density of the mixture of the organic binder is 1.5 to 1.9 g /
The present invention relates to a negative electrode for a lithium secondary battery, which has a cm ³ . The present invention also relates to a negative electrode for a lithium secondary battery, wherein the graphite particles are graphite particles obtained by assembling or bonding a plurality of flat particles so that their orientation planes are non-parallel. The present invention also relates to the negative electrode for a lithium secondary battery according to claim 1 or 2, wherein the graphite particles have an aspect ratio of 5 or less.

The present invention also provides a graphitizable aggregate or graphite and a graphitizable binder with 1 to 50% by weight of a graphitizing catalyst.
An organic binder and a solvent are added to and mixed with graphite particles that have been added, mixed, fired, and crushed, and the mixture is applied to a current collector, the solvent is dried, and then pressure is applied to integrate the mixture. The present invention relates to a method for producing a negative electrode for a lithium secondary battery, which comprises: Furthermore, the present invention is arranged such that the negative electrode for a lithium secondary battery, or the negative electrode for a lithium secondary battery manufactured by the above manufacturing method, and a positive electrode are arranged to face each other with a separator interposed therebetween, and an electrolyte solution is injected into the periphery thereof. Lithium secondary battery.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In a negative electrode for a lithium secondary battery of the present invention, a mixture of graphite particles and an organic binder and a current collector are integrated, and the graphite particles and the binder after integration are integrated. The mixture has a density of 1.5 to 1.9 g / cm ³ .
The density is preferably in the range of 1.55 to 1.85 g / cm ³ , more preferably 1.6 to 1.85 g / cm ³ , and even more preferably 1.6 to 1.8 g / cm ³ . By increasing the density of the mixture of graphite particles and the binder constituting the negative electrode in the present invention, the lithium secondary battery obtained using this negative electrode can have a high energy density per volume. If the density of the mixture of graphite particles and the organic binder exceeds 1.9 g / cm ³ , the rapid charging characteristics deteriorate, and if it is less than 1.5 g / cm ³ , the energy density per volume of the obtained lithium secondary battery. Becomes smaller.

The graphite particles used in the negative electrode for a lithium secondary battery of the present invention may be those having a density within the above range. For example, natural graphite can be used. It is preferable to use graphite particles in which a plurality of particles are aggregated or bonded so that the orientation planes are not parallel. In the present invention, the flat particles are particles having a shape having a major axis and a minor axis, and do not have a perfect spherical shape. For example, those having a scaly shape, a scaly shape, a part of a lump shape, etc. are included in this. In the graphite particles, the orientation planes of the plurality of flat particles are non-parallel, and the flat surface having the shape of each particle, in other words, the plane closest to the flat surface as the orientation surface, the plurality of flat particles are It means a state in which the respective orientation planes are gathered in a certain direction without being aligned.

In the graphite particles, the flat particles are aggregated or bonded, but the bonding means that the mutual particles are tar,
Through a carbonaceous material that carbonizes a binder such as pitch, it means a state of being chemically bonded, and the particles with each other are not chemically bonded, but due to their shape, The state in which the shape of the aggregate is maintained. From the viewpoint of mechanical strength, those bonded are preferable. In one graphite particle, the number of flat particles to be aggregated or combined is preferably three or more. The size of each flat particle is preferably 1 to 100 μm in particle diameter, and is preferably 2/3 or less of the average particle diameter of graphite particles aggregated or bonded.

When the graphite particles are used for the negative electrode, it is difficult for the graphite particles to be oriented on the current collector and the negative electrode graphite absorbs lithium.
Since it is easily released, the rapid charge / discharge characteristics and cycle characteristics of the obtained lithium secondary battery can be improved. In addition, FIG. 1 shows a scanning electron micrograph of the particle structure of an example of the graphite particles used in the present invention. In FIG.
(A) is a scanning electron micrograph of the outer surface of the graphite particles used in the present invention, and (b) is a scanning electron micrograph of the cross section of the graphite particles. In (a), many fine flake-shaped graphite particles are present, and it can be observed that the graphite particles are formed by binding the particles with their orientation planes non-parallel to each other.

Graphite particles having an aspect ratio of 5 or less are preferable because the particles tend not to be oriented on the current collector and lithium is easily absorbed and released similarly to the above. More preferably, the aspect ratio is 1.2-5. When the aspect ratio is less than 1.2, the contact area between the particles is reduced, so that the conductivity tends to decrease. For the same reason, the lower limit of the more preferable range is 1.3 or more. Further, the upper limit of the more preferable range is 3 or less, and when the aspect ratio is larger than this, the rapid charge / discharge characteristics tend to be deteriorated. Therefore, the particularly preferable aspect ratio is 1.3 to 3. The aspect ratio is represented by A / B, where A is the length in the major axis direction of the graphite particles and B is the length in the minor axis direction. The aspect ratio in the present invention is obtained by enlarging graphite particles with a microscope, arbitrarily selecting 100 graphite particles, measuring A / B, and taking the average value thereof. Further, the structure of the graphite particles having an aspect ratio of 5 or less is preferably an aggregate or a combination of smaller graphite particles, so that the flat particles are plural and the orientation planes are non-parallel. It is more preferable to use graphite particles that are aggregated or bonded together.

The graphite particles used in the present invention preferably have a specific surface area of 8 m ² / g or less, more preferably 5 m ² / g or less. When the graphite particles are used for the negative electrode, the rapid charge / discharge characteristics and cycle characteristics of the obtained lithium secondary battery can be improved, and the irreversible capacity at the first cycle can be reduced. When the specific surface area exceeds 8 m ² / g, the irreversible capacity of the obtained lithium secondary battery in the first cycle tends to be large, the energy density is small, and many binders are used when forming the negative electrode. Tends to be needed. The specific surface area of the obtained lithium secondary battery is more preferably from 1.5 to ⁵ m ² / g from the viewpoint that the rapid charge / discharge characteristics, cycle characteristics, etc. are further improved.
Highly preferred is from ^{2 to 5} m ² / g. The specific surface area can be measured by a known method such as the BET method (nitrogen gas adsorption method).

Further, the crystal interlayer distance d (002) in the X-ray wide-angle diffraction of each graphite particle used in the present invention is 3.3.
It is preferably 8 Å or less, more preferably 3.37 Å or less, and further preferably 3.36 Å or less. The crystallite size Lc (002) in the c-axis direction is 500.
It is preferably Å or more, more preferably 1000 to 10000 Å. The discharge capacity tends to increase as the inter-crystal distance d (002) decreases or the crystallite size Lc (002) in the c-axis direction increases.

The method for producing the negative electrode for a lithium secondary battery of the present invention is not particularly limited, but 1 to 50% by weight of a graphitization catalyst is added to and mixed with a graphitizable aggregate or graphite and a graphitizable binder. First, graphite particles are obtained by pulverizing after firing, and then an organic binder and a solvent are added to the graphite particles and mixed, and the mixture is applied to a current collector and dried to remove the solvent. After removal, it can be obtained by pressurizing and integrating to obtain the above density.

As the aggregate which can be graphitized, for example, coke powder, a carbide of a resin or the like can be used, but there is no particular limitation as long as it is a powder material which can be graphitized. Of these, coke powder such as needle coke that is easily graphitized is preferable.
As graphite, for example, natural graphite powder, artificial graphite powder, etc. can be used, but there is no particular limitation as long as it is in powder form. The particle size of the graphitizable aggregate or graphite is preferably smaller than the particle size of the graphite particles produced in the present invention.

Further, as the graphitization catalyst, for example, graphitization catalysts of metals such as iron, nickel, titanium, silicon and boron, and their carbides and oxides can be used. Of these, silicon or boron carbides or oxides are preferred. The addition amount of these graphitization catalysts is preferably 1 to 50% by weight, more preferably 5% by weight based on the obtained graphite particles.
To 40% by weight, more preferably 5 to 30% by weight
If the amount is less than 1% by weight, the aspect ratio and the specific surface area of the graphite particles tend to be large, and the crystal growth of graphite tends to be poor. On the other hand, if it exceeds 50% by weight, uniform mixing is difficult. Workability tends to deteriorate.

As the binder, for example, in addition to tar and pitch, organic materials such as thermosetting resins and thermoplastic resins are preferable. The binder content is preferably 5 to 80% by weight, more preferably 10 to 80% by weight, more preferably 15 to 80% by weight, based on the flattenable aggregate or graphite. Is more preferable.
If the amount of the binder is too large or too small, the graphite particles to be produced tend to have a large aspect ratio and a large specific surface area. The method of mixing the graphitizable aggregate or the graphite and the binder is not particularly limited and may be performed using a kneader or the like, but it is preferable to mix at a temperature equal to or higher than the softening point of the binder. Specifically, when the binder is pitch, tar or the like, it is preferably 50 to 300 ° C, and when it is a thermosetting resin, 20 to 100 ° C is preferable.

Next, the above mixture is fired and graphitized. The mixture may be molded into a predetermined shape before this treatment. Furthermore, after molding, it may be crushed before graphitization to adjust the particle size and then graphitized. The firing is preferably performed under the condition that the mixture is not easily oxidized, and examples thereof include a method of firing in a nitrogen atmosphere, an argon gas atmosphere, and a vacuum. The graphitization temperature is preferably 2000 ° C or higher, more preferably 2500 ° C or higher, and further preferably 2800 ° C to 3200 ° C. If the graphitization temperature is low, the graphite crystals will not develop well,
The discharge capacity tends to decrease and the added graphitization catalyst tends to remain in the graphite particles produced. If the graphitization catalyst remains in the graphite particles to be produced, the discharge capacity will decrease. If the graphitization temperature is too high, the graphite may sublime.

Next, it is preferable to grind the obtained graphitized product. The method of pulverizing the graphitized material is not particularly limited,
For example, a known method such as a jet mill, a vibration mill, a pin mill or a hammer mill can be used. The average particle size of the crushed particles is preferably 1 to 100 μm, and is 10 to 50 μm.
More preferably, it is μm. If the average particle size is too large, the surface of the electrode to be produced tends to have irregularities. In the present invention, the average particle size can be measured with a laser diffraction particle size distribution meter.

According to the present invention, a plurality of flat particles can be aggregated or combined so that the orientation planes are non-parallel through the above-mentioned steps, and the aspect ratio is 5.
The following graphite particles can be obtained, and the specific surface area is 8
Graphite particles of m ² / g or less can be obtained.

The obtained graphite particles are mixed with a material containing an organic binder and a solvent and formed into a sheet shape, a pellet shape or the like. As the organic binder, for example,
Polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, butyl rubber, polymer compounds having high ionic conductivity, etc. can be used. Polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile and the like can be used as the polymer compound having a high ionic conductivity in the present invention. Of these, polymer compounds having a high ionic conductivity are preferable, and polyvinylidene fluoride is particularly preferable.

The mixing ratio of the graphite particles and the organic binder is
An organic binder is added in an amount of 3 to 1 to 100 parts by weight of the graphite particles.
It is preferable to use 0 part by weight. The solvent is not particularly limited, and N-methyl 2-pyrrolidone, dimethylformamide, isopropanol and the like can be used. The amount of the solvent is not particularly limited as long as it can be adjusted to a desired viscosity, but 30 to 70% by weight based on the mixture is preferably used.

As the current collector, for example, a metal current collector such as a foil of nickel or copper or a mesh can be used. The integration can be performed by a molding method such as roll and press, or these may be combined and integrated. The negative electrode thus obtained is arranged so that the positive electrode faces each other with the separator interposed therebetween, and the electrolytic solution is injected to allow rapid charging compared with a lithium secondary battery using a conventional carbon material for the negative electrode. A lithium secondary battery having excellent discharge characteristics and cycle characteristics and a small irreversible capacity can be manufactured.

The material used for the positive electrode of the lithium secondary battery in the present invention is not particularly limited, and LiNiO 2 may be used.
₂ , LiCoO ₂ , LiMn ₂ O _4, etc. can be used alone or in combination. As the electrolytic solution, LiClO ₄ ,
LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSO ₃ CF ₃
It is possible to use a so-called organic electrolyte solution in which a lithium salt such as the above is dissolved in a non-aqueous solvent such as ethylene carbonate, diethyl carbonate, dimethoxyethane, dimethyl carbonate, tetrahydrofuran, propylene carbonate or the like.

As the separator, for example, a nonwoven fabric containing polyolefin such as polyethylene or polypropylene as a main component, a cloth, a microporous film, or a combination thereof can be used. Note that FIG. 2 shows a partial cross-sectional front view of an example of the cylindrical lithium secondary battery. The cylindrical lithium secondary battery shown in FIG. 2 is obtained by winding a positive electrode 1 processed into a thin plate and a negative electrode 2 processed in the same manner with a separator 3 such as a polyethylene microporous membrane stacked on top of each other. This is inserted into a battery can 7 made of metal or the like to be hermetically sealed. The positive electrode 1 is joined to the positive electrode lid 6 via the positive electrode tab 4, and the negative electrode 2 is joined to the battery bottom portion via the negative electrode tab 5. The positive electrode lid 6 is fixed to the battery can 7 with a gasket 8.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 50 parts by weight of coke powder having an average particle size of 8 μm, 20 parts by weight of tar pitch, 5 parts by weight of silicon carbide and 15 parts by weight of coal tar were mixed and stirred at 100 ° C. for 1 hour. Then, it was fired at 2800 ° C. in a nitrogen atmosphere and then pulverized to prepare graphite particles having an average particle diameter of 25 μm. As a result of arbitrarily selecting 100 of the obtained graphite particles and measuring the average value of the aspect ratio, it was 1.5. The BET specific surface area of the obtained graphite particles was 2.1 m ² / g, and the interlayer distance d (00
2) was 3.365Å, and the crystallite size Lc (002) was 1000Å or more. Further, according to the scanning electron micrograph (SEM photograph) of the obtained graphite particles, the graphite particles had a structure in which flat particles were aggregated or combined so that the plurality of orientation planes were non-parallel.

Next, 90% by weight of the obtained graphite particles was added with N-
Polyvinylidene fluoride (PVDF) dissolved in methyl-2-pyrrolidone was added in a solid content of 10% by weight and kneaded to obtain a graphite paste. This graphite paste has a thickness of 10 μm
N-methyl-2-
Pyrrolidone was removed and the mixture was compressed with a pressure of 30 MPa with a press to obtain a sample electrode having a mixture layer of graphite particles and PVDF with a thickness of 80 μm and a density of 1.55 g / cm ³ .

The obtained sample electrode was subjected to constant current charging / discharging by the three-terminal method and evaluated as a negative electrode for a lithium secondary battery. FIG. 3 is a schematic diagram of a lithium secondary battery. Evaluation of the sample electrode was performed by using a glass cell 9 as shown in FIG.
And a solution of dimethyl carbonate (DMC) (EC and DMC in a volume ratio of 1: 1) dissolved at a concentration of 1 mol / liter was put, and a sample electrode 11, a separator 12 and a counter electrode 13 were laminated. Then, the reference electrode 14 was hung from above and a lithium secondary battery was produced. In addition, metallic lithium was used for the counter electrode 13 and the reference electrode 14, and a polyethylene microporous membrane was used for the separator 12. Using the obtained lithium secondary battery, graphite particles of the sample electrode and PVDF were provided between the sample electrode 11 and the counter electrode 13.
5 mV at a constant current of 0.2 mA / cm ^{2 with} respect to the area of the mixture
(Vvs.Li/Li+) and charged to 1V (Vvs.Li/L
The test of discharging to i +) was repeated 50 cycles, but no decrease in discharge capacity was confirmed. In addition, as a quick charge / discharge characteristic evaluation, charging was performed at a constant current of 0.3 mA / cm ² , and the discharge current was changed to 0.5, 2.0, 4.0 and 6.0 mA / cm ² , and the graphite at this time was changed. Table 1 shows the discharge capacity with respect to the volume of the mixture of particles and PVDF.

Example 2 A sample electrode was obtained through the same steps as in Example 1 except that the compressive force in the press was 40 MPa. The mixture of graphite particles and PVDF of the obtained sample electrode had a thickness of 80 μm and a density of 1.63 g / cm ³ . Next, a lithium secondary battery was manufactured through the same steps as in Example 1 and the same test as in Example 1 was performed, but no reduction in discharge capacity was confirmed. In addition, as a quick charge / discharge characteristic evaluation, the discharge capacity when charging with a constant current of 0.3 mA / cm ² and changing the discharge current to 0.5, 2.0, 4.0 and 6.0 mA / cm ^2. Is shown in Table 1.

Example 3 A sample electrode was obtained through the same steps as in Example 1 except that the compression force in the press was 80 MPa. The mixture of graphite particles and PVDF of the obtained sample electrode had a thickness of 80 μm and a density of 1.75 g / cm ³ . Next, a lithium secondary battery was manufactured through the same steps as in the example, and the same test as in Example 1 was performed, but no decrease in discharge capacity was confirmed.
As a quick charge / discharge characteristic evaluation, the battery was charged with a constant current of 0.3 mA / cm ² , and the discharge current was 0.5, 2.0, 4.0 and 6.
Table 1 shows the discharge capacities when changed to 0 mA / cm ² .

Example 4 Example 1 except that the compression force in the press was 100 MPa.
A sample electrode was obtained through the same steps as. The mixture of graphite particles and PVDF of the obtained sample electrode had a thickness of 80 μm and a density of 1.85 g / cm ³ . Next, a lithium secondary battery was manufactured through the same steps as in Example 1 and the same test as in Example 1 was performed, but no reduction in discharge capacity was confirmed. In addition, as a quick charge / discharge characteristic evaluation, the discharge capacity when charging with a constant current of 0.3 mA / cm ² and changing the discharge current to 0.5, 2.0, 4.0 and 6.0 mA / cm ^2. Is shown in Table 1.

Comparative Example 1 A sample electrode was obtained through the same steps as in Example 1 except that the compressive force in the press was 20 MPa. The mixture of graphite particles and PVDF of the obtained sample electrode had a thickness of 80 μm and a density of 1.45 g / cm ³ . Next, a lithium secondary battery was manufactured through the same steps as in Example 1 and the same test as in Example 1 was performed, but no reduction in discharge capacity was confirmed. In addition, as a quick charge / discharge characteristic evaluation, the discharge capacity when charging with a constant current of 0.3 mA / cm ² and changing the discharge current to 0.5, 2.0, 4.0 and 6.0 mA / cm ^2. Is shown in Table 1.

Comparative Example 2 Example 1 except that the compressive force in the press was 140 MPa.
A sample electrode was obtained through the same steps as. The mixture of graphite particles and PVDF in the obtained sample electrode had a thickness of 80 μm and a density of 1.93 g / cm ³ . Then, a lithium secondary battery was manufactured through the same steps as in Example 16, and the same test as in Example 16 was carried out. As a result, the discharge capacity decreased by 15.7%.
As a quick charge / discharge characteristic evaluation, the battery was charged with a constant current of 0.3 mA / cm ² , and the discharge current was 0.5, 2.0, 4.0 and 6.
Table 1 shows the discharge capacities when changed to 0 mA / cm ² .

[0034]

[Table 1]

As shown in Table 1, the lithium secondary battery using the negative electrode for a lithium secondary battery of the present invention has a high discharge capacity and excellent rapid discharge characteristics.

[0036]

The negative electrode for a lithium secondary battery according to claim 1 is suitable for a high capacity lithium secondary battery. Claim 2
The negative electrode for a lithium secondary battery described in 3 and 3 is suitable for a lithium secondary battery having a high capacity and excellent in rapid charge / discharge characteristics and cycle characteristics. According to the manufacturing method of the fourth aspect, a negative electrode for a lithium secondary battery, which has a high capacity and is excellent in rapid charge / discharge characteristics and cycle characteristics, and which is suitable for a lithium secondary battery, can be obtained. The lithium secondary battery according to claim 5 has a high capacity and is excellent in rapid charge / discharge characteristics and cycle characteristics.

[Brief description of drawings]

FIG. 1 is a scanning electron microscope photograph of graphite particles used in the present invention, (a) is a photograph of an outer surface of the particle, and (b) is a photograph of a cross section of the particle.

FIG. 2 is a partially sectional front view of a cylindrical lithium secondary battery.

FIG. 3 is a schematic diagram of a lithium secondary battery used for measuring charge / discharge characteristics and irreversible capacity in an example of the present invention.

[Explanation of symbols]

1 positive electrode 2 Negative electrode 3 separator 4 Positive tab 5 Negative electrode tab 6 Positive lid 7 battery cans 8 gasket 9 glass cells 10 Electrolyte 11 Sample electrode (negative electrode) 12 separators 13 counter electrode (positive electrode) 14 reference pole

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuo Yamada, Inventor Kazuo Yamada 3-3-1 Ayukawa-cho, Hitachi City, Ibaraki Yamashita Plant, Hitachi Chemical Co., Ltd. (56) Reference JP-A-6-275321 (JP, A) ) JP-A-8-69798 (JP, A) JP-A-6-318459 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/02-4/04 H01M 4 / 58 H01M 10/40

Claims (10)

(57) [Claims] 1. A negative electrode for a lithium secondary battery, wherein a mixture of graphite particles and an organic binder and a current collector are integrated with each other, wherein the graphite particles have an aspect ratio of 1.2 to 5, and pressure, The density of the mixture of the graphite particles and the organic binder after integration is 1.5 to 1.9 g / cm ³ , and the crystallite size Lc (002) of the graphite particles in the c-axis direction is 500 Å or more. Yes (however, the crystallite size Lc of the graphite particles in the c-axis direction)
(Except when (002) is 800 Å or less) Lithium secondary battery negative electrode. 2. The specific surface area of graphite particles is 1.5 to ⁵ m ² /
The negative electrode for a lithium secondary battery according to claim 1, which is g. 3. The crystallite size L of the graphite particles in the c-axis direction.
c (002) is 1000-10000Å.
Or the negative electrode for a lithium secondary battery according to 2 above. 4. Graphite particles and organic bonds after pressure and integration
The density of the mixture of the adhesive is 1.6 to 1.85 g / cm ³ And
The lithium secondary battery according to any one of claims 1 to 3.
Negative electrode for pond. 5. Graphite particles and organic bonds after pressure and integration
The density of the mixture of the adhesive is 1.6 to 1.8 g / cm ³ Is
The lithium secondary battery according to claim 1.
Negative electrode. 6. A graphite particle used for producing a negative electrode for a lithium secondary battery, wherein the graphite particle is a mixture of the graphite particle and an organic binder and a current collector. It is used for producing a negative electrode for a lithium secondary battery having a density of 1.5 to 1.9 g / cm ³ , and its aspect ratio is 1.2 to 5, and the c axis of graphite particles. Direction crystallite size Lc (00
Graphite particles for a negative electrode of a lithium secondary battery, wherein 2) is 500 Å or more (except when the crystallite size Lc (002) of the graphite particles in the c-axis direction is 800 Å or less). 7. The specific surface area of the graphite particles is 1.5 to ⁵ m ² /
The graphite particles for a negative electrode of a lithium secondary battery according to claim 6, which is g. 8. The crystallite size L of the graphite particles in the c-axis direction
Claim c (002) is 1000～10000A 6
Alternatively, the graphite particles for a lithium secondary battery negative electrode according to item 7 . 9. Graphite particles and organic bonds after pressure and integration
The density of the mixture of the adhesive is 1.6 to 1.85 g / cm ³ And
The lithium secondary battery according to any one of claims 6 to 8.
Graphite particles for pond negative electrode. 10. Graphite particles and organic system after pressure and integration
The density of the binder mixture is 1.6 to 1.8 g / cm ³ And
The lithium secondary battery according to any one of claims 6 to 8.
Graphite particles for pond negative electrode.