JP2008066128A - Negative electrode active material for lithium ion battery, and its manufacturing method, cathode for lithium ion battery, and lithium ion battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative electrode active material for a lithium ion battery which is higher in charge and discharge capacity than a conventional one. <P>SOLUTION: The negative electrode active material for the lithium ion battery composed of a carbon material and silicon carbide is manufactured after passing through a process of coating or mixing polysilane to the carbon material, and a process of heat treating the carbon material in which polysilane is coated or mixed to form silicon carbide on the carbon material. As the carbon material, a carbon fiber which is formed by oxidizing and polymerizing a compound having an aromatic ring, by forming a fibril state polymer, and by calcining the fibril state polymer is preferable. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a negative electrode active material for a lithium ion battery, a negative electrode active material for a lithium ion battery produced by the method, a negative electrode for a lithium ion battery comprising the negative electrode active material for the lithium ion battery, and the lithium ion battery The present invention relates to a lithium ion battery including a negative electrode, and particularly relates to a negative electrode active material for a lithium ion battery having a high charge / discharge capacity.

  Recently, lithium ion batteries are widely used as portable terminals and mobile communication devices. Since the lithium ion battery has the highest energy density among the existing secondary batteries, it is considered to use the lithium ion battery as an auxiliary power source for a hybrid vehicle or a fuel cell vehicle or as a large power source for stationary use. .

The lithium ion battery is an electrolysis in which a negative electrode (for example, a carbon material such as graphite) having the same characteristics as a positive electrode (for example, LiCoO ₂ ) having a layered structure capable of electrochemically inserting and extracting lithium ions dissolves lithium ions. A battery having a structure facing each other through a liquid, and generally has a structure in which a porous polymer film that can permeate an electrolytic solution is disposed between both electrodes in order to prevent a short circuit between a positive electrode and a negative electrode Yes.

In general, graphite (soft carbon) is used as the carbon material used for the negative electrode of the lithium ion battery, and the graphite has charge / discharge cycle characteristics, charge / discharge efficiency (particularly, initial charge / discharge efficiency). ) Is high. However, when graphite is used, when lithium ions are intercalated into graphite to form LiC ₆ , no more lithium can be inserted. Therefore, when graphite is used, the charge / discharge capacity is limited to a theoretical capacity of 372 mAh / g. On the other hand, hard carbon has been studied as a negative electrode active material capable of obtaining a high capacity, but it has problems that initial charge / discharge efficiency is lower than that of soft carbon, and discharge capacity per volume is inferior to graphite. .
CMC Publishing, “Secondary battery materials for the past 10 years and beyond”

  Then, the objective of this invention is providing the negative electrode active material for lithium ion batteries whose charging / discharging capacity is higher than before, and its manufacturing method. Another object of the present invention is to provide a negative electrode for a lithium ion battery comprising such a negative electrode active material for a lithium ion battery and a lithium ion battery comprising the negative electrode for a lithium ion battery.

  As a result of earnest studies to achieve the above object, the present inventor has applied or mixed a polysilane solution to a carbon material, followed by heat treatment to produce silicon carbide on the carbon material and silicon carbide. By using this composite material as a negative electrode active material of a lithium ion battery, it was found that the charge / discharge capacity of the lithium ion battery was greatly improved, and the present invention was completed.

That is, a method for producing a negative electrode active material for a lithium ion battery comprising the carbon material of the present invention and silicon carbide,
Applying or mixing polysilane to the carbon material;
Heat-treating the carbon material coated or mixed with the polysilane to produce silicon carbide (SiC) on the carbon material.

  In a preferred embodiment of the method for producing a negative electrode active material for a lithium ion battery according to the present invention, the carbon material is produced by oxidative polymerization of a compound having an aromatic ring to produce a fibril-like polymer, and firing the fibril-like polymer. Carbon fiber.

In another preferred embodiment of the method for producing a negative electrode active material for a lithium ion battery of the present invention, the carbon material coated or mixed with the polysilane is heat-treated in an inert gas atmosphere to convert the polysilane to polycarbosilane. Further, heat treatment is performed in air and in an inert gas atmosphere to convert the polycarbosilane into silicon carbide, thereby generating silicon carbide on the carbon material. Here, the polysilane comprises a repeating unit represented by the formula: [—Si (CH ₃ ) ₂ —], and the polycarbosilane comprises a repeating unit represented by the formula: [—SiH (CH ₃ ) —CH ₂ —]. Preferably it consists of.

In another preferred embodiment of the method for producing a negative electrode active material for a lithium ion battery according to the present invention, the carbon material coated or mixed with the polysilane is irradiated with ultraviolet rays in an inert gas atmosphere, and further subjected to heat treatment under reduced pressure. The polysilane is converted into silicon carbide to produce silicon carbide on the carbon material. Here, the polysilane is composed of a repeating unit represented by the formula: [—Si (CH ₃ ) ₂ —] and a repeating unit represented by the formula: [—Si (CH ₃ ) (C ₆ H ₅ ) —]. It is preferable to become.

  In the method for producing a negative electrode active material for a lithium ion battery of the present invention, the silicon carbide is preferably β-type silicon carbide (β-SiC).

  The negative electrode active material for lithium ion batteries of the present invention is manufactured by the above method, and the negative electrode for lithium ion batteries of the present invention includes the negative electrode active material for lithium ion batteries. The lithium ion battery of the present invention includes the negative electrode for a lithium ion battery.

  According to the present invention, a negative electrode active material for a lithium ion battery having a high charge / discharge capacity can be produced by applying or mixing a polysilane solution to a carbon material, followed by heat treatment to generate silicon carbide on the carbon material. it can. Moreover, the charge / discharge capacity of a lithium ion battery can be greatly improved by using the negative electrode active material for a lithium ion battery.

<Anode active material for lithium ion battery and method for producing the same>
Below, the negative electrode active material for lithium ion batteries of this invention and its manufacturing method are demonstrated in detail. The method for producing a negative electrode active material for a lithium ion battery according to the present invention includes a step of applying or mixing polysilane to a carbon material, and heat-treating the carbon material coated or mixed with the polysilane to produce silicon carbide on the carbon material. The negative electrode active material for a lithium ion battery of the present invention is characterized by being produced by the method. Since the surface of the negative electrode active material for a lithium ion battery of the present invention is suitable for adsorption of lithium ions, a large amount of lithium ions can be adsorbed. Therefore, the charge / discharge capacity of the lithium ion battery using the negative electrode active material for lithium ion battery of the present invention is greatly improved as compared with the conventional lithium ion battery.

  The carbon material used in the method for producing a negative electrode active material of the present invention requires that lithium ions can be occluded / released electrochemically. Among such carbon materials, a compound having an aromatic ring is subjected to oxidative polymerization to produce fibrils. Particularly preferred is a carbon fiber produced by forming a polymer and firing the fibril polymer. The carbon material used for the negative electrode of the conventional lithium ion battery is usually a powder, and as a result of the expansion and contraction of the negative electrode accompanying the charge / discharge cycle of the battery, an electrically insulating part is generated and charged. The discharge capacity may decrease. However, since the carbon fiber has a three-dimensionally continuous structure, even if the negative electrode expands and contracts with the charge / discharge cycle of the battery, it is difficult to produce an electrically insulating portion. Capacity is difficult to decrease. Therefore, the lithium ion battery using the carbon fiber as a negative electrode active material has significantly improved cycle characteristics as compared with a conventional lithium ion battery.

  Examples of the compound having an aromatic ring as a raw material for the fibril-like polymer include a compound having a benzene ring and a compound having an aromatic heterocyclic ring. Here, aniline and aniline derivatives are preferred as the compound having a benzene ring, and pyrrole, thiophene and derivatives thereof are preferred as the compound having an aromatic heterocycle. These compounds having an aromatic ring may be used singly or as a mixture of two or more.

  The fibrillar polymer obtained by oxidative polymerization of the compound having an aromatic ring generally has a three-dimensional continuous structure, and preferably has a diameter of 30 nm to several hundred nm, more preferably 40 nm to 500 nm, The length is preferably 0.5 μm to 100 mm, and more preferably 1 μm to 10 mm.

As the oxidative polymerization method, various methods such as an electrolytic oxidative polymerization method and a chemical oxidative polymerization method can be used. Among them, the electrolytic oxidative polymerization method is preferable. Moreover, in oxidative polymerization, it is preferable to mix an acid with the compound which has a raw material aromatic ring. In this case, the negative ion of the acid is taken into the fibril polymer synthesized as a dopant to obtain a fibril polymer excellent in conductivity, and the conductivity of the carbon fiber is further improved by using this fibril polymer. be able to. As the acid to be mixed in the polymerization, can be used various _{ones, HBF 4, H 2 SO 4} , HCl, may be exemplified HClO ₄ or the like. Here, the concentration of the acid is preferably in the range of 0.1 to 3 mol / L, and more preferably in the range of 0.5 to 2.5 mol / L.

In the case of obtaining a fibrillated polymer by electrolytic oxidation polymerization, a pair of electrode plates serving as a working electrode and a counter electrode are immersed in a solution containing a compound having an aromatic ring, and the oxidation potential of the compound having an aromatic ring between both electrodes is exceeded. Or a current having such a condition that a voltage sufficient to polymerize the compound having an aromatic ring may be applied, whereby a fibril polymer is formed on the working electrode. Used As an example of methods for the synthesis of fibrillar polymer by electrolytic oxidative polymerization method, stainless steel as a working electrode and a counter electrode, platinum, a plate or a porous material or the like made of a good conductive material such as carbon, these and H ₂ SO _4, was immersed in an electrolyte solution containing a compound having an acid and an aromatic ring of HBF _4, etc., 0.1~1000mA / cm ² between the electrodes, preferably by passing current of 0.2~100mA / cm ^2, a working electrode Examples thereof include a method of polymerizing and depositing a fibrillated polymer on the side. Here, the concentration of the compound having an aromatic ring in the electrolytic solution is preferably in the range of 0.05 to 3 mol / L, and more preferably in the range of 0.25 to 1.5 mol / L. Moreover, in addition to the said component, you may add a soluble salt etc. to an electrolyte solution suitably in order to adjust pH.

  The fibrillated polymer obtained on the working electrode as described above is washed with a solvent such as water or an organic solvent, dried, then fired, preferably fired in a non-oxidizing atmosphere and carbonized. A fibril-like three-dimensional continuous carbon fiber is obtained. Here, the drying method is not particularly limited, and examples thereof include a method using a fluidized bed drying device, an air dryer, a spray dryer, etc., in addition to air drying and vacuum drying. In addition, the firing conditions are not particularly limited, and may be set so as to obtain an optimum conductivity. Particularly, when high conductivity is required, the temperature is 500 to 3000 ° C., preferably 600 to 2800. The temperature is preferably 0.5 to 6 hours at ° C. Note that examples of the non-oxidizing atmosphere include a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere, and in some cases, a hydrogen atmosphere can also be used.

The carbon fiber having a three-dimensional continuous structure obtained by firing the fibril-like polymer preferably has a diameter of 30 nm to several hundred nm, more preferably 40 nm to 500 nm, and a length of 0.5 μm to 100 mm. Preferably, the thickness is 1 μm to 10 mm, the surface resistance is preferably 10 ⁶ to 10 ⁻² Ω, and more preferably 10 ⁴ to 10 ⁻² Ω. Further, the carbon fiber preferably has a residual carbon ratio of 95 to 30%, and more preferably 90 to 40%. Since the carbon fiber has a structure in which the entire carbon is three-dimensionally continuous, the carbon fiber has higher conductivity than the granular carbon.

The polysilane used for the manufacturing method of the negative electrode active material of this invention is not specifically limited, The various polysilane conventionally used as a raw material of silicon carbide can be used. Examples of the polysilane include polysilanes represented by the formula: [Si (CH ₃ ) ₂ ] _n , formula: [Si (CH ₃ ) (C ₆ H ₅ )] _m [Si (CH ₃ ) ₂ ] _{n and the} like ( In the formula, n and m are the number of repeating units).

  In the method for producing a negative electrode active material of the present invention, the polysilane is applied or mixed with the carbon material. Here, it is preferable that polysilane is dissolved in an organic solvent such as toluene and applied as a solution to the carbon material or mixed with the carbon material. The solution concentration is not particularly limited, and can be appropriately selected according to the silicon carbide content in the target negative electrode active material. Further, after application or mixing of the solution, it is preferable to fix the polysilane on the carbon material by drying under vacuum or the like.

  In the method for producing a negative electrode active material of the present invention, next, a carbon material coated or mixed with polysilane is heat-treated to generate silicon carbide on the carbon material. Here, as a method for producing silicon carbide by heat treatment, (1) a carbon material coated or mixed with polysilane is heat-treated in an inert gas atmosphere at, for example, 400 to 500 ° C. to convert polysilane to polycarbosilane. And then heat-treating in air, for example, at 300 to 450 ° C., and further heat-treating in an inert gas atmosphere, for example, at 1000 to 1500 ° C. to convert polycarbosilane to silicon carbide, (2) A method of converting polysilane into silicon carbide by irradiating a carbon material coated or mixed with polysilane with ultraviolet rays in an inert gas atmosphere and further heat-treating it under reduced pressure, for example, at 1000 to 1200 ° C. It is done. Examples of the inert gas include argon and nitrogen.

In the method (1), it is preferable to use a polysilane composed of a repeating unit represented by the formula: [—Si (CH ₃ ) ₂ —] as the polysilane. In this case, the formula: [—SiH (CH ₃ ) A polycarbosilane composed of a repeating unit represented by —CH ₂ —] is produced. On the other hand, in the above method (2), the polysilane is represented by the formula: [—Si (CH ₃ ) ₂ —] and the formula: [—Si (CH ₃ ) (C ₆ H ₅ ) —]. It is preferable to use polysilane composed of repeating units. In addition, the silicon carbide formed on the carbon material by the above method (1) or (2) is usually β-type silicon carbide.

  The negative electrode active material for a lithium ion battery produced by the above-described method is composed of a carbon material and silicon carbide formed on the carbon material, and can adsorb a large amount of lithium ions. In addition, the content rate of the silicon carbide in the negative electrode active material for lithium ion batteries of this invention has the preferable range of 5-20 mass%.

<Anode for lithium ion battery>
Next, the negative electrode for a lithium ion battery of the present invention will be described in detail. The negative electrode for a lithium ion battery according to the present invention is characterized by including the above negative electrode active material for a lithium ion battery. Here, it is preferable that the content rate of the said negative electrode active material for lithium ion batteries in the negative electrode for lithium ion batteries of this invention is 50-100 mass% of the whole negative electrode. When the content of the negative electrode active material in the negative electrode is less than 50% by mass, the charge / discharge capacity per unit mass of the lithium ion battery may not be sufficiently improved.

  The negative electrode for a lithium ion battery of the present invention can be mixed with a conductive auxiliary agent and a binder as necessary. Examples of the conductive auxiliary agent include acetylene black, and the binder is polyvinylidene fluoride ( PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC) and the like. These additives can be used at a blending ratio similar to the conventional one.

  There is no restriction | limiting in particular as a shape of the negative electrode for lithium ion batteries of this invention, It can select suitably from well-known shapes as an electrode. For example, a sheet shape, a columnar shape, a plate shape, a spiral shape, and the like can be given.

<Lithium ion battery>
Next, the lithium ion battery of the present invention will be described in detail. The lithium ion battery of the present invention includes the above-described negative electrode for a lithium ion battery, and further includes other members that are usually used in the technical field of lithium ion batteries, such as a positive electrode, an electrolyte, and a separator. Since the lithium ion battery of the present invention includes the above-described negative electrode for a lithium ion battery, the charge / discharge capacity is high.

Examples of the active material for the positive electrode of the lithium ion battery of the present invention include lithium-containing composite oxides such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiFeO _2, and LiFePO ₄ , lithium metal, V ₂ O ₅ , and V ₆ O _13. Preferable examples include metal oxides such as MnO ₂ and MnO ₃ , metal sulfides such as TiS ₂ and MoS ₂ , and conductive polymers such as polyaniline. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together. If necessary, the positive electrode can be mixed with a conductive additive and a binder, and as the conductive auxiliary and binder, those exemplified in the above-mentioned negative electrode are blended in the same manner as in the past. Can be used in proportions.

As the electrolyte of the lithium ion battery of the present invention, a nonaqueous electrolytic solution or a polymer electrolyte can be used. The nonaqueous electrolytic solution is usually prepared by dissolving a supporting salt in an aprotic organic solvent, and may contain various additives as desired. Here, examples of the aprotic solvent include 1,2-dimethoxyethane, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, γ-valerolactone, and ethyl methyl carbonate. . As supporting salts, LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N and Li (C ₂ F ₅ SO ₂ ) ₂ lithium salt such as N. The concentration of the supporting salt in the nonaqueous electrolytic solution is not particularly limited, but is preferably in the range of 0.2 to 1.5 mol / L (M).

  The polymer electrolyte preferably contains a polymer and the supporting salt, more preferably contains the aprotic organic solvent, and may further contain various additives depending on the purpose. As the polymer used for the polymer electrolyte, all polymers usually used for gel electrolytes for polymer batteries can be used, and specifically include polyethylene oxide, polypropylene oxide, polyacrylate, polyacrylonitrile, ethylene oxide units. Polyacrylate etc. are mentioned.

  Other members that can be used in the lithium ion battery of the present invention include a separator interposed between positive and negative electrodes in a role of preventing current short-circuiting due to contact between both electrodes. As the material of the separator, it is possible to reliably prevent contact between the two electrodes and to allow the electrolyte to pass through or to contain, for example, synthesis of polytetrafluoroethylene, polypropylene, polyethylene, cellulose, polybutylene terephthalate, polyethylene terephthalate, etc. Preferred examples include resin non-woven fabrics and thin layer films. These may be a single substance, a mixture or a copolymer. Among these, a polypropylene or polyethylene microporous film having a thickness of about 20 to 50 μm, a film made of cellulose, polybutylene terephthalate, polyethylene terephthalate, or the like is particularly suitable. In the present invention, in addition to the separators described above, known members that are normally used in batteries can be suitably used.

  The form of the lithium ion battery of the present invention described above is not particularly limited, and various known forms such as a coin type, a button type, a paper type, a square type or a spiral type cylindrical battery are preferably exemplified. . In the case of the button type, a lithium ion battery can be manufactured by preparing a sheet-like positive electrode and negative electrode and sandwiching a separator between the positive electrode and the negative electrode. In the case of a spiral structure, for example, a lithium ion battery can be manufactured by preparing a sheet-like positive electrode, sandwiching a current collector, and stacking and winding up the sheet-like negative electrode on the current collector.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Example 1)
<Manufacture of three-dimensional continuous carbon fiber>
In an acidic aqueous solution containing aniline 0.5 mol / L and sulfuric acid 1.0 mol / L, carbon paper [manufactured by Toray] was installed as the working electrode, a platinum plate was installed as the counter electrode, and a constant current of 35 mA / cm ² at room temperature. Was applied, and electrolytic oxidation polymerization was performed until the total amount of electricity reached 3 C / cm ² , and polyaniline was electrodeposited on the working electrode. The obtained polyaniline was thoroughly washed with pure water and then vacuum-dried for 24 hours. Thereafter, the obtained polyaniline was heated together with carbon paper to 950 ° C. at a rate of temperature increase of 3 ° C./min in an Ar reduced pressure atmosphere, and held at that temperature for 1 hour to perform a firing treatment. When the obtained fired product was observed by SEM, it was confirmed that fibril-like and three-dimensional continuous carbon fibers having a diameter of 50 to 300 nm were formed on the carbon paper.

<Formation of silicon carbide on carbon fiber>
To the carbon fiber produced by the above method, a toluene solution (concentration: 10% by mass) of polysilane represented by the formula: [Si (CH ₃ ) ₂ ] _n is applied, dried under vacuum, and applied onto the carbon fiber. Polysilane was fixed. Thereafter, the carbon fiber fixed with polysilane was baked at 450 ° C. in an argon atmosphere to convert the polysilane to polycarbosilane represented by the formula: [SiH (CH ₃ ) —CH ₂ ] _n . The obtained mixture was fired at 350 ° C. in air, and further fired at 1300 ° C. in a nitrogen stream to produce a carbon fiber-silicon carbide composite (silicon carbide content: 5 mass%).

<Production and Evaluation of Electrode and Battery>
Next, the obtained carbon fiber-silicon carbide composite was punched out together with carbon paper into a size of 16 mmφ to produce a negative electrode. Using this negative electrode, a half cell having lithium metal as the positive electrode was assembled, and a charge / discharge test was conducted. As the electrolytic solution, the concentration of the mixed solvent (EC / EMC volume ratio = 1/2) to, LiPF ₆ (the supporting salt) 1M (mol / L) of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) The non-aqueous electrolyte dissolved in (1) was used. In the charge / discharge test, charging was performed at a constant current of 0.5 mA and then held for 5 minutes at a constant voltage. Discharging was performed at a constant current of 0.5 mA and the lower limit voltage was 1.5V. As a result, the obtained half cell had an initial discharge capacity of 300 Ah / kg, a discharge capacity after 20 cycles of 310 Ah / kg, and the discharge capacity was confirmed to be larger than that of the conventional battery.

(Comparative Example 1)
Using hard carbon [manufactured by Kureha Chemical Co., Ltd.] and heat-treated acetylene black as a conductive auxiliary agent in a mass ratio of 1: 1, a small amount of ethanol was dropped and kneaded, and the obtained kneaded product was SUS316 (16 mmφ) ) A negative electrode was prepared by pressure bonding to a mesh. A half cell was assembled in the same manner as in Example 1 except that the negative electrode thus prepared was used, and a charge / discharge test was performed. As a result, the obtained half cell had an initial discharge capacity of 260 Ah / kg, a discharge capacity after 20 cycles of 170 Ah / kg, and the discharge capacity was confirmed to be significantly smaller than that of the battery of the example.

Claims (10)

Applying or mixing polysilane to the carbon material;
And a step of heat-treating the carbon material coated or mixed with the polysilane to form silicon carbide on the carbon material. A method for producing a negative electrode active material for a lithium ion battery comprising a carbon material and silicon carbide.   2. The lithium ion according to claim 1, wherein the carbon material is a carbon fiber formed by oxidative polymerization of a compound having an aromatic ring to form a fibril polymer, and firing the fibril polymer. 3. A method for producing a negative electrode active material for a battery.   The carbon material coated or mixed with the polysilane is heat-treated in an inert gas atmosphere to convert the polysilane to polycarbosilane, and further heat-treated in the air and in an inert gas atmosphere to obtain the polycarbosilane. The method for producing a negative electrode active material for a lithium ion battery according to claim 1, wherein the method is converted into silicon carbide to produce silicon carbide on the carbon material. The polysilane has the formula: consisting repeating unit represented by said polycarbosilane has the formula _{[- - Si (CH 3)} 2]: [- SiH (CH 3) -CH 2 -] by a repeating unit represented by The manufacturing method of the negative electrode active material for lithium ion batteries of Claim 3 characterized by these.   The carbon material coated or mixed with the polysilane is irradiated with ultraviolet light in an inert gas atmosphere, and further heat-treated under reduced pressure to convert the polysilane into silicon carbide, thereby generating silicon carbide on the carbon material. The manufacturing method of the negative electrode active material for lithium ion batteries of Claim 1 characterized by these. The polysilane consists of a repeating unit represented by the formula: [—Si (CH ₃ ) ₂ —] and a repeating unit represented by the formula: [—Si (CH ₃ ) (C ₆ H ₅ ) —]. The manufacturing method of the negative electrode active material for lithium ion batteries of Claim 5 characterized by the above-mentioned.   The method for producing a negative electrode active material for a lithium ion battery according to any one of claims 1, 3, and 5, wherein the silicon carbide is β-type silicon carbide.   The negative electrode active material for lithium ion batteries manufactured by the method in any one of Claims 1-7.   The negative electrode for lithium ion batteries containing the negative electrode active material for lithium ion batteries of Claim 8.   A lithium ion battery comprising the negative electrode for a lithium ion battery according to claim 9.