JP3512549B2 - Negative electrode for lithium secondary battery and lithium secondary battery using the negative electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an improved component of a lithium secondary battery and a lithium secondary battery having the component.

[0002]

2. Description of the Related Art In recent years, there has been remarkable progress in downsizing, thinning, and lightening of electronic devices. Particularly in the OA field, the size and weight of electronic devices have been reduced from desktop types to laptop types and notebook types. In addition, the field of new small electronic devices such as electronic notebooks and electronic still cameras has emerged.In addition to the miniaturization of conventional hard disks and floppy disks, the development of memory cards, which are new small memory media, has been promoted. ing. In the wave of the miniaturization, thinning, and weight reduction of such electronic devices, high performance is also required for secondary batteries that support such electric power. Under such a demand, development of a lithium secondary battery as a high energy density battery replacing a lead battery or a nickel cadmium battery has been rapidly promoted.

(A) As a positive electrode active material of a lithium secondary battery, TiS ₂ , MoS ₂ , CoO ₂ , V ₂ O ₅ , FeS ₂ ,
There are transition metal oxides such as NbS ₂ , ZrS ₂ , VSe ₂ , and MnO ₂ , or transition metal chalcogen compounds, and many examples using inorganic materials as active materials have been studied. Such a material is capable of electrochemically reversing lithium ions into and out of its structure, and by utilizing this property, development of a lithium nonaqueous electrolyte secondary battery has been promoted. Since a lithium non-aqueous electrolyte secondary battery using such an inorganic material as an active material generally has a high true density of the active material itself, it is easy to construct a battery having a high energy density, and the occlusion and release of lithium are performed by the active material. In the case of intercalation and deintercalation in the crystal structure, it is easy to construct a battery with excellent voltage flatness, but if more lithium ions are accumulated in the crystal structure than necessary, the crystal structure Of the non-aqueous electrolyte secondary battery, which significantly reduces the function of the non-aqueous electrolyte secondary battery as an active material. This indicates that the electrode for a non-aqueous electrolyte secondary battery is vulnerable to overdischarge. In the development process of lithium non-aqueous electrolyte secondary batteries using such inorganic materials as active materials, reversible occlusion of anions has recently been considered as a potential electrode active material for lithium non-aqueous electrolyte secondary batteries. ,
There was a discovery of a conductive polymer capable of performing an electrode reaction by release. Conductive polymers have characteristics such as light weight and high output density as electrode materials, and also have excellent current collection properties due to their inherent properties of conductivity, and exhibit high cycle characteristics even at 100% discharge depth. In addition, it has features that are not found in inorganic materials, such as good molding processability as an electrode.
Examples of conductive polymers include polyacetylene (eg,
JP-A-56-136489), polypyrrole (for example,
The 25th Battery Symposium, Abstracts of Lectures, P2561, 198
4), polyaniline (for example, The 50th Annual Meeting of the Electrochemical Society, Abstracts of Lectures, P2281, 1984) and the like. Further, a composite electrode of a conductive polymer and an inorganic active material has been proposed (for example, Japanese Patent Application Laid-Open No. 63-10216).
2). In particular, a high energy density cathode having excellent processability, potential flatness, and current characteristics was developed by combining a conductive polymer and an inorganic active material under specific conditions.
No. 129997.

(B) Lithium nonaqueous electrolyte secondary batteries have the technical problem of developing a negative electrode in addition to the development of a positive electrode as described above. When lithium metal is used as an electrode as the negative electrode active material, a high electromotive force can be obtained, and there is an advantage that it is lightweight and easily has a high energy density. However, lithium metal generates dendrites by charging and discharging, and has a disadvantage that the cycle life of a battery is short because the dendrites decompose an electrolytic solution. Further, when the dendrite further grows, it reaches the positive electrode, causing a short circuit in the battery.
The use of a lithium alloy as the negative electrode alleviates the above problem, but does not provide a satisfactory capacity as a secondary battery.
Therefore, it has been proposed to use a carbon material capable of inserting and extracting lithium as a negative electrode active material. However, the prototype batteries using a carbon material for the negative electrode, which are currently being announced, do not fully utilize the capabilities of lithium-ion batteries.
It is considered that the energy density of the negative electrode and the chargeable / dischargeable current density are not so high. In other words, a highly crystalline carbon material can theoretically be expected to have an energy density of 372 mAh / g. However, the energy density of the processed negative electrode, particularly the energy density of the processed negative electrode, is higher than that of such an electrode active material. This is because the volume energy density is considerably low and the internal impedance of the electrode is high, so that the energy density is high at a low current density, but the energy density of the negative electrode is significantly reduced when charging and discharging with a large current. In addition, since the change in the crystal structure due to charge and discharge is large, the strength of the electrode is reduced during repeated charge and discharge, and the cycle characteristics are not sufficient. Further, even if the initial capacity is large, the performance as a secondary battery cannot be satisfied, for example, the capacity deteriorates due to repeated charging and discharging, and the capacity rapidly decreases. As the carbon material, highly crystalline carbon is preferable, but among them, graphite alone does not always provide satisfactory results in terms of capacity, cycle characteristics, etc. due to matching with an electrolytic solution. It is.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a lithium secondary battery capable of discharging a heavy load having a high energy and a high cycle life when a carbon anode capable of inserting and extracting lithium is used as the anode active material of the lithium secondary battery. It is an object to provide a negative electrode for a secondary battery and a lithium secondary battery using the negative electrode.

[0006]

A first feature of the present invention is that:
The negative electrode is made of polyvinyl pyridine-based
It is characterized by being formed using a binder
The surface spacing (d ₀₀₂ ) in the C-axis direction is 3.4 ° or less.
Negative electrode for lithium secondary battery containing more than one kind of carbon material
About. The second feature of the present invention is that the negative electrode contains a lithium salt.
2. The method according to claim 1, wherein
The present invention relates to a negative electrode for a secondary lithium battery .

Hereinafter, each component of the battery of the present invention will be described in detail. The lithium secondary battery of the present invention basically includes a positive electrode, an electrolyte layer, and a carbon-based negative electrode capable of inserting and extracting lithium.

[0008] In general, carbon materials constituting a carbon electrode include pyrolytic carbons, cokes, carbon blacks, and the like.
Examples thereof include graphite, glassy carbon, activated carbon, carbon fiber, calcined organic polymer, and mixtures thereof. Among them, graphite having a particularly high crystallinity and a large lithium storage capacity is desirable as a negative electrode material. As the negative electrode active material,
Insulating or semiconducting carbon, coal, pitch, synthetic polymer, or natural polymer obtained by baking a synthetic polymer such as phenol or polyimide or a natural polymer in a reducing atmosphere at 400 to 800 ° C. to 800 to 1300. Conductive carbon, coke, pitch, synthetic polymer and natural polymer obtained by firing in a reducing atmosphere at
Although what is obtained by baking under a reducing atmosphere at a temperature of 000 ° C. or higher is used, a carbon body is preferable, and among them, mesophase pitch and coke are 2,500 ° C.
The carbon body and natural graphite fired in the above reducing atmosphere have excellent potential flatness and have preferable electrode characteristics. However, since the crystal structure change accompanying charge / discharge is large, the cycle characteristics are poor, and the charge / discharge at a large current is difficult.

The present inventors have fabricated negative electrodes using various carbon materials and measured the characteristics thereof. As a result, two or more different carbon materials having a plane spacing (d ₀₀₂ ) of 3.4 ° or less in the C-axis direction were obtained. It has been found that when used, electron conduction between carbon material particles can be performed smoothly, so that the energy density is high and the cycle life is long. The d ₀₀₂ is 3.4%
When the above carbon material is used, the energy density of the negative electrode decreases. In particular, when the average particle diameter of two or more types of carbon materials having d ₀₀₂ of 3.4 ° or less is different, when processed into a negative electrode, the carbon material having a small particle diameter enters the gap between the carbon materials having a large particle diameter. Therefore, the density of the negative electrode can be increased, which is preferable. In particular, as the two or more types of carbon materials,
d ₀₀₂ is a carbon material and d ₀₀₂ of less than 3.37Å 3.37~
It is preferable to use a 3.4% carbon material. A carbon material having d ₀₀₂ of 3.37 ° or less has a large lithium storage capacity.
However, most of carbon materials with developed crystals have high electron conductivity in the crystal plane direction or crystal axis direction because most of the carbon materials are plane-orientated or axially-oriented. The electronic conductivity decreases. Therefore, d ₀₀₂
Is less than 3.37 °, the electron conductivity between the carbon material particles is poor. The carbon material having a d ₀₀₂ of 3.37 to 3.4 ° has a crystal orientation that has not yet been developed or has a point orientation, but has low electron conduction directionality and sufficient electron conductivity. . Therefore, a carbon material having d ₀₀₂ of less than 3.37 ° and d
_The present negative electrode using a carbon material having a ₀₀₂ of 3.37 to 3.4% has excellent current collecting characteristics, and thus has a high energy density even in heavy load discharge.

[0010] Among the carbon materials, the average particle size of the type of carbon material having the smallest average particle size is 80% or less, preferably 80% or less of the average particle size of the type of carbon material having the largest average particle size. Preferably it is 5%. If it is 80% or more, the density of the negative electrode decreases, which is not preferable. The average particle diameter of the carbon material having d ₀₀₂ of less than 3.37 ° used in the negative electrode of the present invention is 1 to 40 μm, preferably 2 to 30 μm, and more preferably 2 to 20 μm. Average particle size is 1μ
Since the carbon material having a diameter of m or less easily migrates in the battery, the internal resistance of the secondary battery tends to increase due to a short circuit of the secondary battery or clogging of the separator. If it is 40 μm or more, it is difficult to produce a uniform negative electrode. d ₀₀₂ is 3.37 to 3.4
The average particle diameter of the carbon material Å is 1 to 30 μm, preferably 1 to 25 μm, and more preferably 1 to 20 μm. If the average particle size is 1 μm or less, the carbon material is likely to move, and thus the internal resistance of the secondary battery is likely to increase due to short-circuiting of the secondary battery or clogging of the separator. 3
If the thickness is 0 μm or more, it is difficult to form a uniform negative electrode, and the current collecting characteristics of the negative electrode also deteriorate. The _{d002 of the} carbon material group having the largest average particle diameter used in the negative electrode of the present invention is preferably smaller than the _{d002 of the} carbon material group having the smallest average particle diameter. That is, it is preferable to make the carbon material having a large d ₀₀₂ enter the gaps between the particles of the carbon material having a small d _{002 from} the viewpoint of improving the energy density and current collection characteristics of the negative electrode. d
_It is preferable that the carbon material having a smaller average ₀₀₂ has such a configuration because the lithium storage capacity is inherently higher and the directionality of electron conductivity occurs, and a more preferable configuration is a carbon material having a maximum average particle diameter. The material d ₀₀₂ is 3.37Å
D of the carbon material having a minimum average particle diameter of less than
₀₀₂ is 3.37 to 3.4 °.

The carbon anode of the present invention uses a carbon body and a binder which are previously formed in layers by a wet papermaking method or the like.
This may be used as an electrode by laminating it with a current collector by a method such as adhesion and pressure bonding, but a uniform coating solution in which the carbon material is dispersed in an appropriate solvent is applied onto the current collector. A layer formed by coating and drying is preferable from the viewpoint of uniformity of layers, adhesion between layers, and the like. It is more preferable to apply the above-mentioned coating material on the current collector by using these application methods, and after drying, apply the next layer in the same manner.
Examples of a method of applying the coating liquid include coating methods such as a wire bar, a blade, and a die coating method, but are not limited thereto. The carbon anode can be formed in various shapes and sizes, but is preferably formed in a film shape. As a solvent used when preparing the carbon negative electrode coating liquid, as a solvent in which the binder can be dissolved or dispersed, water, methanol, alcohols such as ethanol, acetone, methyl ethyl ketone,
Ketones such as methyl isobutyl ketone, aromatic solvents such as toluene and xylene, amides such as dimethylformamide, ethylene glycol, methylene glycol,
Glycols such as propylene glycol, ethers such as tetrahydrofuran and dioxane, N-methylpyrrolidone, and a single or mixed solvent thereof can be used, but are not limited thereto.

As a method for dispersing the carbon material constituting the carbon anode in a solvent, a method using a ball mill, a sand mill, a roll mill, a homogenizer or the like can be used. Further, the viscosity is preferably from 400 cP to 20,000 cP. When the viscosity is 400 cP or less, the filler of the carbon component precipitates in the solution, and a uniform coating liquid cannot be obtained. If the viscosity is 20,000 cP or more, the viscosity is too large to be used as a coating liquid. When the method of forming an electrode by using a binder is used, the binder may be polyvinyl acetate, polyvinyl chloride, polymethyl methacrylate, acrylic resin, polytetrafluoroethylene, polyethylene, chlorosulfonated polyethylene, polystyrene, polypropylene, or polyolefin. Vinylidene fluoride, polyvinyl fluoride, polyvinyl pyridine, nitrile rubber, polybutadiene, butyl rubber, styrene /
Examples thereof include butadiene rubber, nitrocellulose, cyanoethylcellulose, polyacrylonitrile, and polychloroprene. These may be used alone, or may be used by mixing or further enhancing the electrolytic solution resistance by copolymerization or the like. In particular, when a polyvinylpyridine-based binder is used, the strength of the negative electrode does not decrease even when charge and discharge of the negative electrode are repeated, so that a high cycle life is preferable. The polyvinyl pyridine-based binder is preferably one in which a cross-linking structure such as epoxy, urethane, or acrylic is introduced into polyvinyl pyridine to reduce dissolution in a non-aqueous electrolyte.
When a polyvinylpyridine-based binder is used, LiCl, LiBr, LiBF ₄ , LiClO ₄ , Li
It preferably contains a lithium salt such as PF ₆ , LiCF ₃ SO ₃ , and LiN (CF ₃ SO ₂ ) ₂ . By using a lithium salt, the flexibility and strength of the negative electrode and the binding property of the electrode active material can be significantly increased. The thickness of the negative electrode is 1 to 1000 μm, preferably 10 to 300 μm
It is. If it is 1 μm or less, it is disadvantageous in terms of energy density, and if it is 1000 μm or more, it is disadvantageous in terms of current collection efficiency.
These electrodes are preferably used by controlling the density and the like by pressing, improving the strength and conductivity of the electrodes, and improving the volume energy density. The electrode manufactured using the carbon material of the present invention has excellent workability and is flexible, so that it is suitable for manufacturing a film-shaped electrode, and exhibits excellent performance as an electrode when making a paper-shaped battery. .

The positive electrode active material used in the battery of the present invention is a transition metal oxide such as TiS ₂ , MoS ₂ , V ₂ O ₅ , MnO ₂ , CoO ₂ , a transition metal chalcogen compound, and a complex thereof with Li ( Li composite oxide; LiMnO ₂ , L
iMn ₂ O ₄ , LiCoO ₂ , LiNO _2, etc.) one-dimensional graphite compound which is a thermal polymer of an organic substance, carbon fluoride, graphite, or 10 ⁻² S / c in a doped state
a conductive polymer having an electrical conductivity of m or more, specifically, polymers such as polyaniline, polypyrrole, polyazulene, polyphenylene, polyacetylene, polyacene, polyphthalocyanine, poly-3-methylthiophene, polypyridine, polydiphenylbenzidine and the like. However, it is preferable to use a conductive polymer that exhibits high cycle characteristics even at a discharge depth of 100% and is relatively resistant to overdischarge as compared with inorganic materials. In addition, since the conductive polymer is a plastic in terms of moldability and processability, it can make use of features that have not existed before. Although the conductive polymer has the above advantages, the secondary battery using the conductive polymer for the positive electrode has a low volume energy density due to a low density of the active material, In order to perform a smooth charge / discharge reaction, it is necessary to use an excess There is a problem that a liquid is required. This is disadvantageous in improving the energy density. On the other hand, as the active material having a high volume energy density, it is conceivable to use the above-mentioned inorganic chalcogenide compounds and inorganic oxides for the positive electrode. There are problems that rapid charge and discharge are difficult, reversibility to overdischarge is poor, and cycle life is shortened. In addition, since it is difficult to form the inorganic active material as it is, it is often press-formed using a tetrafluoroethylene resin powder or the like as a binder, but in such a case, the mechanical strength of the electrode can be said to be sufficient. In addition, when lithium ions are excessively accumulated in overdischarge, the crystal structure is destroyed, and the function as a secondary battery is not achieved.

In order to solve such problems of the organic and inorganic active materials, it is conceivable to use an organic and inorganic composite active material. In this case, the polymer active material used is required to exhibit high electric conductivity by electrochemical doping, and the electrode material is required to have an electric conductivity of 10 ⁻² S / cm or more. Also, high ion conductivity is required for the ion diffusivity. These polymer materials have a high electric conductivity to have a current collecting ability, a binding ability as a polymer, and also function as an active material. In addition, since the conductive polymer is insulated at a low potential, even when the composite positive electrode is in an overdischarged state, the conductive polymer is insulated, so that unnecessary lithium ions are contained in the inorganic active material contained therein. Prevent it from accumulating,
This prevents the crystal structure of the inorganic active material from being destroyed. As a result, an electrode that is substantially resistant to overdischarge can be formed. The conductive polymer used for the composite positive electrode as described above has the ability as an active material, does not dissolve in the electrolytic solution,
A conductive material having a binding property between polymer materials and fixing an inorganic active material as a binder. At this time, the inorganic active material is in a form that is entirely covered by the conductive polymer, and as a result, the entire periphery of the inorganic active material becomes conductive. Examples of such a conductive polymer include redox active materials such as polyacetylene, polypyrrole, polythiophene, polyaniline, and polydiphenylbenzidine, and a remarkable effect is particularly observed in nitrogen-containing compounds. These conductive polymer materials are required to have high ionic conductivity not only in conductivity but also in ion diffusivity. Among these, polypyrrole, polyaniline, and copolymers thereof are preferable because they have a relatively large electric capacity per weight and can be relatively stably charged and discharged in a general-purpose nonaqueous electrolyte. More preferred is polyaniline. The inorganic active material used for the composite positive electrode preferably has excellent potential flatness. Specifically, an oxide of a transition metal such as V, Co, Mn, or Ni or a composite oxide of the transition metal and an alkali metal is used. Taking account of stable electrode potential, voltage flatness and energy density in the electrolyte, crystalline vanadium oxide is preferable, and vanadium pentoxide is particularly preferable. The reason is that the potential flat portion of the discharge curve of crystalline vanadium pentoxide is relatively close to the electrode potential accompanying insertion and desorption of the anion of the conductive polymer.

Examples of the current collector of the negative electrode used in the present invention include a metal sheet such as stainless steel, gold, platinum, nickel, aluminum, molybdenum, and titanium, a metal foil, a metal net, a punching metal, and an ex-band metal. ,
Alternatively, a mesh or nonwoven fabric made of metal-plated fiber, metal-deposited wire, metal-containing synthetic fiber, or the like can be used. Particularly, copper foil is excellent in adhesion and current collecting properties. On the other hand, the positive electrode current collector includes the above-described current collector of the negative electrode. Aluminum is preferable in consideration of electric conductivity, chemical stability, electrochemical stability, economy, workability, light weight, and the like. Furthermore, the surface of the positive electrode and / or negative electrode current collector layer used in the present invention is preferably roughened. By performing the surface roughening, the contact area of the active material layer is increased, the adhesion is also improved, and the impedance as a battery is reduced. In the preparation of an electrode using a coating solution, the adhesion between the active material and the current collector can be significantly improved by performing a surface roughening treatment. Examples of the surface roughening treatment include polishing with an emery paper, blasting, and chemical or electrochemical etching, whereby the current collector can be roughened. In particular, in the case of aluminum, etched aluminum is preferable. The etching treatment can effectively roughen the surface on the order of micrometer without deforming the aluminum or greatly reducing its strength, and is the most preferable method for roughening the aluminum.

The battery of the present invention basically comprises a positive electrode, a negative electrode and an electrolyte. If necessary, a separator can be used. An electrolyte or a solid electrolyte is used as the electrolyte of the present invention. Examples of the electrolyte for the lithium secondary battery of the present invention include a solution in which an electrolyte salt is dissolved in a non-aqueous solvent. Examples of the non-aqueous solvent include cyclic carbonate solvents (propylene carbonate, ethylene carbonate, butylene carbonate), chain carbonate solvents (dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl isopropyl carbonate), amide solvents (N-methylformamide, N- Ethylformamide, N, N-dimethylformamide, N-
Methylacetamide, N, N-dimethylacetamide,
N-ethylacetamide, N-methylpyrrolidinone),
Lactone solvents (γ-butyl lactone, γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxazolidin-2-one, etc.), alcohol solvents (ethylene glycol, propylene glycol, glycerin, methyl cellosolve, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, diglycerin, polyoxyalkylene glycol, cyclohexanediol, xylene glycol, etc., ether solvent (methylal, 1,2-dimethoxyethane, 1,2 -Diethoxyethane, 1-ethoxy-2-methoxyethane, alkoxypolyalkylene ethers, etc., nitrile solvents (benzonitrile, acetonitrile, 3-methoxypropionitrile, etc.), phosphoric acids and phosphate esters solvents (normal phosphoric acid, metaphosphoric acid) , Pyrophosphoric acid, poly Acid, phosphorous acid, trimethyl phosphate, etc.), 2-imidazolidinones (1,3-dimethyl-2-imidazolidinone, etc.), pyrrolidones, sulfolane solvents (sulfolane, tetramethylene sulfolane), furan solvents (tetrahydrofuran, 2 -Methyltetrahydrofuran, 2,5-dimethoxytetrahydrofuran),
Dioxolane, dioxane, dichloroethane alone or a mixture of two or more solvents can be used. Of these, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, contains a chain carbonate such as methyl isopropyl carbonate, further ethylene carbonate, propylene carbonate,
It is preferable to contain a cyclic carbonate such as butylene carbonate.

As the electrolyte salt of the lithium battery of the present invention, a salt which is dissolved in a non-aqueous solvent and has high ionic conductivity is used. Such materials include, for example, alkali metal ions as cations and Cl as anions.
^{-, Br -, I -,} SCN -, ClO 4 -, BF 4 -, PF 6 -,
SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ^{− and the} like can be exemplified, and among them, a sulfonate is preferable. Examples of the sulfonate include LiN (CF ₃ SO ₂ ) ₂ , Li
CF ₃ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , C ₆ F ₉ SO ₃ L
i, C ₈ F ₁₇ SO ₃ Li and the like, and particularly, LiN (CF
₃ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ are preferred. Also,
As the electrolyte salt used in the lithium secondary battery of the present invention,
A mixture of the sulfonate and another type of electrolyte salt other than the sulfonate may be used. Compounds that provide other types of electrolyte salts other than sulfonates include, for example, Li
_{PF 6, LiSbF 6, LiAsF 6} , LiBF 4, LiC
_{lO 4, LiI, LiBr, KPF} 6, KClO 4, Na
PF ₆ , [(n-Bu) ₄ N] BF ₄ , [(n-Bu)
₄ N] ClO ₄ , LiAlCl _4, LiBR ₄ (R is a phenyl group or an alkyl group), LiTFPB, {LiB [Ph
(—CF ₃ ) ₂ -3,5] ₄ , Ph is a phenyl group｝, Li
Examples include AlCl _4, but are not particularly limited thereto. Among the electrolyte salts, as described above, LiN (CF ₃ SO ₂ ) ₂ has high ionic conductivity, excellent heavy-load discharge characteristics, and excellent low-temperature characteristics.
It is preferable as an electrolyte salt for a lithium secondary battery. However, LiN (CF ₃ SO ₂ ) ₂ is corrosive, and the corrosion is remarkable especially when the positive electrode current collector layer is made of aluminum. The above-mentioned corrosiveness means that the elution current of aluminum flows when an electric field is applied, and the present inventors have studied to suppress this corrosiveness.
By adding another electrolyte salt to N (CF ₃ SO ₂ ) ₂ , the corrosiveness could be suppressed. As the other electrolyte salt, the above-mentioned cation, the addition of an electrolyte salt composed of a combination of anions was effective, but from the viewpoint of corrosion prevention, the composite cathode of the present invention, more preferably from the viewpoint of matching with the composite anode, At least one compound represented by the following formulas (1) to (3) and / or LiX, LiSbX ₆ , LiA
It has been found that a particularly remarkable effect is exhibited by using at least one lithium salt represented by lX ₄ and LiSCN (X is a halogen).

Embedded image M (BF ₄ ) x (1) (R ¹ R ² R ³ R ⁴ ) NBF ₄ (2) LiPF ₆ (3) [In the above formula, M represents an alkali metal or an alkaline earth metal. X is 1 or 2, and R ¹ , R ² , R ³ and R ⁴ each represent an alkyl group. As the tetrafluoroborate salt represented by the above formula (1) or (2), specifically, for example, as the compound of the formula (1), those in which M is Li, Na, K, Ca, Mg, etc. And the compound of the formula (2) is, for example, Li
BF ₄ , (CH ₃ ) ₄ NBF ₄ , (CH ₃ CH ₂ ) ₄ NBF ₄ ,
(CH ₃ CH ₂ CH ₂ CH ₂ ) ₄ NBF ₄ , (CH ₃ CH ₂ CH
₂ CH ₂ ) ₂ (CH ₃ ) ₂ NBF _{4 and the} like. The concentration of the electrolyte salt varies depending on the electrode and electrolyte used, but is preferably 0.1 to 10 mol / l. 0.1mol
/ L or less, energy density cannot be obtained and 10
If it is at least mol / l, it will be difficult to prepare.

As the separator, it is preferable to use a separator having a low resistance to the ion transfer of the electrolyte solution and having an excellent solution retention. Examples of such a separator include a glass fiber filter, a nonwoven fabric filter made of polymer fibers such as polyester, Teflon, polyflon, and polypropylene, and a nonwoven fabric filter in which glass fibers are mixed with these polymer fibers. Further, a solid electrolyte can be used in place of or in combination with these electrolytes and separators. The solid electrolyte is preferable because it has no liquid leakage and has high safety when the battery is heated. Examples of the solid electrolyte used in the present invention include, for example, AgCl, AgBr, AgI, Li
Metal halides such as I, RbAg ₄ I ₅ , RbAg ₄
I ₄ CN ion conductor and the like. In the organic system, polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, polyacrylonitrile and the like as a polymer matrix and a solid solution in which the above-described electrolyte salt is dissolved, or a cross-linked form thereof, low-molecular-weight polyethylene oxide, polyethyleneimine, Examples include a solid polymer electrolyte in which an ion dissociating group such as a crown ether is grafted to a polymer main chain. Alternatively, a gel-like polymer solid electrolyte having a structure in which the above-mentioned electrolytic solution is contained in a high-molecular-weight polymer may be used. The gel polymer solid electrolyte is obtained by adding a polymerizable compound to the above-mentioned electrolytic solution,
Polymerization is performed by heat or light to solidify the electrolyte. More specifically, those described in WO91 / 14294 are used. As the polymerizable compound, for example, an acrylate compound (for example, methoxydiethylene glycol acrylate, methoxydiethylene alcohol methacrylate) is converted from benzoyl peroxide, azobisisobutyronitrile, methylbenzoyl formate, benzoin isopropyl ether, furfuryl acrylate, trimethylolpropane acrylate. And the like to polymerize using a polymerization initiator such as the above to solidify the electrolytic solution. Among such solid electrolytes, it is preferable to use a gel polymer solid electrolyte from the viewpoint of ionic conductivity and flexibility.

Hereinafter, embodiments of the present invention will be described.

[0020] Example 1 d ₀₀₂ polyvinylidene fluoride 15 parts by weight of each 50 parts by weight of the average carbon material particle size 10μm and d ₀₀₂ is the average particle diameter of 10μm carbon material 3.380Å in 3.355Å Was weighed, N-methylpyrrolidone was added and mixed to form a paste. This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

[0021] Example 2 d ₀₀₂ polyvinylidene fluoride 15 parts by weight of each 50 parts by weight of the average carbon material particle size 12μm and d ₀₀₂ is the average particle diameter of 8μm carbon material 3.375Å in 3.356Å Was weighed, N-methylpyrrolidone was added and mixed to form a paste. This is applied to a copper foil of 20 μm,
After drying, an electrode having a thickness of the electrode active material layer of 60 μm was produced.

[0022] Comparative Example 1 d ₀₀₂ average particle diameter were weighed polyvinylidene fluoride 15 parts by weight to 100 parts by weight of carbon material of 10μm in 3.355A, and the paste was mixed with a N- methylpyrrolidone . This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

[0023] Comparative Example 2 d ₀₀₂ is the average particle diameter were weighed polyvinylidene fluoride 15 parts by weight to 100 parts by weight of carbon material of 10μm in 3.375A, and the paste was mixed with a N- methylpyrrolidone . This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

[0024] Comparative Example 3 d ₀₀₂ average particle size of 10μm carbon material and d ₀₀₂ of the average particle diameter of 10μm at 3.43Å polyvinylidene fluoride 15 parts by weight each of 50 parts by weight of the carbon material in 3.355Å Was weighed, N-methylpyrrolidone was added and mixed to form a paste. This is applied to a copper foil of 20 μm,
After drying, an electrode having a thickness of the electrode active material layer of 60 μm was produced.

Negative electrode performance test The electrode characteristics of the negative electrodes of Examples 1 and 2 and Comparative Examples 1, 2 and 3 were measured. 1M LiPF ₆ of ethylene carbonate and dimethyl carbonate (1: 1 by volume) was used as the electrolyte.
Used in a mixed solvent. The negative electrode was charged to 0 V with respect to the lithium electrode, discharged at 0.8 V at each current value, and the energy density of the negative electrode was measured.

[Table 1]

Example 3 55 parts by weight of a carbon material having a d ₀₀₂ of 3.355 ° and an average particle diameter of 12 μm, and a d ₀₀₂ of 3.38 ° and an average particle diameter of 1
45 parts by weight of a 2 μm carbon material and 15 parts by weight of polyvinylidene fluoride were weighed, N-methylpyrrolidone was added and mixed to form a paste. This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

[0027] Example 4 d ₀₀₂ is the average particle size an average particle size of the carbon material of 12μm is 55 parts by weight and d ₀₀₂ at 3.38Å in 3.355Å 7
The carbon material of μm was weighed at 45 parts by weight and 15 parts by weight of polyvinylidene fluoride, and N-methylpyrrolidone was added and mixed to form a paste. This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

Example 5 55 parts by weight of a carbon material having a d ₀₀₂ of 3.355 ° and an average particle diameter of 25 μm, and a d ₀₀₂ of 3.38 ° and an average particle diameter of 7
A carbon material of μm was weighed at 45 parts by weight and 15 parts by weight of polyvinylidene fluoride, and N-methylpyrrolidone was added and mixed to form a paste. This was applied to a copper foil of 20 μm and dried to produce an electrode having an electrode active material layer having a thickness of 60 μm, but the film thickness was not uniform.

Example 6 55 parts by weight of a carbon material having a d ₀₀₂ of 3.356 ° and an average particle diameter of 10 μm, and a d ₀₀₂ of 3.38 ° and an average particle diameter of 1
45 parts by weight of a 5 μm carbon material and 15 parts by weight of polyvinylidene fluoride were weighed, and N-methylpyrrolidone was added and mixed to form a paste. This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

Example 7 55 parts by weight of a carbon material having a d ₀₀₂ of 3.357 ° and an average particle size of 12 μm, and a d ₀₀₂ of 3.37 ° and an average particle size of 8
45 parts by weight and 10 parts by weight of a polyvinyl pyridine-based binder (manufactured by Koei Chemical Co., Ltd.) were weighed, and N-methylpyrrolidone was added thereto and mixed to form a paste. This was applied to a 20 μm copper foil and dried to prepare an electrode having an electrode active material layer thickness of 60 μm.

Example 8 A negative electrode was produced in the same manner as in Example 7, except that 5 parts by weight of LiBF ₄ was added to produce the negative electrode. In the present negative electrode, the electrode active material did not fall off or peel off even at 90 ° bending.

Negative electrode performance test The electrode characteristics of Examples 3 to 8 were measured. 2ML for electrolyte
A solution prepared by dissolving iN (CF ₃ SO ₂ ) ₂ in a mixed solvent of ethylene carbonate and propylene carbonate in a ratio of 1: 1 (volume ratio) was used. The negative electrode was charged to 0 V with respect to the lithium electrode, discharged at 0.8 V at each current value, and the energy density of the negative electrode was measured. Examples 4, 7, 8
For, the cycle life was also measured.

[Table 2]

[Table 3]

Example 9 A beaker cell was produced using the negative electrode produced in Example 8. For the positive electrode, polyaniline and vanadium pentoxide 3: 7
The electrodes (weight ratio) were combined (the initial capacity was 2 mAh). As the electrolytic solution, a solution prepared by dissolving 2M LiN (CF ₃ SO ₂ ) ₂ in a 7: 3 (volume ratio) mixed solvent of ethylene carbonate and propylene carbonate was used. 2.5V ~
The battery was charged and discharged between 3.7 V, and the discharge capacity at 20 ° C. was measured as a battery characteristic. The charge / discharge current was 4 mA.

Comparative Example 4 A beaker cell was prepared and the battery characteristics were measured in the same manner as in Example 9 except that lithium was used for the negative electrode in Example 9.

[Table 4]

Example 10 Natural graphite (d ₀₀₂ = 3.357 °, average particle size = 13 μm)
m) and mesophase pitch in a reducing atmosphere at 2500 ° C.
(D ₀₀₂ = 3.371 °, average particle size =
5 μm) at a ratio of 1: 1 (parts by weight) is dissolved in N-methylpyrrolidone together with polyvinylidene fluoride, and these are mixed and dispersed in an inert gas using a roll mill to obtain a coating solution. This coating solution is applied on an Al current collector using a wire bar, and dried in the air at a temperature of 80 ° C. for 20 minutes to obtain a sheet-like electrode having a thickness of 60 μm. A Li plate was used as a counter electrode, and the electrolyte was EC (ethylene carbonate): DME (dimethoxyethane) =
7: 3 (parts by weight) 1 liter of the mixed solution
₃ SO ₃ dissolved at a ratio of 2 mol (2M LiCF ₃ S
The O ₃ / denoted as 7E3DME), an electrolyte solution EC (ethylene carbonate): DME = 7: to a mixture a 1 liter 3 (parts by weight), which was dissolved in a proportion of LiBF ₄ 2 moles (2MLiBF ₄ / 7E3DME)
And two types were prepared. The measuring method is Hokuto Denko HJ
Using a -201B charge / discharge measurement device, the battery was charged at a current of 0.7 mA until the battery voltage became -0.05 V, and after a 1-hour pause, the battery voltage was reduced to 0.7 mA at a current of 0.7 mA.
The battery was discharged until the voltage reached 8 V. Thereafter, charging and discharging were repeated, and the energy densities at the 5th and 40th cycles at 20 ° C. were evaluated as battery characteristics.

[Table 5]

Example 11 The negative electrode of Example 10 was the same as the negative electrode except that stainless steel was used as the current collector. The electrolyte was EC (ethylene carbonate): PC (propylene carbonate): DMC =
For 1 liter of a mixture of 5: 2: 3 (parts by weight), Li
A battery using a solution in which N (CF ₃ SO ₂ ) ₂ was dissolved at a ratio of 2.0 mol (expressed as 2M imide / 5E2P3DMC) was evaluated for battery characteristics by the same measurement method as in Example 10. The results are shown in Table 6 below.

[Table 6]

Example 12 The battery characteristics of the negative electrode of Example 11 were evaluated in the same manner as in Example 11 except that copper was used for the current collector. The results are shown in Table 7 below.

[Table 7]

Example 13 N-methylpyrrolidone was added to a mixture of LiCoO ₂ , artificial graphite, and polyvinylidene fluoride in a ratio of 85: 8: 7 (parts by weight) to form a paste. To a thickness of 20 μm) and dried to form a positive electrode. A bolt-nut type cell was produced using the electrode produced in Example 1 as a negative electrode. A microporous polypropylene film was used as a separator. As the electrolyte, a solution in which 1.4 M LiN (CF ₃ SO ₂ ) ₂ was mixed with ethylene carbonate and diethyl carbonate at a ratio of 1: 1 (volume ratio) was used. In addition, the shape of the positive electrode and the negative electrode was a disk shape with a diameter of 1.6 cm. 2 mA, 4.1 V,
The charge / discharge test was repeated under the conditions of constant current / constant voltage charge for 3 hours and constant current discharge of 2 mA to 2.8 V, and a discharge capacity at 20 ° C. was measured as a battery characteristic.
The results are shown in Table 8 below.

Example 14 In Example 13, Li _0.3 Mn was used instead of LiCoO _2.
A positive electrode was produced in the same manner as in Example 13 except that O ₂ was used, and a bolt-nut type cell was produced. 2 mA, 3.5
The charge / discharge test was repeated under the conditions of V, constant-current constant-voltage charge for 3 hours, and constant-current discharge of 2 mA up to 2 V to perform a charge / discharge test, and a discharge capacity at 20 ° C. was measured as a battery characteristic.
The results are shown in Table 8 below.

EXAMPLE 15 N-methylpyrrolidone was added to a mixture of Li _0.3 MnO ₂ , polypyrrole, and polyvinylidene fluoride in a ratio of 85: 8: 7 (parts by weight) to form a paste. (Thickness: 20 μm) was applied at a thickness of 60 μm and dried to prepare a positive electrode. Example 14 except that this positive electrode was used.
In the same manner as in the above, a bolt-nut type cell was prepared and subjected to a charge / discharge test to measure a discharge capacity at 20 ° C. as battery characteristics. The results are shown in Table 8 below.

Example 16 In Example 15, an electrolyte obtained by dissolving 0.5 M LiPF ₆ and 1 M LiN (CF ₃ SO ₂ ) ₂ in a 6: 4 (volume ratio) mixed solvent of ethylene carbonate and dimethyl carbonate was used. A bolt-nut type cell was prepared and subjected to a charge / discharge test in the same manner as in Example 15 except for using the battery, and a discharge capacity at 20 ° C. was measured as a battery characteristic. The results are shown in Table 9 below.

Example 17 In Example 16, a bolt-nut type cell was prepared and subjected to a charge / discharge test in the same manner as in Example 16 except that the negative electrode prepared in Example 2 was used as the negative electrode. The discharge capacity was measured. The results are shown in Table 9 below.

[Table 8]

[Table 9]

Example 18 Preparation of Negative Electrode A Natural graphite (d ₀₀₂ = 3.355 °, average particle size = 12 μm)
m) and pitch coke carbon (d ₀₀₂ = 3.375 °,
(Average particle size = 7 μm) and 60: 3 polyvinylidene fluoride
The mixture was mixed at a ratio of 0:10 (parts by weight), and N-methylpyrrolidone was added to form a paste.
0 μm was applied and dried to produce a negative electrode A.

Example 19 Preparation of Negative Electrode B Mesophase pitch-based carbon fiber (d ₀₀₂ = 3.366)
Å, average particle size = 25 μm) and pitch coke-based carbon (d
₀₀₂ = 3.375 °, average particle size = 7 μm) and polyvinylidene fluoride in a ratio of 40:50:10 (parts by weight), and add N-methylpyrrolidone to form a paste.
70 μm was applied on a 10 μm copper foil and dried to prepare a negative electrode B.

Example 20 Preparation of Negative Electrode C Natural graphite (d ₀₀₂ = 3.355 °, average particle size = 12 μm)
m) and a carbon body obtained by firing mesophase microspheres (d ₀₀₂ =
3.380 °, average particle size = 2 μm) and polyvinylidene fluoride in a ratio of 50:40:10 (parts by weight).
-Add methylpyrrolidone to make a paste, 10μ
m was coated on a copper foil having a thickness of 70 m and dried to prepare a negative electrode C.

Example 21 Preparation of Negative Electrode D Natural graphite (d ₀₀₂ = 3.355 °, average particle size = 12 μm)
m) and fluid coke carbon (d ₀₀₂ = 3.377)
Å, average particle size = 6 μm) and polyvinylidene fluoride in 6
The mixture was mixed at a ratio of 0:30:10 (parts by weight), N-methylpyrrolidone was added to make a paste, 70 μm was applied on a 10 μm copper foil, and dried to prepare a negative electrode D.

Example 22 Preparation of Negative Electrode E A negative electrode E was prepared by adjusting the thickness of the negative electrode D to 45 μm in an active material layer by roll pressing.

Example 23 Preparation of Negative Electrode F Natural graphite (d ₀₀₂ = 3.355 °, average particle size = 12 μm)
m) and fluid coke carbon (d ₀₀₂ = 3.377)
{Average particle size = 6 μm), a polyvinylpyridine-based binder, and LiBF ₄ at a ratio of 60: 30: 10: 5 (parts by weight), and adding N-methylpyrrolidone to form a paste to form a 10 μm copper foil 70 μm was applied on the top and dried to prepare a negative electrode F.

Example 24 Preparation of Negative Electrode G The negative electrode F was prepared by adjusting the thickness of the active material layer of the negative electrode F to 45 μm by roll pressing.

Comparative Example 5 Preparation of Negative Electrode H Natural graphite (d ₀₀₂ = 3.355 °, average particle size = 12 μm)
m), a polyvinylpyridine-based binder and LiBF ₄ at a ratio of 90: 10: 5 (parts by weight), N-methylpyrrolidone was added to form a paste, and 70 μm was applied on a 10 μm copper foil and dried. . The thickness of the active material layer was adjusted to 45 μm by a roll press to produce a negative electrode H.

Comparative Example 6 Preparation of Negative Electrode I In the preparation of the negative electrode H, pitch coke carbon (d ₀₀₂ = 3.45 °, average particle size = 15 μm) was used instead of natural graphite.
A negative electrode I was produced in the same manner as in Comparative Example 5, except that m) was used.

REFERENCE EXAMPLE 1 Preparation of Positive Electrode A Vanadium pentoxide and polyaniline were mixed at a weight ratio of 9: 1, and N-methylpyrrolidone was added for dissolution and dispersion, and 100 μm on stainless steel (20 μm thick).
Coating and drying were performed to produce positive electrode A.

Reference Example 2 Preparation of Positive Electrode B In the preparation of positive electrode A of Reference Example 1, an etched aluminum foil (25
positive electrode B was prepared in the same manner except that μm) was used.

Example 25 The negative electrode A of Example 18 and the positive electrode A of Reference Example 1 were punched out on a disk having a diameter of 2 cm, respectively, and a coin battery was produced using a polypropylene microporous film as a separator. The electrolyte solution was prepared by mixing 1.5 M LiN (CF ₃ SO ₂ ) ₂ with ethylene carbonate and dimethyl carbonate at a volume ratio of 6:
What was dissolved in the mixed solvent of No. 4 was used. 3.7V, 2m
A, constant current constant voltage charging for 3 hours, 2 mA up to 2.6 V
The charge / discharge was repeated under the constant current discharge conditions described above, and the discharge capacity at 20 ° C. was measured as the battery characteristics. Table 10 shows the results.
It was shown to.

Example 26 A battery was fabricated in the same manner as in Example 25 except that the negative electrode B of Example 19 was used instead of the negative electrode A, and the battery characteristics were evaluated. Table 10 shows the results.

Example 27 In Example 25, 1.5 M LiN (CF ₃ S
A battery was prepared in the same manner except that a solution of O ₂ ) ₂ dissolved in a mixed solvent of γ-butyl lactone and dimethoxyethane in a volume ratio of 6: 4 was used, and the battery characteristics were evaluated. Table 10 shows the results.

Example 28 In Example 26, 1.4 M LiN was added to the electrolyte salt of the electrolytic solution.
A battery was prepared in the same manner as in Example 26 except that (CF ₃ SO ₂ ) ₂ and 0.1 M tetrabutylammonium tetrafluoroboric acid were used, and the battery characteristics were evaluated. Table 10 shows the results.

Example 29 In Example 26, 1.4 M LiN was added to the electrolyte salt of the electrolytic solution.
A battery was fabricated in the same manner as in Example 26 except that (CF ₃ SO ₂ ) ₂ and 0.1 M LiSbF ₆ were used, and the battery characteristics were evaluated. Table 11 shows the results.

Example 30 In Example 26, 1.3 M LiN was added to the electrolyte salt of the electrolytic solution.
A battery was prepared in the same manner as in Example 26 except that (CF ₃ SO ₂ ) ₂ and 0.2 M LiBF ₄ were used, and the battery characteristics were evaluated. Table 11 shows the results.

[Table 10]

[Table 11]

Example 31 A battery was prepared in the same manner as in Example 30, except that the positive electrode B was used as the positive electrode, and the battery characteristics were evaluated. Table 12 shows the results.

Example 32 A battery was prepared in the same manner as in Example 31 except that the negative electrode C was used as the negative electrode, and the battery characteristics were evaluated. Table 12 shows the results.

Example 33 A battery was prepared in the same manner as in Example 31 except that the negative electrode D was used as the negative electrode, and the battery characteristics were evaluated. Table 12 shows the results.

Example 34 A battery was prepared in the same manner as in Example 31 except that the negative electrode F was used as the negative electrode, and the battery characteristics were evaluated. Table 12 shows the results.

[Table 12]

Example 35 A battery was fabricated in the same manner as in Example 31, except that the negative electrode E was used as the negative electrode. Discharge current of 4
The battery characteristics were evaluated in the same manner as in Example 31 except that mA was used. Table 13 shows the results.

Example 36 A battery was prepared in the same manner as in Example 35 except that the negative electrode G was used as the negative electrode, and the battery characteristics were evaluated. Table 13 shows the results.

Comparative Example 7 A battery was prepared in the same manner as in Example 35 except that the negative electrode H was used as the negative electrode, and the battery characteristics were evaluated. Table 13 shows the results.

Comparative Example 8 A battery was prepared in the same manner as in Example 35 except that the negative electrode I was used as the negative electrode, and the battery characteristics were evaluated. Table 13 shows the results.

[Table 13]

Example 37 A 4 cm × 5 cm sheet battery was prepared using the negative electrode E and the positive electrode A. 1.5 M LiN (C
13.8 g of ethoxydiethylene glycol acrylate and 0.2 g of trimethylolpropane triacrylate are dissolved in 86 g of an electrolyte obtained by dissolving F ₃ SO ₂ ) ₂ in a mixed solvent of ethylene carbonate, propylene carbonate and dimethyl carbonate in a volume ratio of 5: 1: 4. And a solution in which 0.1 g of benzoin isopropyl ether was mixed was irradiated with UV light to use a gelled polymer solid electrolyte. A polypropylene microporous film was used as a separator to prevent a short circuit. A polyethylene / aluminum / polyethylene terephthalate laminate film was used for the exterior material. The prepared battery was charged at 10 mA, 3.7 V, 4
The battery was charged and discharged under the conditions of constant voltage charging for 10 hours and constant current discharging of 10 mA up to 2.6 V, and the discharge capacity at 20 ° C. was measured as battery characteristics. Table 14 shows the results.

Example 38 Using the negative electrode G and the positive electrode B, a 4 cm × 5 cm sheet battery was manufactured. 1.2 M LiN (C
13.8 g of ethoxydiethylene glycol acrylate and 0.2 g of F ₃ SO ₂ ) ₂ and 0.3 M LiBF ₄ in 86 g of an electrolytic solution obtained by dissolving ethylene carbonate, propylene carbonate and dimethyl carbonate in a mixed solvent having a volume ratio of 5: 1: 4. A gel polymer solid electrolyte produced by irradiating a solution obtained by mixing trimethylolpropane triacrylate and 0.1 g of benzoin isopropyl ether with UV light was used. A polypropylene microporous film was used as a separator to prevent a short circuit. A polyethylene / aluminum / polyethylene terephthalate laminate film was used for the exterior material. The battery characteristics of the fabricated battery were evaluated in the same manner as in Example 37. Table 14 shows the results.
It was shown to.

Example 39 A battery was prepared in the same manner as in Example 38 except that LiPF ₆ was used instead of LiBF ₄ , and the battery characteristics were evaluated. Table 14 shows the results.

Comparative Example 9 A battery was prepared in the same manner as in Example 38 except that the negative electrode H was used instead of the negative electrode G, and the battery characteristics were evaluated. Table 15 shows the results.

Comparative Example 10 A battery was prepared in the same manner as in Example 38 except that the negative electrode I was used instead of the negative electrode G, and the battery characteristics were evaluated. Table 15 shows the results.

[Table 14]

[Table 15]

Example 40 A 4 cm × 5 cm sheet battery was prepared using the above-mentioned negative electrode E and positive electrode A. 1.2 M LiN (C
A solid solution of F ₃ SO ₂ ) ₂ and a crosslinked polyethylene oxide-polypropylene oxide copolymer was used. A polyethylene / aluminum / polyethylene terephthalate laminate film was used for the exterior material. 3.7V at 1mA
When the battery was discharged at a constant current of 1 mA to 2.5 V, a discharge capacity of 28.1 mAh was obtained. The discharge capacity when charge / discharge was repeated 100 cycles was 26.5 mAh.

[0074]

Operation and Effect of the Invention A negative electrode for a lithium secondary battery having a high energy density and capable of discharging a heavy load is provided. 2. Provide a negative electrode with a high cycle life. 3. Provide a flexible and high cycle life negative electrode. 4. A lithium secondary battery having a high capacity and a long cycle life was obtained. 5. A lithium secondary battery that solved the problems of the organic and inorganic electrode active materials was obtained. 6. A lithium secondary battery was obtained in which the surface of the current collector layer was roughened to improve the adhesion between the electrode active material and the current collector without deforming the current collector layer or reducing its strength. 7. A lithium secondary battery having a high capacity and a long cycle life was obtained. 8. A lithium secondary battery in which the current collector layer, particularly the aluminum positive electrode current collector layer was prevented from being corroded, was obtained. 9. A lithium secondary battery with high capacity and improved cycle characteristics was obtained. 10. A lithium secondary battery with improved cycle characteristics was obtained. 11. By using the solid electrolyte, a highly reliable lithium secondary battery having no electrolyte leakage was obtained.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 7-46235 (32) Priority date February 10, 1995 (Feb. 10, 1995) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 7-134801 (32) Priority date May 8, 1995 (5.8.1995) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 7-137236 (32) Priority date May 11, 1995 (May 11, 1995) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 7-196952 ( 32) Priority date July 10, 1995 (July 7, 1995) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 7-297499 (32) Priority date 1995 October 20, 1995 (Oct. 20, 1995) (33) Priority claiming country Japan (JP) (72) Inventor Kiyoshi Komura 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72 Inventor Toshige Fujii 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Miko Kurosawa 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Invention Person Hiroyuki Iechi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yoshitaka Hayashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Tomohiro Inoue 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-6-318459 (JP, A) JP-A-5-121066 (JP, A) JP-A-8 −180864 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/00-4/62 H01M 10/40

Claims (2)

(57) [Claims] 1. A negative electrode comprising two or more carbon materials,
Formed using an n-pyridine binder.
Characterized in that the surface spacing (d ₀₀₂ ) in the C-axis direction is
Lithium containing two or more carbon materials of 3.4% or less
Negative electrode for secondary batteries. 2. The negative electrode contains a lithium salt.
The negative for a lithium secondary battery according to claim 1, wherein
very.