JPH10106578A - Lithium battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an active material from exfoliating or slipping off from an electricity collecting body consisting of a metal by enhancing the tight attachment of the active material with a porous metal member. SOLUTION: As a binding agent for an active material, a chemical compound is used as containing a pre-polymer, preferably polyoxy-alkylene component, which can be dispersed uniformly in water. One favorable example of such compound containing polyoxy-alkylene component is a diacrylate series compound containing the polyoxy-alkylene component according to the equation given beside the text, where R1 , R2 , and R3 are low-grade alkyl radical of a carbon number of 1-6, and the conditions should be met that X>=1 and Y>=0 or X>=0 and Y>=1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium battery using an active material into which lithium ions can be inserted and desorbed.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable reduction in the size and weight of electronic devices, and accordingly, there has been a great demand for smaller and lighter batteries that serve as power supplies. In the field of primary batteries, small and lightweight batteries such as lithium batteries have already been put to practical use, but since these are primary batteries, they cannot be used repeatedly, and their uses have been limited. On the other hand, in the field of secondary batteries, lead storage batteries, nickel-cadmium storage batteries, nickel-hydrogen storage batteries, and the like have been conventionally used, but these have major problems in terms of size and weight reduction.

Therefore, lithium-ion batteries have come into practical use as small, lightweight, high-capacity, chargeable / dischargeable batteries, and are used in portable electronic and communication devices such as small video cameras, mobile phones, and notebook personal computers. Is now available. This type of lithium ion battery uses a carbon-based material capable of inserting and extracting lithium ions as a negative electrode active material, and uses LiCoO ₂ , LiNiO ₂ , L as a positive electrode active material.
using IMN ₂ O _4, LiFeO lithium-containing transition metal oxides such as _2, the ion conductor obtained by dissolving a lithium salt as a solute using an organic solvent as an electrolytic solution, after assembling the battery, the positive electrode active material by the first charging This is a battery in which lithium ions discharged from the battery enter the carbon particles and can be charged and discharged.

[0004] The electrode of this lithium ion battery is, for example, LiCoO _{2 as} a positive electrode active material in a positive electrode,
Conductive agents such as carbon materials such as acetylene black and graphite, organic polymers such as polyvinylidene fluorite (PVDF) and ethylene propylene diene monomer (EPDM) as binders, and organic solvents such as N-methylpyrrolidone The mixture is kneaded to prepare a paste-like positive electrode mixture, the positive electrode mixture is applied to a metal current collector, pressed, heated and dried, and then rolled to obtain a positive electrode.

[0005] On the other hand, in the negative electrode, N-methylpyrrolidone is used as a negative electrode active material such as carbon, an organic polymer such as polyvinylidene fluorite (PVDF) or ethylene propylene diene monomer (EPDM) as a binder (binder). A negative electrode mixture in the form of a paste is prepared by kneading a solution dissolved in an organic solvent such as the above, applied to a metal current collector, pressed, heated and dried, and then rolled to form a negative electrode.

[0006]

By the way, when each electrode mixture is constituted using a binder (binder) made of an organic polymer such as polyvinylidene fluorite (PVDF) or ethylene propylene diene monomer (EPDM),
Although these organic polymers have good binding properties to the metal current collector, these organic polymers are insoluble in water, and thus necessitate the use of an organic solvent such as N-methylpyrrolidone.

Here, since the organic solvent has high volatility and is flammable, it is inconvenient to handle the organic solvent, and there is a problem that an explosion-proof facility must be introduced into the electrode manufacturing facility. Therefore, when an organic solvent is used, the manufacturing process becomes complicated, and the organic solvent itself is expensive and the manufacturing equipment is expensive, resulting in a problem that the manufacturing cost of the battery increases.

On the other hand, as a binder using water which is easy to handle as a solvent, a mixture of cellulose and styrene butadiene rubber (SBR) is known.
However, a binder in which cellulose and styrene-butadiene rubber (SBR) are mixed has a problem in that the adhesion of the active material to the metal current collector is weak because the adhesion to the metal current collector is weak. Was. In addition, cellulose has OH groups and styrene-butadiene rubber (SB).
Since R) has a large number of C ＝ C double bonds, there is a problem that the reactivity with the electrode material, particularly the active material, is large.

In view of the above, the present invention has been made in view of the above-mentioned problems, and simplifies the manufacturing equipment, improves the adhesion between the active material and the porous metal, and reduces the active material from the metal current collector. The purpose of the present invention is to prevent peeling or falling off.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a lithium battery using an active material into which lithium ions can be inserted and desorbed. In the described invention, a reaction-curable binder that is uniformly dispersed in water is used as a binder for the active material. As described above, when a reaction-curable binder that is uniformly dispersed in water is used as a binder, water can be used as a solvent when preparing a slurry or a paste. The handling becomes much easier as compared with the above, and the safety at the time of manufacturing the electrode is greatly improved.

[0011] The reaction-curable binder is a binder that is cured by polymerization. As a result, the binding strength is high, the adhesion between the active material and the metal current collector is improved, the peeling or falling off of the active material from the metal current collector can be prevented, and the battery has good initial charge / discharge efficiency and cycle characteristics. The characteristics are improved. As a result, it is possible to improve the yield and the reliability.

According to the second aspect of the present invention, a compound containing a polyoxyalkylene component is used as the above-mentioned reaction-curable binder which is uniformly dispersed in water.
Since the polyoxyalkylene component is uniformly dispersed in water, the surroundings of the active material particles are covered with the polyoxyalkylene component, and the reaction between the active material and the electrolyte is suppressed. Cycle characteristics are improved.

[0013] In a third aspect of the present invention, the reactive curable binder is a compound containing a polyoxyalkylene component which cures when heated or irradiated with an electromagnetic wave or an electron beam. As described above, when the compound containing the polyoxyalkylene component is cured by heating or irradiating an electromagnetic wave or an electron beam, it becomes possible to cure the active material after applying the active material to the metal current collector. The active material can be uniformly applied to the metal current collector, so that uneven application can be prevented.

[0014] In a fourth aspect of the present invention, the compound containing a polyoxyalkylene component is a diacrylate compound having the following structural formula.

[0015]

Embedded image

However, R ₁ , R ₂ , and R ₃ are H or have 1 to 1 carbon atoms.
6 represents a lower alkyl group, wherein X ≧ 1 and Y ≧ 0 or X
Those satisfying the conditions of ≧ 0 and Y ≧ 1.

Since the diacrylate compound having such a structural formula has a polyethylene glycol (CH ₂ CH ₂ O) _X component, the hydrophilicity is improved and the compound is more uniformly dispersed in water.

According to a fifth aspect of the present invention, the compound containing a polyoxyalkylene component is a monoacrylate compound having the following structural formula.

[0019]

Embedded image

However, R ₁ , R ₂ , and R ₃ are H or have 1 to 1 carbon atoms.
6 represents a lower alkyl group, wherein X ≧ 1 and Y ≧ 0 or X
Those satisfying the conditions of ≧ 0 and Y ≧ 1.

Since the monoacrylate compound having such a structural formula has a polyethylene glycol (CH ₂ CH ₂ O) _X component as in the invention of claim 4, the hydrophilic property is improved and the monoacrylate compound is more uniformly dispersed in water. I will be.

According to a sixth aspect of the present invention, the compound containing a polyoxyalkylene component is polyethylene glycol triacrylate having the following structural formula.

[0023]

Embedded image

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are H or a lower alkyl group having 1 to 6 carbon atoms, A ≧ 1 and B, C, D, E, F ≧ 0 or B ≧ 1 and A, C, D,
E, F ≧ 0 or C ≧ 1 and A, B, D, E, F ≧ 0 or D ≧ 1 and A, B, C, E, F ≧ 0 or E ≧ 1 and A, B, C, D, F ≧ 0 or F ≧ 1 and A, B,
Those satisfying the condition of C, D, E ≧ 0.

Since the triacrylate compound having such a structural formula has a polyethylene glycol (CH ₂ CH ₂ O) _X component as in the inventions of claims 4 and 5, the hydrophilicity is improved and the water content is further increased. To be uniformly dispersed.

In the invention according to claim 7, when the active material is a positive electrode active material, LiCoO ₂ , LiNi
At least one selected from O ₂ and LiCo _X Ni _(1-X) O ₂ is contained. Since these positive electrode active materials are active materials having excellent charge / discharge characteristics, use of such a positive electrode active material makes it possible to obtain a lithium battery having excellent charge / discharge characteristics.

In the invention according to claim 8, when the above-mentioned active material is a negative electrode active material, it is a carbon material. Since a carbon material is a negative active material having excellent charge / discharge characteristics, the use of such a negative electrode active material makes it possible to obtain a lithium battery having excellent charge / discharge characteristics.

Further, according to the present invention, lithium ions are inserted and inserted.
A method for manufacturing a lithium battery using a detachable active material. In order to solve the above-mentioned problem, in the invention according to claim 9, the active material and a reaction-curable mold uniformly dispersed in water are provided. A mixing step of mixing the adhesive and water to form a slurry or paste, an application step of applying the slurry or paste to the metal current collector, and a reaction hardening type in the slurry or paste applied to the metal current collector. And a curing step of curing the binder.

As described above, since a slurry or a paste is prepared by using water as a reaction-curable binder which is uniformly dispersed in water, the handling becomes much easier than when an organic solvent is used. In addition, safety during the production of the electrode is remarkably improved, and explosion-proof equipment is not required, thereby enabling cost reduction. In addition, after the slurry or paste is applied to the metal current collector, the reaction curable binder is cured in the curing step, so that the active material can be uniformly applied to the metal current collector. The occurrence of unevenness can be prevented, and the adhesion between the metal current collector and the active material can be improved.

The tenth aspect of the present invention is to cure the reactive curable binder by heating or irradiating an electromagnetic wave or an electron beam in an inert atmosphere. As described above, when the reaction-curable binder is cured by heating or irradiating an electromagnetic wave or an electron beam in an inert atmosphere, the reaction-curable binder is easily and easily prepared without providing new curing equipment. Can be cured.

In the invention described in claim 11, the reaction-curable binder is selected from the compounds containing any of the polyoxyalkylene components described in claims 2 to 5. When a compound containing such a polyoxyalkylene component is used, it is uniformly dispersed in water and covers the periphery of the active material particles, so that the reaction between the active material and the electrolytic solution is suppressed, and the charge / discharge characteristics and cycle characteristics are reduced. improves.

[0032]

Embodiments of the present invention will be described below. a. Reaction curable binder As the reaction curable binder of the present invention, a prepolymer which is uniformly dispersed in water (a water-soluble binder is naturally uniformly dispersed in water), preferably polyoxy A compound containing an alkylene component is used. As the compound containing a polyoxyalkylene component, a diacrylate compound containing a polyoxyalkylene component having the following structural formula is preferable.

[0033]

Embedded image

(However, R ₁ , R ₂ and R ₃ are H or carbon 1
6 to lower alkyl groups satisfying the condition of X ≧ 1 and Y ≧ 0 or X ≧ 0 and Y ≧ 1. Of the diacrylate compounds containing a polyoxyalkylene component having the above structural formula, polyethylene glycol diacrylate and polyethylene glycol dimethacrylate are particularly suitable.

Further, a monoacrylate compound containing a polyoxyalkylene component having the following structural formula is preferred.

[0036]

Embedded image

(However, R ₁ , R ₂ , and R ₃ are H or C 1
6 to lower alkyl groups satisfying the condition of X ≧ 1 and Y ≧ 0 or X ≧ 0 and Y ≧ 1. Among the monoacrylate compounds containing a polyoxyalkylene component having the above structural formula, polyethylene glycol monoacrylate and polyethylene glycol monomethacrylate are particularly suitable.

Further, a triacrylate compound containing a polyoxyalkylene component having the following structural formula is preferred.

[0039]

Embedded image

(However, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆
Represents H or a lower alkyl group having 1 to 6 carbon atoms, and A ≧ 1 and B, C, D, E, F ≧ 0 or B ≧ 1 and A, C,
D, E, F ≧ 0 or C ≧ 1 and A, B, D, E, F ≧
0 or D ≧ 1 and A, B, C, E, F ≧ 0 or E ≧
1 and A, B, C, D, F ≧ 0 or F ≧ 1 and A,
B, C, D, E satisfying the condition of ≧ 0. Of the triacrylate compounds containing a polyoxyalkylene component having the above structural formula, polyethylene glycol triacrylate and polyethylene glycol trimethacrylate are particularly suitable.

In addition to the above, urethane acrylate compounds, hydroxy acrylate compounds, vinyl ethers, alicyclic epoxies and the like containing a polyoxyalkylene component can be used.

Here, the number of Xs in the polyethylene glycol (PEG) (CH ₂ CH ₂ O) _X component of the acrylate compound is determined based on whether the acrylate compound is insoluble in water, or soluble or soluble in water. There is a close relationship with whether they are evenly dispersed. For example, in the case of a diacrylate type, when X ≦ 4, it is insoluble in water and does not disperse uniformly in water, and when X ≧ 5, it disperses uniformly in water.
Further, in the case of a monoacrylate type, when X ≦ 2, it is insoluble in water and does not disperse uniformly in water, and when X ≧ 4, it disperses uniformly in water.

B. Active Material As the negative electrode active material, a carbon-based material capable of inserting and extracting lithium ions, for example, graphite, carbon black, coke, glassy carbon, carbon fiber, or a fired body thereof is suitable. Further, an oxide such as tin oxide or titanium oxide capable of inserting and extracting lithium ions may be used. On the other hand, as the positive electrode active material, a lithium-containing transition metal compound capable of accepting lithium ions as a guest, for example, LiCoO ₂ , LiNiO ₂ , LiCo _X N
i _(1-X) O ₂ , LiCrO ₂ , LiVO ₂ , LiMnO ₂ ,
αLiFeO ₂ , LiTiO ₂ , LiScO ₂ , LiYO ₂
And the like, but in particular, LiCoO ₂ , LiNiO ₂ , L
It is preferable to use iCo _X Ni _(1-X) O ₂ alone or to mix and use two or more of them. Further, a conductive polymer such as polyacetylene or polyaniline may be used.

C. Electrode After mixing the negative electrode active material, the reaction-curable binder, and water to form a slurry or paste, in the case of a slurry, apply it to a metal current collector using a die coater, a doctor blade, or the like, and paste In the case of (1), a negative electrode is formed by coating the metal current collector by a roller coating method or the like. On the other hand, after mixing the positive electrode active material, the reaction curable binder, the conductive agent and water to form a slurry or paste, in the case of a slurry, a die coater, a doctor blade or the like is used to form a metal current collector. In the case of application and paste, it is applied to a metal current collector by a roller coating method or the like to form a positive electrode. Note that additives such as polyethylene oxide, polyacrylonitrile, and cellulose may be added to the slurry or paste.

D. Curing method In the step of curing the reactive curable binder in each of the positive and negative electrodes prepared as described above, oxygen is present as a polymerization inhibitor of the reactive curable binder, and air is present. This is performed in an atmosphere not to be performed, for example, in a vacuum or in an inert gas such as a nitrogen gas or an argon gas.

As a method of curing the reaction-curable binder, a method of irradiating electromagnetic waves such as ultraviolet rays, X-rays, gamma rays, microwaves, high-frequency waves and infrared rays or an electron beam, or a method of heating is suitable. However, from the viewpoints of production facilities, ease of production, and the like, a method of heat curing by heating or a method of curing by irradiation with microwaves is particularly preferable. The heating temperature is 50-40.
It is preferable to heat in a temperature range of 0 ° C.

E. Separator and electrolytic solution As a separator that separates the positive and negative electrodes produced as described above, the positive and negative electrodes are separated without physical contact, and have high electrical insulation and high ion permeability. In addition, a synthetic resin microporous membrane or a gel-like solid electrolyte that has a low electric resistance and is chemically stable to the electrolytic solution is used. As a specific synthetic resin microporous membrane, a microporous membrane made of an inexpensive polyolefin resin having low reactivity with an organic solvent is preferable.

The electrolyte is an ionic conductor in which a lithium salt is dissolved as a solute in an organic solvent, has a high ionic conductivity, is chemically and electrochemically stable with respect to each of the positive and negative electrodes, and Wide operating temperature range and high safety,
Use cheap ones.

As the organic solvent, an aprotic solvent having no ability to supply hydrogen ions is used. For example, ethylene carbonate (EC), propylene carbonate (P
C), sulfolane (SL), tetrahydrofuran (THF), γ-butyrolactone (GBL), dimethyl carbonate (DMC), diethyl carbonate (DE
C), ethyl methyl carbonate (EMC), 1,2 dimethoxyethane (DME) and the like, or a mixed solvent thereof are preferred.

As a solute, a lithium salt having a strong electron-withdrawing property is used. For example, LiBF ₄ , LiClO ₄ , LiPF
_{6, LiAsF 6, LiCF 3 SO} 3, Li (CF 3 SO 2)
₂ N, etc. LiC ₄ F ₉ SO ₃ are suitable.

Each electrode is impregnated with an electrolyte obtained by adding the above-mentioned reaction-curable prepolymer to an electrolytic solution comprising the above-mentioned organic solvent and the above-mentioned solute, and is cured by heat or irradiated with electromagnetic waves or electron beams. By doing so, it becomes possible to produce a gel-like solid electrolyte battery.

As described above, when the reaction-curable binder of the present invention is used, water can be used as a solvent for preparing a slurry or a paste. The handling becomes much easier, the safety during the production of the electrodes is greatly improved, and the initial charge / discharge efficiency and cycle characteristics are improved. Although the detailed reason why the initial charge / discharge efficiency and the cycle characteristics are improved is not clear, it can be inferred that the reason is as follows.

That is, the polyoxyalkylene component comprises a polyethylene glycol (PEG) component having hydrophilicity,
Since it has an acrylate component having hydrophobicity, the dispersibility of the active material in the slurry or paste is improved, and the hydrophobic part in the slurry or paste is covered as a molecular film in the direction of the active material, thereby forming active material particles. It can be assumed that the periphery of the surface is covered with the binder. For this reason, it can be assumed that the reaction between the active material and the electrolytic solution is suppressed, and the initial charge / discharge efficiency and cycle characteristics are improved.

In addition, the reaction-curable binder of the present invention has little reactivity with the active material after the reaction-curing because there is no substance such as C ＝ C bond or active hydrogen. Therefore, the amount of the binder to be added can be freely selected, and a desired electrode strength can be obtained. Thereby, it is supposed that the adhesion to the current collector becomes extremely good, and the initial charge / discharge efficiency and the cycle characteristics contribute to the improvement.

As described above, in the present invention, since an expensive organic solvent is not used, the safety at the time of battery production can be improved,
In addition to cost reduction, the use of a reaction-curing binder improves electrode strength and adhesion to the current collector, and improves battery characteristics such as initial charge / discharge efficiency and cycle characteristics. become able to. As a result, it is possible to improve the yield and the reliability.

Example 1 Polyethylene glycol diacrylate (X = 9, Y = 0 and having a molecular weight of 508 in the structural formula) was used as a reaction-curable binder. Graphite is mixed at a weight ratio of 5: 130: 50 to obtain a slurry for a negative electrode. This negative electrode slurry is applied to a metal current collector made of copper foil, and then rolled to form a negative electrode. Then, the negative electrode is subjected to a heat treatment at 350 ° C. for about one hour in a nitrogen gas atmosphere to obtain a negative electrode plate.

The electrode area of the negative electrode plate thus obtained was set to 4 cm ² as a working electrode, and a lithium metal plate having a sufficiently large electrochemical capacity with respect to this working electrode was used as a counter electrode and at the same time. A single-pole cell is constructed using the lithium metal plate as a reference electrode. The capacity of a negative electrode plate having an electrode area of 4 cm ² is 12.3 mAh. The monopolar cell is accommodated in a container, and 30 parts by weight of ethylene carbonate (EC) and diethyl carbonate (DEC) are contained in the container.
1MLi as an electrolyte salt in a mixed solvent consisting of 70 parts by weight
The test battery 1 is constructed by injecting the electrolyte solution to which ClO ₄ has been added.

The test battery 1 was charged at a constant current of 0.4 mA for 1
After charging until the voltage reaches V, a constant current of 0.4 mA
When a cycle test in which a charge / discharge cycle of discharging to 1 V was repeated was performed, an experimental result as shown by a solid line A in FIG. 1 was obtained.

Example 2 Polyethylene glycol diacrylate (X = 9, Y = 0 and having a molecular weight of 508 in the structural formula shown above) was used as a reactive curable binder. Positive electrode mixture (LiCoO ₂ :
Ketjen Black: Graphite = 90: 8: 2 (weight ratio) is mixed at a weight ratio of 3: 130: 100 to prepare a slurry for the positive electrode. This positive electrode slurry is applied to a metal current collector made of aluminum foil, and then rolled to obtain a positive electrode. Then, the positive electrode is subjected to a heat treatment at a temperature of 150 ° C. for about one hour in a nitrogen gas atmosphere to obtain a positive electrode plate.

The electrode area of the positive electrode plate thus obtained was set to 4 cm ² as a working electrode, and a lithium metal plate having a sufficiently large electrochemical capacity with respect to this working electrode was used as a counter electrode, and the same as that of the working electrode. A single-pole cell is constructed using the lithium metal plate as a reference electrode. The capacity of the positive electrode plate having an electrode area of 4 cm ² is 11.3 mAh. The monopolar cell is accommodated in a container, and 30 parts by weight of ethylene carbonate (EC) and diethyl carbonate (DEC) are contained in the container.
1MLi as an electrolyte salt in a mixed solvent consisting of 70 parts by weight
The test battery 2 is formed by injecting the electrolytic solution to which ClO ₄ is added.

The test battery 2 was operated at a constant current of 1 mA for 4.2.
A charge / discharge cycle was repeated in which the battery was charged to V and then discharged at a constant current of 1 mA until the voltage reached 3 V. As a result, an experimental result as shown by a solid line B in FIG. 2 was obtained.

Example 3 Using the negative electrode plate manufactured in Example 1 and the positive electrode plate manufactured in Example 2, the negative electrode plate and the positive electrode plate were superposed and wound with a separator interposed therebetween. A cylindrical battery of 18650 (diameter: 18 mm, height: 65 mm) was manufactured by inserting the battery into a cylindrical container, and 30 parts by weight of ethylene carbonate (EC) and diethyl carbonate (DE) were placed in the container.
C) 1M as an electrolyte salt in a mixed solvent consisting of 70 parts by weight
A test battery 3 is formed by injecting an electrolyte solution to which LiClO ₄ has been added. The capacity of the test battery 3 was 1350 mA.
h.

The test battery 3 was set to 4.1 V at 1350 mA.
When a cycle test is performed in which a charge / discharge cycle is repeated in which the battery is charged with a constant current until the voltage becomes constant and charged at 4.1 V for 2 hours and then discharged at a constant current of 1350 mA until the voltage becomes 3 V, the solid line in FIG. Experimental results as shown by C were obtained.

Comparative Example 1 Polyvinylidene fluorite (PVDF) as a binder
And the PVDF, N-methylpyrrolidone, and graphite are mixed at a weight ratio of 5: 250: 95 to prepare a slurry for a negative electrode. This negative electrode slurry is applied to a metal current collector made of copper foil, then rolled and heated to remove N-methylpyrrolidone to obtain a negative electrode plate. The negative electrode plate thus obtained has a working electrode with an electrode area of 4 cm ^2, and a lithium metal plate having a sufficiently large electrochemical capacity with respect to this working electrode is used as a counter electrode, and a lithium metal plate of the same degree is used. A monopolar cell is constructed using the plate as a reference electrode. The capacity of a negative electrode plate having an electrode area of 4 cm ² is 12.3 mAh.

The monopolar cell is accommodated in a container, and an electrolyte solution in which 1 M LiClO ₄ is added as an electrolyte salt to a mixed solvent composed of 30 parts by weight of ethylene carbonate (EC) and 70 parts by weight of diethyl carbonate (DEC) in the container. To form a test battery 4.

The test battery 4 was charged at a constant current of 0.4 mA to 1
After charging until the voltage reaches V, a constant current of 0.4 mA
When a cycle test in which a charge / discharge cycle of discharging to 1 V was repeated was performed, an experimental result as shown by a dotted line D in FIG. 1 was obtained.

Comparative Example 2 Polyvinylidene fluorite (PVDF) as a binder
The slurry for the positive electrode was prepared by mixing the PVDF, N-methylpyrrolidone, and the positive electrode mixture (LiCoO ₂ : Ketjen Black: Graphite = 90: 8: 2 (weight ratio)) at a weight ratio of 5: 110: 100. And This positive electrode slurry is applied to a metal current collector made of aluminum foil, and then rolled and heated to remove N-methylpyrrolidone to obtain a positive electrode plate.

The positive electrode plate thus obtained has a working electrode with an electrode area of 4 cm ^2, and a lithium metal plate having a sufficiently large electrochemical capacity with respect to this working electrode is used as a counter electrode and at the same time. A single-pole cell is constructed using the lithium metal plate as a reference electrode. The capacity of the positive electrode plate having an electrode area of 4 cm ² is 11.3 mAh. The monopolar cell is accommodated in a container, and 30 parts by weight of ethylene carbonate (EC) and diethyl carbonate (DEC) are contained in the container.
1MLi as an electrolyte salt in a mixed solvent consisting of 70 parts by weight
The test battery 5 is constructed by injecting the electrolyte solution to which ClO ₄ has been added.

The test battery 5 was operated at a constant current of 1 mA for 4.2.
A charge / discharge cycle in which the battery was charged until the voltage reached V and then discharged at a constant current of 1 mA until the voltage reached 3 V was repeated. As a result, an experimental result as shown by a dotted line E in FIG. 2 was obtained.

COMPARATIVE EXAMPLE 3 Using the negative electrode plate prepared in Comparative Example 1 and the positive electrode plate prepared in Comparative Example 2, the negative electrode plate and the positive electrode plate were superposed and wound via a separator. A cylindrical battery of 18650 (diameter: 18 mm, height: 65 mm) was manufactured by inserting the battery into a cylindrical container, and 30 parts by weight of ethylene carbonate (EC) and diethyl carbonate (DE) were placed in the container.
C) 1M as an electrolyte salt in a mixed solvent consisting of 70 parts by weight
The test battery 6 is constructed by injecting the electrolyte solution to which LiClO ₄ has been added. The capacity of the test battery 6 was 1350 mA.
h.

The test battery 6 was set to 4.1 V at 1350 mA.
When a cycle test is performed in which a charge / discharge cycle is repeated in which the battery is charged at a constant current until the voltage becomes constant and is charged at 4.1 V for 2 hours and then discharged at a constant current of 1350 mA until the voltage becomes 3 V, the dotted line in FIG. Experimental results as indicated by F were obtained.

Experimental Results In FIG. 1, it can be seen that the discharge capacity characteristic A of the test battery 1 of Example 1 is superior to the discharge capacity characteristic D of the test battery 4 of Comparative Example 1. Further, in FIG. 2, it can be seen that the discharge capacity characteristic B of the test battery 2 of Example 2 is superior to the discharge capacity characteristic E of the test battery 5 of Comparative Example 2. Further, in FIG. 3, it can be seen that the discharge capacity characteristic C of the test battery 3 of Example 3 is superior to the discharge capacity characteristic F of the test battery 6 of Comparative Example 3.

The reason why such excellent characteristics are obtained is that each electrode of each embodiment uses the reactive curable binder of the present invention, so that the reaction between the active material and the electrolytic solution is suppressed. It is thought that due to the improvement of the electrode strength and the improvement of the adhesion of the active material to the current collector, the fall and separation of the active material due to the expansion and contraction of the electrode due to charge and discharge of the active material are suppressed. Can be

In the above embodiment, a lithium battery using a carbon-based active material as the negative electrode active material has been described. However, the reactive curable binder of the present invention is a lithium battery using metal lithium as the negative electrode active material. Obviously, it can be applied to the positive electrode active material.

[Brief description of the drawings]

FIG. 1 is a graph showing characteristics of discharge capacity with respect to the number of charge / discharge cycles in Example 1 and Comparative Example 1 of the present invention.

FIG. 2 is a graph showing characteristics of discharge capacity with respect to the number of charge / discharge cycles in Example 2 and Comparative Example 2 of the present invention.

FIG. 3 is a graph showing characteristics of discharge capacity with respect to the number of charge / discharge cycles in Example 3 and Comparative Example 3 of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Terashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (11)

[Claims] 1. A lithium battery using an active material into which lithium ions can be inserted and desorbed, wherein a reaction-curable binder that is uniformly dispersed in water is used as a binder for the active material. Features lithium battery. 2. The lithium battery according to claim 1, wherein a compound containing a polyoxyalkylene component is used as the reaction-curable binder that is uniformly dispersed in water. 3. The reaction-curable binder according to claim 2, wherein the reaction-curable binder is a compound containing a polyoxyalkylene component which is cured by heating or irradiation with an electromagnetic wave or an electron beam. Lithium battery. 4. The lithium battery according to claim 2, wherein the compound containing the polyoxyalkylene component is a diacrylate compound having the following structural formula. Embedded image Here, R ₁ , R ₂ and R ₃ represent H or a lower alkyl group having 1 to 6 carbon atoms, and X ≧ 1 and Y ≧ 0 or X ≧ 0 and Y ≧
One that satisfies condition 1. 5. The lithium battery according to claim 2, wherein the compound containing the polyoxyalkylene component is a monoacrylate compound having the following structural formula. Embedded image Here, R ₁ , R ₂ and R ₃ represent H or a lower alkyl group having 1 to 6 carbon atoms, and X ≧ 1 and Y ≧ 0 or X ≧ 0 and Y ≧
One that satisfies condition 1. 6. The lithium battery according to claim 2, wherein the compound containing the polyoxyalkylene component is a triacrylate compound having the following structural formula. Embedded image However, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are H or 1 carbon atoms.
~ 6 lower alkyl groups, A ≧ 1 and B, C, D,
E, F ≧ 0 or B ≧ 1 and A, C, D, E, F ≧ 0 or C ≧ 1 and A, B, D, E, F ≧ 0 or D ≧ 1 and A, B, C, E, F ≧ 0 or E ≧ 1 and A, B,
C, D, F ≧ 0 or F ≧ 1 and A, B, C, D, E ≧
Those satisfying the condition of 0. 7. When the active material is a positive electrode active material, LiC
_{oO 2, LiNiO 2, LiCo X} Ni (1-X) lithium battery according to any one of claims 1 to claim 6, characterized in that it contains at least one selected from O _2. 8. The lithium battery according to claim 1, wherein the active material is a carbon material when the active material is a negative electrode active material. 9. A method for producing a lithium battery using an active material into which lithium ions can be inserted and desorbed, wherein the active material, a reaction-curing binder uniformly dispersed in water, and water are used. A mixing step of mixing to form a slurry or paste; an application step of applying the slurry or paste to a metal current collector; and a reaction curing type binder in the slurry or paste applied to the metal current collector. And a curing step of curing the lithium battery. 10. The method according to claim 9, wherein the curing step is a step of curing the reactive curable binder by heating or irradiating an electromagnetic wave or an electron beam in an inert atmosphere. Manufacturing method of lithium battery. 11. The method according to claim 9, wherein the reaction-curable binder is selected from the compounds containing any of the polyoxyalkylene components according to any one of claims 2 to 6. A method for producing the lithium battery according to the above.