JPH05326021A - Secondary battery - Google Patents

Abstract

PURPOSE:To provide a secondary battery having a large battery capacity and excellent in charge-discharge characteristic by setting the mean particle diameter of the primary particles of electrochemical active material in a complex positive electrode and a complex negative electrode to an assigned value or less. CONSTITUTION:A secondary battery is formed of a complex positive electrode 2 and a complex negative electrode 4, composed of electrochemical active material, a binder made of an organic compound being dissolved and/or dispersed in solvent, and electron conductive material, and electrolyte 3, which is a ion conductive high molecular compound made of high molecular material in which at least one kind of ionic compound is dissolved, and having a polyether structure. The complex positive electrode 2 is composed of the electrochemical active material whose primary particles have an mean particle diameter of 5mum or less, the binder, and the electron conductive material. The complex negative electrode 4 is made of the electrochemical active material being carbon powder whose primary particles have the mean particle diameter of 5mum or less and the binder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery that operates reversibly at ambient temperature, and relates to an improved electrolyte, a positive electrode and a negative electrode, and an improved method for manufacturing a battery.

[0002]

2. Description of the Related Art Recent microelectronics is
As typified by power supplies for memory backup of various electronic devices, by accommodating batteries inside electronic devices and integrating them with electronic elements and circuits, batteries can be made smaller, lighter, thinner, and have higher energy density. There is a strong demand for batteries that have them. In recent years, small and lightweight batteries such as lithium batteries have already been put into practical use in the field of primary batteries, but the fields of application thereof are limited. Therefore, secondary batteries using non-aqueous electrolytes, which can be made smaller and lighter, are drawing more attention as batteries that replace conventional lead batteries and nickel-cadmium batteries. Many research institutions are currently studying it because of the fact that nothing satisfying practical properties such as characteristics has been found.

On the other hand, as an electrolyte for a battery or an electrochemical device other than a battery using an electrochemical reaction, that is, an electric double layer capacitor, an electrochromic element or the like, a liquid electrolyte is generally used, and an organic electrolyte is used as an electrolyte. Although the one in which a compound is dissolved has been used, the liquid electrolyte is likely to cause liquid leakage to the outside of parts, elution of electrode substances, and further volatilization of the liquid electrolyte itself, so that the long-term reliability of the electrochemical device is high. However, there have been problems such as scattering of the electrolytic solution in the sealing process.

Therefore, in order to improve the liquid leakage resistance and the long-term storage stability, an ion conductive polymer compound having high ion conductivity has been reported, and further research is being conducted as one of the means for solving the above problems. It is being advanced.

The ion-conducting polymer compounds currently being studied are homopolymer or copolymer linear polymers having ethylene oxide as a basic unit, reticulated crosslinked polymers, comb polymers, etc. For the purpose of increasing the ionic conductivity in the above, it has been proposed and implemented to prevent the crystallization of the above ion-conductive polymer compound by using a crosslinked polymer or a comb polymer. In particular, the ion conductive polymer compound using the above network cross-linked polymer is useful because it has high mechanical strength and good ionic conductivity at low temperature.

When designing a battery that is smaller, lighter, and has a higher energy density, the present inventor has studied a battery called a thin battery (having a thickness of 100 to 500 μm (or a sheet-shaped battery) per unit cell). did. However, when the above-mentioned ion-conductive polymer compound is used as a thin film as an electrolyte, it is technically somewhat difficult to produce thin-film metallic lithium having a quality sufficiently comparable to that, and the battery manufacturing process is complicated. Has become a problem. Furthermore, when used as a secondary battery,
Due to the problems of lithium dendrite formation and interfacial passivation, there has also been a problem of limiting the use of metallic lithium.

Therefore, research on lithium metal-containing alloys represented by lithium-aluminum, lithium-lead, and lithium-tin alloys has been actively conducted. However, as represented by a lithium-aluminum alloy,
Since these alloys have low strength, the electrodes are cracked or miniaturized by repeated charging / discharging, and thus cycle characteristics have not been improved.

As another method for suppressing dendrite formation of lithium, attempts have been made to select an electrolyte salt and improve the separator. Among them, the polypropylene non-woven fabric conventionally used for the separator has been tried. It has been attempted to suppress lithium dendrites by laminating glass fiber non-woven fabric, etc.
The essential solution has not been reached.

Therefore, at present, many research institutes have particularly studied electrode active materials utilizing intercalation of layered compounds or a doping phenomenon, and these are electrochemical reactions during charging and discharging. In this case, theoretically, a complicated chemical reaction does not occur, so that extremely excellent charge / discharge cycle performance is expected.

The example of using a carbonaceous material as an electrode active material has also appeared as a solution to problems such as cycle characteristics and self-discharge characteristics of the electrode active material. The characteristics of this carbonaceous material are high dope capacity, low self-discharge rate, excellent cycle characteristics, and most notably, a base potential very close to that of metallic lithium.

However, the electrode active material utilizing the intercalation of the layered compound or the doping phenomenon causes expansion / contraction of the electrode active material due to charging / discharging. In a composite electrode composed of an ion conductive polymer compound, an electrode active material, and optionally an electron conductive material, when various kinds of electrode active materials are selected, the charge / discharge cycle performance is improved in several kinds of composite electrodes. It turned out to be much worse. That is,
It was found that it is necessary to select a binder suitable for the electrode active material when manufacturing the composite electrode.

Further, when the above ion-conductive polymer compound is applied as an electrolyte of an electrochemical device, it is necessary to reduce the thickness of the electrolyte to reduce the internal resistance. In the case of the above ion-conductive polymer compound, a uniform thin film can be easily processed into an arbitrary shape, but that method becomes a problem. For example, a method of casting a solution of an ion-conductive polymer compound to evaporate and remove the solvent, a method of coating a polymerizable monomer or macromer on a substrate and heating polymerization, or curing by irradiation with actinic rays. There is a way.

However, although it is possible to form a uniform thin film by using the above-mentioned method, when actually assembling a battery, an electrochromic device or the like in the step of laminating an ion-conductive polymer compound thin film between electrodes, In some cases, the electrolyte layer was damaged by compressive deformation, resulting in a slight short circuit.
In particular, if the mechanical strength of the ion-conductive polymer compound thin film is insufficient, the thin film will be damaged during handling and short-circuited, resulting in a marked decrease in battery performance. Furthermore, when the surface area of the ion-conductive polymer compound is increased, the above problem becomes more likely to occur.

In particular, when lithium metal is used as the negative electrode active material, the lithium metal is eluted as lithium ions during discharge of the battery, the volume of the negative electrode is reduced, and lithium ions are incorporated into the positive electrode active material, so that the positive electrode is positively charged. Increases the volume of. The ion conductive polymer compound is required to have characteristics capable of coping with these changes. The same applies to the case where the positive electrode and the negative electrode utilize intercalation or a doping phenomenon.

These phenomena are greatly affected by the smoothness of the electrode surface. Further, when the smoothness of the electrode surface is poor, a problem such as a slight short circuit occurs when the battery is assembled and a charge / discharge cycle test is performed. That is, there is a major cause that the above-mentioned ion-conductive polymer compound thin film causes breakage or a slight short circuit due to the unevenness present on the electrode surface. There are two methods for solving these problems. Can be considered.

That is, one is to improve the mechanical strength of the ion conductive polymer compound, and the other is to improve the smoothness of the electrode surface.

As a method for improving the mechanical strength of the above ion conductive polymer compound, various methods have been reported in which an inorganic oxide is contained in the ion conductive polymer compound.
(For example, JP-A-2-155173 and JP-A-2-174
However, on the surface of the above-mentioned inorganic oxide, -O
Since functional groups such as H groups are present and it is difficult to remove them easily, there is an extremely high risk that these will cause a side reaction when assembling a battery or an electrochromic device. In the case of a battery, this side reaction remarkably appears in the form of a decrease in discharge capacity and a decrease in cycle characteristics when stored for a long period of time. Therefore, when the above-mentioned method is used, there is a big problem when applied to a battery.

Therefore, in order to solve the above problem, it is necessary to improve the smoothness of the electrode surface, and for that purpose, controlling the particle size of the electrode active material becomes one problem.

Further, in order to form a uniform thin film of the above ion-conductive polymer compound by the above-mentioned method, a method of mainly heat-polymerizing has heretofore been simple and often used.
However, the heating polymerization time becomes very long and it is difficult to improve the production rate, a temperature gradient is likely to occur in the heating furnace, and it is necessary to heat in an inert gas atmosphere. There was a problem of becoming large.

The present inventors prepared a thin battery (sheet-shaped battery) by arranging an electrolyte layer composed of the above ion-conductive polymer compound alone between the composite positive electrode and the composite negative electrode in the form of a sheet. I tried. However, according to the above-mentioned method, there is a problem in the method of making good contact at the interface between the composite electrode and the electrolyte layer, and usually the contact interface resistance becomes large, so that battery characteristics, especially cycle characteristics and charging / charging after long-term storage are It had a great adverse effect on the discharge characteristics.

Therefore, an attempt was made to apply the above-mentioned ion-conductive polymer compound composition liquid on the surface of the composite positive electrode or the surface of the composite negative electrode and heat-polymerize it, or to cure it by irradiation of ultraviolet rays. Compared to the method described above, it has become possible to improve the contact at the interface between the composite electrode and the electrolyte layer.However, in the above method, when the composite electrode is applied to the surface of the composite electrode, It is difficult to completely cure the penetrating ion-conductive polymer compound liquid, and even in a thin battery that is cured by irradiation with the above ultraviolet rays, considering the charge / discharge characteristics after long-term storage,
It wasn't perfect.

In addition, in the curing method by heat polymerization, when the above-mentioned method is applied, the heat polymerization time is long and, in addition, the bias of the polymerization initiator occurs in the ion conductive polymer compound composition liquid. However, there is a problem that the cross-linked network has a more irregular structure and the like, which is a major problem in addition to the problem of the above-mentioned production speed and equipment.

[0023]

In view of the above problems of the prior art, therefore, the present invention aims to improve battery characteristics and produce high-performance electrodes. In the present invention, in a battery using an ion-conductive polymer compound, It has a very high workability, there is no fear of liquid leakage to the outside, and it provides a battery with long-term reliability and safety. In addition, it has high performance, high energy density, and is small and lightweight. A sheet-shaped battery is provided.

[0024]

In order to achieve the above object, the present invention is to dissolve and / or dissolve an electrochemically active substance in a solvent.
Alternatively, a composite positive electrode (A) and a composite negative electrode (B) composed of a binder composed of a dispersed organic compound, and optionally an electron conductive substance, and a polymer in which at least one ionic compound is dissolved An ion-conducting polymer compound composed of a substance, which has a polyether structure and is composed of an electrolyte (C) composed of a polymer compound having ion conductivity, in the composite positive electrode ( A) is composed of an electrochemically active substance having an average primary particle size of 5 μm or less, the binder and an electron conductive substance, and the composite negative electrode (B) has an average primary particle size of 5 μm. The first invention comprises the following carbon powder, which is an electrochemically active substance and the binder.

Further, an electrolyte layer (C) made of the above ion-conductive polymer compound is arranged on the surface of the composite positive electrode (A) and the surface of the composite negative electrode (B), and the electrolyte layer (C) is irradiated with the ionizing radiation. Is to form the second invention.

Further, the above-mentioned ion-conductive polymer compound is a polymer compound which is a polyether having a reactive double bond in which at least one ionic compound is dissolved, and has a high degree of forming a crosslinked network structure by a polymerization reaction. A third aspect of the present invention is that the polymer compound is a high molecular compound, and the carbon powder in the composite negative electrode (B) is crushed carbon fiber and / or carbon powder in an inert gas atmosphere. According to a fourth aspect of the present invention, the carbon powder has an average primary particle diameter of 5 μm or less, and the ion-conductive polymer compound contains a substance capable of dissolving an ionic compound. The composite positive electrode (A), the composite negative electrode (B), and the ion conductive polymer composed of the electrochemically active substance and the ion conductive polymer compound. The above object is achieved by providing an electrolyte layer (C) composed of a compound.

By disposing the electrolyte layer (C) composed of the ion conductive polymer compound on both electrode surfaces of the composite positive electrode (A) and the composite negative electrode (B), good contact at the electrode interface is achieved. And the contact interface resistance decreases.
As a result, the problem of lithium deposition around the composite negative electrode, which has been a problem in the past, is uniformly distributed, and the problem that lithium deposition is partially concentrated to cause an internal short circuit is eliminated.

Further, when the sheet-shaped battery is assembled, the electrolyte layer (C) composed of the above ion-conductive polymer compound has a double structure, so that an internal short circuit due to a pinhole or the like can be prevented. .. Further, since the electrolyte layers are in contact with each other, the contact interface resistance becomes very small.

Further, as the positive electrode active material, for example, LiCo _X
Since the average particle diameter of the primary particles of the positive electrode active material represented by Ni _1-X O ₂ (0 ≤ X ≤ 1) is 5 µm or less, the above ion-conductive polymer compound thin film has irregularities on the composite positive electrode surface. Is not present, damage or slight short circuit does not occur, and the average particle size of the primary particles is 5 μm or less, reversibility is improved, and the capacity as the positive electrode active material is increased, The charge and discharge characteristics are excellent.

Carbon fiber and / or carbon powder, which is the negative electrode active material, is crushed in an inert gas atmosphere to obtain carbon powder having an average primary particle size of 5 μm or less. Since the thin film does not have unevenness on the surface of the composite negative electrode, it does not cause breakage or a minute short circuit. Further, the average particle size of the primary particles is 5 μm or less, the surface area of the carbon powder is improved, Since a smooth electrochemical reaction proceeds on the surface of the electrode, the capacity as the negative electrode active material increases, and the Li ion doping / dedoping property becomes excellent. Further, since the electrochemically active surface is not lost by pulverizing in an inert gas atmosphere, deterioration in cycle life characteristics, self-discharge characteristics, current efficiency characteristics, etc. is not seen.

When a binder comprising an organic compound dissolved and / or dispersed in a solvent is used, a binder solution prepared by dissolving the organic compound in the solvent and an electrode active material dispersed therein is used as a coating liquid. The method and a method of using a dispersion of an electrode active material in a dispersion of the organic compound and a dispersant for dispersing the organic compound as a coating solution are common, but are not limited thereto. Absent.
When the electrode is produced, a method of forming the electrode by coating and drying the coating liquid on the positive electrode current collector and the negative electrode current collector is preferable, but not limited thereto.

Examples of the above organic compounds include the following. That is, acrylonitrile, methacrylonitrile, vinylidene fluoride, vinyl fluoride,
Chloroprene, vinylidene chloride, ethylene, propylene, cyclic dienes (eg cyclopentadiene, 1,3
-Cyclohexadiene and the like) and copolymers of the above organic compounds, but not limited thereto.

The ion-conductive polymer compound of the present invention, in which a metal salt is dissolved in a polyether-crosslinked polymer compound, is a crosslinked polymer formed by an ether bond, and therefore has no intermolecular hydrogen bond. The structure has a low transition temperature, and migration of dissolved metal salt ions becomes extremely easy.

Further, for example, a polymer having a crosslinked network structure obtained by reacting a mixture of polyethylene glycol dimethacrylate or diacrylate and polyethylene glycol monomethacrylate or monoacrylate may be used.

Next, as the ionic compound which is soluble in the polymer compound thus obtained, for example, LiCl
O ₄ , LiBF ₄ , LIASF ₆ , LiPF ₆ , LiI, LiBr, Li ₂ B ₁₀ C
l ₁₀ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiSCN, NaI, NaSCN, NaB
An inorganic ionic salt containing one of Li, Na, or K such as r, NaClO ₄ , KClO ₄ , KSCN, (CH ₃ ) ₄ NBF ₄ , (CH ₃ ) ₄ NBr, (C
₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr, (nC ₄ H ₉ ) ₄ NCl
O ₄ , (nC ₄ H ₉ ) ₄ NI, (C ₂ H ₅ ) ₄ N-maleate, (C ₂ H ₅ ) ₄ N-benzo
ate, quaternary ammonium salts such as (C ₂ H ₅ ) ₄ N-phtalate, and organic ionic salts such as lithium stearylsulfonate, sodium octylsulfonate, and lithium dodecylbenzenesulfonate. These ionic compounds are 2
You may use together 1 or more types.

The mixing ratio of such an ionic compound is
The ratio of the ionic compound to the ether-bonded oxygen of the polymer compound is 0.0001 to 5.0 mol, and preferably 0.005 to 2.0 mol. If the amount of the ionic compound used is too large, an excess ionic compound, for example, an inorganic ionic salt does not dissociate, but simply mixes, resulting in a decrease in ionic conductivity.

The mixing ratio of the ionic compound is
The appropriate compounding ratio differs depending on the electrode active material. For example,
In the battery using intercalation of the layered compound, it is preferable that the ionic conductivity of the electrolyte is around the maximum, and in the battery using the conductive polymer that utilizes the doping phenomenon as the electrode active material, It is necessary that the ion concentration in the electrolyte can be changed by the discharge.

The method for containing the ionic compound is not particularly limited. For example, a method of dissolving the ionic compound in an organic solvent such as methyl ethyl ketone or tetrahydrofuran, uniformly mixing with the organic compound, and then removing the organic solvent by vacuum decompression. And so on.

Next, in the present invention, the ion-conductive polymer compound may contain a substance capable of dissolving the ionic compound contained in the ion-conductive polymer compound, and this kind of substance is contained therein. As a result, the ionic conductivity can be remarkably improved without changing the basic skeleton of the polymer compound.

As the substance capable of dissolving the ionic compound, cyclic carbonate such as propylene carbonate or ethylene carbonate; cyclic ester such as γ-butyrolactone; tetrahydrofuran or its derivative,
Ethers such as 1,3-dioxane, 1,2-dimethoxyethane and methyldiglyme; Nitriles such as acetonitrile and benzonitrile; Dioxalane or a derivative thereof; Sulfolane or a derivative thereof alone or a mixture of two or more thereof. Is mentioned. However, it is not limited to these. Moreover, the mixing ratio and the mixing method are arbitrary.

Regarding the method for disposing the ion conductive polymer of the present invention on the surface of the composite positive electrode and the surface of the composite negative electrode, for example, roller coating such as an applicator roll, screen coating, doctor blade method, spin coating, It is desirable that the composition is applied to the surface of the composite positive electrode and the surface of the composite negative electrode in any thickness and in any shape using a means such as a bar coder, but is not limited thereto.

Further, by using the above ion-conductive polymer compound as an electrolyte layer (separator), it is possible to suppress the generation of dendrite of lithium in the peripheral portion of the composite negative electrode, and it is excellent in mechanical strength and heat. It is possible to provide a chemically and electrochemically stable electrolyte layer.

Further, as the negative electrode active material used for the composite negative electrode, the following battery electrode materials can be mentioned.

That is, a carbonaceous material such as carbon,
[For example, the carbonaceous material is analyzed by X-ray diffraction or the like; lattice spacing (d002) 3.35 to 3.40 Å a-axis crystallite size La 200 Å or more c-axis crystallite size Lc 200 Å or more True density 2.00 to 2.25 g / cm
³ Also, carbon powder (average particle diameter of 15 μm or less) obtained by firing an anisotropic pitch at a temperature of 2000 ° C. or higher, or carbon fiber is preferable, but it is not limited to these ranges. ]

Regarding the method of disposing the composite positive electrode and composite negative electrode of the present invention on the positive electrode current collector and the negative electrode current collector, for example, roller coating such as an applicator roll, screen coating, doctor blade method, spin coating, etc. It is desirable to be applied to any thickness and any shape by using a means such as coating or bar coder, but it is not limited thereto. Using these means it is possible to increase the real surface area of the electrochemically active material in contact with the electrolyte layer and the current collector.

In these cases, carbon such as graphite, carbon black, acetylene black, etc. (the carbon here has characteristics completely different from the carbon in the above-mentioned negative electrode active material), if necessary. ) And a conductive material such as a metal powder or a conductive metal oxide can be mixed in the composite positive electrode and the composite negative electrode to improve electron conduction.

When manufacturing the composite positive electrode and the composite negative electrode, several kinds of dispersants and dispersion media can be added in order to obtain a uniform mixed dispersion system. Further, it is also possible to add a thickener, a bulking agent, an adhesion aid and the like. By adding the above-mentioned substance, it becomes possible to maintain a uniform mixed dispersion system in a form very close to the primary particles for a long time without aggregating the positive electrode active material particles and the negative electrode active material particles.

The ionizing radiation described in the claims is γ
Rays, X-rays, electron rays, neutron rays and the like can be mentioned. The method of using these ionizing radiations in cross-linking the ion conductive polymer compound is very efficient. That is,
Not only the energy efficiency of the ionizing radiation, for example, when forming various composite positive electrodes, composite negative electrodes and electrolytes, it is possible to easily control the degree of cross-linking of the ion conductive polymer compound, and thus the ionizing property By controlling the dose of radiation, it becomes possible to prepare electrochemically optimal electrodes and electrolytes.

The positive electrode current collector plate is preferably made of a material such as aluminum, stainless steel, titanium or copper, and the negative electrode current collector plate is preferably made of a material such as stainless steel, iron, nickel or copper, but is not particularly limited thereto. is not.

[0050]

EXAMPLES The details of the present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 A sheet-shaped battery of the present invention was manufactured according to the following procedure. a) LiCoO ₂ (average particle size of primary particles: 2.5 μm) was used as the positive electrode active material of the battery, acetylene black was used as the conductive agent, and a mixture with a dimethylformamide solution of polyacrylonitrile was used as the composite positive electrode.

The method for producing this composite positive electrode is as follows. That is, a mixture of LiCoO ₂ and acetylene black in a weight ratio of 85:15 and a mixture of a polydimethylacamide solution of polyacrylonitrile (2 wt% solution) were mixed in a dry inert gas atmosphere,
Mixed in a weight ratio of 2.4: 2. A mixture of these
A positive electrode current collector plate made of aluminum was cast by screen coating on a current collector having a conductive carbon film formed thereon. Then, the composite positive electrode was formed by drying in a dry inert gas atmosphere. The thickness of the composite positive electrode coating film formed on the positive electrode current collector was 60 μm.

B) Next, polyethylene glycol diacrylate (molecular weight: 5000) and polyethylene glycol monoacrylate (molecular weight: 400) are mixed in a weight ratio of 6: 4 to form an ion conductive polymer compound on the composite positive electrode. 30 parts by weight of the organic compound mixed with 6 parts by weight of lithium tetrafluoroborate, 32 parts by weight of 1,2-dimethoxyethane and 32 parts by weight of γ-butyrolactone were mixed in a dry inert gas atmosphere to obtain the above composite. The film was cast on the positive electrode by screen coating, and then the ion conductive polymer compound layer was cured by irradiating it with an electron beam having an electron dose of 8 Mrad in a dry inert gas atmosphere. The thickness of the electrolyte layer thus obtained was 25 μm.

C) Toluene solution of ethylene-propylene-cyclopentadiene copolymer using carbon powder (average particle size of primary particles: 3.7 μm) crushed in an inert gas atmosphere as the negative electrode active material of the battery. Was used as a composite negative electrode.

The method for producing this composite negative electrode is as follows. That is, the above carbon powder and ethylene-propylene-
Toluene solution of cyclopentadiene copolymer (2 wt
% Solution) in a dry inert gas atmosphere,
Mixed in a weight ratio of 2: 5. These mixtures were cast by screen coating on a negative electrode current collector plate made of stainless steel. Then, the composite negative electrode was formed by drying in a dry inert gas atmosphere. The composite negative electrode formed on the negative electrode current collector had a thickness of 30 μm.

D) Next, polyethylene glycol diacrylate (molecular weight: 5000) and polyethylene glycol monoacrylate (molecular weight: 400) are mixed in a weight ratio of 6: 4 to form an ion conductive polymer compound on the composite negative electrode. 30 parts by weight of the organic compound mixed with 6 parts by weight of lithium tetrafluoroborate, 32 parts by weight of 1,2-dimethoxyethane and 32 parts by weight of γ-butyrolactone were mixed in a dry inert gas atmosphere to obtain the above composite. The film was cast on the negative electrode by screen coating, and then the ion conductive polymer compound layer was cured by irradiating it with an electron beam having an electron dose of 8 Mrad in a dry inert gas atmosphere. The thickness of the electrolyte layer thus obtained was 25 μm.

E) Electrolyte layer obtained in d) / composite negative electrode /
Negative electrode current collector and positive electrode current collector / composite positive electrode / obtained in b)
The sheet-shaped battery of Example 1 of the present invention was produced by bringing the electrolyte layer into contact with each other.

FIG. 1 is a sectional view of the sheet-shaped battery of the present invention. In the figure, 1 is a positive electrode current collector made of aluminum,
It also serves as the exterior. 2 is a composite positive electrode, a LiCoO ₂ positive active material, acetylene black as a conductive agent, an organic compound mixed with polyacrylonitrile as the binder. Further, 3 is an electrolyte layer composed of the ion conductive polymer compound of the present invention. Reference numeral 4 represents a composite negative electrode, and carbon powder was used as the negative electrode active material, and an ethylene-propylene-cyclopentadiene copolymer was used as the binder. Reference numeral 5 is a negative electrode current collector plate made of stainless steel, which also serves as an exterior. 6 is a sealing agent made of modified polypropylene.

Comparative Example 1 A sheet-shaped battery of Comparative Example 1 was produced according to the following procedure. a) LiCoO ₂ (average particle size of primary particles: 7.8 μm) was used as the positive electrode active material of the battery, acetylene black was used as the conductive agent, and a mixture with a dimethylformamide solution of polyacrylonitrile was used as the composite positive electrode.

The composite positive electrode of Comparative Example 1 was produced by the same method as in Example 1. The thickness of the composite positive electrode coating film formed on the positive electrode current collector was 60 μm.

B) Carbon powder crushed in air as the negative electrode active material of the battery (average particle size of primary particles: 8.5 μm)
Was mixed with a toluene solution of a copolymer of ethylene-propylene-cyclopentadiene and used as a composite negative electrode. The composite negative electrode of Comparative Example 1 was produced by the same method as in Example 1. The thickness of the composite negative electrode formed on the negative electrode current collector was 30 μm.

C) Next, 30 parts by weight, 6 parts by weight of lithium tetrafluoroborate, 32 parts by weight of 1,2-dimethoxyethane and γ are used to form an ion conductive polymer compound layer on the composite negative electrode. A mixture of 32 parts by weight of butyrolactone and 0.03 parts by weight of benzylmethyl ketal was cast by screen coating on the above composite negative electrode in a dry inert gas atmosphere, and then 20 mW / in a dry inert gas atmosphere. The ion-conductive polymer compound layer was cured by irradiating with cm ² of ultraviolet rays for 60 seconds. The thickness of the electrolyte layer thus obtained was 50 μm.

D) Electrolyte layer / composite negative electrode obtained in c) /
The sheet-shaped battery of Comparative Example 1 was produced by bringing the negative electrode current collector into contact with the positive electrode current collector / composite positive electrode obtained in a).

The electrode area of the sheet-shaped batteries of Example 1 and Comparative Example 1 can be variously changed by the manufacturing process, but in this Example and Comparative Example, the electrode area is set to 100 cm ² . What was done was produced.

Using this sheet-shaped battery, 50 μA at 25 ° C.
/ Cm ^{2 A} constant current charge / discharge cycle test was performed. In addition,
The above charge / discharge cycle test was performed with a charge end voltage of 4.1 V and a discharge end voltage of 2.7 V. FIG. 2 shows the relationship between the number of charge / discharge cycles and the battery capacity. As can be seen from FIG. 2, the sheet-shaped battery according to the present invention exhibits excellent charge / discharge cycle characteristics as compared with the sheet-shaped battery of the comparative example.

[0066]

As is apparent from the above description, a composite positive electrode composed of an electrochemically active substance, a binder made of an organic compound dissolved and / or dispersed in a solvent, and optionally an electron conductive substance. An ion-conductive polymer compound comprising (A) and a composite negative electrode (B), and a polymer substance in which at least one ionic compound is dissolved,
An average particle of primary particles of the electrochemically active substance in the composite positive electrode and the composite negative electrode, in a battery comprising an electrolyte (C) composed of a polymer compound having a polyether structure and having ion conductivity. When the diameters are 5 μm or less, reversibility is improved, the battery capacity is increased, and the charge / discharge characteristics are excellent. Further, an electrolyte layer (C) made of the above ion-conductive polymer compound is arranged on the surface of the composite positive electrode (A) and the surface of the composite negative electrode (B), and the electrolyte layer (C) is formed by irradiation with ionizing radiation. By doing so, compared to conventional thermal methods and curing methods by UV irradiation, workability is significantly improved, and there is no damage or slight short circuit, so it is possible to achieve uniform quality. Is. As a result, battery characteristics can be improved, high-performance electrodes can be manufactured, workability in the battery manufacturing process and battery performance can be improved, and there is no risk of liquid leakage to the outside, and long-term reliability is maintained. Further, it is possible to provide a highly safe battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sheet-shaped battery of the present invention.

FIG. 2 is a graph showing the relationship between the number of charge / discharge cycles and the battery capacity of the sheet-shaped battery of Example 1 and the sheet-shaped battery of Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode collector 2 Composite positive electrode 3 Electrolyte layer 4 Composite negative electrode 5 Negative electrode collector 6 Sealant

Claims (5)

[Claims] 1. A composite positive electrode (A) and a composite negative electrode (B) composed of an electrochemically active substance, a binder composed of an organic compound dissolved and / or dispersed in a solvent, and an electron conductive substance. An ion conductive polymer compound composed of a polymer substance in which at least one ionic compound is dissolved, the polymer compound having a polyether structure and having ion conductivity Electrolyte (C)
In the secondary battery including the composite positive electrode (A), the composite negative electrode (B) is composed of an electrochemically active substance having an average primary particle size of 5 μm or less, the binder, and an electron conductive substance. 2) is composed of an electrochemically active substance, which is a carbon powder having an average primary particle diameter of 5 μm or less, and the binder, and a secondary battery. 2. An electrolyte layer (C) made of the ion conductive polymer compound is disposed on the surface of the composite positive electrode (A) and the surface of the composite negative electrode (B), and the electrolyte layer (C) is irradiated with ionizing radiation. The secondary battery according to claim 1, wherein C) is formed. 3. A polymer compound in which the ion-conductive polymer compound is a polyether having a reactive double bond in which at least one ionic compound is dissolved, and a polymer compound forming a crosslinked network structure by a polymerization reaction. The secondary battery according to claim 1, which is a molecular compound. 4. The secondary battery according to claim 1, wherein the ion conductive polymer compound contains a substance capable of dissolving the ionic compound. 5. The carbon powder in the composite negative electrode (B) becomes carbon powder having an average primary particle diameter of 5 μm or less by crushing carbon fibers and / or carbon powder in an inert gas atmosphere. The secondary battery according to claim 1, wherein: