JPH0668906A - Secondary battery - Google Patents

Abstract

PURPOSE:To provide a miniature, light, and sheetlike battery, by composing a secondary battery of electrochemical active material, a binding agent composed of an organic compound dispersed in a solvent, composite positive and negative electrodes composed of optional electron conductive material, and an electrolyte composed of a macromolecule compound having ion conductivity and polyether structure. CONSTITUTION:A sheetlike battery is composed of a positive electrode collector 1, serving also as a cover and made of aluminum; a composite positive electrode 2, in which LiCoO2 is used for positive electrode active material, acetylene black is used for a conductive agent, and an organic compound in which polyacrylonitrile is mixed is used for a bonding agent; an electrolyte layer 3, composed of an ion conductive macromolecule compound; a composite negative electrode 4, in which carbon powder is used for negative electrode active material, and the copolymer of ethylene-propylene-cyclopentadiene is used for a binding agent; a negative electrode collector 5, serving also as a cover and made of stainless steel; and a sealing agent 6 composed of denatured polypropylene. Thus, performance and an energy density is increased with fluid- leakage eliminated.

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 producing a battery.

[0002]

2. Description of the Related Art Recent microelectronics is
As represented by memory backup power supplies for various electronic devices, battery storage in electronic devices and integration with electronic elements and circuits have made batteries smaller, lighter, thinner, and have a higher energy density. There is a strong demand for batteries that have them. In recent years, in the field of primary batteries, small and lightweight batteries such as lithium batteries have already been put into practical use, but their fields of use 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 researched are homopolymers or copolymers of ethylene oxide as a basic unit, such as linear polymers, reticulated crosslinked polymers or comb polymers. 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 reticulated crosslinked 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 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 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 have also been problems 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 due to repeated charging / discharging, so that the cycle characteristics have not been improved.

As another method for suppressing the 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 is tried. It has been attempted to suppress lithium dendrite 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 in 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 doping capacity, low self-discharge rate, excellent cycling 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 with 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 the electrode active material 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 make the electrolyte thin so as 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.

Conventionally, the method of mainly heat-polymerizing has been simple and widely used. However, it is difficult to improve the production rate by heating polymerization time becomes very long,
There is a problem that a temperature gradient is likely to occur in the heating furnace and that the heating furnace and ancillary equipment become large in size because it is necessary to heat in an inert gas atmosphere.

Furthermore, the inventors of the present invention arrange a thin electrolyte sheet (sheet-shaped battery) by arranging an electrolyte layer made of the above ion-conductive polymer compound alone between the composite positive electrode and the composite negative electrode in the form of a sheet. Tried to make. 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. 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 with 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 method described above, when 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 ultraviolet light, considering the charge / discharge characteristics after long-term storage,
It wasn't perfect.

Further, 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 is generated in the ion conductive polymer compound composition liquid. However, there is a problem that the cross-linked network has a more irregular structure, which is a major problem in addition to the problem of the above-mentioned production speed and equipment.

[0017]

In view of the above problems of the prior art, therefore, the present invention aims to improve battery characteristics and to manufacture 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 is small and lightweight with high performance and high energy density. A sheet-shaped battery is provided.

[0018]

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 made of a dispersed organic compound and optionally an electron conductive material: a high concentration in which at least one ionic compound is dissolved. An ion-conducting polymer compound composed of a molecular substance, which is a battery having an electrolyte (C) composed of a polymer compound having a polyether structure and having ion conductivity. It is an invention of item 1.

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 / or the surface of the composite negative electrode (B), and the electrolyte layer (C) is irradiated with ionizing radiation to form the electrolyte layer (C). The second invention is to form the electrolyte layer (C).

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 formation of a crosslinked network structure by a polymerization reaction. A third invention is that the polymer compound is a molecular compound, and the ion-conductive polymer compound contains a substance capable of dissolving the ionic compound. The composite positive electrode (A) composed of the electrochemically active substance and the ion conductive polymer compound, the composite negative electrode (B), and the electrolyte layer (C) composed of the ion conductive polymer compound. The above-mentioned object is achieved by providing.

By placing 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 when metal lithium is used for the negative electrode is uniformly distributed, and the deposition of lithium is partially concentrated to cause an internal short circuit.

Further, when the sheet-shaped battery is assembled, the electrolyte layer (C) composed of the 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 is very small.

When a binder composed of an organic compound dissolved and / or dispersed in a solvent is used, a binder solution prepared by dissolving the organic compound in a solvent and an electrode active material dispersed therein is used as a coating liquid. A general method, a method of using a dispersion of an electrode active material in a dispersion liquid of the organic compound and a dispersant for dispersing the organic compound as a coating liquid, etc., is not limited to these. Absent.
When the electrode is prepared, 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-mentioned organic compounds include the following. That is, acrylonitrile, methacrylonitrile, vinylidene fluoride, vinyl fluoride,
Examples thereof include polymers such as chloroprene, vinyl pyridine and derivatives thereof, vinylidene chloride, ethylene, propylene, cyclic dienes (for example, cyclopentadiene, 1,3-cyclohexadiene) and copolymers of the above organic compounds. It is not limited to.

The ion-conducting polymer compound of the present invention, in which a metal salt is dissolved in a polyether-crosslinking 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 with 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
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 ion 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 merely 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 for the discharge to be able to respond to changes in the ion concentration in the electrolyte.

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 significantly improved without changing the basic skeleton of the polymer compound.

Examples of the substance capable of dissolving the ionic compound include cyclic carbonates such as propylene carbonate and ethylene carbonate; cyclic esters such as γ-butyrolactone; tetrahydrofuran or its derivatives,
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 compounding ratio and the compounding method are arbitrary.

Regarding the method of 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 a desired thickness and a desired 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 positive electrode active material used in the composite positive electrode of the present invention, the following battery electrode materials can be mentioned.

That is, CuO, Cu ₂ O, Ag ₂ O, CuS, CuSO
Group I metal compounds such as ₄ ; Group IV metal compounds such as TiS ₂ , SiO ₂ , SnO, V ₂ O ₅ , V ₆ O ₁₂ , VO _X , Nb ₂ O ₅ , Bi ₂ O ₃ , Sb
Group V metal compounds such as ₂ O ₃ , Cr0 ₃ , Cr ₂ O ₃ , MoO ₃ , W
Group VI metal compounds such as O ₃ and SeO ₂ and V such as MnO ₂ and Mn ₂ O ₃
Group II metal compounds, Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , Ni
Group VIII metal compounds such as O, CoO ₃ , and CoO, or general formulas Li _X MX ₂ , Li _X MN _Y X ₂ (M and N are I to VIII group metals, and X is a chalcogen compound such as oxygen or sulfur. , Etc., for example, a metal compound such as a lithium-cobalt-based composite oxide or a lithium-manganese-based composite oxide, and a conductive material such as polypyrrole, polyaniline, polyparaphenylene, polyacetylene, or polyacene-based material. Polymer compounds, pseudo-graphite structure carbonaceous materials, etc., are not limited to these.

Further, examples of the negative electrode active material used in the composite negative electrode include the following battery electrode materials.

That is, a carbonaceous material such as carbon,
[For example, the above-mentioned 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 size of 15 μm or less) obtained by firing an anisotropic pitch at a temperature of 2000 ° C. or more, or carbon fiber is preferable, but of course these It is not limited to the range. ] Or lithium metal-containing alloys such as lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys, but are not limited thereto. These negative electrode active materials can be used alone or in combination of two or more.

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 in arbitrary thickness and arbitrary 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 completely different characteristics 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 the composite positive electrode and the composite negative electrode are manufactured, several kinds of dispersants and dispersion media can be added in order to obtain a uniform mixed dispersion system. Further, it is possible to add a thickener, a bulking agent, an adhesion aid, and the like.

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, the ionization 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.

[0044]

EXAMPLES The details of the present invention are 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 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, LiCoO ₂ and acetylene black 8
A mixture of a 5:15 weight ratio and a mixture of polyacrylonitrile dimethylformamide solution (2 wt% solution) in a dry inert gas atmosphere, 2.4:
Mixed in a weight ratio of 2. These mixtures were cast by screen coating on a current collector having a conductive carbon film formed on the surface of a positive electrode current collector plate made of aluminum. 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 in order 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. It was cast on the positive electrode by screen coating and then irradiated with an electron beam having an electron dose of 8 Mrad in a dry inert gas atmosphere to cure the ion conductive polymer compound layer. The thickness of the electrolyte layer thus obtained was 25 μm.

C) Carbon powder was used as the negative electrode active material of the battery, and a mixture with a toluene solution of a copolymer of ethylene-propylene-cyclopentadiene was used as the composite negative electrode.

The method for producing this composite negative electrode is as follows. That is, 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, in order to form an ion conductive polymer compound on the composite negative electrode, polyethylene glycol diacrylate (molecular weight: 5000) and polyethylene glycol monoacrylate (molecular weight: 400) are mixed in a weight ratio of 6: 4. 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-like battery of the present invention. In the figure, 1 is a positive electrode current collector made of aluminum,
It also serves as the exterior. Reference numeral 2 is a composite positive electrode, and an organic compound obtained by mixing LiCoO ₂ as a positive electrode active material, acetylene black as a conductive agent, and polyacrylonitrile as a binder was used. Further, 3 is an electrolyte layer made of the ion conductive polymer compound of the present invention. Reference numeral 4 represents a composite negative electrode in which 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. No. 6 is a sealing agent made of modified polypropylene.

Comparative Example 1 A sheet-shaped battery of Comparative Example 1 was manufactured according to the following procedure. a) LiCoO ₂ was used as the positive electrode active material of the battery, acetylene black was used as the conductive agent, and polyethylene glycol diacrylate (molecular weight: 5000) and polyethylene glycol monoacrylate (molecular weight: 400) were mixed with 6:
A mixture with an organic compound mixed in a weight ratio of 4 was used as a composite positive electrode.

The method for producing this composite positive electrode is as follows. That is, LiCoO ₂ and acetylene black 8
In a mixture of 5:15 by weight, 10 parts by weight of the above organic compound, 1 part by weight of lithium tetrafluoroborate, 1,
A mixture of 10 parts by weight of 2-dimethoxyethane and 10 parts by weight of γ-butyrolactone was mixed in a dry inert gas atmosphere at a weight ratio of 10: 3. These mixtures were cast by screen coating on a current collector having a conductive carbon film formed on the surface of a positive electrode current collector plate made of aluminum. Then, the composite positive electrode was cured by irradiating it with an electron beam having an electron dose of 12 Mrad 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, 30 parts by weight of the organic compound, 6 parts by weight of lithium tetrafluoroborate, and 32 parts by weight of 1,2-dimethoxyethane for forming an ion conductive polymer compound on the composite positive electrode. And γ-butyrolactone 32
A mixture of parts by weight was cast by screen coating on the above composite positive electrode in a dry inert gas atmosphere, and then, in a dry inert gas atmosphere, the electron dose was 8 Mr.
The ion conductive polymer compound layer was cured by irradiating an electron beam of ad. The thickness of the electrolyte layer thus obtained was 25 μm.

C) Carbon powder was used as the negative electrode active material of the battery and mixed with an organic compound in which polyethylene glycol diacrylate (molecular weight: 5000) and polyethylene glycol monoacrylate (molecular weight: 400) were mixed in a weight ratio of 6: 4. This was used as a composite negative electrode.

The method for producing this composite negative electrode is as follows. That is, carbon powder, 10 parts by weight of the organic compound, 1 part by weight of lithium tetrafluoroborate, 10 parts by weight of 1,2-dimethoxyethane and 10 parts of γ-butyrolactone.
Mixing parts by weight in a dry inert gas atmosphere,
Mixed in a weight ratio of 8: 2. These mixtures were cast by screen coating on a negative electrode current collector plate made of stainless steel. Then, the composite negative electrode was cured by irradiating it with an electron beam having an electron dose of 15 Mrad 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, in order to form an ion conductive polymer compound layer on the composite negative electrode, the organic compound 30 is added.
Parts by weight, 6 parts by weight of lithium tetrafluoroborate, 32 parts by weight of 1,2-dimethoxyethane and 3 of γ-butyrolactone
Mix 2 parts by weight in a dry inert gas atmosphere,
It is cast by screen coating on the above composite negative electrode, then, in a dry inert gas atmosphere, the electron dose is 8M.
The ion conductive polymer compound layer was cured by irradiating the electron beam of rad. The thickness of the electrolyte layer thus obtained was 25 μm.

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

Comparative Example 2 A sheet-shaped battery of Comparative Example 1 was manufactured according to the following procedure. a) The composite positive electrode of Comparative Example 2 was manufactured 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.

C) The composite negative electrode of Comparative Example 2 was manufactured 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.

D) Next, 30 parts by weight, 6 parts by weight of lithium tetrafluoroborate, 32 parts by weight of 1,2-dimethoxyethane and γ were formed in order 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 benzyl methyl 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 it with ultraviolet rays of cm ² for 60 seconds. The thickness of the electrolyte layer thus obtained was 25 μm.

E) Electrolyte layer obtained in d) / composite negative electrode /
A 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 b).

The electrode areas of the sheet-shaped batteries of Example 1 and Comparative Examples 1, 2, and 3 can be variously changed depending on the manufacturing process, but in this Example and Comparative Example, the electrode area is changed. The thing made into 100 cm < ² > was produced.

[0065] Using the sheet-like battery, the charge end voltage at 25 ℃ 4.1 V, 50μA / cm 2 constant current - discharge cycle of the constant-voltage charge and discharge end voltage 2.7 V, constant current discharge of 50 .mu.A / cm ² The test was conducted. 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 battery according to the present invention exhibits excellent charge / discharge cycle characteristics as compared with the sheet battery of the comparative example.

Next, after the sheet-shaped battery was manufactured, the sheet-shaped battery stored at 60 ° C. for 100 days was charged at 25 ° C. with a cutoff voltage of 4.1 V.
50 .mu.A / cm ² constant current - constant voltage charge, and discharge end voltage 2.7 V, the 50 .mu.A / cm ² charge-discharge cycle test of constant current discharge was performed. FIG. 3 shows the results of the above charge / discharge cycle test of the sheet-like battery stored at 60 ° C. for 100 days. Figure 3
2 shows the relationship between the number of charge / discharge cycles and the battery capacity of a sheet-shaped battery stored at 60 ° C. for 100 days. As can be seen from FIG. 3, the sheet-shaped battery according to the present invention exhibits excellent charge-discharge cycle characteristics even after long-term storage, as compared with the sheet-shaped battery of the comparative example.

[0067]

As is clear 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. (A) and composite negative electrode (B): an ion-conducting polymer compound composed of a polymer substance in which at least one ionic compound is dissolved, having a polyether structure, In the battery comprising the electrolyte (C) composed of a polymer compound having a property, the ion conductive polymer compound is formed on the surface of the composite positive electrode (A) and / or the surface of the composite negative electrode (B). By arranging an electrolyte layer (C) which is formed by irradiation with ionizing radiation and forming the electrolyte layer (C) by irradiation with ionizing radiation, workability is remarkably improved as compared with the conventional thermal method and curing method by ultraviolet irradiation. And, it is possible to enhance the uniformity of quality. From this, it is possible to improve the workability of the battery manufacturing process and the battery performance for the purpose of improving the battery characteristics and producing high-performance electrodes. Furthermore, there is no fear of liquid leakage to the outside and long-term reliability. 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 sheet-shaped battery of Example 1, Comparative Examples 1 and 2.
3 is a graph showing the relationship between the number of charge / discharge cycles and the battery capacity of the sheet-shaped battery of FIG.

FIG. 3 is a sheet-shaped battery of Example 1, Comparative Examples 1 and 2.
3 is a graph showing the relationship between the number of charge / discharge cycles and the discharge capacity after the sheet-shaped battery of Example 1 was stored at 60 ° C. for 100 days.

[Explanation of symbols]

 1 Positive Electrode Current Collector 2 Composite Positive Electrode 3 Electrolyte Layer 4 Composite Negative Electrode 5 Negative Current Collector 6 Sealant

Claims (4)

[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 optionally an electron conductive substance. ) And: an ion-conductive polymer compound composed of a polymer substance in which at least one ionic compound is dissolved, the polymer having a polyether structure and having ion conductivity A secondary battery having an electrolyte (C) composed of a compound. 2. An electrolyte layer (C) made of the above ion-conductive polymer compound is disposed on the surface of the composite positive electrode (A) and / or the surface of the composite negative electrode (B), and the electrolyte is irradiated by ionizing radiation. The secondary battery according to claim 1, wherein the layer (C) is formed. 3. The polymer compound according to claim 1, wherein the ion conductive polymer compound is a polyether having a reactive double bond in which at least one ionic compound is dissolved. Secondary battery. 4. The secondary battery according to claim 1, wherein the ion-conductive polymer compound contains a substance capable of dissolving the ionic compound.