JP2000294203A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight secondary battery of simple structure superior in the productivity, safety and durability of the battery, capable of preventing the liquid leakage and the entrance of air, water and the like caused by fracture, and free from the impairing of the battery characteristic such as rated characteristic and the like. SOLUTION: In a secondary battery where a battery element 4 comprising a positive electrode material and a negative electrode material connected to a collector and layered through a non-fluidity electrolyte layer, and containing an ionic metallic component is packed and sealed in a case, the battery element 4 is held and pressed by a top plate 6 and a bottom plate 13 of the case with the force of 100-3000 g to 1 cm2 on the basis of a projected area of the battery element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery, and more particularly, to a secondary battery having excellent production efficiency, high safety, excellent durability, and excellent late characteristics and cycle characteristics.

[0002]

2. Description of the Related Art In recent years, the production of batteries has been rapidly increasing with the development of portable electronic devices, and the demand for backup batteries has been steadily increasing due to the spread of personal computers and word processors. Demand for secondary batteries that can be charged and used for a long period of time has been rapidly increasing as batteries used for these applications. Carbon that uses lithium as an electromotive substance and can absorb lithium by intercalation with lithium is used. Alternatively, a lithium secondary battery using a chalcogen compound has attracted attention.

However, lithium has an extremely high activity with respect to water, and has problems such as ignition due to liquid leakage or inactivation of lithium due to invasion of air or moisture, and the sealing thereof is required to have a high degree of sealing. . As means for reducing such troubles, it has been practiced to make the electrolyte filled between the positive electrode and the negative electrode non-fluidized by using a gelling agent or the like to prevent liquid leakage. As a result, the housing for covering the battery element does not require rigidity for maintaining its shape, and a flexible film can be used, thereby reducing the size of the secondary battery and increasing the degree of freedom in shape. did. However, in order to use the secondary battery as a secondary battery for a long period of time, it is necessary to provide a coating that has no risk of breakage and has no risk of intrusion of air and moisture in addition to non-fluidization.

As a method of covering and sealing a plate-shaped battery element, a method of sandwiching a battery element between two flexible synthetic resin films and sealing the periphery under reduced pressure to seal the battery element has also been proposed. In this case, however, there is a problem that the volume is increased due to the surrounding sealing portion protruding, and that the external force acts on the corner of the outer edge of the battery element to easily break the battery element. Also, in particular,
In a non-fluid electrolyte secondary battery in which the negative electrode material and the positive electrode material are laminated in a flat plate shape to increase the electric capacity, the electrical coupling between the electrodes is important, and if the electrode material peels off, the late characteristics In addition, there is a problem that the cycle characteristics deteriorate. However,
In a conventional method in which a battery element is sandwiched between flexible synthetic resin films and sealed under reduced pressure, air enters through the synthetic resin film or through the sealed portion, whereby the pressing force of the electric element gradually decreases. There's a problem.

[0005]

The present invention is excellent in productivity, has no liquid leakage due to breakage, does not invade air, moisture, etc., is excellent in safety and durability, and does not deteriorate battery characteristics such as late characteristics. It is intended to provide a light-weight, simple structure secondary battery.

[0006]

Means for Solving the Problems The present invention has been made as a result of intensive studies to achieve the above object, and a positive electrode material and a negative electrode material bonded to a current collector are interposed through a non-fluid electrolyte layer. In a secondary battery in which battery elements containing ionic metal components are stacked and loaded in a housing member and sealed, 100 to 3000 g per 1 cm ^{2 based on} the projected area of the battery element by the top plate and the bottom plate of the housing member. The present invention provides a secondary battery characterized in that the battery element is configured to squeeze the battery element with the force of (1).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A secondary battery according to the present invention is a battery element comprising a positive electrode material and a negative electrode material electrically connected to a current collector, laminated via a non-fluid electrolyte layer and containing an ionic metal component. Is sealed in a thin-walled housing member.
The ionic metal component is a metal component which becomes an ion and electrochemically participates in charging / discharging of the secondary battery and generates an electromotive force, and usually lithium is used. Hereinafter, the present invention will be described using a lithium secondary battery as an example.

The positive electrode material 1 or the negative electrode material 2 is usually formed in a plate shape so as to be connected to the current collector 5 as shown in FIG. The connection with the current collector 5 can be performed by using the current collector 5 as a core material and laminating electrode materials on both surfaces thereof. It may be formed on only one side of the current collector according to the purpose. As the current collector 5, generally, a metal foil such as an aluminum foil or a copper foil can be used. The thickness is appropriately selected, but is preferably 1 to 30 μm. If the thickness is too small, the mechanical strength becomes weak, which causes a problem in production. If it is too thick, the capacity of the battery as a whole decreases.

It is preferable that the surface of the current collector be subjected to a roughening treatment in advance, since the adhesive strength of the electrode material is increased. Examples of the surface roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. Examples of the mechanical polishing method include a method of polishing the surface of the current collector with a polishing cloth paper having abrasive particles fixed thereon, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like. Further, an intermediate layer may be formed on the surface of the current collector to increase the adhesive strength and the conductivity. Further, the shape of the current collector 5 may be a plate shape, a net-like body, a punching metal, or the like.

[0010] As a positive electrode material, occludes lithium ions.
Both inorganic and organic compounds can be used as long as they can be released. Examples of the inorganic compound include a transition metal oxide, a composite oxide of lithium and a transition metal, and a chalcogen compound such as a transition metal sulfide. Here, the transition metal is F
e, Co, Ni, Mn and the like are used. Specifically, M
Transition metal oxides such as nO, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ ; composite oxides of lithium and transition metals such as lithium nickelate, lithium cobaltate and lithium manganate; TiS ₂ , FeS, MoS _And transition metal sulfides such as ₂ . These compounds may be partially substituted with elements in order to improve their properties. Examples of the organic compound include polyaniline, polypyrrole, polyacene, disulfide-based compounds, and polysulfide-based compounds. These inorganic compounds and organic compounds may be mixed and used as a positive electrode material. Preferred are compounds containing manganese or cobalt, such as lithium cobaltate or lithium manganate, especially compounds containing manganese. The particle size of the positive electrode material may be appropriately selected depending on the balance with other components of the battery.
Usually, it is preferably from 1 to 30 μm, especially from 1 to 10 μm, because battery characteristics such as initial efficiency and cycle characteristics are improved.

As a negative electrode material capable of inserting and extracting lithium ions that can be used for the negative electrode, a carbon-based material such as graphite and coke is usually mentioned. Such a carbon-based material can also be used in the form of a mixture or coating with a metal, metal salt, oxide, or the like. Examples of the negative electrode material include oxides and sulfates of silicon, tin, zinc, manganese, iron, nickel and the like, metallic lithium, Li-Al, Li-Bi.
Lithium alloys such as -Cd and Li-Sn-Cd, lithium transition metal nitrides, and silicon can also be used. Preferably, it is graphite or coke in terms of capacity.
The average particle size of the negative electrode material is usually 12 μm or less, preferably 10 μm or less, from the viewpoint of improving battery characteristics such as initial efficiency, late characteristics, and cycle characteristics. If the particle size is too large, the electron conductivity deteriorates. Also, usually 0.5 μm
The thickness is preferably 7 μm or more.

Since these positive and negative electrode materials are usually bound on a current collector, it is preferable to use a binder. As the binder, inorganic compounds such as silicate and glass, and various resins mainly composed of polymers can be used. Examples of the resin include alkane-based polymers such as polyethylene, polypropylene, and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polystyrene, polymethylstyrene, polyvinylpyridine, and poly-N-vinylpyrrolidone. Acrylic polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide; polyfluorinated Fluorinated resins such as vinyl, polyvinylidene fluoride, and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl acetate such as polyvinyl acetate and polyvinyl alcohol Alcohol polymers; polyvinyl chloride, halogen-containing polymers such as polyvinylidene chloride; and conductive polymers such as polyaniline can be used. Further, a mixture of the above-mentioned polymers, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, or the like can also be used. The molecular weight of these resins is preferably 10,000
~ 3,000,000, more preferably 100,000 ~ 1
000000. If it is too low, the strength of the coating film decreases, which is not preferable. If it is too high, the viscosity becomes high and it becomes difficult to form an electrode.

The electrode may contain additives, such as conductive materials and reinforcing materials, which exhibit various functions, powders, fillers, and the like, if necessary. The conductive material is not particularly limited as long as it can impart conductivity by mixing an appropriate amount with the active material, but usually, acetylene black, carbon black, carbon powder such as graphite, and various metal fibers,
Foil and the like. As additives, trifluoropropylene carbonate, vinylene carbonate, 1,6-
Dioxaspiro [4,4] nonane-2,7
-Dione, 12-crown-4-ether and the like can be used to increase the stability and life of the battery. As the reinforcing material, various inorganic or organic spherical or fibrous fillers can be used.

The compounding amount of the binder to 100 parts by weight of the electrode material is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight. If the amount of the resin is too small, the strength of the electrode decreases. If the amount of the resin is too large, the amount of voids in the electrode decreases, and the proportion of the ion mobile phase described below decreases. As a method of forming the positive electrode material and the negative electrode material on the current collector, for example, a powdery electrode material is mixed with a solvent together with a binder, and a ball mill, a sand mill, a twin-screw kneader, or the like, which is formed into a dispersed paint, A method of coating on a current collector and drying is preferably performed. In this case, the type of the solvent used is not particularly limited as long as it is inert to the electrode material and can dissolve the binder. For example, any of commonly used inorganic and organic solvents such as N-methylpyrrolidone can be used. Can also be used.

Further, the electrode material layer may be formed by a method of pressing or spraying on the current collector in a state where the electrode material is mixed with a binder and heated and softened. Furthermore, it can also be formed by firing the electrode material alone on the current collector. Usually, an ion mobile phase is formed in the positive electrode material and the negative electrode material. The higher the proportion of the ion mobile phase in the electrode, the easier the ion migration, and the higher the proportion, the better the rate characteristics, while the lower the proportion, the higher the capacity. Preferably it is 10 to 50% by volume. The thickness of the positive electrode and the negative electrode is preferably thicker in terms of capacity, and thinner in terms of rate. The film thickness is usually at least 20 μm, preferably at least 30 μm, more preferably at least 50 μm, most preferably at least 80 μm. On the other hand, the upper limit of the electrode film thickness is usually 200 μm or less, preferably 1 μm or less.
It is 50 μm or less. As the material of the ion mobile phase, the same material as the material of the non-fluid electrolyte layer described later can be used.

In the above description, the case where the electrode is composed of the electrode material and the ion mobile phase formed therein has been described. Of course, the structure is not limited as long as it has a function as an electrode. The negative electrode may be formed only of lithium metal. The non-fluid electrolyte layer 3 interposed between the positive electrode material 1 and the negative electrode material 2 has a function of electrochemically bonding the positive electrode and the negative electrode in the same manner as a normal electrolytic solution, and has low fluidity and low shape retention. Is used.

The supporting electrolyte used in the non-fluid electrolyte layer is stable as an electrolyte with respect to the positive electrode material and the negative electrode material, and lithium ions move to perform an electrochemical reaction with the positive electrode material or the negative electrode material. Any non-aqueous substance obtained can be used. LiPF ₆ in particular, LiAsF _6, LiSbF _6, L
iBF ₄ , LiClO ₄ , LiI, LiBr, LiC
1, LiAlCl, LiHF ₂ , LiSCN, LiSO
Lithium salts such as ₃ CF _2, and the like. Among them, LiPF ₆ and LiClO ₄ are particularly preferable.

When these supporting electrolytes are used in the state of being dissolved in a non-aqueous solvent, the concentration is generally 0.5 to 2.5 m
ol / L. The nonaqueous solvent in which these supporting electrolytes are dissolved is not particularly limited, but a solvent having a relatively high dielectric constant is preferably used. Specifically, ethylene carbonate, cyclic carbonates such as propylene carbonate, dimethyl carbonate, diethyl carbonate, acyclic carbonates such as ethyl methyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, glymes such as dimethoxyethane, γ-butyrolactone and the like Examples thereof include lactones, sulfur compounds such as sulfolane, and nitriles such as acetonitrile. One or two of these
Mixtures of more than one species can also be used.

Of these, one or more solvents selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are particularly preferred. is there. In addition, those in which a part of hydrogen atoms in these molecules are substituted with halogen or the like can also be used. Further, additives and the like may be added to these solvents. As additives, for example, trifluoropropylene carbonate, vinylene carbonate,
1,6-Dioxaspiro [4,4] nonane
-2,7-done, 12-crown-4-ether and the like can be used for the purpose of enhancing the stability, performance and life of the battery.

As the non-fluid electrolyte layer, a gel electrolyte can be used. The gel electrolyte is mainly composed of an electrolyte containing a supporting electrolyte and a solvent, and contains a polymer for gelation, and the electrolyte is held in a polymer network, so that the fluidity as a whole is significantly reduced. Things. The properties such as ionic conductivity are similar to those of a normal electrolytic solution, but the fluidity, volatility and the like are significantly suppressed, and the safety is enhanced. The ratio of the polymer in the gel electrolyte is preferably 1 to 50%. If the temperature is too low, the electrolyte cannot be held, and the liquid leaks. If it is too high, the ionic conductivity will decrease and the battery characteristics will deteriorate.

In order to form a gel electrolyte layer, there may be mentioned a method in which an electrolyte material containing a monomer is used, and this is polymerized to polymerize it. Polymers capable of performing such a reaction include those produced by polycondensation of polyester, polyamide, polycarbonate, polyimide, etc., those produced by polyaddition such as polyurethane, polyurea, etc., and acrylics such as polymethyl methacrylate. Derivative polymers and polyvinyl acetates such as polyvinyl acetate and polyvinyl chloride are also produced by addition polymerization, etc., but the polymerization is easy to control and the high polymerization produced by addition polymerization does not generate by-products during polymerization. It is desirable to use molecules. In particular, a method of polymerizing a monomer having a reactive unsaturated group is preferable because of its high productivity.

Examples of the monomer having such a reactive unsaturated group include acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, and ethoxyethyl methacrylate. , Methoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N, N diethylaminoethyl acrylate, N, N dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, N-vinylpyrrolidone, diethylene glycol diacrylate, triethylene glycol Diacrylate, tetraethylene glycol diacrylate, poly Chi glycol diacrylate,
Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and the like can be used, and those which are preferable in terms of reactivity, polarity, safety, and the like may be used alone or in combination.

As a method for polymerizing these monomers, there are methods using heat, ultraviolet rays, electron beams and the like, but a method using heat or ultraviolet rays is effective from the viewpoint of high productivity. In this case, in order to make the reaction proceed effectively, a polymerization initiator that reacts with ultraviolet light may be added to the electrolytic solution. Usable UV polymerization initiators include benzoin, benzyl, acetophenone, benzophenone, Michler's ketone, biacetyl, benzoyl peroxide and the like, and those which are preferable in terms of reactivity, polarity, safety and the like may be used alone or in combination. In the case of polymerization by heat, it is easy to control the reaction rate. In particular, by changing the type and amount of thermal polymerization initiator, the amount of monomer and the number and type of reactive groups in the monomer, the structure of the gel can be controlled and the ionic conductivity etc. Can be improved. Further, since the whole reaction proceeds uniformly, a uniform gel can be formed.

At the time of thermal polymerization, a polymerization initiator may be added to control the reaction. Available thermal polymerization initiators include 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane,
2-bis- [4,4-di (tert-butylperoxycyclohexyl) propane], 1,1-di (tert-butylperoxy) -cyclohexane, tert-butylperoxy-3,5,5-trimethylhexa Nonate, tertiary butyl peroxy-2-ethyl hexanonate, dibenzoyl peroxide and the like can be used,
Those which are preferable in terms of reactivity, polarity, safety and the like may be used alone or in combination.

In order to form a gel electrolyte layer, a method of using an electrolyte material containing a polymer which can be gelled by cooling and cooling the polymer to room temperature can also be adopted. In this case, as the polymer that can be used, any polymer can be used as long as it forms a gel with respect to an electrolytic solution and is stable as a battery material. Examples thereof include polyvinyl pyridine and poly-N-vinyl pyrrolidone. Acrylic polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide; polyfluorinated Fluorinated resins such as vinyl and polyvinylidene fluoride; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride What And the like. Further, a mixture of the above-mentioned polymers, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, or the like can also be used.

Since the electrolyte and the electrolyte used in the lithium battery usually have polarity, it is preferable that the polymer also has a certain degree of polarity. The molecular weight of these polymers is preferably in the range from 10,000 to 5,000,000. If the molecular weight is low, it is difficult to form a gel. If the molecular weight is high, the viscosity becomes too high and handling becomes difficult. The concentration of the polymer in the electrolytic solution may be appropriately selected according to the molecular weight, but is preferably from 0.1% by weight to 30% by weight. If the concentration is 0.1% by weight or less, it is difficult to form a gel, the retention of the electrolyte is reduced, and problems of flow and liquid leakage may occur. When the concentration is 30% by weight or more, the viscosity becomes too high to cause difficulty in the process, and the proportion of the electrolytic solution is reduced, the ionic conductivity is reduced, and the battery characteristics such as late characteristics may be deteriorated.

As the electrolyte layer, a solid electrolyte layer may be used. As the solid electrolyte, various known solid electrolytes can be used. For example, it can be formed by mixing the polymer used in the gel electrolyte and the supporting electrolyte salt at an appropriate ratio. In this case, in order to increase conductivity, it is preferable to use a polymer having a high polarity and to have a skeleton having many side chains. As the non-fluid layer, a gel electrolyte or a solid electrolyte impregnated in a spacer such as a porous film or a nonwoven fabric may be used. The thickness of the electrolyte layer is usually 5 to 200 μm,
Preferably it is 10 to 100 μm.

The battery element 4 comprising the positive electrode material 1, the negative electrode material 2, and the non-fluid electrolyte layer 3 can have a structure suitable for the purpose. For example, as shown in FIG. 1, a positive electrode material composition is laminated on a current collector 5 to obtain a plate-shaped positive electrode material 1. The negative electrode material 2 is formed in a plate shape by the same method, and the positive electrode material 1 and the negative electrode material 2 formed in the plate shape are laminated via the non-fluid electrolyte layer 3. When a high-capacity battery or a high-voltage battery is intended, the positive electrode material 1 and the negative electrode material 2 are alternately laminated via the non-fluid electrolyte layer 3 as shown in FIG.

The number of the positive electrode material 1 and the negative electrode material 2 to be laminated is arbitrary, but the number of the positive electrode material 1 and the negative electrode material 2 is generally the same. The planar shape of the electrode material is arbitrary such as a circle, a quadrilateral, and a polygon. In the case of a quadrilateral, the current collector 5 of the positive electrode material 1
As shown in FIG. 3, a protruding piece 5a protruding from the positive electrode material 1 is formed on one side of one side of the electrode, and a protruding piece 5b is formed on the current collector 5 of the negative electrode material 2 on the opposite side of the same side. As shown in FIG. 4, the protruding protruding pieces 5a and 5b are vertically connected to each other to form a positive and negative electrode lead wire connecting terminal, thereby obtaining a large capacity battery element 4. Can be.

The battery element 4 thus obtained is loaded in a housing member and sealed. As the housing member, a metal or alloy such as aluminum and copper, a plated metal such as nickel-plated iron and copper, and a synthetic resin can be used, but a metal with high elasticity and a synthetic resin are preferably laminated. Composite material is used. As the composite material 6,
As shown in FIG. 5A, a layer in which a metal layer 7 and a synthetic resin layer 8 are stacked can be used. The metal layer 7 in the composite material 6 is used to prevent infiltration of water or maintain shape retention, and is made of aluminum, iron, copper, nickel,
Single metals such as titanium, molybdenum, gold, stainless steel,
An alloy such as Hastelloy or a metal oxide such as aluminum oxide may be used. Particularly, aluminum having excellent workability is preferable. The metal layer 7 can be formed using a metal foil, a metal deposition film, a metal sputter film, or the like.

In the present invention, the synthetic resin protects the housing member or prevents erosion by the electrolyte, and the elastic modulus and the tensile elongation are not limited. Therefore, the synthetic resin in the present invention includes what is generally called an elastomer. As synthetic resins, thermoplastics, thermoplastic elastomers, thermosetting resins,
Plastic alloy is used. These resins include those in which a filler such as a filler is mixed.

The thermoplastic resin includes polyethylene, polypropylene, modified polyolefin, ionomer, polyvinyl alcohol, ethylene-vinyl acetate copolymer (EV
A), ethylene-vinyl acetate-vinyl alcohol terpolymer (EVOH), polyvinylidene chloride, polyvinyl chloride, amorphous polyolefin (transparent, for example, Nippon Zeon / trade name: ZEONEX), polyamide, polyethylene terephthalate, poly Butylene terephthalate, polycarbonate, polystyrene, styrene copolymer (AB
S resin, AS resin, SMA resin, ACS resin, ASA resin, etc.), polyacrylonitrile, polyoxymethylene,
Polymethyl methacrylate, polyphenylene ether,
Polyphenylene sulfide, polyetheretherketone (PEEK), polyetherketone, polyimide, polyetherimide, polyamideimide, fluororesin (polytetrafluoroethylene, tetrafluoroethylene hexafluoropropylene copolymer, vinylidene fluoride, etc.) And liquid crystal polymers (eg, aromatic polyester-based Mitsubishi Engineering Plastics / trade name: Novaculate), polyarylate, polymethylpentene, polysulfone, and norbornene-based resins (eg, JSR / trade name: Arton).

A thermoplastic elastomer can be processed in the same manner as a thermoplastic resin, and is a general term for a material whose molded article exhibits rubber elasticity, and has a hard segment (hard phase) and a soft segment (soft phase) in its molecular structure. In the styrene system, polystyrene is used for the hard phase, butadiene, isoprene and the like are used for the soft phase. In the case of polyester, a hard phase is polyester and the soft phase is polyether. In the case of polyamide, a hard phase is polyamide and a soft phase is polyether. In addition, there are olefin-based, polyvinyl chloride-based, urethane-based and chlorinated polyethylene.

Thermosetting resins include phenol resins, phenol aralkyl resins, furan resins, amino resins (urea resins, melamine resins, benzoguanamine resins), unsaturated polyester resins, diallyl phthalate resins, epoxy resins, vinyl ester resins, and phenoxy resins. , Polyurethane, silicone resin. Plastic alloys
The above thermoplastic materials are arbitrarily melt-mixed. As commercialized examples, alloys of polycarbonate and ABS resin, polyamide, polyphenylene ether, polybutylene terephthalate, etc. are known in the case of polycarbonate, and alloys of polyamide and ABS resin, polyphenylene ether, polyolefin are known in the case of polyamide. .

As shown in FIG. 5B, the composite material 6 has a synthetic resin layer 8a on the outer surface of the metal layer 7 for functioning as a protective layer, and an inner surface for preventing corrosion by the electrolyte. A three-layer structure in which the synthetic resin layers 8b functioning as corrosion-resistant layers are laminated can be provided. In this case, the resin used for the protective layer is preferably a resin having excellent chemical resistance and mechanical strength, such as polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, and polyamide.

As the corrosion-resistant layer, a synthetic resin having chemical resistance is used, and for example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer and the like can be used. As shown in FIG. 6, the composite material 6 includes a metal layer 7 and a synthetic resin 8a for forming a protective layer.
An adhesive layer 9 may be provided between the corrosion-resistant layer forming synthetic resin layers 8b. Using these metals, synthetic resins, or composite materials, the battery element is housed and sealed in a box-shaped housing member configured to sandwich the battery element between the top plate and the bottom plate.

The shapes of the battery element and the secondary battery are not particularly limited, but it is desirable that the battery element be formed in a flat plate shape and housed in a thin housing member. The accommodation member can have the shape shown in FIG. The first housing member 11 and the second housing member 1 shown in FIG.
The first housing member 11 has a bottom plate 13 at a lower portion, and a side wall 14 is provided upright around the bottom plate 13 to form a box-like body.
A housing 15 for the battery element 4 is formed.

The second housing member 12 has the top plate 1
6 around which a side wall 17 is suspended.
Side wall 14 of housing member 11 and side wall 17 of second housing member 12
Are formed to fit each other. In FIGS. 7 and 8, the bottom plate 13 of the first housing member 11 is curved so that the center portion swells inside, and the center portion of the top plate 16 of the second housing member 12 is inside. It is curved to swell. When the battery element 4 is housed and sealed using the housing member 10, as shown in FIG.
3. The central portion of the top plate 16 comes into contact with the battery element 4 and is pressed outward to have a substantially flat shape. However, since the bottom plate 13 and the top plate 16 are formed in a curved shape, the central portion thereof presses the battery element 4. 19 is a sealing strip.

The strength of pressing the battery element 4 between the top plate 16 and the bottom plate 13 of the housing member 10 is 100 to 3000 g, preferably 500 to 2000 g per 1 cm ^{2 based on} the planar projected area of the battery element 4. It is said. In the present invention, the object is to clamp the battery element 4 by the housing member 10, and swelling into the inside is a means for that purpose.
The shape when accommodating is not limited, and the top plate 16 or the bottom plate 13 may be depressed when viewed from the outside, or may be flat or swollen.

Housing member 1 for clamping battery element 4
As 0, various structures can be adopted. As shown in FIG. 10, by forming a projection 20 projecting inward at the center of the bottom plate 13 and the top plate 16, the battery element 4 can be pressed. . Therefore, in the present invention, swelling is
A structure in which at least a part of the bottom plate 13 and the top plate 16, preferably a central portion protrudes inward from a peripheral edge thereof is generically referred to. In addition, as shown in FIG.
The bulging portion can be formed inside by forming the plurality of grooves 21 by bending the 6.

The shape of the bent portion can be various structures, and as shown in FIG.
22 can also be formed. Further, as shown in FIG. 13, it is also effective to fill the battery element accommodating portion with the foam 23 together with the formation of the bulging portion. In this case, foam 2
3 may be loaded with a foamed sheet-like body, or may be filled with a foaming resin such as urethane or foamable styrene to foam the housing member 10 after sealing.

Further, the bottom plate 13 and the top plate 16 are formed using bimetal or shape memory alloy, and when the battery element 4 is heated to a high temperature, the clamping pressure of the battery element 4 is reduced. You can also. The first accommodating member 11 and the second accommodating member 12 may be connected to each other and bonded with an adhesive, or may be sealed by attaching a belt-like body 19 to a side edge of the fitted portion. . The band-like body 19 preferably has excellent airtightness, and a metal such as aluminum or stainless steel, or a synthetic resin such as polyolefin, polyester, or polyamide can be used.

The strip 19 may be formed by winding a long body having an adhesive or a pressure-sensitive adhesive applied to one side thereof along the fitting portion side edge 18 of the housing member 10. It is also possible to form a shrinkable narrow-width cylindrical body, and insert the housing member 10 into the shrinkable body to shrink it, thereby sealing the housing. The outer shape of the housing member 10 is not particularly limited, and may have a rectangular plane as shown in FIG. 7, a polygonal shape such as a circular shape, a hexagonal shape, an octagonal shape, or an oblong shape.

The housing member 10 can be formed by injection molding, vacuum molding, air pressure molding, press molding, etc. when formed using a synthetic resin, and can be formed by drawing when formed from a metal or composite material. . After injection molding, metal may be deposited by sputtering or the like.
The pressing force may be further applied by reducing the pressure inside the housing member 10.

[0045]

As described above, according to the present invention, there is obtained a secondary battery which can be used stably for a long time without delamination of the electrode material, without deterioration in battery performance such as late characteristics and cycle characteristics. be able to. Further, according to the present invention, a lightweight secondary battery having a simple configuration can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of an electrode material used in the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a battery element used in the present invention.

FIG. 3 is a plan view of the battery element in FIG. 2;

FIG. 4 is a perspective view showing a lead terminal portion of the current collector.

FIGS. 5A and 5B are longitudinal sectional views each showing a structure of a composite sheet used in the present invention.

FIG. 6 is a longitudinal sectional view showing the structure of another example of the composite sheet used in the present invention.

FIG. 7 is a perspective view of a housing member used in the present invention.

FIG. 8 is a longitudinal sectional view of the housing member of FIG. 7;

FIG. 9 is a longitudinal sectional view showing a state where a battery element is loaded in the housing member of FIG. 8;

FIG. 10 is a longitudinal sectional view showing another example of the housing member used in the present invention.

FIG. 11 is a perspective view showing another example of the housing member.

FIG. 12 is a perspective view showing still another example of the housing member.

FIG. 13 is a perspective view showing still another example of the housing member.

[Explanation of symbols]

 1. Positive electrode material 2. Negative electrode material 3. 3. Non-fluid electrolyte layer Battery element 5. Current collector 5a, 5b Current collector projection 6. Composite sheet 7. Metal layer 8.8a, 8b Synthetic resin layer 10. Housing member 11. First housing member 12. Second accommodation member 13. Bottom plate 14. Sidewall 15. Battery element housing 16. Top plate 17. Side wall 19. Band-like body 20. Protrusion 21. Groove 22. Polygonal bulge 23. Foam

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaaki Mita 3-10, Ushidori, Kurashiki-shi, Okayama Prefecture Mizushima Works Mitsubishi Chemical Corporation F-term (reference) 5H011 AA01 AA04 CC02 CC06 CC10 DD01 DD11 5H029 AJ02 AJ05 AK02 AK03 AK05 AK16 AK18 AL01 AL02 AL06 AL07 AL11 AL12 AM00 AM02 AM03 AM04 AM05 AM07 AM16 DJ02 DJ12 EJ01 EJ11 EJ12 HJ15

Claims (7)

[Claims] 1. A secondary battery wherein a positive electrode material and a negative electrode material bonded to a current collector are laminated via a non-fluid electrolyte layer, and a battery element containing an ionic metal component is loaded in a housing member and sealed. In the battery, 100 to 1 cm ^{2 based on} the projected area of the battery element by the top plate and the bottom plate of the housing member.
A secondary battery characterized in that a battery element is sandwiched by a force of 3000 g. 2. The secondary battery according to claim 1, wherein at least one of the top plate and the bottom plate of the housing member is formed so as to swell inside. 3. The secondary battery according to claim 1, wherein a housing member in which at least one of the top plate and the bottom plate has a swelling portion swelling therein is partially formed. 4. The housing member according to claim 1, wherein at least one of the top plate and the bottom plate is formed of a thin plate-like member and has a bulging portion which is bent and formed to protrude inward. Rechargeable battery. 5. The secondary battery according to claim 1, wherein, after the battery element is loaded in the housing member, an external pressure is applied to the housing member to clamp the battery element. 6. The secondary battery according to claim 1, wherein the housing member is made of a metal thin plate or a composite material in which a metal layer and a synthetic resin layer are laminated. 7. The secondary battery according to claim 1, wherein the cathode material is a chalcogen compound, the anode material is a carbon material, and the ionic metal component is a lithium compound.