JP2000251852A - Non-aqueous secondary battery and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery easy to manufacture, superior in moisture resistance and having a thin covering body by forming a moisture protection layer for continuously covering the entire outside surface of the covering body. SOLUTION: This battery 1 is composed by covering an entirely battery body 2 with a covering body 3 formed of a film, and a moisture protection layer is formed on the surface of the film by means of metal deposition or the like. A pair of lead wires 4 are extended from the battery body and extended outside through the the covering body. The battery body 2 is composed by laminating a positive electrode a negative electrode and a non-flowable electrolyte layer. In order to cover the battery body with the covering body 3, the battery body 2 is caught by two sheets or one folded sheet, and the sheets or the edges of the folded sheet are bonded to each other in the circumference thereof by means of thermal welding or the like. Preferably, the moisture protection layer is formed of a film formed, by applying a paint containing metal foil to the covering body covering the battery body or formed of a silicon oxide film formed through sputtering on the the covering body covering the battery body, or the covering body is formed of resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous secondary battery, and more particularly to a non-aqueous secondary battery having an improved enclosing body for a battery body and a method of manufacturing the same. More specifically, the present invention relates to a non-aqueous secondary battery suitable for application to a thin battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a thin battery, a thin battery body (for example, a power generating element comprising a laminate of a positive electrode, a separator and a negative electrode) is made of aluminum and a resin film as disclosed in JP-A-8-83596 and JP-A-10-214606. And those wrapped with a laminate film of the above.

Japanese Patent Application Laid-Open No. 9-320550 discloses that a battery body (power generation element) is inserted into a package comprising a case and a cap made of a synthetic resin such as polycarbonate in which metal foils are laminated and integrated in a sandwich manner. A battery comprising the same is described. In the publication, after a power generating element is inserted into the case, a cap is fitted to the case, and the fitting portion is fused by heating or ultrasonic waves.

[0004]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 8-83596
No. 10-214606, in a battery in which the battery body is wrapped with a laminate film, there is a possibility that moisture may enter from the mating surface from the sealing portion between the films.

[0005] Even when the package is made up of a metal foil integrated case and a cap as disclosed in Japanese Patent Application Laid-Open No. 9-320550, there is also a risk that moisture may infiltrate from the fused portion between the case and the cap.

[0006] The present invention solves the various problems described above,
It is an object of the present invention to provide a non-aqueous secondary battery which is easy to manufacture, has excellent moisture permeability, and has a small thickness of an envelope.

[0007]

According to a non-aqueous secondary battery of the present invention, in a battery having a battery body and an envelope for enclosing the battery body, the entire outer surface of the envelope is continuous. And a moisture-proof layer for encapsulation.

According to the non-aqueous secondary battery of the present invention,
Even if a sealing part, a fusion part, and the like are present in the envelope, a moisture-proof layer is provided on the entire outer surface of the envelope so as to cover them.

In the present invention, the moisture-proof piece is formed by sputtering,
A metal layer formed by vapor deposition or plating is preferred. Further, as the moisture-proof layer, a coating film containing a metal foil or a sputtered film of silicon oxide (SiOx) is also preferable.

When a non-fluid electrolyte is used as the electrolyte of the battery body, the electrolyte can be prevented from leaking,
The effect of the present invention is more remarkable.

In the method of manufacturing a non-aqueous secondary battery according to the present invention, after enclosing the battery main body with an envelope, a moisture-proof layer is formed so as to continuously envelope the entire outer surface of the envelope. It is characterized by the following.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-aqueous secondary battery according to an embodiment will be described with reference to FIGS. 1 and 2 are cross-sectional views of the battery according to the embodiment.

The battery 1 shown in FIG. 1 is obtained by enclosing the entire battery body 2 (excluding terminals) with an envelope 3 made of a film, and the surface (outer surface) of this film is The moisture-proof layer is formed by vapor deposition of metal or the like. Note that a pair of lead wires 4 extend from the battery main body 2, and the lead wires 4 extend through the envelope 3 to the outside.
The battery main body 2 has a structure in which a positive electrode 5, a negative electrode 6, and a non-fluid electrolyte layer 7 are laminated.

To enclose the battery body 2 with the enclosing body 3,
The battery body may be sandwiched between the two leaf sheets or the folded one leaf sheet, and then the sheets may be joined around the battery body by bonding or heat welding.

Examples of the sheet include polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, polyamide, ethylene-vinyl acetate copolymer, polyvinylidene chloride, polyvinyl chloride, polyimide, fluorine resin and the like. Thermoplastic resins, thermoplastic elastomers, elastomers, and polyurethanes are preferred. The thickness is 10-1
It is preferably about 000 μm, especially about 50 to 300 μm.

The moisture-proof layer is made of aluminum, zinc, gold, silver,
Metals such as chromium, nickel, copper, cobalt, titanium, and platinum are sputtered, vapor-deposited or plated to a thickness of 0.
Those formed on the surface of the sheet to have a thickness of about 01 to 10 μm, particularly about 0.5 to 3 μm are preferable.

The moisture-proof layer may be formed by applying a paint containing a metal foil of aluminum, copper, stainless steel, nickel or the like. The thickness of the metal foil is preferably from 0.1 to 10 μm, particularly preferably from 0.5 to 3 μm. The size (average diameter of the major axis and minor axis of the surface of the foil) of the metal foil is preferably 1 to 50 μm, particularly preferably about 10 to 30 μm. As a resin component of the paint for dispersing the metal foil, phenol resin, epoxy resin, silicone resin,
Furan resins, polyester resins, urea resins, melamine resins, phthalic resins, vinyl acetate, vinyl chloride, styrene, acrylic resins, fluororesins, celluloses and the like can be used. The paint may be a solvent-based paint or an aqueous emulsion type paint.

Further, the moisture-proof layer is made of SiOx (x is 1 to 2).
) May be used. In this case, the film thickness is preferably about 0.01 to 10 μm, particularly about 0.5 to 3 μm.

Each of these moisture-proof pieces is formed after the battery body 2 is covered with the envelope 3, and covers the entire outer surface of the battery continuously and substantially continuously.
That is, it covers the end faces of the sheet of the envelope 3 and between the end faces of the sheet. Thereby, invasion of moisture into the envelope 3 is almost completely prevented. At this time, if a conductive material such as metal is used as the material of the moisture-proof layer, care must be taken because short-circuiting may occur if the moisture-proof layer comes into contact with the lead wires extending from the envelope to the outside. It is.

In the embodiment shown in FIG. 2, the battery main body 1 is housed in a synthetic resin case 8 as an envelope. A moisture-proof layer is formed on the outer surface of the case 8.
The case 8 is preferably composed of a main body 8a and a cap 8b attached to the main body 8a and sealed by adhesion or fusion.

The synthetic resin constituting the case 8 includes polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polystyrene, ABS resin, polyacrylonitrile, polyoxymethylene, polyvinyl chloride,
Epoxy resin, polyurethane, plastic alloy (for example, an alloy of polycarbonate and ABS resin) and the like can be used.

The same moisture-proof layer as that of the embodiment shown in FIG. 1 can be used. This moisture-proof layer is formed after the battery main body is accommodated in the case main body 8a and the cap 8b is attached, thereby continuously covering the entire outer surface of the case 8 without any breaks. That is, the sealing portion between the case body 8a and the cap 8b is also covered. As a result, intrusion of moisture into the case 8 is almost completely prevented.

In the above example, an example in which the envelope is made of only a resin is given. However, in the present invention, a laminate film composed of a resin layer and a metal layer can be used as the envelope. When the laminate film is used as the envelope, since the laminate film itself has a certain moisture-proofing ability, providing a moisture-proof layer on the outside of the laminate film can more reliably prevent the penetration of moisture. In addition, when a flexible envelope such as a laminate film is used, the sealing of the battery body can be performed under reduced pressure, so that a pressing force can be easily applied between the layers of the battery body. Has the effect of being able to fully demonstrate.

Further, a layer can be further provided outside such as a resin protective layer for mechanical protection of the moistureproof layer is provided outside the moistureproof layer.

The present invention is suitable as a thin-film battery, and particularly suitable for application to a lithium secondary battery. Therefore, a preferred configuration in the case where the battery shown in FIGS. explain.

This lithium secondary battery has a structure in which a positive electrode, a negative electrode, and a non-fluid electrolyte layer are laminated. The positive electrode or the negative electrode is obtained by laminating a positive electrode material or a negative electrode material on both surfaces (in some cases, one surface) of a sheet-shaped current collector as a core material.

As the current collector for the positive electrode, a metal foil of aluminum, stainless steel, nickel or the like can be used. Particularly, aluminum is suitable. As the current collector for the negative electrode, a metal foil of copper, stainless steel, nickel or the like can be used. Particularly, copper is preferable, but a net or a punched metal may be used instead of the foil. The thickness of the current collector is preferably about 1 to 30 μm.

As a positive electrode material, occludes lithium ions.
Both inorganic and organic compounds can be used as long as they can be released. As the inorganic compound, a transition metal oxide, a composite oxide of lithium and a transition metal, a transition metal sulfide, specifically, a transition metal oxide such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , Composite oxides of lithium and a transition metal, such as lithium nickelate, lithium cobaltate, and lithium manganate; and transition metal sulfides, such as TiS ₂ , FeS, and MoS ₂ . These compounds may be partially substituted with elements in order to improve their properties. As the organic compound, for example, polyaniline, polypyrrole,
Examples include polyacene, disulfide-based compounds, and polysulfide-based compounds.

As the negative electrode material, carbonaceous materials such as graphite and coke are usually mentioned, and oxides and sulfates such as silicon, tin, zinc, manganese, iron and nickel, metallic lithium, Li-Al, Li -Bi-Cd, Li-Sn
Lithium alloys such as -Cd, lithium transition metal nitrides, silicon and the like can also be used.

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.

The positive electrode material and the negative electrode material may contain additives, such as conductive materials and reinforcing materials, exhibiting various functions, powders, fillers, and the like, as necessary.

The positive electrode material layer and the negative electrode material layer are preferably thicker in terms of capacity and thinner in terms of rate. Film thickness is usually 2
It is at least 0 μm, preferably at least 30 μm, more preferably at least 50 μm, most preferably at least 80 μm. The upper limit of the electrode film thickness is usually 200 μm or less, preferably 150 μm or less.

The non-fluid electrolyte layer 13 interposed between the positive electrode 11 and the negative electrode 12 has a function of electrochemically bonding the positive electrode and the negative electrode similarly to a normal electrolytic solution, and has a low fluidity and a low shape retention. Is used.

As a supporting electrolyte used for the non-fluid electrolyte layer, the supporting electrolyte is stable 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, LiB
F ₄ , LiClO ₄ , LiI, LiBr, LiCl, Li
Lithium salts such as AlCl, LiHF ₂ , LiSCN, and LiSO ₃ CF ₂ are mentioned. Of these, Li
PF ₆ and LiClO ₄ are preferred.

Examples of the non-aqueous solvent for dissolving the electrolyte include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane and the like, and lactones such as γ-butyl lactone; Sulfur compounds such as sulfolane,
One or more of nitriles such as acetonitrile are exemplified.

As the non-fluid layer, a gel electrolyte can be used. A gel electrolyte is one in which an electrolyte containing a supporting electrolyte and a solvent contains a polymer for gelation, and the electrolyte is held in a polymer network and the overall fluidity is significantly reduced. .

As the polymer used for the gel electrolyte,
Examples thereof include polyester, polyamide, polycarbonate, polyimide, polyurethane, polyurea, polymethyl methacrylate, polyvinyl acetate, and polyvinyl chloride. Preferably, it is a poly (meth) acrylate polymer.

Incidentally, a solid electrolyte layer may be used as the non-fluid electrolyte layer. As the non-fluid layer, a gel electrolyte or a solid electrolyte impregnated in a porous film or a nonwoven fabric may be used.

The thickness of the non-fluid electrolyte layer is usually from 5 to 20.
0 μm, preferably 10 to 100 μm.

For the purpose of a large capacity battery, it is preferable that the positive electrode and the negative electrode are alternately laminated via a non-fluid electrolyte layer. That is, the protruding pieces are formed on the positive electrode and the negative electrode, the protruding pieces of the positive electrode are laminated, and the protruding pieces of the negative electrode are laminated, thereby increasing the capacity of the battery.

The number of the positive electrode and the negative electrode to be laminated is arbitrary, but the number of the positive electrode and the negative electrode is generally the same.

The planar shape of the electrode material is arbitrary such as a circle, a quadrilateral, a polygon, and the like. The size is also arbitrary. For example, one side or the diameter is several cm to several tens cm.

[0043]

Example 1 A flat thin lithium polymer battery shown in FIGS. 1 and 2 was manufactured by the following method.

Production of Positive Electrode On a 30 mm × 45 mm aluminum foil having a thickness of 25 μm,
A solution composed of iCoO ₂ , acetylene black and PVDF (polyvinylidene fluoride) is applied, dried, and has a thickness of 6
A 5 μm positive electrode sheet was obtained. A part of the aluminum foil was extended to form a 3 mm wide terminal protruding piece.

Production of Negative Electrode A solution composed of graphite and PVDF (polyvinylidene fluoride) was applied on a copper foil of 31 mm × 46 mm and 25 μm in thickness and dried to obtain a 50 μm thick negative electrode sheet. In addition, a part of the copper foil was extended to be a terminal protruding piece having a width of 3 mm.

Diethylene glycol ethyl ether acrylate and tetraethylene glycol diacrylate are dissolved in a solution in which LiPF ₆ is dissolved at a concentration of 1 mol / L in a 1: 1 mixed solvent of propylene carbonate and ethylene carbonate, and t-butyl is used as an initiator. Peroxy-2-ethoxyhaysanoate was added to the above solution to obtain an electrolyte raw material.

After the polypropylene / polyethylene mixed non-woven fabric having a thickness of 60 μm was placed on the positive electrode, they were impregnated with the electrolyte raw material. After the electrolyte material was also impregnated on the negative electrode, the positive electrode and the negative electrode were laminated with the active material layer inside. Next, this is heated at 90 ° C. for 20 minutes to polymerize the acrylate-based monomer in the electrolyte raw material to form a polyacrylate-based polymer, gel the electrolyte raw material, and form a flat plate including a positive electrode, a negative electrode, and a non-fluid electrolyte layer. A unit battery was obtained. Furthermore, a battery element (battery main body) was obtained by laminating these unit batteries in 15 layers. The dimensions of this battery body are 32mm x 47mm x 3m
m. In addition, the protruding pieces for each terminal were laminated and a lead wire was connected.

[0048] Encapsulated modified polyethylene (Mitsubishi Chemical Corporation / trade name MODI)
The CAP) film was folded in two, the above-mentioned battery body was sandwiched, and the film around the battery body under reduced pressure was joined by heat fusion. Next, this was masked around the terminal, and then a vacuum deposition apparatus CU manufactured by Shibaura Mechatronics Co., Ltd.
Using -36PV-160E, a deposited film of aluminum having a thickness of 2 μm was formed on the entire surface. It was recognized that the battery manufactured in this manner was extremely excellent in permeation resistance.

Example 2 Instead of the above-mentioned film wrapping, the battery body was made of polypropylene (Nippon Polychem / Novec PP) and had a thickness of 500 μm and external dimensions of 33.5 mm × 48.5 mm.
It was housed in a × 4.5 mm case. This case includes a case body and a cap. After fusing both, 2μ
As in Example 1, a moisture-proof layer made of aluminum was deposited. Except for this, a battery was manufactured in the same manner. It was recognized that the battery manufactured in this manner was extremely excellent in permeation resistance.

Examples 3 and 4 Batteries were manufactured in the same manner except that a coating film containing a metal foil was formed on the entire outer surface of the film or the case. The obtained battery was found to be extremely excellent in permeation resistance. The metal foil is made of aluminum, and has an average diameter of 15 μm and an average thickness of 1 μm. The coating film resin was vinyl acetate, and was a water-based emulsion type paint.
The average thickness of the coating is 6 μm. The coating amount of metal foil is 2
g / m ² .

Examples 5 and 6 SiOx (x = 2) on the entire outer surface of the film or case
A battery was manufactured in the same manner as in Examples 1 and 2, except that a sputtered film (thickness: 1 μm) was formed. This battery was also found to be extremely excellent in permeation resistance.

[0052]

As described above, according to the present invention, a non-aqueous secondary battery in which the battery body is encapsulated by the envelope can be efficiently manufactured. The envelope of the manufactured non-aqueous secondary battery has a moisture-proof layer on the outer surface, and is extremely excellent in moisture permeability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a battery according to an embodiment.

FIG. 2 is a cross-sectional view of a battery according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Battery main body 3 Enclosure 4 Lead wire 8 Case 8a Case main body 8b Cap

Continued on the front page F term (reference) 4K029 AA11 BA01 BA03 BA46 BC00 BD00 CA01 CA05 5H011 AA10 CC02 CC05 CC06 CC10 DD18 DD21 5H029 AJ00 AJ14 AK02 AK03 AK05 AK16 AL01 AL02 AL06 AL11 AL12 AM00 AM02 AM03 AM04 AM04 DJ07 BJ01 EJ05 EJ12

Claims (9)

[Claims] 1. A battery having a battery main body and an encapsulation body enclosing the battery main body, wherein a moisture-proof layer is provided to continuously enclose the entire outer surface of the encapsulation body. Non-aqueous battery. 2. The non-aqueous secondary battery according to claim 1, wherein said moisture-proof layer comprises a metal layer. 3. The non-aqueous secondary battery according to claim 1, wherein the moisture-proof layer is formed by sputtering, vapor-depositing, or plating on an envelope enclosing the battery body. battery. 4. The non-aqueous secondary battery according to claim 1, wherein the moisture-proof layer comprises a coating film formed by applying a coating material including a metal foil to an enclosing body enclosing the battery body. . 5. The non-aqueous secondary battery according to claim 1, wherein the moisture-proof layer is formed of a silicon oxide film formed by sputtering an enclosing body enclosing the battery body. 6. The non-aqueous secondary battery according to claim 1, wherein the battery body has a positive electrode, a negative electrode, and a non-fluid electrolyte layer. 7. The non-aqueous secondary battery according to claim 1, wherein the envelope is made of a resin. 8. The non-aqueous secondary battery according to claim 1, wherein the envelope comprises a resin layer and a metal layer. 9. After the battery body is wrapped by the wrapping body,
A method for manufacturing a non-aqueous secondary battery, comprising forming a moisture-proof layer so as to continuously cover the entire outer surface of the envelope.