JP2002245983A - Material for wrapping lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide material constitution free to stably seal a lithium ion battery without short-circuiting a barrier layer and a tab of an armoring body by heat and pressure of heat sealing at the time of sealing the battery by inserting a lithium ion battery main body in the armoring body with polyolefine resin as a heat sealing layer and heat-sealing its peripheral edge in wrapping the lithium ion battery. SOLUTION: This wrapping material for the lithium ion battery to heat-seal the peripheral edge of the lithium ion battery by inserting the lithium ion battery main body in the armoring body of the lithium ion battery constituted of at least a base material layer, an adhesive layer 1, a chemical conversion treated layer 1, aluminum, a chemical conversion treated layer 2, an adhesive layer 2 and a heat-sealing layer constitutes its characteristic feature of including an adhesive polymethlpentene layer in the heat sealing layer, and the heat sealing layer includes a coextrusion film made of a polyolefine layer, the adhesive polymethylpentene layer and the polyolefine layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material for a lithium ion battery having a liquid or solid organic electrolyte (polymer polymer electrolyte) having moisture resistance and content resistance, and an outer package for packaging a lithium ion battery body. The present invention relates to an adhesive film interposed between a body, a tab portion of the battery, and a package.

[0002]

2. Description of the Related Art A lithium ion battery, also called a lithium secondary battery, is a battery which comprises a solid polymer, a gel polymer, a liquid or the like as an electrolyte and generates an electric current by the movement of lithium ions. The negative electrode active material includes a material composed of a high molecular polymer. The structure of the lithium secondary battery is composed of a positive electrode current collector (aluminum, nickel) /
Cathode active material layer (metal oxide, carbon black, metal sulfide, electrolyte, polymer cathode material such as polyacrylonitrile) / electrolyte layer (carbonate electrolyte such as propylene carbonate, ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate, etc.) , Lithium salt inorganic solid electrolyte, gel electrolyte) / negative electrode active material (lithium metal, alloy, carbon, electrolyte, polymer negative electrode material such as polyacrylonitrile) / negative electrode current collector (copper, nickel,
Stainless steel) and an outer package for packaging them. Lithium ion batteries are used for personal computers, portable terminal devices (mobile phones, PDAs, etc.), video cameras, electric vehicles, storage batteries for energy storage, robots, satellites, and the like. As the outer package of the lithium-ion battery, a metal can formed by pressing a metal into a cylindrical or rectangular parallelepiped container, or a plastic film, a laminate made of a composite film obtained by laminating a metal foil, etc. (Hereinafter referred to as an exterior body) was used. There are the following problems as an exterior body of a lithium ion battery. In a metal can, the shape of the battery itself is determined because the outer wall of the container is rigid. Therefore, since the hardware side is designed to match the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom of the shape is reduced. Therefore, there is a tendency to use the bag-shaped exterior body. The material composition of the outer package is composed of at least a base material layer, a barrier layer, a heat seal layer and an adhesive layer for bonding the respective layers, from the necessary physical properties, workability, economy, and the like as a lithium ion battery. To provide an intermediate layer. A pouch is formed from the laminated body having the above-described configuration of the lithium ion battery, or at least one side is press-molded to form a storage portion of the lithium ion battery to store the lithium ion battery body, and a pouch type or an embossed type (lid) (With body covering), a required portion of each periphery is sealed with a heat seal to form a lithium ion battery. The heat seal layer is required to have a heat seal property with respect to a tab (metal) as well as a heat seal property between the heat seal layers, and an acid-modified polyolefin resin having metal adhesive property is used as the heat seal layer. As a result, adhesion to the tab portion is ensured.

However, when an acid-modified polyolefin resin is laminated as a heat seal layer of an exterior body, its workability is inferior to that of a general polyolefin resin.
Due to the high cost, etc., a method is adopted in which a general polyolefin resin layer is used as the heat seal layer of the exterior body, and an adhesive film that can be thermally bonded to both the heat seal layer and the tab is interposed in the tab portion. I was In particular,
As shown in FIG. 10A, between the tab 4 and the heat seal layer 14 'of the laminate 10', an adhesive film having heat sealability to both the metal and the heat seal layer of the exterior material. By interposing 6 ', the sealing property at the tab portion was ensured. As the adhesive film, a film made of the unsaturated carboxy-grafted polyolefin, metal cross-linked polyethylene, or a copolymer of ethylene or propylene with acrylic acid or methacrylic acid can be used.

[0004]

However, when the heat seal layer of the laminate constituting the exterior body of the lithium ion battery (hereinafter referred to as the exterior body) is made of a polyethylene resin, the lithium ion battery body is housed in the exterior body. When the adhesive film 6 'made of an acid-modified polyethylene single layer is used, for example, when the tab is present, as shown in FIG. The heat seal layer 14 'and the adhesive film layer 6' of the outer package are melted together by the heat and pressure of
Further, the pressure may be pushed out of the region of the pressing portion. As a result, the aluminum foil as the barrier layer 12 'of the exterior body 10' and the tab 4 'made of metal may contact (S) and short-circuit. Similarly, when the heat seal layer of the laminate is made of a polypropylene resin,
Adhesive film 6 consisting of acid-modified polypropylene single layer
Even when 'was used, the aluminum foil as the barrier layer 12 ′ of the exterior body 10 ′ came into contact with the tab 4 made of metal, and short-circuiting sometimes occurred. An object of the present invention is to provide a lithium-ion battery package, in which, when a lithium-ion battery body is inserted into an exterior body having a polyolefin-based resin as a heat-sealing layer and the periphery thereof is heat-sealed and sealed, the heat of heat sealing is reduced. It is an object of the present invention to provide a material structure capable of stably sealing without a short circuit between a barrier layer and a tab of an exterior body due to pressure.

[0005]

The above objects can be attained by the present invention described below. The invention described in claim 1 includes at least a base material layer, an adhesive layer 1, a chemical conversion treatment layer 1,
A packaging material for a lithium ion battery in which a lithium ion battery main body is inserted into an exterior body of a lithium ion battery composed of aluminum, a chemical conversion treatment layer 2, an adhesive layer 2, and a heat sealing layer, and the periphery thereof is heat sealed. The packaging material for a lithium ion battery is characterized in that the sealing layer includes an adhesive polymethylpentene layer. Claim 2
The heat-seal layer is a co-extruded film comprising a polyolefin layer, an adhesive polymethylpentene layer, and a polyolefin layer. The invention according to claim 3 provides at least a substrate layer, an adhesive layer 1, aluminum, a chemical conversion treatment layer, an adhesive layer 2,
A lithium-ion battery packaging material for inserting a lithium-ion battery body into a lithium-ion battery exterior body composed of a heat-sealing layer and heat-sealing the periphery thereof, wherein the heat-sealing layer includes an adhesive polymethylpentene layer. And a packaging material for a lithium ion battery. The invention described in claim 4 is characterized in that the heat seal layer described in claim 3 is a co-extruded film composed of a polyolefin layer, an adhesive polymethylpentene layer, and a polyolefin layer. The invention described in claim 5 is any one of claims 1 to 4.
Is formed by a dry lamination method. The invention described in claim 6 is
The adhesive layer 2 according to any one of claims 1 to 4 is a coating baking layer of an acid-modified polyolefin. The invention described in claim 7 is claim 1 to claim 1.
The adhesive layer 2 according to any one of claims 4 to 5 is an extruded layer of an acid-modified polyolefin.
The invention described in claim 8 is characterized in that an adhesive film is interposed between the exterior body of the lithium ion battery according to any one of claims 1 to 7 and the tab portion of the lithium ion battery body. Is what you do. According to a ninth aspect of the present invention, in the heat seal layer according to any one of the first to eighth aspects, the polyolefin layer is formed of polypropylene, polyethylene, a copolymer of ethylene and butene, a copolymer of propylene and butene, And a mixture containing at least one of a copolymer of ethylene and butene, a simple substance or an ionomer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a moisture-proof property,
In addition, the productivity is good, and the outer body is formed using a lithium ion battery packaging material comprising a heat sealing layer of a polyolefin resin, and when the lithium ion battery body is packaged, the sealing performance at the tab portion is secured. In particular, the present invention relates to a packaging material for a lithium ion battery which does not cause a short circuit with the barrier layer of the outer package in the tab portion, and has a heat-seal layer including an adhesive polymethylpentene layer. The details will be described below with reference to the drawings and the like.

FIG. 1 is a diagram for explaining an embodiment of a packaging material for a lithium ion battery according to the present invention as a sectional view.
(C) shows a dry laminating method, a heat laminating method, and an extruding laminating method when the heat seal layer is made of a co-extruded film including an adhesive polymethylpentene layer. FIG. 2 is a diagram showing a layer structure at a tab portion of a packaging material for a lithium ion battery of the present invention,
(A), a diagram for explaining the material and the positional relationship (one side) of the lithium ion battery tab, the outer package, and the adhesive film, (b)
It is sectional drawing explaining the state in which the tab, the adhesive film, and the exterior body before the heat sealing in the tab part contacted, (c) It is explanatory drawing which shows the state after sealing. FIG. 3 is an explanatory view of a method of fixing an adhesive film in bonding a packaging material for a lithium ion battery and a tab. FIG. 3 is a perspective view for explaining a method of mounting an adhesive film in bonding a packaging material for a lithium ion battery and a tab. FIG. 4 is an explanatory view of a method of fixing an adhesive film to be interposed between the outer casing and the tab portion during heat sealing. FIG. 5 is a perspective view illustrating a pouch type exterior body of a lithium ion battery. FIG. 6 is a perspective view illustrating an embossed type exterior body of the lithium ion battery. FIGS. 7A and 7B are views for explaining molding in an emboss type, (a) a perspective view, (b) an exterior body main body formed by embossing, (c) a cross-sectional view of a part X ₂ -X ₂ ,
(D) is a Y ₁ part enlarged view. FIG. 8 is a cross-sectional view illustrating an example of a layer configuration of a laminate forming an exterior body of a lithium-ion battery. FIG. 9 is a cross-sectional view illustrating an example of a layer configuration of another laminated body that forms the exterior body of the lithium-ion battery.

A tab of a lithium ion battery has a thickness of about 50 to 2000 μm and a width of about 2.5 to 20 mm, and its material is AL, Cu (including Ni plating), Ni, or the like. . Further, the heat seal layer of the exterior body of the lithium ion battery is formed of a resin capable of heat sealing the heat seal layers. It is desirable to use a resin that can be heat-sealed directly to the tab as the heat-sealing layer. However, as described above, a resin material having a single-layer or multi-layer structure of a general polyolefin such as polyethylene or polypropylene, or a blend thereof is used. As a sealing layer, a method is adopted in which the tab and the heat sealing layer are mutually heat-sealed with an adhesive film and sealed.

[0009] The exterior body of the lithium ion battery is required to have the performance of maintaining the performance of the lithium ion battery body for a long period of time, and a base material layer, a barrier layer, a heat seal layer and the like are laminated by various lamination methods. I have. In particular, when the heat seal layer of the laminate constituting the exterior body of the lithium-ion battery (hereinafter, exterior body) is made of a polyolefin resin or the like, the lithium-ion battery body is housed in the exterior body, and the periphery thereof is sealed and sealed. When an acid-modified polyolefin is used as the adhesive film in the portion where the tab is present, for example, as shown in FIG. 10 (b), heat and pressure for heat sealing are used to adhere to the heat seal layer of the outer package. Melts together with the conductive film layer,
Further, the layer inside the barrier layer 12 'of the outer package and the adhesive film layer 6' which have been the insulating layer may be pushed out of the region of the pressurized portion by the pressurization. As a result, the aluminum foil serving as the barrier layer 12 'of the outer package may come into contact with the metal tab 4' to cause a short S.

The present inventors have conducted intensive studies on the prevention of the short S, and as a result, have found that at least the heat seal layer of the outer package is formed of a coextruded film comprising a polyolefin layer, an adhesive polymethylpentene layer, and a polyolefin layer. As a result, the present inventors have found that the above-mentioned problems can be solved, and have completed the present invention. That is, as a configuration example of the packaging material for a lithium ion battery of the present invention, FIG.
As shown in (a), the heat seal layer is a laminate formed by coextruding three layers of a polyolefin layer, an adhesive polymethylbenten layer, and a polyolefin layer, and formed by a dry lamination method with a barrier layer.

The polyolefin may be any one which can be thermally welded to the sealant layer, and may be polypropylene, polyethylene, a copolymer of ethylene and butene, a copolymer of propylene and butene, a copolymer of propylene, ethylene and butene, a simple substance of ionomer or It can be appropriately selected from a mixture containing at least one.

Specifically, the polyolefin resin is
Propylene resin (homotype, copolymer of ethylene and propylene, copolymer of ethylene and propylene and butene), ethylene resin (low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene Copolymer of ethylene and butene, copolymer of ethylene and acrylic acid or methacrylic acid derivative, copolymer of ethylene and phenyl acetate, ethylene containing metal ions) and polyethylene resin grafted with unsaturated carboxylic acid Or a simple substance or a blend of a polypropylene resin.

The adhesive polymethylbenthene resin as a component of the heat seal layer of the packaging material for a lithium ion battery of the present invention has excellent interlayer adhesion in coextrusion with an olefin resin and has a melting point of a polyolefin layer ( 8
0 to 160 ° C.), and an acid-modified polyolefin layer (75
(160 ° C.), the polyolefin layer and the acid-modified polyolefin layer are thinly crushed by heat when heat sealed, but the adhesive polymethylbenten layer remains as an insulating layer without crushing.

The adhesive polymethylbenten has a melting point of 18
Add a tackifier to trimethylpentene resin at 0 ° C or higher
Terpene resin (terpene phenol, aromatic modified resin, hydrogenation), rosin derivative (hydrogenation, disproportionation, dimerization, esterification), alicyclic saturation Examples include hydrocarbon resins, limonene resins, alkylphenol resins, xylene resins, and coumarone indene resins. The heat seal layer of the present invention is a three-layer coextruded film consisting of a polyolefin layer: an adhesive polymethylbenten layer: an acid-modified polyolefin layer, and the layer ratio can be determined as appropriate, but (1-4): ( Two
8): (1-4) is appropriate. Also, adhesive TP
The thickness of X needs to be at least 10 μm or more. 10μ
If it is less than m, a short circuit occurs when heat sealing. The layer thickness of the three-layer coextruded film is desirably at least one tenth of the thickness of the tab used.

The co-extruded layer containing the adhesive polymethylbenten layer serving as the heat seal layer of the packaging material for a lithium ion battery of the present invention has no heat adhesion to metal. An adhesive film having heat sealability is interposed between the outer package and both the heat seal layer and the tab.

As the adhesive film, a film made of an acid-modified polyolefin, which has thermal adhesiveness to both the heat seal layer and the tab, is used. As the acid-modified polyolefin resin, an unsaturated carboxy-grafted polyolefin, a metal-crosslinked polyethylene, a copolymer of ethylene and an acrylic acid or methacrylic acid derivative, a simple substance of a copolymer of ethylene and phenyl acetate, or a blend thereof is used. be able to.

Further butene component as needed, terpolymer component comprising 3 ingredients copolymer of ethylene and butene and propylene, a low crystalline copolymer of ethylene and butene having a density of 900 kg / m ^3, an amorphous ethylene And a propylene copolymer, a propylene-α-olefin copolymer component and the like can be added in an amount of 5% or more.

The tab 4 is made of aluminum (AL).
When M) is used, it is desirable to perform a chemical conversion treatment on the aluminum surface to prevent dissolution and corrosion of the aluminum surface by hydrogen fluoride generated by a reaction between the electrolyte of the lithium battery and moisture. The chemical conversion treatment is specifically to form an acid-resistant film such as a phosphate, a chromate, a fluoride, and a triazine thiol compound. (3) Phosphoric acid chromate treatment using a compound composed of a compound and phosphoric acid is favorable. Alternatively, a chemical conversion treating agent containing a metal such as molybdenum, titanium, zircon, or a metal salt in a resin component containing at least a phenol resin was good.

When the lithium ion battery packaging material and the adhesive film 6 formed by the above-described method are interposed between the outer package 5 and the tab 4 of the lithium battery 1 and heat-sealed, FIG. As shown in (1), the short circuit can be avoided because the adhesive polymethylbenten layer 14b remains as an insulating layer. However, the presence of the TPX layer improves the heat resistance as a heat seal layer and reduces It is considered that the resin layer is less likely to be crushed by heat and pressure at the time of heat sealing as compared with the resin layer.

The lithium ion battery packaging material forms an outer package for packaging the lithium ion battery body. Depending on the type of the outer package, a pouch type as shown in FIG. 5 and a pouch type as shown in FIGS. FIG. 6 (b) or FIG. 6 (c)
There is an embossed type as shown in FIG. The pouch type includes a bag type such as a three-sided seal, a four-sided seal, and a pillow type. FIG. 5 illustrates the pouch type as a pillow type. In the emboss type, a concave portion may be formed on one side as shown in FIG. 6A, or a concave portion may be formed on both surfaces as shown in FIG. The four sides of the periphery may be sealed by heat sealing. There is also a type in which concave portions are formed on both sides of a folded portion as shown in FIG. 6C, and a lithium ion battery is housed and three sides are heat-sealed.

When the heat seal layer 14 of the outer package is made of a material having no heat sealing property with respect to metal, the adhesive film 6 is provided between the outer package 5 and the tab 4 as described above.
The specific method is, for example, as shown in FIG.
As shown in FIG. 3B, the adhesive films 6 are placed above and below the tab sealing seal of the lithium ion battery main body 2 (actually, they are fixed by temporary sealing), and the exterior
And heat-sealed while holding the tab portion therebetween to seal.

As a method of interposing the adhesive film 6 on the tab 4, as shown in FIG. 3D or 3E, a film of the adhesive film 6 may be wound around a predetermined position of the tab 4. . The tab 4 and the adhesive film 6 are shown in FIG.
As shown in FIG. 7, the acid-modified polyolefin 21 of the adhesive film 6 may be welded to the tub 4 in advance by mk. Alternatively, as shown in FIG. 4B, the tab 4 and the adhesive film 6 may be used while being temporarily attached wk. Further, as shown in FIG. 4 (c) or FIG. 4 (d), temporary attachment wk or welding mk may be performed on the surface of the heat seal layer 14 of the exterior body 10 in advance. When aluminum (ALM) is used as the tab 4, a chemical conversion treatment may be performed on the aluminum surface to prevent dissolution and corrosion of the aluminum surface by hydrogen fluoride generated by a reaction between the electrolyte of the lithium ion battery and moisture. desirable. The chemical conversion treatment is specifically to form an acid-resistant film such as a phosphate, a chromate, a fluoride, and a triazine thiol compound. (3) Phosphoric acid chromate treatment using a compound composed of a compound and phosphoric acid is favorable. Or, a resin component containing at least a phenolic resin, molybdenum,
Chemical conversion treatment agents containing metals such as titanium and zircon, or metal salts were good.

When the adhesive film 6 for a tab of a lithium ion battery of the present invention is hermetically sealed by being interposed between the outer package and the tab, the seal after the hermetic seal is shown in FIG.
As shown in (2), the adhesive TPX layer remains between the barrier layer and the tab of the outer package, and functions as an insulating layer for preventing short circuit between the barrier layer and the tab.

Further, the acid-modified polyolefin layer of the adhesive film adheres to the tab to prevent moisture from entering from outside, to prevent leakage of components of the lithium ion battery body as contents, and to prevent electrolyte in the battery. This is to prevent the tab surface from being corroded by hydrogen fluoride HF generated by the reaction between the component and moisture.

Next, an example of the material of the exterior body 10 to which the packaging material for a lithium ion battery of the present invention is applied will be described.
As shown in FIG. 8A to FIG.
For example, it is composed of at least a base material layer 11, an adhesive layer 16, a barrier layer 12, a chemical conversion treatment layer 15 (2), an adhesive resin layer 13, and a heat seal layer 14. When the exterior body is an embossed type, as shown in FIG. 8A or 8B, the base material layer 11, the adhesive layer 16, and the chemical conversion layer 15 are used.
(1) The structure includes a barrier layer 12, a chemical conversion treatment layer 15 (2), an adhesive resin layer 13, and a heat seal layer 14.

Further, a specific example of the layer structure is shown in FIGS.
(H). The adhesion between the heat seal layer 14 and the chemical conversion treatment layer (2) is performed by any one of a dry lamination method, a sandwich lamination method, a co-extrusion lamination method, and a heat lamination method. In the case of using aluminum in a pouch, the aluminum chemical conversion treatment may be performed on one side of the heat seal layer alone or on both sides of the base material layer side and the heat seal layer side.

Further, when the sandwich laminating method or the co-extrusion laminating method is used among the above laminating methods, the obtained laminate is subjected to pre-heating or post-heating described later to improve the adhesive strength. . Further, by providing the liquid paraffin layer 19, the moldability is improved and the crack resistance of the heat seal layer is improved.
In addition, the formability is improved by applying and applying a so-called slip agent layer 17 such as erucic acid amite {amoleic acid amite} or bisoleic acid amite at least on the surface of the base material layer.

When the packaging material for the lithium ion battery is embossed, the laminated packaging material 10 is press-molded to form the recess 7 as shown in FIGS. 7 (a) to 7 (d). At this time, the press-molded male mold 21 and the laminate 1
If the slip with the heat seal layer 14 of 0 is poor, a stable molded product may not be obtained.

The inventors of the present invention have shown in FIG.
As shown in (d), by coating liquid paraffin 19 on the innermost surface of the heat seal layer 14 made of the polyolefin resin of the outer package, embossability is improved, and cracks are generated in the heat seal layer. It has been confirmed that packaging materials that are difficult to handle can be obtained.

The liquid paraffin layer 19 is a chain hydrocarbon oil, and its physical property is 0.83 to 0.8.
7. The viscosity is 7.6 to 80 mm ^{2 /} S (37.5 ° C.), the molecular weight is about 300 to 500, and the distillation temperature under the conditions of 10 mmHg is 140 to 245 ° C. The liquid paraffin in the packaging material for a lithium ion battery of the present invention and the method for producing the same has a specific gravity of 0.8.
3, viscosity 7.7mm ^{2 /} S (37.5 ° C), molecular weight 30
A distillation temperature of about 141 ° C. under the conditions of 0 and 10 mmHg can be suitably used.

By coating the heat seal layer with liquid paraffin, part or all of the liquid paraffin penetrates into the polypropylene layer or polyethylene layer of the heat seal layer and swells the polypropylene layer or polyethylene layer to form a heat seal layer. Becomes softer,
It is thought that it becomes easier to stretch. As a result of coating the heat seal layer 14 with liquid paraffin, stress generated during embossing is dispersed, and cracks in the heat seal layer made of polyolefin resin (heat seal layer of the packaging material for lithium ion batteries) generated during molding are reduced. In addition, the coated liquid paraffin has improved surface lubricity due to its effect as a lubricant. In addition, at least the base material layer 11 generally contains a lubricant represented by erucic acid amite ゛, oleic acid amite ゛, stearic acid amite ゛, biserucic acid amite マ イ, bisoleic acid amite ゛, bisstearic acid amite ゛At least one of isopropyl alcohol,
It was also found that by applying a solution in a solvent such as ethyl acetate, toluene, or methyl-ethyl-ketone, and coating and applying the solution, the surface slipperiness was improved and the moldability was improved.

Further, the present inventors have found that a laminate having good embossing properties, no occurrence of delamination between the base material layer and the barrier layer during embossing or heat sealing, and suppressing intrusion of moisture. In addition, as a result of intensive research on packaging materials that can be used as an exterior body for lithium-ion batteries that have content resistance, as a result of chemical conversion treatment on both sides of aluminum, After laminating a saturated carboxylic acid graft polyolefin and a polyolefin (film or resin) by a sandwich lamination method or a co-extrusion method, it has been confirmed that the above problem can be solved by heating the obtained laminate.

The base material layer 11 in the outer package is made of a stretched polyester or nylon film. At this time, as the polyester resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolyester, Polycarbonate and the like. As nylon, polyamide resin, that is, nylon 6,
Nylon 6,6, a copolymer of Nylon 6 and Nylon 6,6, Nylon 6,10, polymethaxylylene adipamide (MXD6) and the like.

When the base material layer 11 is used as a lithium ion battery, it is a portion which is in direct contact with the hardware, so that a resin layer having an insulating property is basically preferable. In consideration of the presence of pinholes in the film alone and the occurrence of pinholes during processing, the base material layer needs to have a thickness of 6 μm or more, and the preferred thickness is 12 to 30 μm.

The base layer 11 can be laminated to improve pinhole resistance and insulation when the battery is used as an outer package. When the base material layer is formed into a laminate, the base material layer includes at least one resin layer of two or more layers, and each layer has a thickness of 6 μm or more, preferably 12 to 25 μm. Examples of laminating the substrate layer include the following 1) to 8). 1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched stretched polyethylene terephthalate Also, mechanical suitability of the packaging material (stability of transportation in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance) ) When the exterior body for a lithium ion battery is embossed as a secondary process, the purpose is to reduce the frictional resistance between the mold and the substrate layer during embossing, or to reduce the friction between the substrate and the electrolyte layer In order to protect the base material layer, the base material layer is multilayered, and a fluorine resin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, or a resin layer made of a blend thereof are provided on the surface of the base material layer. Is preferred. For example, 3) Fluorine-based resin / stretched polyethylene terephthalate (fluorine-based resin is formed into a film or liquid coating and then dried) 4) Silicone-based resin / stretched polyethylene terephthalate (silicone-based resin is film-like or liquid 5) Fluorine resin / stretched polyethylene terephthalate /
Stretched nylon 6) Silicone resin / Stretched polyethylene terephthalate / Stretched nylon 7) Acrylic resin / Stretched nylon (Acrylic resin is cured in film form or liquid coating followed by drying) 8) Acrylic resin + polysiloxane grafted acrylic resin / Stretched nylon (acrylic resin film
Or cured by drying after liquid coating)

The barrier layer 12 is a layer for preventing water vapor from particularly entering the inside of the lithium ion battery from the outside. The barrier layer 12 has a pinhole and a workability (pouching, embossing formability) of the barrier layer alone. To stabilize, and to have a pinhole resistance aluminum or metal having a thickness of 15 μm or more, such as nickel, or an inorganic compound, for example,
A film obtained by depositing silicon oxide, alumina, or the like may be used, but the barrier layer preferably has a thickness of 20 to 80 μm.
m of aluminum. In order to further improve the occurrence of pinholes and to make the type of the exterior body of the lithium ion battery an embossed type, in order to eliminate the occurrence of cracks and the like in embossing, the present inventors use aluminum used as a barrier layer. Has an iron content of 0.
By setting the content to 3 to 9.0% by weight, preferably 0.7 to 2.0% by weight, the extensibility of aluminum is better than that of aluminum not containing iron, and the pinhole formed by bending as a laminate is formed. It has been found that the occurrence of cracks is reduced and that the side walls can be easily formed when the embossed type exterior body is molded. The iron content is 0.3
When the amount is less than 10% by weight, effects such as prevention of generation of pinholes and improvement in embossability are not recognized. When the iron content of the aluminum exceeds 9.0% by weight, flexibility as aluminum increases. It is impaired and the bag-making properties of the laminate deteriorate.

The aluminum produced by the cold rolling has the flexibility and the flexibility under the conditions of annealing (so-called annealing treatment).
Although the strength and hardness of the waist change, the aluminum used in the present invention is harder than the hard treated product without annealing.
Aluminum with a tendency to soften slightly or completely annealed is preferred. The degree of flexibility, waist strength, and hardness of aluminum, that is, the conditions of annealing,
What is necessary is just to select suitably according to workability (pouching, embossing). For example, in order to prevent wrinkles and pinholes during embossing, it is desirable to use annealed soft aluminum according to the degree of forming.

The present inventors have been able to obtain a laminate which is satisfactory as the packaging material by subjecting the front and back surfaces of aluminum, which is the barrier layer 12 of the packaging material for lithium ion batteries, to chemical conversion treatment. The chemical conversion treatment is specifically to prevent delamination between aluminum and the substrate layer during embossing by forming an acid-resistant film such as a phosphate, a chromate, a fluoride, and a triazine thiol compound. And hydrogen fluoride generated by the reaction between the electrolyte of the lithium-ion battery and moisture, to prevent the dissolution and corrosion of the aluminum surface, especially the dissolution and corrosion of aluminum oxide present on the aluminum surface, and To improve delamination between the base layer 11 and the aluminum 12 at the time of embossing and heat sealing, and at the inner surface of the aluminum by the hydrogen fluoride generated by the reaction between the electrolyte and moisture. An effect of preventing delamination was obtained. As a result of studying the effect of chemical conversion treatment on the aluminum surface using various substances, among the above-mentioned acid-resistant film-forming substances, phenolic resin, chromium fluoride (3) compound, and phosphoric acid The phosphoric acid chromate treatment using the treated product was good. Alternatively, a chemical conversion treating agent containing a metal such as molybdenum, titanium, zircon, or a metal salt in a resin component containing at least a phenol resin was good.

When the exterior body of the lithium-ion battery is embossed, delamination between the aluminum and the base layer during embossing can be prevented by performing a chemical conversion treatment on both surfaces of aluminum.

The inventors of the present invention have conducted intensive studies on a laminating method exhibiting stable adhesive strength. As a result, the base layer 11 and one side of the chemical conversion treated barrier layer 12 are dry-laminated, and the other On the surface, acid-modified polyolefin 1
In the case of extruding the heat-sealing layer 14 by sandwich lamination, the acid-modified polyethylene resin 13 and the heat-sealing layer (polyethylene resin or polypropylene resin) 14 are co-extruded to form a laminate. By heating the resin under the condition that the resin has a softening point or higher, a laminate having a predetermined adhesive strength could be obtained. As a specific method of the heating, there are methods such as a hot roll contact type, a hot air type, near or far infrared rays, but any heating method may be used in the present invention, and as described above, the adhesive resin is softened. What is necessary is just to be able to heat above the point temperature.

As another method, in the sandwich lamination or the co-extrusion lamination, the aluminum 12 is heated to a condition where the surface temperature of the heat seal layer side reaches the softening point of the acid-modified polyolefin resin. Also, a laminate having stable adhesive strength could be obtained. Although a polyethylene resin can be used as the adhesive resin, in this case, the lamination surface of the extruded polyethylene molten resin film on the aluminum side can be laminated while performing ozone treatment.

In the adhesive film 6 for a lithium ion battery tab, the respective layers in the laminate forming the outer package are appropriately formed into a film-forming property, a laminating process, and a secondary processing of a final product (pouching, embossing). For the purpose of improving and stabilizing suitability, a surface activation treatment such as a corona treatment, a blast treatment, an oxidation treatment, and an ozone treatment may be performed.

[0043]

EXAMPLES The adhesive film for a lithium ion battery tab of the present invention will be described more specifically by way of examples. In the chemical conversion treatment applied to the barrier layer of the exterior body, an aqueous solution composed of a phenol resin, a chromium fluoride (3) compound, and phosphoric acid is applied as a treatment liquid by a roll coating method in each of Examples and Comparative Examples. Baking was performed under the condition that the temperature was 180 ° C. or higher. The amount of chrome applied is 2mg /
m ² (dry weight). In the following examples and comparative examples, a pouch type exterior body has a width of 30 mm.
The width and length are set to 50 mm (both inner dimensions), and in the case of an embossed type exterior body, each is set to a single-sided embossed type, and the shape of the concave portion (cavity) of the mold is set to 30 mm.
The moldability was evaluated by press molding with a size of × 50 mm and a depth of 3.5 mm. [Example 1] (Pouch type) A chemical conversion treatment was applied to both sides of 20 μm of aluminum, and a stretched polyester film (thickness 12
μm) by dry lamination, and then
An acid-modified polyethylene resin (20 μm, unsaturated carboxylic acid-grafted polyethylene) is placed in a state where the other surface of the chemically treated aluminum is heated to a temperature higher than the softening point of the acid-modified polyethylene resin as an adhesive resin by far infrared rays and hot air.
As an adhesive resin, a linear low-density polyethylene resin (20 μm) serving as a heat seal layer / adhesive TPX (melting point 19
0 ° C., 10 μm) / linear low-density polyethylene resin (20
A pillow-type pouch was formed using a laminate obtained by laminating a co-extruded film (50 μm) having a structure of μm) by a sandwich lamination method. In addition, an acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene, 50 μm) was used as the adhesive film. 100
A lithium ion battery main body having an aluminum tab having a thickness of 4 μm and a thickness of 4 mm was inserted into the outer package, and heat sealing conditions were 190 ° C., 1.0 MPa, and 3.
Seal as 0 sec. Specimen Example 1 was used. [Example 2] (pouch type) A chemical conversion treatment was applied only to the heat seal layer side of aluminum 20 μm, and a stretched polyester film (thickness 12 μm) was bonded to the non-chemical conversion side by a dry lamination method. A co-extruded film (80 μm) composed of a propylene / ethylene copolymer resin (20 μm) / adhesive polymethylbenthene layer (melting point: 200 ° C., 40 μm) / propylene / ethylene copolymer (20 μm) serving as a heat seal layer. A pouch was formed using a laminate obtained by lamination by a dry lamination method. Further, as the adhesive film, acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene, 40 μm)
m) was used. After temporarily attaching the adhesive film above and below a tab portion of a lithium ion battery body having an aluminum tab having a thickness of 100 μm and a width of 10 mm, the adhesive film was inserted into the exterior body, and heat sealing conditions were set at 190 ° C.
Sealed as 2.0 MPa, 3.0 sec. Specimen Example 2 was used. [Example 3] (Embossed type) A chemical conversion treatment was applied to both surfaces of aluminum 40 µm, and a stretched nylon film (thickness 25 µm) was formed on one surface of the chemical conversion treatment.
m) was laminated by dry lamination, and then an emulsion of acid-modified polyethylene was applied to the other surface of the chemical conversion-treated aluminum, dried and baked at a temperature of 190 ° C., and then heat-sealed to the baked surface. Low-density polyethylene resin (20 μm) / adhesive TPX (2
A laminate obtained by laminating a coextruded film (60 μm) having a structure of 0 μm) / linear low-density polyethylene (20 μm) by a heat laminating method was embossed, and a non-molded laminate was used as a cover material. In addition, an acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene, 30 μm) was used as the adhesive film. 200μ
A lithium ion battery main body having an aluminum tab having a thickness of 10 m and a width of 10 mm was inserted into the outer package, and heat sealing conditions were 190 ° C., 1.0 MPa, and 5.
Seal as 0 sec. Specimen Example 3 was used. [Example 4] (Embossed type) A chemical conversion treatment was applied to both surfaces of aluminum 40 µm, and a stretched nylon film (thickness 25 µm) was formed on one surface of the chemical conversion treatment.
m) by dry lamination, and then, on the other side of the chemically treated aluminum, acid-modified polypropylene as an adhesive resin (15 μm in thickness, unsaturated carboxylic acid-grafted polypropylene), and propylene and ethylene as heat seal layers. And butene copolymer resin (20μ
m) / adhesive TPX (20 μm) / coextruded film (60 μm) composed of propylene, ethylene and butene copolymer resin (20 μm) was sandwich-laminated to form a primary laminate. The primary laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polyethylene resin by hot air to form a secondary laminate, which was then embossed. In addition, an acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene, 60 μm) was used as the adhesive film. 100μ
A lithium ion battery body having an aluminum tab having a thickness of 6.0 m and a width of 6.0 mm was inserted into the outer package, and heat sealing conditions were 190 ° C., 2.0 MPa, and 1 MPa.
Seal as 0.0 sec. Specimen Example 4 was used. [Example 5] (Embossed type) A chemical conversion treatment was applied to both surfaces of aluminum 40 µm, and a stretched nylon film (thickness 25 µm) was formed on one surface of the chemical conversion treatment.
m) by a dry lamination method, and then, on the other surface of the chemically treated aluminum, as a heat seal layer, a medium density polyethylene (20 μm) / adhesive polymethylbenten layer (30 μm) / medium density polyethylene (2
0 μm) by a dry lamination method to obtain a laminated body and emboss molding. The secondary laminate that was not molded was used as a cover material to form an exterior body. A film (50 μm) made of a copolymer of ethylene and methacrylic acid (60 μm) was formed as an adhesive film. A lithium-ion battery main body having a thickness of 100 μm and a tab made of aluminum and having a width of 4 mm was inserted into the outer package, and sealed under heat sealing conditions of 190 ° C., 1.0 MPa, and 5.0 seconds.
Specimen Example 5 was used.

[Comparative Example 1] (Pouch type) A chemical conversion treatment was applied to both sides of 20 μm of aluminum, and a stretched polyester film (thickness: 12
μm) by dry lamination, and then
The other surface of the chemically treated aluminum is heated by a far-infrared ray and hot air to a temperature higher than the softening point of the acid-modified polyethylene resin as the adhesive resin, and the acid-sealed polyethylene resin (20 μm) is used as the adhesive resin to form a heat seal layer. A pillow-type pouch was formed using a laminate obtained by sandwich laminating a linear low-density polyethylene resin film (30 μm). Also, the adhesive film
An acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene) having a thickness of 50 μm was used. 100 μm thickness, 4
The adhesive film was temporarily attached to the upper and lower sides of the tab portion of the lithium ion battery body having an aluminum tab having a width of 1 mm, and inserted into the outer package.
Sealed at 90 ° C, 1.0 MPa, 2.5 sec. Sample Comparative Example 1 was used. [Comparative Example 2] (Pouch type) A chemical conversion treatment was applied to both surfaces of aluminum 20 μm, and a stretched polyester film (thickness 12
μm) by dry lamination, and then
The other surface of the chemically treated aluminum was heated by far infrared rays and hot air to a temperature higher than the softening point of the acid-modified polypropylene resin as the adhesive resin, and the acid-modified polypropylene resin (20 μm unsaturated carboxylic acid-grafted polypropylene) was bonded to the adhesive resin. As a heat seal layer of a copolymer film of propylene, ethylene and butene (100 μm).
A pillow-type pouch was formed using a laminate obtained by sandwich laminating m). Further, as an adhesive film, a polypropylene-based acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene) 20
0 μm was prepared. The adhesive film was temporarily attached to the upper and lower sides of the tab portion of the lithium ion battery main body having an aluminum tab having a thickness of 100 μm and a width of 4 mm, and inserted into the outer package.
Sealed as 2.0 MPa, 3 sec. Sample Comparative Example 2 was used. [Comparative Example 3] (Embossed type) A chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness: 25 μm) was applied to one surface of the chemical conversion treatment.
m) by a dry lamination method, and then a linear low-density polyethylene film (thickness: 30 μm) is sandwiched on the other surface of the chemically treated aluminum by using an acid-modified polyethylene as an adhesive resin (thickness: 20 μm). It was laminated to form a primary laminate. The primary laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polyethylene resin by hot air, and then embossed, and the unmolded primary laminate was used as a cover to form an outer package. Also, a high-density polyethylene resin (50 μm) was prepared as an adhesive film.
The surface of acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene) of the adhesive film was temporarily attached to the top and bottom of the tab portion of the lithium-ion battery body having an aluminum tab having a thickness of 200 μm and a width of 4 mm as the tab side. And inserted into the outer package, and set the heat sealing conditions to 19
Seal at 0 ° C., 1.0 MPa, 5 sec. Sample Comparative Example 3 was used. [Comparative Example 4] (Embossed type) A chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness: 25 μm) was formed on one surface of the chemical conversion treatment.
m) by dry lamination, and then, on the other surface of the chemically treated aluminum, a copolymer film of propylene and ethylene using an acid-modified polypropylene as an adhesive resin (unsaturated carboxylic acid-grafted polypropylene having a thickness of 20 μm). (Thickness: 30 μm) was sandwich-laminated to form a primary laminate. The primary laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polyethylene resin by hot air, and then embossed, and the unmolded primary laminate was used as a cover to form an outer package. In addition, as an adhesive film, 1
An acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene) having a thickness of 00 μm was prepared. 100 μm
The adhesive films were temporarily attached to the top and bottom of the tab portion of a lithium ion battery body having an aluminum tab having a thickness of 4 mm and a width of 4 mm, and inserted into the outer package. The sample was sealed at a pressure of 0.2 MPa and 10.0 seconds, to thereby obtain a sample comparative example 4.

<Evaluation method> (1) Presence or absence of short-circuit between the tab and the barrier layer of the exterior body A short-circuit state between the tab part and the exterior body was checked by cutting the heat-seal part of the tab part and confirming a photograph of a cross section. If there is a possibility of short-circuit between the tab and the barrier layer of the outer package, check the contact with a tester. Among them, the samples for which short-circuit was confirmed by the tester were defined as the number of short-circuits. 2) Confirmation of leakage The heat-sealed product was stored at 80 ° C. for 24 hours, and leakage of the content from the tab portion was confirmed. Contents: 3 g of a mixed solution of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (1: 1: 1) so that the electrolytic solution becomes 1M LiPF ₆ .

<Results> In all of Examples 1 to 5,
There were no shorts or leaks in the tabs.
In Comparative Example 1, 70 samples out of 500 samples were on the verge of short-circuiting, and 25 samples actually short-circuited. There were no leaks. In Comparative Example 2,
In 50 of the 500 samples, short samples were on the verge of shorting, and in fact, 20 samples actually short-circuited. There was no leakage. In Comparative Example 3, 30 samples out of 500 samples were short-circuited, but there was no leakage. In Comparative Example 4, 40 samples out of 500 samples were on the verge of short-circuiting, and 30 samples actually short-circuited. There were no leaks. With respect to the evaluation items other than the short, both the examples and the comparative examples were good.

[0047]

By providing at least the adhesive polymethylbenten layer on the heat seal layer of the lithium ion battery packaging material of the present invention, the lithium ion battery main body is housed in the pouch or embossed portion of the outer package and the periphery thereof is formed. At the time of heat-sealing, there is no possibility that the barrier layer of the package and the tab contact (short) including the adhesive film interposed between the tab of the lithium ion battery and the package. In addition, by the chemical conversion treatment applied to both surfaces of the aluminum of the exterior body, it is possible to prevent the occurrence of delamination between the base material layer and the aluminum at the time of embossing and at the time of heat sealing. Is formed by a sandwich lamination method or a co-extrusion laminating method, the aluminum is formed by hydrogen fluoride generated by the reaction between the electrolyte of the lithium ion battery and moisture by heating during the formation of the laminate or heating after the formation of the laminate. This is an exterior body that can prevent corrosion of the surface, thereby also preventing delamination with the content-side layer of aluminum.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a packaging material for a lithium ion battery of the present invention, in which (a) a cross-sectional view showing a layer configuration of the packaging material for a lithium ion battery, and (b) a lithium ion battery tab, an outer package, and an adhesive film. FIG. 4 is a cross-sectional view illustrating a state in which a tab, a heat-sealed tab, an adhesive film, and an exterior body are in contact with each other at a tab portion in a tab portion.

FIG. 2 is a schematic cross-sectional view of a tab portion after being heat-sealed with a packaging material for a lithium ion battery of the present invention and an adhesive film.

FIG. 3 is an explanatory view of a method of fixing an adhesive film in bonding a wrapping material for a lithium ion battery and a tab.

FIG. 4 is a perspective view illustrating a method of attaching an adhesive film in bonding a packaging material for a lithium ion battery and a tab.

FIG. 5 is a perspective view illustrating a pouch type exterior body of a lithium ion battery.

FIG. 6 is a perspective view illustrating an embossed type exterior body of the lithium ion battery.

FIG. 7 illustrates molding in an emboss type.
(A) a perspective view, (b) an embossed exterior body body,
(C) X ₂ -X ₂ parts cross-sectional view, an enlarged view (d) Y ₁ parts.

FIG. 8 is a cross-sectional view illustrating an example of a layer configuration of a laminate forming an exterior body of a lithium ion battery.

FIG. 9 is a cross-sectional view illustrating a layer configuration example of another laminated body forming an exterior body of a lithium ion battery.

FIG. 10 is a cross-sectional view showing a state in which a barrier layer and a tab are short-circuited using a conventional adhesive film.

[Explanation of symbols]

 S Short section between tab and barrier layer H Heat seal hot plate f Fold line wk Temporary adhesion mk Welding 1 Lithium ion battery 2 Lithium ion battery main body 3 Cell (power storage unit) 4 Tab (electrode) 5 Outer body 6 Adhesive film (Tab) 7) Concave portion 8 Side wall 9 Sealing portion 10 Laminate (packaging material for lithium ion battery) 11 Base layer 12 Aluminum (barrier layer) 13 Acid-modified polyolefin layer 13c Acid-modified polyolefin layer (coating) 13d Acid-modified polyolefin layer ( Extrusion) 14 Heat seal layer (polyolefin) 14a, 14c Polyolefin 14b Adhesive polymethylbenten layer 15 Chemical conversion layer 16 Adhesive layer 17 Slip agent layer 19 Liquid paraffin layer 20 Press molded part 21 Male type 22 Female type 23 Cavity

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Yamada 1-1-1 Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo F-term in Dai Nippon Printing Co., Ltd. 5H011 AA02 AA03 AA10 CC02 CC06 CC10 DD03 DD09 DD13 DD14 FF02 FF04 GG08 GG09 HH02 HH13 JJ02

Claims (9)

[Claims] 1. A lithium-ion battery main body is inserted into a lithium-ion battery exterior body comprising at least a base material layer, an adhesive layer 1, a chemical conversion layer 1, aluminum, a chemical conversion layer 2, an adhesive layer 2, and a heat seal layer. A lithium ion battery packaging material having a heat-sealed peripheral edge, wherein the heat seal layer includes an adhesive polymethylpentene layer. 2. The packaging material for a lithium ion battery according to claim 1, wherein the heat seal layer is a co-extruded film comprising a polyolefin layer, an adhesive polymethylpentene layer, and a polyolefin layer. 3. A lithium-ion battery body is inserted into an exterior body of a lithium-ion battery comprising at least a base material layer, an adhesive layer 1, aluminum, a chemical conversion layer, an adhesive layer 2, and a heat seal layer, and the periphery is heat-sealed. A packaging material for a lithium ion battery, comprising: an adhesive polymethylpentene layer in the heat sealing layer. 4. The packaging material for a lithium ion battery according to claim 3, wherein the heat seal layer is a co-extruded film comprising a polyolefin layer, an adhesive polymethylpentene layer, and a polyolefin layer. 5. The packaging material for a lithium ion battery according to claim 1, wherein said adhesive layer 2 is formed by a dry lamination method. 6. The packaging material for a lithium ion battery according to claim 1, wherein at least said adhesive layer 2 is a coating and baking layer of an acid-modified polyolefin. 7. The packaging material for a lithium ion battery according to claim 1, wherein at least the adhesive layer 2 is an extruded layer of an acid-modified polyolefin. 8. The lithium ion battery according to claim 1, wherein an adhesive film is interposed between the exterior body of the lithium ion battery and the tab portion of the lithium ion battery body. For packaging material. 9. The polyolefin layer of the heat seal layer is made of polypropylene, polyethylene, a copolymer of ethylene and butene, a copolymer of propylene and butene, a copolymer of propylene, ethylene and butene, and a simple substance or at least one of ionomers. The packaging material for a lithium ion battery according to any one of claims 1 to 8, wherein the packaging material comprises a mixture containing the same.