JP2002289157A - Adhesive film for tab of lithium cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material constitution which ensures stable hermetic sealing without electrical shorts between a barrier layer of a facing package and an electrode tab by the heat and pressure of heat-sealing, when, in lithium cell packaging, a lithium cell body is encased in the package having a heat- sealing layer of polyethylene, and the rim of the package is hermetically heat- sealed. SOLUTION: The facing package material of the lithium cell body comprises a base layer, an adhesive layer, an aluminum layer, a conversion-coated layers, and the heat-sealing layer of polyolefin resin. On the electrode tab of the lithium cell, and between the tab and the package, intervenes an adhesive film which comprises an extrusion laminated film composed of an electron beam crosslinked polyolefin film and an acid-modified polyolefin film adhering to the tab, further wherein the electron beam crosslinked polyolefin film is of polyethylene or polypropylene.

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 battery having a liquid or solid organic electrolyte (polymer polymer electrolyte) having moisture resistance and content resistance, and an exterior body for packaging a lithium battery body. The present invention relates to an adhesive film interposed between a tab portion of the battery and an outer package.

[0002]

2. Description of the Related Art A lithium battery is also referred to as a lithium secondary battery. As an electrolyte, a solid polymer, a gel polymer,
A battery that is made of a liquid or the like and generates an electric current by the movement of lithium ions, and includes a battery in which the positive and negative electrode active materials are made of a polymer. The structure of the lithium secondary battery is as follows: a positive electrode current collector (aluminum, nickel) / a positive electrode active material layer (a metal positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte solution, polyacrylonitrile) / an electrolyte layer (propylene) Carbonate-based electrolytes such as carbonate, ethylene carbonate, dimethyl carbonate, and ethylene methyl carbonate; inorganic solid electrolytes composed of lithium salts; gel electrolytes) / Negative electrode active materials (lithium metals, alloys, carbon, electrolytes, and polymers such as polyacrylonitrile) A negative electrode material) / a negative electrode current collector (copper, nickel, stainless steel) and an outer package that packages them. Applications of lithium batteries include personal computers, portable terminal devices (mobile phones, PDAs, etc.), video cameras, electric vehicles,
Used for energy storage batteries, robots, satellites, etc. As the exterior body of the lithium battery, a metal can formed by pressing a metal into a cylindrical or rectangular parallelepiped container,
Alternatively, a laminate (hereinafter referred to as an exterior) formed of a laminate formed of a composite film obtained by laminating a plastic film, a metal foil, or the like has been used. There are the following problems as an exterior body of a lithium 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 at least a base material layer from the necessary physical properties as a lithium battery, workability, economy, and the like.
It is composed of a barrier layer, a heat seal layer and an adhesive layer for adhering each of the above layers, and an intermediate layer may be provided as necessary. A pouch is formed from the laminated body having the above-described configuration of the lithium battery, or at least one side is press-molded to form a storage section for the lithium battery to store the lithium battery body, and a pouch type or an embossed type (covering the lid body) is formed. In (1), a necessary portion of each peripheral edge is sealed by heat sealing to obtain a lithium 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. 9A, between the tab 4 and the heat seal layer 14 'of the laminate 10', an adhesive film having a heat seal property with respect 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 battery (hereinafter referred to as the exterior body) is made of a polyethylene resin, the lithium battery body is housed in the exterior body, and The periphery is sealed by sealing, but when the adhesive film 6 ′ made of an acid-modified polyethylene single layer is used in the portion where the tab is present as shown in FIG. 9B, heat and pressure for heat sealing are used. As a result, the heat seal layer 14 'and the adhesive film layer 6' of the outer package may be melted together, and may be extruded out of the region of the pressurized portion by pressurization. As a result, the aluminum foil 12 ′ that is the barrier layer 12 ′ of the exterior body 10 ′
And the tab 4 ′ made of metal may contact (S) and cause a short circuit. Similarly, when the heat seal layer of the laminate is made of a polypropylene resin, even if the adhesive film 6 ′ made of an acid-modified polypropylene single layer is used,
In some cases, the aluminum foil as the barrier layer 12 ′ of 0 ′ and the tab 4 made of metal contact (S) and short-circuit. An object of the present invention is to provide a lithium battery package, in which a lithium battery main body is inserted into an exterior body having a polyolefin-based resin as a heat seal layer, and the periphery thereof is heat-sealed and sealed. 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.

[0005]

The above objects can be attained by the present invention described below. That is, claim 1
The invention described in the above, the lithium battery body is inserted at least into the base body layer, the adhesive layer, the chemical conversion treatment layer 1, the aluminum, the chemical conversion treatment layer 2, and the lithium battery exterior body composed of the heat seal layer of the polyolefin resin, When heat-sealing the periphery, the adhesive film interposed between the outer package and the tab portion is a multilayer film obtained by extrusion-laminating an acid-modified polyolefin on at least a polyolefin film cross-linked with an electron beam. Of an adhesive film used for a tab portion of a lithium battery. Claim 2
The invention described in (1) is characterized in that the polyolefin film according to claim 1 is a polyethylene film. The invention according to claim 3 is characterized in that the polyolefin film according to claim 1 is a polypropylene film. According to a fourth aspect of the present invention, a lithium battery main body is provided on a lithium battery exterior body including at least a base material layer, an adhesive layer, a chemical conversion treatment layer 1, aluminum, a chemical conversion treatment layer 2, and a polyethylene resin heat seal layer. When inserted, when heat sealing the periphery, the adhesive film to be interposed between the exterior body and the tab portion,
It is a multilayer film in which polyethylene and acid-modified polyethylene are co-extruded to form a film, and then crosslinked to a gel fraction of 5 to 80%. According to a fifth aspect of the present invention, a lithium battery main body is inserted into an exterior body of a lithium battery including at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, and a heat seal layer of a polyolefin resin, and the periphery is heated. At the time of sealing, the adhesive film interposed between the outer package and the tab portion is a multilayer film obtained by extrusion laminating an acid-modified polyolefin on at least a polyolefin film cross-linked with an electron beam. The invention according to claim 6 is characterized in that the polyolefin film according to claim 5 is a polyethylene film. The polyolefin film according to claim 7 is a polypropylene film. The invention according to claim 8 is that the lithium battery main body is inserted into a lithium battery exterior body composed of at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, and a heat seal layer of a polyolefin resin, and the periphery is heated. When sealing, the adhesive film to be interposed between the outer package and the tab portion is a multilayer film obtained by co-extruding polyethylene and acid-modified polyethylene and then crosslinking the gel fraction to 5 to 80%. And an adhesive film used for a lithium battery tab.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a moisture-proof property,
And, the productivity is good, the exterior body is formed using a lithium battery packaging material comprising a heat sealing layer of a polyolefin resin, and when the lithium battery body is packaged, the sealing property at the tab portion is ensured. Regarding an adhesive film that does not cause a short circuit with the barrier layer of the exterior body in the tab portion,
The adhesive film is a multilayer film obtained by extrusion-laminating an acid-modified polyolefin as a layer to be adhered to a tab on at least a polyolefin film crosslinked with an electron beam. Hereinafter, the present invention will be described in more detail with reference to the drawings and the like. Alternatively, it is a multilayer film obtained by co-extruding a polyolefin and an acid-modified polyolefin as a layer to be bonded to a tab, and then performing a crosslinking treatment.

FIG. 1 is a view for explaining the adhesive film of the present invention. FIG. 1A is a cross-sectional view showing a layer structure of the adhesive film.
(B) A diagram illustrating the material and positional relationship (one side) of the lithium battery tab, the outer package, and the adhesive film, and (c) the tab, the heat-sealed tab, the adhesive film, and the outer package in the tab section were in contact with each other. It is sectional drawing explaining a state, (d) It is typical sectional drawing of the tab part after heat sealing. FIG. 2 is a perspective view illustrating a method for mounting an adhesive film in bonding a packaging material for a lithium battery and a tab. FIG. 3 is a diagram illustrating a method of interposing the adhesive film between the tab and the outer package according to the present invention. FIG. 4 is a perspective view illustrating a pouch type exterior body of a lithium battery. FIG. 5 is a perspective view illustrating an embossed type exterior body of a lithium battery. FIG. 6 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. 7 is a cross-sectional view illustrating an example of a layer configuration of a laminate forming an exterior body of a lithium battery. FIG. 8 is a cross-sectional view illustrating an example of a layer configuration of another laminated body forming the exterior body of the lithium battery.

[0008] A tab of a lithium battery has a thickness of 50
２０００2000 μm, width is about 2.5-20 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 battery is formed of a resin capable of heat sealing the heat seal layers. It is desirable to use a resin that can be directly heat-sealed to the tab as the heat-sealing layer, but as described above, a general polyolefin, for example, a single-layer or multi-layer resin material of a blend of a single substance or a blend of polyethylene or polypropylene. A method is adopted in which a heat seal layer is formed, and the tab and the heat seal layer are mutually heat-sealed with an adhesive film so as to be sealed.

[0009] The exterior body of the lithium battery is required to have the performance of maintaining the performance of the lithium battery main body for a long period of time, and a base layer, a barrier layer, a heat seal layer, and the like are laminated by various lamination methods. In particular, the heat seal layer of the laminated body constituting the exterior body of the lithium battery (hereinafter referred to as the exterior body) is made of, for example, a low-density polyethylene resin, and the lithium battery body is housed in the exterior body, and the periphery thereof is sealed. When sealing, in the part where the tab exists,
When acid-modified polyethylene is used as the adhesive film, as shown in FIG. 9B, heat and pressure for heat sealing cause the heat seal layer 14 'and the adhesive film layer 6' of the outer package to melt together. In addition, both the layer inside the barrier layer 12 ′ of the outer package and the adhesive film layer 6 ′ that have been the insulating layer are extruded out of the region of the pressurized portion by the pressurization. is there. As a result, the aluminum foil as the barrier layer 12 'of the outer package may come into contact with the metal tab 4' (S) to cause a short circuit.

The present inventors have conducted intensive studies on the prevention of the short circuit, and as a result, have found that the problem can be solved by changing the material and configuration of the adhesive film, thereby completing the present invention. Reached. That is, as the adhesive film of the present invention, FIG.
As shown in (b), between the metal tab 4 and the innermost layer 14 of the outer package, at least an electron beam cross-linked polyolefin 22 and an acid-modified polyolefin 21 as a layer to be bonded to the tab are extrusion-laminated in a multilayer. By using a film, the short circuit due to heat sealing can be avoided. That is, while having a heat-sealing property with respect to the heat seal layer 14 and the tab 4 of the outer package 10, even when subjected to heat and pressure when the lithium ion battery body is inserted into the outer package and hermetically sealed. In order to enable the maintenance of the film-like insulating layer, the adhesive film has a two-layer structure, the tab 4 (metal side) is an acid-modified polyolefin layer 21, and the side of the exterior body that is bonded to the heat seal layer is an electronic part. It is a polyolefin 22 which is linearly crosslinked. In the present invention, the electron beam cross-linked polyolefin functions as an insulating layer at the time of the hermetic sealing. That is, after the heat sealing under the heat sealing conditions of the hermetic seal, the temperature of 180 to 220 ° C., the pressure of 0.5 to 5.0 MPa, and the time of 1.0 to 10 sec, as shown in FIG. The electron beam crosslinked polyolefin layer 22 remains between the part 4 and the barrier layer 12 of the exterior body in the form of a film to maintain insulation. Or, as the adhesive film of the present invention,
As shown in FIGS. 1 (a) and 1 (b), between the metal tab 4 and the innermost layer 14 of the outer package, at least the electron-beam-crosslinked polyolefin 22 has an electron as a layer that adheres to the tab. By using a multilayer film of the acid-modified polyolefin 21 which is linearly crosslinked, the short circuit due to heat sealing can be avoided. That is, the exterior body 1
In addition to having heat-sealing properties with respect to the heat-sealing layer 14 and the tub 4, the film-like insulating layer can be subjected to heat and pressure when the lithium-ion battery body is inserted into the outer package and hermetically sealed. In order to enable maintenance, the adhesive film has a two-layer structure, the tab 4 (metal side) is an acid-modified polyolefin layer 21 cross-linked with an electron beam, and the bonding side of the exterior body to the heat seal layer is cross-linked with an electron beam. The resulting polyolefin 22 is obtained. In the present invention, the electron beam cross-linked polyolefin and the electron beam cross-linked acid-modified polyolefin layer function as an insulating layer at the time of the hermetic sealing. That is, the heat sealing conditions of the hermetic seal,
After heat sealing at a temperature of 180 to 220 ° C., a pressure of 0.5 to 5.0 MPa, and a time of 1.0 to 10 sec, as shown in FIG.
2, the electron beam crosslinked polyolefin layer 22
And the acid-modified polyolefin layer remains in the form of a film to maintain the insulating property.

Polyethylene crosslinks in the molecule by electron beam cross-linking, and at room temperature, as well as at high temperatures above the melting point, such as tensile strength, piercing strength, and compressive strength are improved. The level of crosslinking of the film is indicated as gel fraction. The gel fraction indicates the proportion of a gel (insoluble polymer chain) in a crosslinked polyethylene resin that has become insoluble in a solvent such as xylene. When the gel fraction is less than 5%, the degree of crosslinking is insufficient. When the lithium ion battery body is inserted into the outer package and sealed, there is a risk of short-circuiting. When the gel fraction exceeds 80%, the degree of cross-linking is too large, the heat sealing property is reduced, and the sealing property is reduced. May not be obtained.

The gel fraction referred to in the present invention is an index indicating the degree of cross-linking of a cross-linked polyolefin by electron beam, ultraviolet ray, gamma ray, thermal cross-linking and the like. The gel fraction in a cross-linked polyolefin resin insoluble in a solvent such as xylene is used. It represents the ratio of insoluble polymer chains).

For example, a resin material obtained by subjecting polyethylene having a melting point of 105 ° C. to electron beam crosslinking so that the gel fraction becomes 20% and 50% is 190 times smaller than a resin material having no electron beam crosslinking.
℃, surface pressure 1.0MPa, high temperature at 3 seconds, small amount of compressive strain, 80% non-electronic crosslinked product, 40% 20% gel fraction resin, 40% 50% gel fraction Become. However, ordinary polypropylene is decomposed by electron beam irradiation. However, polypropylene has a polyethylene component, a butene component, a terpolymer component composed of a ternary copolymer of ethylene, butene and propylene, and a low crystal density of 900 kg / m ³ . 5% or more of a copolymer of ethylene and butene, a copolymer of amorphous ethylene and propylene, a propylene α-olefin copolymer component and the like are crosslinked by electron beam to form a crosslink in the molecule, and the room temperature The mechanical strength under high temperature above the melting point, of course, such as tensile strength, piercing strength,
Compressive strength is improved. For example, a terpolymer component consisting of a ternary copolymer of ethylene, butene and propylene is
A resin material obtained by subjecting polypropylene having a melting point of 145 ° C. to which 0% was added to electron beam crosslinking so that the gel fraction becomes 20% and 50% is 190 ° C. and a surface pressure of 1.10 ° A high temperature at 0 MPa for 3 seconds, the amount of compressive strain is small, and the non-electronically crosslinked product is 70%, while the 20% gel fraction resin material is 50%, and the 50% gel fraction product is 35%. In addition, even when compared at the same thickness, polyethylene and polypropylene cross-linked in this way are generated at a small edge (so-called burr) on the tab 4 during heat sealing as compared with non-electron beam cross-linked polyethylene and polypropylene. This also has the effect of preventing short circuit due to pinholes. The tab portion needs to be bonded to metal as described above. In this case, the acid-modified polyolefin resin which is welded to the metal by heat sealing includes unsaturated carboxy-grafted polyolefin (polyethylene type, polypropylene type), metal cross-linked polyethylene, a copolymer of ethylene and an acrylic acid or methacrylic acid derivative, ethylene And a copolymer of acetic acid and vinyl acetate, or a blend thereof. Further, these effects due to cross-linking are similarly exhibited in an acid-modified polyolefin.

The adhesive film for a tab of the present invention includes:
It may be a multilayer film in which a film obtained by co-extrusion of a polyethylene resin and an acid-modified polyethylene resin to form a film is crosslinked to a gel fraction of 5 to 80%.

The adhesive film of the present invention is a two-layer film, and the layer ratio, that is, the thickness ratio of the electron-crosslinked polyolefin layer to the acid-modified polyolefin layer can be appropriately determined. Further, the thickness of the electron-crosslinked polyolefin layer must be at least 10 μm or more. If the thickness of the electron beam crosslinked polyolefin layer is less than 10 μm, short-circuit occurs when heat sealing. Also, when co-extruding a polyethylene resin and an acid-modified polyethylene resin to form a film,
Although the layer ratio can be appropriately selected, the thickness of the electron-crosslinked polyolefin layer and the acid-modified polyethylene resin must be at least 5 μm or more, and the total of the two layers must be 10 μm or more. If the thickness of the electron beam crosslinked polyolefin layer is less than 10 μm, a short circuit occurs when heat sealing. The layer thickness of the two-layer film is desirably at least one sixth of the thickness of the tab used.

The packaging material for the lithium battery forms an outer package for packaging the lithium battery body. Depending on the type of the outer package, a pouch type as shown in FIG.
There is an embossed type as shown in FIG. 5 (a), FIG. 5 (b) or FIG. 5 (c). The pouch type includes a bag type such as a three-sided seal, a four-sided seal, and a pillow type. FIG. 4 illustrates the pouch type as a pillow type. In the emboss type, a concave portion may be formed on one surface as shown in FIG. 5A, or a concave portion may be formed on both surfaces as shown in FIG. May be sealed by heat sealing. FIG. 5 (c)
There is also a type in which a concave portion is formed on both sides with a folded portion as shown in FIG.

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. 2B, the adhesive films 6 are placed above and below the tab sealing seal portion of the lithium battery main body 2 (actually, they are fixed with a temporary attachment seal) and inserted into the exterior body 5 to form a tab. Heat sealing is performed with the part sandwiched to seal. At this time, the adhesive film 6 is used in a film-like or rigid state. As a method for interposing the adhesive film 6 on the tab 4, as shown in FIG. 2D or 2E, a film of the adhesive film 6 may be wound around a predetermined position of the tab 4. As shown in FIG. 3A, the tab 4 and the adhesive film 6 may be used by previously welding mk the acid-modified polyolefin 21 of the adhesive film 6 to the tab 4. Alternatively, as shown in FIG. 3B, the tab 4 and the adhesive film 6 may be used while being temporarily attached wk. Further, as shown in FIG. 3 (c) or FIG. 3 (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, 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 specifically forms 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 three components, a compound and phosphoric acid, is preferred. Or
A treatment with a chemical conversion treating agent containing at least a resin such as molybdenum, titanium, zircon, or a metal salt to a resin component containing at least a phenol resin was effective.

When the adhesive film 6 formed by the above-described method is heat-sealed between the outer package 5 of the lithium battery 1 and the tab 4, as shown in FIG. Although the short circuit can be avoided because the polyolefin layer 22 remains as an insulating layer, the heat resistance of the polyolefin forming the polyolefin layer is improved by electron beam crosslinking, and the polyolefin becomes harder.
This is considered to be due to less crushing due to heat and pressure during heat sealing as compared with other adjacent resin layers.

Next, the material of the exterior body to which the adhesive film for a lithium battery tab of the present invention is applied will be described. As shown in FIG. 7A and FIG. 7B, the exterior body includes at least a base material layer 11, an adhesive layer 16, and a chemical conversion treatment layer 1.
5 (1), a barrier layer 12, a chemical conversion treatment layer 15 (2), an adhesive resin layer 13, and a heat seal layer 14. Alternatively, as shown in FIGS. 7C and 7D, at least the base material layer 11, the adhesive layer 16, the barrier layer 12, the chemical conversion layer 15 (2), the adhesive resin layer 13, and the heat seal layer 1
4.

The specific layer structure of the packaging material for a lithium battery of the present invention is shown in FIGS. 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 pre-heated or post-heated to improve the adhesive strength.
In addition, by providing the liquid paraffin layer 15, the moldability is improved, and the crack resistance of the heat seal layer is improved.

When the packaging material for a lithium battery is an embossed type, the laminated packaging material 10 is press-formed to form the recess 7 as shown in FIGS. 6 (a) to 6 (d). In this case, if the slip between the press-molded male mold 31 and the heat seal layer 14 of the laminate 10 is poor, a stable molded product may not be obtained.

The present inventors have proposed a heat seal layer 1 for an exterior body.
It has been confirmed that by coating liquid paraffin on the innermost surface of No. 4, the embossability is improved, and a packaging material that is less likely to crack in the heat seal layer is obtained.

The liquid paraffin is a chain hydrocarbon-based oil having physical properties of a specific gravity of 0.83 to 0.87, a viscosity of 7.6 to 80 mm ^{2 /} S (37.5 ° C.), and a molecular weight of 3
It is about 00 to 500, and the distillation temperature under the condition of 10 mmHg is 140 to 245 ° C. The liquid paraffin in the lithium battery packaging material and the method for producing the same according to the present invention has a specific gravity of 0.83 and a viscosity of 7.
7 mm ^{2 /} S (37.5 ° C.), molecular weight 300, 1
A distillation temperature of about 141 ° C. under the condition of 0 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 liquid paraffin on the heat seal layer, stress generated during embossing is dispersed, and cracks in the heat seal layer made of polyolefin resin (heat seal layer of lithium battery packaging material) generated during molding are reduced or eliminated. In addition, the coated liquid paraffin has improved surface lubricity due to its effect as a lubricant.

In addition, at least to the base material layer, generally internally added to a polyolefin-based resin typified by erucic acid amidite, oleic acid amidite, stearic acid amidite, biserucic acid amidite, bisoleic acid amidite, bisstearic acid amidite. It has also been found that at least one of the lubricants is made into a solution with a solvent such as isopropyl alcohol, ethyl acetate, toluene, methyl-ethyl-ketone, etc., and then coated and applied to improve the surface slipperiness and the moldability.

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 battery, it is a portion that is in direct contact with hardware.
Basically, a resin layer having an insulating property is 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 the pinhole resistance and the 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 30 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, the mechanical suitability of packaging materials (stability of transportation in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance) ) When the embossing type is used for the exterior body for lithium batteries as a secondary process, the purpose is to reduce the frictional resistance between the mold and the substrate layer during embossing, or to protect the substrate layer when an electrolytic solution is attached. In order to do so, the base material layer is multi-layered, and a fluorine-based resin layer, an acrylic-based resin layer, a silicone-based resin layer, a polyester-based resin layer, or a resin layer made of a blend thereof is provided on the surface of the base material layer. preferable. 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 battery from the outside, and stabilizes the pinhole of the barrier layer alone and the workability (pouching, embossability). Aluminum having a thickness of 15 μm or more in order to
A metal such as nickel, or an inorganic compound, for example, a film on which silicon oxide, alumina, or the like is vapor-deposited may be mentioned, but the barrier layer preferably has a thickness of 20 to 80 μm.
Aluminum. In order to further improve the occurrence of pinholes and to make the type of the exterior body of the lithium battery an embossed type, in order to eliminate the occurrence of cracks and the like in embossing, the present inventors have made the use of aluminum used as a barrier layer. The material has an iron content of 0.3-9.
By setting the content to 0% by weight, preferably 0.7 to 2.0% by weight, the aluminum has good ductility and less occurrence of pinholes due to bending as a laminate, compared to aluminum containing no iron. It has been found that the side wall can be easily formed when the embossed type exterior body is molded. The iron content is 0.3% by weight
If less than the above, no effects such as prevention of pinholes and improvement in embossability are observed, and if the iron content of the aluminum exceeds 9.0% by weight, flexibility as aluminum is impaired. As a result, the bag-making properties of the laminate deteriorate.

Further, the aluminum produced by cold rolling has its flexibility and 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 performed a chemical conversion treatment on the front and back surfaces of aluminum, which is the barrier layer 12 of the lithium battery packaging material, to obtain a laminate that is satisfactory as the packaging material. 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 the hydrogen fluoride generated by the reaction between the electrolyte of the lithium battery and moisture prevents the dissolution and corrosion of the aluminum surface, especially the dissolution and corrosion of the aluminum oxide present on the aluminum surface, and Improves adhesiveness (wetting) and improves embossing
The effect of preventing delamination between the base material layer 11 and the aluminum 12 during heat sealing and the effect of preventing delamination on the inner surface of the aluminum by hydrogen fluoride generated by the reaction between the electrolyte and moisture were obtained.

As a result of conducting a chemical conversion treatment on the aluminum surface using various substances and studying its effect, among the above-mentioned acid-resistant film-forming substances, three components of phenol resin, chromium fluoride (3) compound and phosphoric acid were used. Phosphoric acid chromate treatment using those composed of 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 more preferable.

When the exterior body of the lithium battery is an embossed type, delamination between aluminum and the substrate layer during embossing can be prevented by forming a chemical conversion treatment on both surfaces of aluminum.

The inventors of the present invention have conducted intensive studies on a laminating method exhibiting a stable adhesive strength. As a result, the base layer 11 and one side of the barrier layer 12 chemically converted on both sides are dry-laminated, and the other On the surface, acid-modified polyolefin 1
Extrude 3 and heat-seal layer (polyethylene film,
Or, when sandwich laminating the polypropylene film) 14, the acid-modified polyethylene resin 13 and the heat sealing layer (polyethylene resin or polypropylene resin) 14 are co-extruded to form a laminate, and the laminate is formed by the acid-modified polyolefin resin. By heating to a condition at or above the softening point, a laminate having a predetermined adhesive strength could be obtained.

As another method, in the above-mentioned sandwich lamination or co-extrusion lamination, the aluminum 12 is heated to such a condition that the surface temperature on 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, it is also possible to laminate the extruded polyethylene molten resin film while performing ozone treatment on the aluminum-side lamination surface. .

Specific examples of the heating method include a hot roll contact method, a hot air method, and near or far infrared rays. In the present invention, any heating method may be used. Can be heated above its softening point.

Each of the above-mentioned layers in the laminate forming the exterior body of the lithium ion battery is appropriately improved and stabilized in film forming properties, lamination processing, and suitability for secondary processing of final products (pouching, embossing). For the purpose, a surface activation treatment such as a corona treatment, a blast treatment, an oxidation treatment, and an ozone treatment may be performed.

When the adhesive film 6 of the present invention is applied, the heat seal layer 14 of the outer package is made of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, homopolypropylene, ethylene-propylene copolymer,
A single layer or a multilayer using a simple substance or a blend resin of a copolymer of ethylene, propylene and butene is used. A butene component is contained in the heat seal layer 14 and the adhesive resin layer.
Terpolymer component consisting of ternary copolymer of ethylene, butene and propylene, low-density copolymer of ethylene and butene having a density of 900 kg / m3, amorphous ethylene-propylene copolymer, propylene-α-olefin Copolymer components can also be added.

As a laminating method for forming a laminate of a packaging material for a lithium battery to which the adhesive film 6 of the present invention is applied, a dry laminating method, a sandwich laminating method, a co-extrusion laminating method, a heat laminating method, or the like can be used. it can.

[0040]

EXAMPLES The adhesive film for a lithium battery tab of the present invention will be described more specifically with reference to 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 chromium applied is 1 mg / m ²
(Dry weight). In the following examples and comparative examples, the pouch type exterior body has a width of 30 mm,
The length is 50 mm (both inner dimensions), and in the case of an embossed type exterior body, each is a single-sided embossed type, and the shape of the concave portion (cavity) of the mold is 30 mm × 5.
Press molding was performed at 0 mm and depth of 3.5 mm, and the moldability was evaluated. [Example 1] (Pouch type) A chemical conversion treatment was performed on both sides of 20 μm aluminum, and a stretched polyester film (thickness: 12 μm) was adhered to one surface of the chemical conversion treatment by a dry lamination method. The other surface 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 an adhesive resin, and the acid-denatured polyethylene resin (20 μm) is used as an adhesive resin to form a linear low-density heat-sealing layer. A pillow-type pouch was formed using a laminate obtained by sandwich-laminating a polyethylene resin film (30 μm). In addition, as an adhesive film, a gel fraction (A) of 5%
(B) 30% (C) An acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene, 30 μm) as a layer to be bonded to a tab is applied to a linear low-density polyethylene film (20 μm) cross-linked by an electron beam under the conditions of 60%. It was a multilayer film extruded and laminated. 100 μm thickness, 4 mm
Temporarily attach the surface of the acid-modified polyethylene layer of the adhesive film on the upper and lower sides of the tab portion of the lithium battery main body having a tab made of aluminum having a width of aluminum as the tab side, insert it into the outer package, and heat seal conditions. 190 ° C, 1.0MP
a, sealed as 3.0 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 formed on the non-chemical conversion side.
m) is bonded by dry lamination, and then the other surface of the chemically treated aluminum is heated to a temperature higher than the softening point of the acid-modified polypropylene resin as an adhesive resin by far-infrared rays and hot air. A pillow-type pouch was formed using a laminate obtained by sandwich-laminating a polypropylene film (100 μm) serving as a heat seal layer using the resin (20 μm) as an adhesive resin. Further, as an adhesive film, 20% of a copolymer resin of ethylene and butene cross-linked by an electron beam under the conditions of a gel fraction (A) of 10% (B) 30% (C) 60%
Was laminated by extrusion lamination with a polypropylene (20 μm) film containing the above as an acid-modified polypropylene (unsaturated carboxylic acid grafted polypropylene, 30 μm) as a layer to be bonded to the tab. 100 μm thickness, 1
The surface of the acid-modified polypropylene layer of the adhesive film was temporarily attached to the top and bottom of the tab portion of the lithium battery body having an aluminum tab having a width of 0 mm as the tab side, and inserted into the exterior body, and heat sealing conditions were applied. 210 ° C., 2.
Sealed as 0 MPa, 3.0 sec. Specimen Example 2 was used. [Example 3] (Pouch type) A chemical conversion treatment was applied to both surfaces of 20 μm of aluminum, and a stretched polyester film (thickness: 12 μm) was bonded to one surface of the chemical conversion treatment by a dry lamination method. Is heated to a temperature equal to or higher than the softening point of the acid-modified polyethylene resin as an adhesive resin with far infrared rays and hot air, and the acid-modified polyethylene resin (20 μm) is used as the adhesive resin to form a linear low-density polyethylene serving as a heat seal layer. A pillow type pouch was formed using a laminate obtained by sandwich lamination of a resin film (30 μm). As an adhesive film, a linear low-density polyethylene resin (20 μm) and an acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene, 30 μm) resin are coextruded to form a coextruded film, and the gel fraction is obtained by electron beam crosslinking. (A) 5% (B) 45% (C) 65% film was used. The surface of the acid-modified polyethylene layer of the adhesive film is temporarily attached to the top and bottom of the tab portion of the lithium 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. Then, heat sealing was performed at 190 ° C., 1.0 MPa, and 3.0 seconds, and sealing was performed. Specimen Example 3 was used. Example 4 (Emboss Type) Aluminum 40 μm
Chemical conversion treatment on both sides of the film, a stretched nylon film (thickness 25 μm) is bonded to one surface of the chemical conversion treatment by dry lamination, and then acid-modified polyethylene is bonded to the other surface of the chemical conversion treatment aluminum. As a resin (thickness: 20 μm), a linear low-density polyethylene film (density: 0.921, 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 secondary laminate was used as a cover to form an outer package. Also, as an adhesive film,
Gel-fraction (A) 10% (B) 30% (C) A linear low-density polyethylene film (50 μm) crosslinked with an electron beam under the conditions of 60% is coated with an acid-modified polyethylene (unsaturated) Carboxylic acid-grafted polyethylene, 2
0 μm) was formed into a multilayer film by extrusion lamination. 2
The surface of the acid-modified polyolefin layer of the adhesive film was previously welded to the tab above and below the tab portion of the lithium battery main body having an aluminum tab having a thickness of 00 μm and a width of 10 mm with the tab side, And sealed at 180 ° C., 1.0 MPa, 1 sec. Specimen Example 4 was used. [Example 5] (embossed type) Aluminum 40 µm
Chemical conversion treatment on both sides of the substrate, a stretched nylon film (thickness: 25 μm) is laminated to one surface of the chemical conversion treatment by dry lamination, and then acid-modified polypropylene is bonded to the other surface of the chemical conversion treatment aluminum by an adhesive resin. (Thickness 1
5 μm) and a propylene film (density 0.92
1, 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 to form a secondary laminate, which was then embossed. Further, as an adhesive film, 15% of a three-component copolymer resin of ethylene, butene and propylene cross-linked by electron beam under the conditions of gel fraction (A) 10% (B) 30% (C) 60% was blended. An acid-modified polypropylene (unsaturated carboxylic acid grafted polypropylene, 50 μm) as a layer to be adhered to the tab was extrusion-laminated on polypropylene (50 μm) to form a multilayer film. The surface of the acid-modified polypropylene layer of the adhesive film was previously welded to the tab above and below the tab portion of the lithium battery main body having an aluminum tab having a thickness of 500 μm and a width of 10.0 mm with the tab side. Inserted into the body, heat sealing conditions: 220 ° C, 0.1MP
a, Sealed for 4 sec. Specimen Example 5 was used. [Example 6] (embossed type) aluminum 40 µm
Chemical conversion treatment is applied to both surfaces, and a stretched nylon film (thickness: 25 μm) is bonded to one surface of the chemical conversion treatment by dry lamination, and then a linear low-density polyethylene film is attached to the other surface of the chemical conversion treatment aluminum. (Density: 0.921, thickness: 30 μm) were laminated by dry lamination to form an embossed laminate. The secondary laminate that was not molded was used as a cover material to form an exterior body. Further, as an adhesive film, a gel fraction (A) 5% (B) 30% (C) 60%
An acid-modified polyethylene (copolymer of ethylene and acrylic resin derivative, 30 μm) as a layer to be bonded to the tab was extrusion-laminated on a medium density polyethylene film (20 μm) cross-linked with an electron beam under the conditions described above. 100 μm thick, 4 mm wide, above and below the tab portion of the lithium battery body having an aluminum tab having a width of 4 mm,
The adhesive film was welded with the surface of the acid-modified polyethylene facing the tab side, inserted into the exterior body, and sealed under heat sealing conditions of 190 ° C., 1.0 MPa, and 5.0 seconds. Specimen Example 6 was used. [Example 7] (embossed type) aluminum 40 µm
Chemical conversion treatment is applied to both surfaces, and a stretched nylon film (thickness: 25 μm) is bonded to one surface of the chemical conversion treatment by dry lamination, and then a linear low-density polyethylene film is attached to the other surface of the chemical conversion treatment aluminum. (Density: 0.921, thickness: 30 μm) were laminated by dry lamination to form a laminate and embossed. The secondary laminate that was not molded was used as a cover material to form an exterior body. As an adhesive film, a linear low-density polyethylene resin and an acid-modified polyethylene resin were coextruded to a thickness of 20 μm and 30 μm, respectively, to form a film having a thickness of 50 μm. Gel fraction (A) 8% (B) 35% (C) 7
4 %%. The adhesive film is welded to the upper and lower tabs of a lithium battery body having an aluminum tab having a thickness of 100 μm and a width of 4 mm, with the acid-modified polyethylene surface facing the tab side, and inserted into the exterior body. , Heat sealing conditions: 190 ° C, 1.0 MPa, 5.0 sec
As sealed. Specimen Example 7 was used.

[Comparative Example 1] (Pouch type) Aluminum was subjected to a chemical conversion treatment on both sides of 20 μm, and a stretched polyester film (thickness: 12 μm) was adhered to one surface of the chemical conversion treatment by a dry lamination method. The other surface of the aluminum is heated to a temperature equal to or higher than the softening point of the acid-modified polyethylene resin as the adhesive resin by far infrared rays and hot air, and then the acid-modified polyethylene resin (20 μm) is heated.
m) was used as an adhesive resin, and a pillow-type pouch was formed using a laminate obtained by sandwich-laminating a linear low-density polyethylene resin film (30 μm) to be a heat seal layer. Further, as an adhesive film, a linear low-density polyethylene resin was formed to a thickness of 20 μm, and an acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene) was laminated to a thickness of 30 μm. 100 μm
Of the adhesive film, the surface of the acid-modified polyolefin layer of the adhesive film was temporarily attached to the top and bottom of the tab portion of the lithium battery body having an aluminum tab having a thickness of 4 mm and inserted into the exterior body. , Heat sealing conditions 190
C., sealed at 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) was adhered to one surface of the chemical conversion treatment by a dry lamination method. The other surface is heated by a far infrared ray 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) is used as the adhesive resin, and a polypropylene film (100 μm ) Was sandwich-laminated to form a pillow-type pouch using the laminate obtained. Further, 200 μm of a polypropylene-based acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene) was prepared as an adhesive film. 100 μm thickness,
The adhesive film was temporarily attached to the top and bottom of the tab portion of the lithium battery main body having an aluminum tab having a width of 4 mm, and was inserted into the outer package.
Sealed at 0 ° C., 2.0 MPa, 3 sec. Sample Comparative Example 2 was used. Comparative Example 3 (Emboss Type) Aluminum 40 μm
Chemical conversion treatment on both sides of the aluminum sheet, a stretched nylon film (25 μm thick) is laminated to one surface of the chemical conversion treatment by dry lamination, and then acid-modified polyethylene is bonded to the other surface of the chemical conversion treatment aluminum by an adhesive resin. (Thickness 20
μm), a linear low-density polyethylene film (density 0.921, 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. As an adhesive film, a linear low-density polyethylene resin was formed to a thickness of 20 μm.
After cross-linking by electron beam irradiation under the condition of 0% gel fraction, an acid-modified polyethylene (unsaturated carboxylic acid-grafted polyethylene) was laminated to a thickness of 30 μm. 200 μm
Of the adhesive film is temporarily attached to the top and bottom of the tab portion of the lithium battery main body having an aluminum tab having a thickness of 4 mm and having a width of 4 mm as the tab side, and inserted into the exterior body. , Heat sealing conditions 190
C., sealed at 1.0 MPa, 5 sec. Sample Comparative Example 3 was used. [Comparative Example 4] (Embossed type) Aluminum 40 µm
Is subjected to chemical conversion treatment on both sides, and a stretched nylon film (thickness: 25 μm) is adhered to one surface of the chemical conversion treatment by dry lamination, and then acid-modified polypropylene is bonded to the other surface of the chemically treated aluminum by an adhesive resin. (Thickness 2
0 μm) as a polypropylene film (density 0.9
21, 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. Further, an acid-modified polypropylene (unsaturated carboxylic acid-grafted polypropylene) having a thickness of 100 μm was prepared as an adhesive film. 100 μm thickness, 4
The adhesive film was temporarily attached to the top and bottom of the tab portion of the lithium battery main body having an aluminum tab having a width of mm, and inserted into the outer package.
The sample was sealed at a temperature of 0.2 ° C. and a pressure of 0.2 MPa for 10.0 sec.

<Evaluation method> (1) Presence or absence of short circuit between the tab and the barrier layer of the exterior body The 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 by a cross-sectional photograph. 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: A mixed solution of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (1: 1: 1) so as to be 1 M LiPF _{6 in the} electrolytic solution. 3g

<Results> In all of Examples 1 to 7,
There were no shorts in the tab section and no leakage of the contents. In Comparative Example 1, 80 samples out of 100 samples were on the verge of short-circuiting, and 60 samples actually short-circuited. There was no leakage. In Comparative Example 2, 50 samples out of 100 samples were on the verge of short-circuiting, and 40 samples actually short-circuited. Also,
There was no leakage. In Comparative Example 3, there was no short circuit, but the contents leaked between the heat seal layer and the polyethylene of the adhesive film in 80 out of 100 samples. In Comparative Example 4, 60 samples out of 100 samples were on the verge of short-circuiting, and 50 samples actually short-circuited. There was no leakage. With respect to the evaluation items other than the short, both the examples and the comparative examples were good.

[0044]

According to the present invention, when the lithium battery main body is housed in the pouch or embossed portion of the exterior body formed from the packaging material for the lithium battery of the present invention, and the periphery thereof is heat-sealed, the tab of the lithium battery and the exterior body are sealed. The adhesive film to be interposed between, at least an electron beam cross-linked polyolefin film, by extrusion lamination of an acid-modified polyolefin as a layer to be bonded to the tab, at the time of hermetic sealing of a lithium battery, When the barrier layer of the exterior body and the tab contacted (short), the contents did not leak. Further, 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,
When the heat seal layer is formed by the sandwich lamination method or the co-extrusion lamination method, hydrogen fluoride generated by a reaction between the electrolyte of the lithium battery and moisture due to heating during formation of the laminate or heating after formation of the laminate. By preventing corrosion of the aluminum surface due to
This is an exterior body that can also prevent delamination with aluminum on the content side layer.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an adhesive film of the present invention,
(A) a cross-sectional view showing the layer structure of the adhesive film, (b) a diagram illustrating the material and positional relationship (one side) of the lithium battery tab, the outer package, and the adhesive film, and (c) heat sealing at the tab portion. It is sectional drawing explaining the state in which the front tab, the adhesive film, and the exterior body contacted, (d) It is typical sectional drawing of the tab part after heat sealing.

FIG. 2 is a perspective view illustrating a method of mounting an adhesive film in bonding a packaging material for a lithium battery and a tab.

FIG. 3 is a diagram illustrating a method of interposing an adhesive film between a tab and an outer package according to the present invention.

FIG. 4 is a perspective view illustrating a pouch type exterior body of a lithium battery.

FIG. 5 is a perspective view illustrating an embossed type exterior body of a lithium battery.

FIG. 6 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. 7 is a cross-sectional view illustrating an example of a layer configuration of a laminate forming an exterior body of a lithium battery.

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

FIG. 9 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 wk Temporary adhesion mk Welding 1 Lithium battery 2 Lithium battery body 3 Cell (power storage unit) 4 Tab (electrode) 5 Outer body 6 Adhesive film (Tab part) 7 Concave part Reference Signs List 8 side wall portion 9 seal portion 10 laminate (packaging material for lithium battery) 11 base material layer 12 aluminum (barrier layer) 13 acid-modified polyolefin layer (extrusion) 14 heat seal layer 15 chemical conversion layer 16 adhesive layer 17 slip agent layer 19 Liquid paraffin layer 20 Laminate of adhesive film 21 Acid-modified polyolefin layer 22 Polyolefin layer cross-linked by electron beam 30 Press molding part 31 Male type 32 Female type 33 Cavity

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuki Yamada 1-1-1 Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo F-term in Dai Nippon Printing Co., Ltd. 4J004 AA07 BA02 BA03 5H011 FF04 HH02 HH13 KK05

Claims (8)

[Claims] 1. A lithium battery main body is inserted into a lithium battery exterior body comprising at least a base material layer, an adhesive layer, a chemical conversion treatment layer 1, aluminum, a chemical conversion treatment layer 2, and a heat seal layer of a polyolefin resin. When heat sealing, the adhesive film interposed between the exterior body and the tab portion is a multilayer film obtained by extrusion-laminating an acid-modified polyolefin to at least a polyolefin film cross-linked with an electron beam. Adhesive film used for lithium battery tab. 2. The method according to claim 1, wherein the polyolefin film is a polyethylene film.
An adhesive film used for a tab portion of a lithium battery according to item 1. 3. The adhesive film according to claim 1, wherein the polyolefin film is a polypropylene film. 4. A lithium battery main body is inserted into an outer package of a lithium battery comprising at least a base material layer, an adhesive layer, a chemical conversion treatment layer 1, aluminum, a chemical conversion treatment layer 2, and a polyethylene resin heat seal layer. When heat-sealing, the adhesive film to be interposed between the exterior body and the tab portion is a multilayer film crosslinked to a gel fraction of 5 to 80% after co-extrusion of polyethylene and acid-modified polyethylene to form a film. An adhesive film used for a tab portion of a lithium battery. 5. When a lithium battery main body is inserted into a lithium battery outer package composed of at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, and a polyolefin-based resin heat seal layer, and the periphery thereof is heat-sealed. The adhesive film to be interposed between the outer package and the tab portion is at least a polyolefin film cross-linked with an electron beam, and is a multilayer film obtained by extrusion-laminating an acid-modified polyolefin for use in a lithium battery tab portion. Adhesive film. 6. The adhesive film according to claim 5, wherein the polyolefin film is a polyethylene film. 7. The adhesive film according to claim 5, wherein the polyolefin film is a polypropylene film. 8. When a lithium battery main body is inserted into a lithium battery exterior body composed of at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, and a heat seal layer of a polyolefin-based resin, and the periphery thereof is heat-sealed. The adhesive film interposed between the outer package and the tab portion is a multilayer film obtained by co-extruding polyethylene and acid-modified polyethylene and then crosslinking the gel fraction to 5 to 80%. Adhesive film used for lithium battery tab.