JP2016115585A - Sheath material for power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheath material for a power storage device capable of maintaining sufficient moldability and having electrolyte resistance which is hard to be deteriorated even if an electrolyte adheres thereto.SOLUTION: There is provided the sheath material for a power storage device in which, on a first surface of a metal foil, a first corrosion prevention layer and a coating layer are provided in this order, and on a second surface of the metal foil, a second corrosion prevention layer, an adhesive layer and a sealant layer are provided in this order. The coating layer contains at least one additive agent selected from a group consisting of a polyvinyl chloride resin whose polymerization degree is 450-3000, a polyvinyl chloride-polyvinyl acetate copolymer and polyvinyl chloride-polyvinyl acetate terpolymer. The content of an additive material is 1-10 mass% based on the total mass of the coating layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exterior material for an electricity storage device.

  Conventionally, nickel-metal hydride and lead-acid batteries are known as power storage devices such as secondary batteries, but miniaturization is often required due to miniaturization of portable devices and limitations on installation space. Therefore, lithium ion batteries with high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials for lithium-ion batteries (hereinafter sometimes referred to simply as “exterior materials”), but they are lightweight, have high heat dissipation, and can be handled at low cost. Many possible multilayer films have been used.

The electrolyte of the lithium ion battery is composed of an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and an electrolyte. As the electrolyte, a lithium salt such as LiPF ₆ or LiBF ₄ is used. However, these lithium salts generate hydrofluoric acid by a hydrolysis reaction with moisture. Hydrofluoric acid may cause corrosion of the metal surface of the battery member and decrease of the laminate strength between the respective layers of the exterior material made of the multilayer film.

  Therefore, in the exterior material made of a multilayer film, a barrier layer made of a metal foil such as an aluminum foil is provided inside to suppress moisture from entering from the surface of the multilayer film. For example, a packaging material is known in which a heat-resistant base material layer / first adhesive layer / barrier layer / corrosion prevention layer for preventing corrosion due to hydrofluoric acid / second adhesive layer / sealant layer are sequentially laminated. A lithium ion battery using such an exterior material is also called an aluminum laminate type lithium ion battery.

  As a kind of aluminum laminate type lithium ion battery, a recess is formed in a part of the exterior material by cold molding, and the battery contents such as a positive electrode, a separator, a negative electrode, an electrolyte solution are accommodated in the recess, A device is known in which the remaining portion is folded and the edge portion is sealed by heat sealing. Such a battery is also called an embossed type lithium ion battery. In recent years, for the purpose of increasing the energy density, an embossed type lithium ion battery has also been manufactured in which recesses are formed on both sides of an exterior material to be bonded to accommodate more battery contents.

  The energy density of a lithium ion battery increases as the recesses formed by cold forming become deeper. However, the deeper the recesses to be formed, the easier it is for pinholes and breaks during molding of the exterior material. Then, protecting a barrier layer (metal foil) is performed using the stretched film for the base material layer of an exterior material. As described above, the base material layer is usually bonded to the barrier layer via the adhesive layer (see, for example, Patent Document 1).

Japanese Patent No. 3567230

  In the technique of Patent Document 1, a stretched polyamide film or a stretched polyester film having a tensile strength and an elongation amount of a specified value or more is used as a base material layer in order to improve moldability. However, when a stretched polyamide film is used, there is a problem that the stretched polyamide film dissolves when the electrolytic solution adheres to the stretched polyamide film in an electrolyte solution pouring step or the like. Further, when a stretched polyester film is used, there is a problem that the toughness is lowered and the moldability is poor.

  In view of the above circumstances, an object of the present invention is to provide an exterior material for an electricity storage device that can maintain sufficient moldability and has resistance to electrolyte even when an electrolyte is attached.

  The present invention includes a first corrosion prevention layer and a coating layer in this order on a first surface of a metal foil, and a second corrosion prevention layer, an adhesive layer and a sealant layer on the second surface of the metal foil. In order, the coating layer contains at least one additive selected from the group consisting of a polyvinyl chloride resin having a degree of polymerization of 450 to 3000, and a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate terpolymer And the exterior material for electrical storage devices whose content of an additive is 1-10 mass% on the basis of the total mass of a coating layer.

  If it is the exterior material of this invention, while being able to maintain sufficient moldability, it can have electrolyte solution resistance which is hard to change even if electrolyte solution adheres.

  In this invention, it is preferable that the thickness of a coating layer is 3-30 micrometers. Thereby, it becomes easier to maintain the electrolytic solution resistance and moldability.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to maintain sufficient moldability, the exterior material for electrical storage devices which has the electrolyte solution resistance which cannot change easily even if electrolyte solution adheres can be provided. In the present invention, since the adhesive layer that has been used when the stretched film is bonded to the barrier layer is not always necessary, it is possible to realize cost reduction and thickness reduction. In particular, since the layer thickness of the exterior material can be reduced, a large amount of battery contents can be accommodated in a limited space in a housing such as a smartphone.

It is sectional drawing which shows the exterior | packing material for electrical storage devices which concerns on one Embodiment of this invention.

<Exterior materials for electricity storage devices>
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing an electricity storage device exterior material (hereinafter simply referred to as “exterior material”) 1 of the present embodiment.

  The exterior material of the present embodiment includes a first corrosion prevention layer and a coating layer in this order on the first surface of the metal foil, and a second corrosion prevention layer, an adhesive layer, and a second layer on the second surface of the metal foil. A sealant layer is provided in this order. That is, as shown in FIG. 1, the exterior material 1 includes a metal foil 11 that exhibits a barrier function, and a first corrosion prevention layer 12 and a coating layer 13 that are sequentially formed on the first surface of the metal foil 11. The second corrosion prevention layer 14 formed on the second surface of the metal foil 11, and the adhesive layer 15 and the sealant layer 16 sequentially formed on the second corrosion prevention layer 14 are provided. When forming an electricity storage device using the packaging material 1, the coating layer 13 becomes the outermost layer and the sealant layer 16 becomes the innermost layer.

[Metal foil]
As the metal foil 11, various metal foils made of aluminum, stainless steel, or the like can be used. Of these, aluminum foil is preferable from the viewpoints of workability such as moisture resistance and spreadability, and cost. A general soft aluminum foil can be used as the aluminum foil. Among these, an aluminum foil containing iron is preferable from the viewpoint of excellent pinhole resistance and extensibility during molding.

  0.1-9.0 mass% is preferable and, as for content of iron in the aluminum foil (100 mass%) containing iron, 0.5-2.0 mass% is more preferable. When the iron content is 0.1% by mass or more, the exterior material 1 is excellent in pinhole resistance and spreadability. If the iron content is 9.0% by mass or less, the exterior material 1 is excellent in flexibility.

  The thickness of the metal foil 11 is preferably 9 to 200 μm, more preferably 15 to 100 μm, from the viewpoints of barrier properties, pinhole resistance, workability, and the like.

[Coating layer]
The coating layer 13 provides heat resistance in the sealing process when manufacturing the electricity storage device and resistance to electrolytic solution that does not change even if the electrolytic solution adheres, and also generates pinholes that can occur during processing and distribution. Play a role to suppress.

  The coating layer 13 is formed of a resin, and is preferably formed directly on the first corrosion prevention layer 12 formed on the first surface of the metal foil 11, preferably without an adhesive layer. In that case, the coating layer can be formed by applying a resin material to be the coating layer on the first corrosion prevention layer. In addition, when using an adhesive layer, the adhesive agent demonstrated by the item of the adhesive layer mentioned later can be used.

  The coating layer 13 includes a polyvinyl chloride resin. The polyvinyl chloride resin has electrolyte resistance.

  The degree of polymerization of the polyvinyl chloride resin forming the coating layer 13 is 450 to 3000, preferably 700 to 2000. When the degree of polymerization is 450 or more, good resistance to electrolytic solution is easily exhibited. On the other hand, when the degree of polymerization is 3000 or less, the viscosity of the coating liquid does not become too high, and the coating layer 13 can be easily applied. The content of the main agent is 90 to 99% by mass based on the total mass of the coating layer 13 from the relationship with the content of the following additives, but is preferably 95 to 99% by mass.

  The coating layer 13 contains at least one additive selected from the group consisting of a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate terpolymer, in addition to the polyvinyl chloride resin as the main agent. In this case, although content of an additive is 1-10 mass% on the basis of the total mass of the coating layer 13, it is preferable that it is 1-5 mass%. When the content of these additives is 1% by mass or more, the adhesion with the metal foil 11 can be improved. On the other hand, when the content is 10% by mass or less, the electrolytic solution resistance can be further improved. In addition, the content of the vinyl acetate monomer in the vinyl chloride-vinyl acetate copolymer and the vinyl chloride-vinyl acetate terpolymer is preferably 5 to 20% by mass, and more preferably 10 to 15% by mass. When the content of the vinyl acetate monomer is 5% by mass or more, the adhesion with the metal foil 11 can be further improved. On the other hand, heat resistance can be made more favorable in the said content being 20 mass% or less. In addition, examples of the third monomer in the vinyl chloride-vinyl acetate terpolymer include hydroxyalkyl acrylate and alkyl malate.

  3-30 micrometers is preferable and, as for the thickness of the coating layer 13, 5-20 micrometers is more preferable. A moldability can be made more favorable in the thickness of the coating layer 13 being 3 micrometers or more. In addition, in this embodiment, although the thickness of the coating layer 13 can be 30 micrometers or less, it can be set as a structure thinner than the conventional exterior material by this.

[Corrosion prevention layer]
The first corrosion prevention layer 12 and the second corrosion prevention layer 14 (hereinafter referred to as “corrosion prevention layer”) suppress the corrosion of the metal foil 11 due to the electrolytic solution or hydrofluoric acid generated by the reaction between the electrolytic solution and moisture. To play a role. Moreover, it plays the role which raises the adhesive force of the metal foil 11 and the contact bonding layer 15 (When the contact bonding layer is provided also on the 1st corrosion prevention layer 12, it is further the metal foil 11 and the said contact bonding layer).

  Examples of the corrosion prevention layer include a coating film formed by a coating type or immersion type acid-resistant corrosion prevention treatment agent, and a metal oxide layer derived from a metal constituting the metal foil 11. Such a coating film or layer is excellent in the effect of preventing corrosion against acid. As a coating film, for example, a coating film, chromate, phosphate, fluoride, and various thermosetting properties formed by ceriazol treatment with a corrosion inhibitor treatment agent composed of cerium oxide, phosphate and various thermosetting resins Examples thereof include a coating film formed by chromate treatment with a corrosion inhibitor treatment agent made of a resin. In addition, if it is a coating film from which the corrosion resistance of the metal foil 11 is fully obtained, it will not be limited to what was mentioned above. For example, a coating film formed by phosphate treatment, boehmite treatment, or the like may be used. On the other hand, examples of the metal oxide layer derived from the metal constituting the metal foil 11 include layers according to the metal foil 11 used. For example, when an aluminum foil is used as the metal foil 11, the aluminum oxide layer functions as a corrosion prevention layer. These corrosion prevention layers can be used in a single layer or in combination of a plurality of layers. Further, the first corrosion prevention layer 12 and the second corrosion prevention layer 14 may have the same configuration or different configurations. Further, an additive such as a silane coupling agent may be added to the corrosion prevention layer.

  The thickness of the corrosion prevention layer is preferably 10 nm to 5 μm, more preferably 20 to 500 nm, from the viewpoint of the corrosion prevention function and the function as an anchor.

[Adhesive layer]
The adhesive layer 15 is a layer that adheres the metal foil 11 on which the second corrosion prevention layer 14 is formed and the sealant layer 16. The exterior material 1 is roughly divided into two types according to the adhesive component forming the adhesive layer 15, that is, a thermal laminate configuration and a dry laminate configuration.

  In the case of a thermal laminate configuration, the adhesive component that forms the adhesive layer 15 is preferably an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. Since the acid-modified polyolefin-based resin is one in which a polar group is introduced into a part of the non-polar polyolefin-based resin, for example, a non-polar layer formed of a polyolefin-based resin film or the like as the sealant layer 16 is used. Further, when a layer having polarity is used as the second corrosion prevention layer 14, it is possible to firmly adhere to both of these layers. In addition, by using an acid-modified polyolefin-based resin, resistance to contents such as an electrolytic solution is improved, and even if hydrofluoric acid is generated inside the battery, it is easy to prevent a decrease in adhesion due to deterioration of the adhesive layer 15. The acid-modified polyolefin resin used for the adhesive layer 15 may be one type or two or more types.

  Examples of the polyolefin resin used for the acid-modified polyolefin resin include low density, medium density or high density polyethylene; ethylene-α olefin copolymer; homo, block or random polypropylene; propylene-α olefin copolymer. Can be mentioned. In addition, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the aforementioned one, a polymer such as a crosslinked polyolefin, and the like can be used. Examples of the acid that modifies the polyolefin-based resin include carboxylic acid and acid anhydride, and maleic anhydride is preferable.

  In the case of a thermal laminate configuration, the adhesive layer 15 can be formed by extruding the adhesive component with an extrusion device.

  In the case of a dry laminate configuration, as an adhesive component of the adhesive layer 15, for example, a bifunctional or higher functional aromatic or aliphatic isocyanate compound is allowed to act as a curing agent on a main component such as polyester polyol, polyether polyol, or acrylic polyol. A two-component curable polyurethane adhesive may be used. However, since the polyurethane-based adhesive has a highly hydrolyzable bond such as an ester group or a urethane group, a thermal laminate configuration is preferable for applications that require higher reliability.

  The adhesive layer 15 having a dry laminate structure can be formed by applying an adhesive component onto the second corrosion prevention layer 14 and then drying. If a polyurethane adhesive is used, after coating, for example, by aging at 40 ° C. for 4 days or more, the reaction of the hydroxyl group of the main agent and the isocyanate group of the curing agent proceeds to enable strong adhesion. It becomes.

  The thickness of the adhesive layer 15 is preferably 2 to 50 μm, and more preferably 3 to 20 μm from the viewpoints of adhesiveness, followability, workability, and the like.

  As described above, when the adhesive layer is used when forming the coating layer 13 on the first corrosion prevention layer 12, the adhesive layer 15 may be made of, for example, a dry laminate structure as the adhesive constituting the adhesive layer. The two-component curable polyurethane adhesives mentioned above can be used. At this time, the thickness of the adhesive layer is preferably 1 to 10 μm, and more preferably 3 to 7 μm, from the viewpoints of adhesiveness, followability, workability, and the like.

[Sealant layer]
The sealant layer 16 is a layer that imparts sealing properties by heat sealing in the exterior material 1. Examples of the sealant layer 16 include a polyolefin resin, or a resin film made of an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride.

  Examples of the polyolefin resin include low density, medium density or high density polyethylene; ethylene-α olefin copolymer; homo, block or random polypropylene; propylene-α olefin copolymer. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  Examples of the acid that modifies the polyolefin resin include the same acids as those described in the description of the adhesive layer 15.

  The sealant layer 16 may be a single layer film or a multilayer film, and may be selected according to a required function. For example, in terms of imparting moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed can be used.

  The sealant layer 16 may contain various additives such as a flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, and tackifier.

  The thickness of the sealant layer 16 is preferably 10 to 100 μm, more preferably 20 to 60 μm, from the viewpoint of ensuring insulation.

  The exterior material 1 may be a laminate in which a sealant layer 16 is laminated by dry lamination. From the viewpoint of improving adhesion, the sealant layer 15 is made of an acid-modified polyolefin resin and sandwich lamination or coextrusion is used. It is preferable that 16 is laminated.

<Method for manufacturing exterior material for power storage device>
Hereinafter, the manufacturing method of the exterior material 1 of this embodiment is demonstrated. Specifically, although the method which has the following process (1)-(3) is mentioned as the manufacturing method, the following content is an example and the manufacturing method of the exterior | packing material 1 is not limited to the following content.

  Process 1: The process of forming the 1st corrosion prevention layer 12 and the 2nd corrosion prevention layer 14 on both surfaces (1st surface and 2nd surface) of the metal foil 11. FIG.

  Process 2: The process of forming the coating layer 13 on the 1st corrosion prevention layer 12 formed in the 1st surface of the metal foil 11 using the raw material for coating layers (resin material).

  Step 3: A step of bonding the sealant layer 16 on the second corrosion prevention layer 14 formed on the second surface of the metal foil 11 via the adhesive layer 15.

(Process 1)
For example, a corrosion prevention treatment agent is applied to both surfaces of the metal foil 11 and dried to form the first corrosion prevention layer 12 and the second corrosion prevention layer 14. Examples of the corrosion prevention treatment agent include the above-described corrosion prevention treatment agent for ceriazole treatment and corrosion prevention treatment agent for chromate treatment. The coating method of the corrosion inhibitor is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed. Alternatively, by oxidizing the surface of the metal foil 11, metal oxide layers derived from the metal constituting the metal foil 11 on both surfaces of the metal foil 11 (the first corrosion prevention layer 12 and the second corrosion prevention layer). 14). Note that one surface of the metal foil 11 may be treated with a corrosion preventing treatment agent and the other surface may be oxidized.

(Process 2)
On the first corrosion prevention layer 12 formed on the first surface of the metal foil 11, a coating layer raw material (resin material) serving as a coating layer is applied and dried to form the coating layer 13. The application method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed. After coating, for example, the coating layer 13 is obtained by drying the solvent at a temperature of 170 ° C. or higher. In step 2, aging or the like is not necessary. As a result, the tact time can be shortened and the manufacturing efficiency can be remarkably improved.

(Process 3)
An adhesive layer 15 is formed on the second corrosion prevention layer 14 of the laminate in which the coating layer 13, the first corrosion prevention layer 12, the metal foil 11, and the second corrosion prevention layer 14 are laminated in this order. The body and the resin film forming the sealant layer 16 are bonded together. At this time, the adhesive layer 15 and the sealant layer 16 can be coextruded to be laminated on the laminate. Of the both surfaces of the resin film forming the sealant layer 16, at least one surface bonded to the adhesive layer 15 may be corona-treated.

  The exterior material 1 is obtained by the steps (1) to (3) described above. In addition, the process sequence of the manufacturing method of the cladding | exterior_material 1 is not limited to the method of implementing process (1)-(3) sequentially. For example, step (2) may be performed after performing step (3).

  The two exterior materials 1 obtained in this way are prepared and the sealant layers 16 are opposed to each other, or the exterior material 1 is folded back so that the sealant layers 16 are opposed to each other, and become power generation elements and terminals inside. By arranging a tab member or the like and joining the peripheral edges by heat sealing, a cell of an electricity storage device using the exterior material 1 is completed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.

[Materials used]
The material used for preparation of the exterior material of an Example and a comparative example is shown below.
(Coating layer)

(Coating layer side adhesive layer)
Adhesive B-1: Polyester urethane adhesive (two-component curable adhesive comprising polyester polyol and polyisocyanate: layer thickness 5 μm)

(Coating layer side corrosion prevention layer: first corrosion prevention layer)
Corrosion prevention layer C-1: Cerium oxide layer (layer thickness 100 nm)

(Metal foil)
Metal foil D-1: Soft aluminum foil 8079 material (manufactured by Toyo Aluminum Co., Ltd., thickness 30 μm)

(Sealant layer side corrosion prevention layer: Second corrosion prevention layer)
Corrosion prevention layer E-1: Cerium oxide layer (layer thickness 100 nm)

(Sealant layer side adhesive layer)
Adhesive resin F-1: polypropylene resin graft-modified with maleic anhydride (trade name “Admer”, manufactured by Mitsui Chemicals, layer thickness 20 μm)

(Sealant layer)
Film G-1: Unstretched polypropylene film (layer thickness: 40 μm) whose surface on the sealant layer side corrosion prevention layer E-1 side is corona treated

(Preparation of exterior materials)
Corrosion prevention layer E-1 was formed on one surface of metal foil D-1 by direct gravure coating. Next, the corrosion prevention layer C-1 was formed by direct gravure coating on the other surface of the metal foil D-1 where the corrosion prevention layer E-1 was not formed. In the examples, any of coating layer raw materials A-1 (Example 1) to A-8 (Example 8) is applied to the surface of the metal foil D-1 on which the corrosion prevention layer C-1 is formed. And a coating layer was formed.

  On the other hand, in the comparative example, the coating layer raw materials A-9 (Comparative Example 1) to A-12 (Comparative Example 4) were applied to the surface of the metal foil D-1 on which the corrosion prevention layer C-1 was formed. Then, a coating layer was formed. Further, for the coating layer raw materials A-13 (Comparative Example 5) and A-14 (Comparative Example 6), the corrosion prevention layer C was applied to the metal foil D-1 by the dry laminating method using the adhesive B-1. It was bonded to the surface on which -1 was formed.

  Next, after forming the adhesive layer by extruding the adhesive resin F-1 with an extrusion device on the corrosion prevention layer E-1 side of the laminates of the obtained examples and comparative examples, the film G-1 is further formed. A sealant layer was formed by bonding and sandwich lamination. The exterior material of each Example and the comparative example was produced through the above process.

[Various evaluations]
Various evaluations were performed according to the following methods. The evaluation results are shown in Table 2.

[Evaluation of moldability]
The exterior material obtained in each example was cut into a blank shape of 150 mm × 190 mm, cold-molded while changing the molding depth in a molding environment with a room temperature of 23 ° C. and a dew point temperature of −35 ° C., and the moldability was evaluated. .

A punch having a shape of 100 mm × 150 mm, a punch corner R (RCP) of 1.5 mm, a punch shoulder R (RP) of 0.75 mm, and a die shoulder R (RD) of 0.75 mm was used. Evaluation was performed according to the following criteria.
“A”: Deep drawing with a molding depth of 4 mm or more is possible without causing breakage and cracks.
“B”: Deep drawing with a molding depth of 3 mm or more and less than 4 mm is possible without causing breakage or cracks.
“C”: Breaking and cracking occur in deep drawing with a molding depth of less than 3 mm.

[Evaluation of electrolyte resistance]
An electrolyte solution (ethylene carbonate / dimethyl carbonate / diethyl carbonate = 1: 1: 1 wt%, LiPF ₆ , 1M) to which a small amount of water (1500 ppm) was added was dropped on the coating layer of the exterior material obtained in each example, After leaving it for 24 hours, it was wiped off with isopropyl alcohol. Then, the external appearance of the dripping location was evaluated.
“A”: The location where the electrolytic solution was dropped cannot be recognized.
“B”: A contour is generated at a location where the electrolytic solution is dropped, but is not dissolved or damaged.
“C”: The portion where the electrolytic solution was dropped was dissolved or damaged by the electrolytic solution.

  In the examples having the configuration of the present invention, it was possible to provide an exterior material for an electricity storage device that can maintain sufficient moldability and has resistance to electrolytic solution that does not easily change even when the electrolytic solution adheres.

  DESCRIPTION OF SYMBOLS 1 ... Exterior material (exterior material) for electrical storage devices, 11 ... Metal foil, 12 ... 1st corrosion prevention layer, 13 ... Cover layer, 14 ... 2nd corrosion prevention layer, 15 ... Adhesion layer, 16 ... Sealant layer.

Claims (2)

The first corrosion prevention layer and the coating layer are provided in this order on the first surface of the metal foil,
A second corrosion prevention layer, an adhesive layer and a sealant layer are provided in this order on the second surface of the metal foil,
The coating layer contains at least one additive selected from the group consisting of a polyvinyl chloride resin having a polymerization degree of 450 to 3000, and a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate terpolymer,
The content of the additive is 1 to 10% by mass based on the total mass of the coating layer.
Exterior material for electricity storage devices.   The packaging material for an electricity storage device according to claim 1, wherein the coating layer has a thickness of 3 to 30 μm.

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