JP7163743B2 - Electrical storage device packaging material, method for manufacturing electrical storage device packaging material, and electrical storage device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric storage device packaging material, a method for manufacturing the electric storage device packaging material, and an electric storage device.

Conventionally, various types of power storage devices have been developed. In these electric storage devices, an electric storage device element composed of an electrode, an electrolyte and the like needs to be sealed with a packaging material or the like. Metal packaging materials are often used as packaging materials for electric storage devices.

2. Description of the Related Art In recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like have become more sophisticated, power storage devices having various shapes have been desired. In addition, thinning, weight reduction, and the like are required for power storage devices. However, it is difficult to keep up with the diversification of the shape of electric storage devices with the metal packaging materials that have been widely used in the past. Moreover, since it is made of metal, there is a limit to reducing the weight of the packaging material.

Therefore, as a packaging material for electric storage devices that can be easily processed into various shapes and can realize thinness and weight reduction, a film-like laminate in which a base layer / metal layer / heat-fusible resin layer is laminated in order. has been proposed (see Patent Document 1, for example).

In such a film-like packaging material for an electricity storage device, a concave portion is generally formed by molding, and an electricity storage device element such as an electrode or an electrolytic solution is arranged in the space formed by the concave portion, and heat-sealing is performed. By heat-sealing the resin layers to each other, an electricity storage device in which an electricity storage device element is accommodated inside the electricity storage device packaging material is obtained.

JP 2008-287971 A

In recent years, as packaging materials for electric storage devices have become thinner and lighter, the innermost heat-fusible resin layer has become thinner, while the thickness of metal terminals has increased as a countermeasure against large currents. In such an electric storage device, the heat-sealable resin layer, which is the innermost layer, may have defects such as cracks due to molding or bending, while the negative electrode and the metal layer of the electric storage device packaging material, or A short circuit may occur between the metal terminal of the negative electrode and the metal layer of the electrical storage device packaging material. Furthermore, in a short-circuited state, if the electrolyte that has penetrated through defects such as cracks in the heat-sealable resin layer comes into contact with the metal layer, the metal ions (for example, lithium ions) in the electrolyte and the metal that constitutes the metal layer Corrosion reactions that form alloys may occur.

In order to prevent such a corrosive reaction, the present inventor focused on a layer structure in which an intermediate layer is provided between the heat-fusible resin layer, which is the innermost layer, and the metal layer having a barrier function. However, the intermediate layer is simply provided for the purpose of stabilizing the environmental suitability (heat resistance, cold resistance, etc.) of the electric storage device and insulating properties, etc., and can effectively prevent corrosion reactions after bending. It is not designed to (provide corrosion resistance after bending). Therefore, even if an intermediate layer is provided between the metal layer and the intermediate layer, cracks are generated in the intermediate layer during bending, and the same problem of corrosion reaction still occurs. Therefore, it is conceivable to change the resin itself constituting the intermediate layer to a soft resin for the purpose of suppressing the occurrence of cracks during bending and obtaining corrosion resistance after bending. We also faced the problem of adversely affecting the pinhole resistance of the underlying metal layer.

Under such circumstances, the present invention provides a power storage device package comprising a laminate comprising at least a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order. A main object of the present invention is to provide a packaging material for electrical storage devices that has corrosion resistance and pinhole resistance after bending. Another object of the present invention is to provide a method for manufacturing the packaging material for an electricity storage device, and an electricity storage device using the packaging material for an electricity storage device.

The present inventors have made earnest studies to solve the above problems. As a result, the laminate is composed of at least a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, and the indentation elastic modulus of the intermediate layer is 1.5. It has been found that corrosion resistance and pinhole resistance after bending can be obtained with a packaging material for electrical storage devices in a specific range of 0 GPa or more and 5.0 GPa or less.
The present invention is an invention completed by further studies based on these findings.

That is, the present invention provides inventions in the following aspects.
Section 1. At least, it is composed of a laminate comprising a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order,
A packaging material for an electrical storage device, wherein the intermediate layer has an indentation modulus of 1.0 GPa or more and 5.0 GPa or less.
Section 2. Item 2. The electrical storage device packaging material according to Item 1, wherein a ratio of the indentation elastic modulus of the intermediate layer to the indentation elastic modulus of the base material layer is 0.3 or more and 2.9 or less.
Item 3. Item 3. The electrical storage device packaging material according to Item 1 or 2, which has a tensile modulus of 4.0 GPa or more and 10.0 GPa or less.
Section 4. Item 4. The electrical storage device packaging material according to any one of Items 1 to 3, wherein the intermediate layer is at least one resin film selected from the group consisting of polyolefin, polyester, and aliphatic polyamide.
Item 5. Item 5. The electrical storage device packaging material according to any one of Items 1 to 4, wherein the intermediate layer has a thickness of 5 μm or more and 50 μm or less.
Item 6. Item 6. The electrical storage device packaging material according to any one of Items 1 to 5, wherein the heat-fusible resin layer has a thickness of 10 μm or more and 100 μm or less.
Item 7. Item 7. The power storage device according to any one of Items 1 to 6, wherein the heat-fusible resin layer is composed of at least one selected from the group consisting of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin. packaging materials.
Item 8. Item 8. The electrical storage device packaging material according to any one of Items 1 to 7, wherein a peak derived from maleic anhydride is detected when the heat-fusible resin layer is analyzed by infrared spectroscopy.
Item 9. Item 9. The electrical storage device packaging material according to any one of Items 1 to 8, which is used for an electrolyte electrical storage device.
Item 10. At least, a step of obtaining a laminate by laminating a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order,
A method for producing a packaging material for an electricity storage device, wherein the intermediate layer has an indentation modulus of 1.0 GPa or more and 5.0 GPa or less.
Item 11. Item 10. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the electricity storage device packaging material according to any one of Items 1 to 9.

According to the present invention, in an electrical storage device packaging material composed of a laminate comprising at least a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, the intermediate By configuring the layer so as to have a specific indentation modulus, it is possible to provide a packaging material for an electrical storage device that provides corrosion resistance and pinhole resistance after folding. Furthermore, according to the present invention, it is possible to provide a method for manufacturing the electrical storage device packaging material and an electrical storage device using the electrical storage device packaging material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the cross-sectional structure of the packaging material for electrical storage devices of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the cross-sectional structure of the packaging material for electrical storage devices of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the cross-sectional structure of the packaging material for electrical storage devices of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the cross-sectional structure of the packaging material for electrical storage devices of this invention. It is a schematic diagram explaining the evaluation method of electrolytic-solution resistance in an Example. It is a schematic diagram explaining the evaluation method of corrosion resistance after bending in an Example.

The electrical storage device packaging material of the present disclosure is composed of a laminate including at least a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, and the intermediate The indentation modulus of the layer is characterized by being 1.0 GPa or more and 5.0 GPa or less. Hereinafter, the power storage device packaging material of the present disclosure, the method for manufacturing the power storage device packaging material, and the power storage device using the power storage device packaging material will be described in detail with reference to FIGS. 1 to 4 .

In this specification, regarding numerical ranges, the numerical range indicated by "-" means "more than" and "less than". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Laminated structure of electrical storage device packaging material The electrical storage device packaging material of the present disclosure includes at least a base layer 1, a metal layer 3, an adhesive layer 5a, an intermediate layer 7, and a heat It is composed of a laminate having fusible resin layers 4 in this order. In the electrical storage device packaging material of the present disclosure, the substrate layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. The electrical storage device packaging material is molded and/or bent so that the heat-fusible resin layers 4 located at the periphery of the power storage device element are in contact with each other, and the heat-fusible resin layers 4 are heat-fused to each other. Sealing the electrical storage device elements seals the electrical storage device elements.

As shown in FIGS. 2 to 4 , the electrical storage device packaging material of the present disclosure has, if necessary, between the intermediate layer 7 and the heat-sealable resin layer 4, for the purpose of increasing the adhesiveness between them. An adhesive layer 5b may be provided. In addition, as shown in FIGS. 3 and 4, the packaging material for electrical storage devices of the present disclosure is, if necessary, bonded between the base material layer 1 and the metal layer 3 for the purpose of improving the adhesion thereof. An agent layer 2 may be provided. In addition, as shown in FIG. 4, the packaging material for an electricity storage device of the present disclosure, for the purpose of improving design, electrolytic solution resistance, scratch resistance, moldability, etc., may include the base layer 1 as necessary. A surface coating layer 6 may be provided on the side opposite to the metal layer 3 as required. In addition, in the electrical storage device packaging material of the present disclosure illustrated in FIG. 3, the adhesive layer 5b between the intermediate layer 7 and the heat-fusible resin layer 4 may not be provided. Furthermore, in the electrical storage device packaging material of the present disclosure illustrated in FIG. Either one or both of the adhesive layers 5b may not be provided.

The thickness of the laminate constituting the electrical storage device packaging material 10 of the present disclosure is not particularly limited, but the upper limit is preferably about 180 μm or less and about 155 μm or less from the viewpoint of cost reduction, energy density improvement, etc. , about 120 μm or less, and the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more from the viewpoint of maintaining the function of the electricity storage device packaging material to protect the electricity storage device element, Preferred ranges are, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, 60 to 120 μm. degree.

The tensile modulus of the electrical storage device packaging material 10 of the present disclosure is, for example, about 4.0 to 10.0 GPa. The tensile modulus can be adjusted by the type and number of layers constituting the electrical storage device packaging material 10, the type and number of adhesive layers contained in the electrical storage device packaging material 10, and the like. The electrical storage device packaging material 10 as a whole preferably has a viscosity of 4.8 to 7.3 GPa, more preferably 5.0 to 7.3 GPa, and even more preferably 6.0 to 7.3 GPa. The electrical storage device packaging material 10 configured to have such a tensile modulus of elasticity has a good balance between the physical properties of the intermediate layer 7 having a predetermined indentation modulus and the other constituent layers. , the bending resistance of the intermediate layer 7 can be exhibited more satisfactorily. In addition, the tensile modulus is determined using a tensile tester and conforms to the slope obtained from 10.3.2 2 points of JIS K7161-1:2014 (Plastics-Determination of tensile properties-Part 1: General rules). These values are obtained when a test piece of the electrical storage device packaging material 10 is measured under the following measurement conditions. As a measuring device, for example, Instron 5565 (manufactured by Instron Japan) can be used. Since the value of the tensile modulus can vary depending on the in-plane direction of the electrical storage device packaging material 10, the in-plane average value can be used as the value of the tensile modulus. Specifically, the test piece of the electrical storage device packaging material 10 was sampled so that the in-plane direction was shifted by about 22.5 degrees and the eight in-plane directions were the longitudinal directions. The average of the measured values can be used as the in-plane average value.
(Measurement condition)
・Width of test piece: 15 mm
・Measurement temperature 23℃
・Measurement humidity 55%
・Distance between chucks 100mm
・ Tensile speed 100mm/min

2. Each layer [base layer 1] forming the packaging material for the electrical storage device
In the electrical storage device packaging material of the present disclosure, the base layer 1 is a layer located on the outer layer side with respect to the metal layer 3 . The material forming the base material layer 1 is not particularly limited as long as it has insulating properties.

The base material layer 1 may be, for example, a resin film formed of a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Stretched films are preferred. Stretched films include uniaxially stretched films and biaxially stretched films, preferably biaxially stretched films. Examples of stretching methods for forming a biaxially stretched film include successive biaxial stretching, inflation, and simultaneous biaxial stretching. Methods for applying the resin include a roll coating method, a gravure coating method, an extrusion coating method, and the like.

Materials for forming the substrate layer 1 include, for example, resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified products of these resins. Further, the resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Furthermore, it may be a mixture of these resins. Among these, polyesters and polyamides are preferred, and polyamides are more preferred, from the viewpoint of matching the indentation elasticity of the base material layer 1 and the intermediate layer 7 and obtaining good pinhole resistance of the metal layer 3. .

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; derived from terephthalic acid and/or isophthalic acid Hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamide such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing structural units, polyamide MXD6 (polymeta-xylylene Polyamides containing aromatics such as polyamide); Alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); Copolymerization of lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate polyester amide copolymers and polyether ester amide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and polyamides such as these copolymers. These polyamides may be used singly or in combination of two or more.

The indentation modulus of the base material layer 1 is the ratio of the indentation modulus of elasticity of the intermediate layer 7 from the viewpoint of obtaining good pinhole resistance by matching the hardness of the base material layer 1 and the hardness of the intermediate layer 7 described later. (Indentation elastic modulus of intermediate layer 7/indentation elastic modulus of substrate layer 1) is preferably within the range described below for intermediate layer 7 . The indentation elastic modulus of the base material layer 1 is measured using an ultra-micro load hardness tester equipped with a Vickers indenter, in accordance with ISO 14577, with respect to the cross section of the base material layer 1 of the electrical storage device packaging material 10. , are values when the indenter is pushed in and pulled out under the same measurement conditions as those for the indentation elastic modulus of the intermediate layer 7, which will be described later.

The substrate layer 1 may be formed of a single layer of resin film, but may be formed of two or more layers of resin film in order to improve pinhole resistance and insulation. When the substrate layer 1 is formed of two or more layers of resin films, the resins constituting each layer and/or the indentation elastic modulus of each layer may be the same or different. Preferably, the indentation modulus of at least one layer, preferably all layers, satisfies the above range. Further, when the substrate layer 1 is formed of two or more layers of resin films, if any of the layers satisfies the above range for the indentation modulus of elasticity, the layer that satisfies the above range for the indentation elasticity modulus It is more preferable to arrange it so as to be close to the metal layer 3 .

Specific structures of the base layer 1 when the base layer 1 is formed of two or more layers of resin films include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, Examples include laminates of polyester films of two or more layers, preferably laminates of stretched nylon films and stretched polyester films, laminates of stretched nylon films of two or more layers, and laminates of stretched polyester films of two or more layers. is preferred. For example, when the substrate layer 1 is a laminate of two layers of resin films, a laminate of polyester resin films and polyester resin films, a laminate of polyamide resin films and polyamide resin films, or a laminate of polyester resin films and polyamide resin films. A laminate is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. In addition, the polyester resin is resistant to discoloration when, for example, an electrolytic solution adheres to the surface. It is preferably located in the outermost layer.

When forming the base material layer 1 with a multilayer resin film, you may laminate|stack two or more layers of resin films via an adhesive agent. Preferred adhesives are the same as those exemplified for the adhesive layer 2 described later. The method for laminating two or more layers of resin films is not particularly limited, and known methods can be employed. Examples thereof include dry lamination, sandwich lamination, extrusion lamination, thermal lamination, and the like. A lamination method is mentioned. When laminating by dry lamination, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and laminated. The anchor coat layer is formed with the same adhesive as the adhesive layer 2 described later. The thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

At least one of the surface and the inside of the substrate layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. good. Only one type of additive may be used, or two or more types may be mixed and used.

The thickness of the base material layer 1 is not particularly limited as long as it functions as a base material layer. When the substrate layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer is preferably about 2 to 25 μm.

[Adhesive layer 2]
In the electrical storage device packaging material 10 of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the metal layer 3 as necessary for the purpose of enhancing the adhesiveness between them. .

The adhesive layer 2 is made of an adhesive capable of bonding the base material layer 1 and the metal layer 3 together. The adhesive used to form the adhesive layer 2 is not limited, but may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, and the like. Further, it may be a two-liquid curing adhesive (two-liquid adhesive), a one-liquid curing adhesive (one-liquid adhesive), or a resin that does not involve a curing reaction. Further, the adhesive layer 2 may be a single layer or multiple layers.

Specific examples of the adhesive component contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether; polyurethane; epoxy resin; Phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimide; polycarbonate; amino resin such as urea resin and melamine resin; rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; These adhesive components may be used singly or in combination of two or more. Among these adhesive components, polyurethane adhesives are preferred. In addition, an appropriate curing agent can be used in combination with these adhesive component resins to increase the adhesive strength. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of polyurethane adhesives include polyurethane adhesives containing a main agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing type polyurethane adhesives using polyols such as polyester polyols, polyether polyols, and acrylic polyols as main agents and aromatic or aliphatic polyisocyanates as curing agents are preferred. Moreover, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in a side chain in addition to the terminal hydroxyl group of the repeating unit. Since the adhesive layer 2 is made of a polyurethane adhesive, the electrical storage device packaging material is imparted with excellent electrolyte resistance, and even if the electrolyte adheres to the side surface, the base layer 1 is suppressed from peeling off. . Furthermore, it is preferable to use an aromatic polyisocyanate as the curing agent.

The thickness of the adhesive layer 2 when provided between the base material layer 1 and the metal layer 3 is not particularly limited as long as the base material layer 1 and the metal layer 3 can be adhered, but the lower limit is, for example, about 1 μm. As above, about 2 μm or more is mentioned, the upper limit is about 10 μm or less, about 5 μm or less, and the preferred range is about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm. be done.

[Metal layer 3]
In the electrical storage device packaging material 10 of the present disclosure, the metal layer 3 improves the strength of the electrical storage device packaging material and also functions as a barrier layer for preventing water vapor, oxygen, light, etc. from entering the electrical storage device. layer. Specific examples of the metal forming the metal layer 3 include aluminum, stainless steel, titanium, and the like, preferably aluminum. The metal layer 3 can be formed of, for example, a metal foil, a metal vapor deposition film, a film having such a vapor deposition film, or the like. It is preferably formed of metal foil, and more preferably formed of aluminum foil. When the metal layer 3 is made of aluminum foil, the aluminum foil is made of an aluminum alloy. From the viewpoint of preventing the occurrence of wrinkles and pinholes in the metal layer 3 during the production of the electrical storage device packaging material, the metal layer is made of, for example, annealed aluminum (JIS H4160: 1994 A8021H-O, JIS H4160 : 1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

The thickness of the metal layer 3 is not particularly limited as long as it functions as a barrier layer, but from the viewpoint of reducing the thickness of the packaging material for an electric storage device, it is preferably about 100 μm or less, more preferably about 10 to 100 μm. , more preferably about 10 to 80 μm, more preferably about 10 to 50 μm.

In the electrical storage device packaging material 10 of the present disclosure, the provision of the intermediate layer 7 provides excellent electrolytic solution resistance, so the metal layer 3 does not need to be subjected to chromate treatment. If the use of chromium, which causes environmental pollution, is to be avoided and the reduction of the environmental load is emphasized, the metal layer 3 that is not subjected to chromate treatment may be used. , a chromate-treated metal layer 3 may be used.

Examples of chromate treatment include chromate chromate using chromate compounds such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetyl acetate, chromium chloride, and potassium chromium sulfate. Treatment; phosphate chromate treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid; aminated phenol having repeating units represented by the following general formulas (1) to (4) Examples include chromate treatment using a polymer. In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained singly or in any combination of two or more. good too.

In general formulas (1) to (4), X represents a hydrogen atom, hydroxy group, alkyl group, hydroxyalkyl group, allyl group or benzyl group. R ¹ and R ² are the same or different and represent a hydroxy group, an alkyl group or a hydroxyalkyl group. Examples of alkyl groups represented by X, R ¹ and R ² in general formulas (1) to (4) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, A linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group can be mentioned. Examples of hydroxyalkyl groups represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3- Straight or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group and 4-hydroxybutyl group An alkyl group is mentioned. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by formulas (1) to (4) is preferably, for example, 500 to 1,000,000, more preferably about 1,000 to 20,000. preferable.

The amount of the acid-resistant film formed on the surface of the metal layer ³ in the chromate treatment is not particularly limited. preferably about 1.0 mg to about 40 mg, a phosphorus compound of about 0.5 mg to about 50 mg, preferably about 1.0 mg to about 40 mg, and an aminated phenolic polymer of about 1 mg to about 200 mg, preferably about It is desirable that it is contained in a ratio of 5.0 mg to 150 mg.

In the chromate treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of the metal layer 3 by a bar coating method, a roll coating method, a gravure coating method, an immersion method, or the like. is heated to about 70°C to 200°C. Moreover, before applying the chromate treatment to the metal layer 3, the metal layer 3 may be previously subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this manner, the chromate treatment of the surface of the metal layer 3 can be performed more efficiently.

Furthermore, the metal layer 3 may be subjected to a chemical conversion treatment to impart corrosion resistance, if necessary. As a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, specifically, fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, and barium sulfate are dispersed in phosphoric acid. There is a method of forming a corrosion-resistant layer on the surface of the metal layer 3 by coating and baking at 150° C. or higher. A resin layer obtained by cross-linking a cationic polymer with a cross-linking agent may be further formed on the corrosion-resistant layer. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of a polymer containing polyethyleneimine and carboxylic acid, a primary amine-grafted acrylic resin obtained by graft-polymerizing a primary amine to an acrylic backbone, and polyallylamine. Alternatively, derivatives thereof, aminophenol and the like can be mentioned. As these cationic polymers, only one type may be used, or two or more types may be used in combination. Examples of cross-linking agents include compounds having at least one functional group selected from the group consisting of isocyanate groups, glycidyl groups, carboxyl groups, and oxazoline groups, silane coupling agents, and the like. As these cross-linking agents, only one type may be used, or two or more types may be used in combination.

[Adhesion layer 5a]
In the electrical storage device packaging material 10 of the present disclosure, the adhesive layer 5a (first adhesive layer) is a layer provided to bond the metal layer 3 and the intermediate layer 7 together.

The adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7 is made of an adhesive capable of bonding the metal layer 3 and the intermediate layer 7 together. As the resin used for forming the adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7, for example, the adhesive layer 2 provided between the base material layer 1 and the metal layer 3 is exemplified. The same adhesives as those described above can be used. The resin used to form the adhesive layer 5a preferably contains a polyolefin skeleton, and includes polyolefins and acid-modified polyolefins exemplified for the heat-fusible resin layer 4 described later. Whether the resin constituting the adhesive layer 5a contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. Further, when the resin forming the adhesive layer 5a is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers of 1760 cm ⁻¹ and 1780 cm ⁻¹ . However, if the degree of acid denaturation is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

From the viewpoint of firmly bonding the metal layer 3 and the intermediate layer 7, the adhesive layer 5a preferably contains an acid-modified polyolefin. Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component such as carboxylic acid. Acid components used for modification include, for example, carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, and anhydrides thereof. Polyolefins to be modified include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; polypropylene, such as random copolymers (eg, random copolymers of propylene and ethylene); terpolymers of ethylene-butene-propylene, and the like. Among these polyolefins, polyethylene and polypropylene are preferred. Among these acid-modified polyolefins, maleic anhydride-modified polyolefin, and maleic anhydride-modified polypropylene are particularly preferable.

Furthermore, from the viewpoint of making the electrical storage device packaging material excellent in shape stability after molding while reducing the thickness of the electrical storage device packaging material, the adhesive layer 5a is made of a resin composition containing an acid-modified polyolefin and a curing agent. is more preferably a cured product of

Further, the adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7 is selected from the group consisting of an acid-modified polyolefin, a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. A resin composition containing acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. and more preferably a cured product of a resin composition containing an acid-modified polyolefin and a compound having an epoxy group.

Examples of compounds having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure with epoxy groups present in the molecule, and known epoxy resins can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, still more preferably about 200 to 800. In the present disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard sample.

Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolak glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, and the like. An epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more types.

The proportion of the epoxy resin in the adhesive layer 5a is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5a. is more preferred. Thereby, the adhesion between the metal layer 3 and the intermediate layer 7 can be effectively improved.

The thickness of the adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7 is not particularly limited as long as it functions as an adhesive layer. is preferred. From this point of view, the thickness of the adhesive layer 5a is, for example, about 1 to 7 μm, preferably about 2 to 5 μm, more preferably about 2 to 4 μm.

[Intermediate layer 7]
In the electrical storage device packaging material 10 of the present disclosure, the intermediate layer 7 is a layer arranged between the metal layer 3 and the heat-sealable resin layer 4, and has an indentation elastic modulus of 1.0 GPa to 5.0 GPa. is a layer composed of a resin of The intermediate layer 7 in the present disclosure has a single layer structure. A layer having an arbitrary indentation elastic modulus may be arranged between the metal layer 3 and the heat-fusible resin layer 4. Between the metal layer 3 and the heat-fusible resin layer 4, When there are two or more layers satisfying an indentation modulus of 1.0 GPa to 5.0 GPa, the intermediate layer 7 is one of the two or more layers satisfying an indentation modulus of 1.0 GPa to 5.0 GPa. Only the layer closest to the metal layer 3 is referred to. By providing such a specific intermediate layer 7, the electrical storage device packaging material 10 is provided with corrosion resistance and pinhole resistance after bending.

The power storage device packaging material 10 of the present disclosure is characterized in that the indentation elastic modulus of the intermediate layer 7 is 1.0 GPa to 5.0 GPa. If the indentation modulus is less than 1.0 GPa, the hardness balance between the intermediate layer 7 and the base material layer 1, which respectively constitute both sides of the metal layer 3, deteriorates, so that the metal layer 3 is more susceptible to stress. Pinhole resistance deteriorates. When the indentation elastic modulus is less than 1.0 GPa, the pinhole resistance tends to be improved as the thickness of the intermediate layer 7 is reduced with respect to the thickness of the base layer 1, but the degree of improvement is not sufficient. On the contrary, since the thickness of the intermediate layer 7 cannot be secured sufficiently, the corrosion resistance after bending is deteriorated.

On the other hand, when the indentation elastic modulus exceeds 5.0 GPa, the intermediate layer 7 is too hard, and cracks are likely to occur in the intermediate layer 7 itself when the electrical storage device packaging material 10 is bent. When the electrolytic solution that has entered through the cracks reaches the metal layer 3 , a corrosion reaction between the electrolytic solution and the metal layer 3 is likely to occur. In other words, by setting the indentation elastic modulus of the intermediate layer 7 to 5.0 GPa or less, the intermediate layer 7 is provided with excellent bending resistance. Even if it advances and reaches the intermediate layer 7 , the intermediate layer 7 dams up the electrolytic solution, thereby obtaining an excellent separation that prevents it from reaching the metal layer 3 . By preventing cracks from occurring in the intermediate layer 7 in this manner, a corrosive reaction between the electrolytic solution and the metal layer that advances due to cracks in the intermediate layer 7 can be suppressed. Corrosion resistance after bending can be obtained by this. Furthermore, the electrical storage device packaging material 10 suppresses short circuits during heat welding, and also provides excellent insulation properties that suppress short circuits between the negative electrode or the metal terminal of the negative electrode and the metal layer 3 due to foreign matter being caught.

From the viewpoint of further enhancing corrosion resistance and pinhole resistance after bending, the indentation elastic modulus of the intermediate layer 7 is preferably about 1.5 GPa to 5.0 GPa, more preferably about 1.5 GPa to 4.5 GPa. More preferably about 2.0 GPa to 4.0 GPa, more preferably about 2.0 to 3.0 GPa, particularly preferably about 2.0 to 2.3 GPa. The indentation modulus can be adjusted within such a range by selecting a material for forming the intermediate layer 7, which will be described later.

The indentation modulus was measured using a microhardness tester equipped with a Vickers indenter, and according to ISO 14577, the cross section of the intermediate layer 7 of the electrical storage device packaging material 10 was measured under the following measurement conditions. It is a value when pushing and pulling out. As a measuring device, for example, an ultra-microload hardness tester Picodenter HM500 (manufactured by Fisher Instruments) can be used.
(Measurement condition)
・Vickers indenter Diamond indenter of square pyramid with facing angle of 136° ・Measurement temperature 23°C
・Measurement relative humidity 60%RH
・Indentation speed 0.1 μm/sec ・Indentation depth 2 μm
・Holding time: 5 seconds ・Extraction speed: 0.1 µm/second

The indentation modulus of the intermediate layer 7 is determined from the viewpoint of achieving good pinhole resistance of the metal layer 3 by matching the hardness of the intermediate layer 7 and the hardness of the substrate layer 1 described above. The ratio of the indentation elastic modulus of the intermediate layer 7 to the modulus (indentation elastic modulus of the intermediate layer 7/indentation elastic modulus of the base layer 1) is preferably about 0.30 to 2.90, more preferably 0.50 to 2 It is more preferably about 0.70, more preferably about 0.70 to 2.50, even more preferably about 1.10 to 2.00, and about 1.13 to 1.30. is particularly preferred.

From the viewpoint of adjusting the indentation modulus of the intermediate layer 7 within the above range, the material forming the intermediate layer 7 is preferably a resin film. The material forming the intermediate layer 7 includes at least one resin film selected from the group consisting of polyolefins, polyesters, and aliphatic polyamides, from the viewpoint of adjusting the indentation modulus of the intermediate layer 7 within a preferable range. Specific examples include resin films such as polyolefins, polyesters, aliphatic polyamides, and mixtures and copolymers thereof. From the viewpoint of adjusting the indentation modulus of the intermediate layer 7 to a more preferable range, the material forming the intermediate layer 7 may be at least one resin film selected from the group consisting of polyesters and polyolefins. Specific examples include resin films such as polyesters, polyolefins, and mixtures and copolymers thereof. The material forming the intermediate layer 7 is at least one resin film selected from the group consisting of polyester and polyolefin from the viewpoint of adjusting the indentation modulus of the intermediate layer 7 to a more preferable range. and from the viewpoint of more preferably obtaining pinhole resistance, a polyolefin resin film is mentioned. The electrical storage device packaging material 10 of the present disclosure is useful for electrolyte electrical storage devices such as non-aqueous electrolyte electrical storage devices, aqueous electrolyte electrical storage devices, and ionic liquid electrical storage devices. When used as a packaging material for an electricity storage device, among the materials forming the intermediate layer 7, at least one resin film selected from the group consisting of polyesters and polyolefins having high electrolytic solution resistance is preferred. Alternatively, among the materials for forming the intermediate layer 7, a polyolefin resin film having excellent water resistance is more preferable.

Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester. A terephthalate is mentioned. Specific examples of polyolefin include polypropylene, ethylene-propylene copolymer, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymer polymerized using a single-site catalyst. Polymers, metal ion-containing polyethylene, copolymers of ethylene and methacrylic acid or acrylic acid derivatives, polybutene, unsaturated carboxylic acid-grafted polyethylene, unsaturated carboxylic acid-grafted polypropylene, unsaturated carboxylic acid-grafted polymethylpentene, and modified products thereof is mentioned. Both a stretched resin and an unstretched resin can be used as the polyolefin resin. Specific examples of aliphatic polyamides include nylon 6, nylon 66, nylon 12, copolyamides, and the like. These resins may be used singly or in combination of two or more.

The thickness of the intermediate layer 7 is not particularly limited as long as it has a thickness that allows the intermediate layer 7 to be formed into a film by itself. From the point of view of reducing More preferably, it is about 10 to 30 μm.

In the electrical storage device packaging material 10 of the present disclosure, any layer other than the intermediate layer 7 may be interposed between the metal layer 3 and the heat-fusible resin layer 4. The ratio of the thickness of the intermediate layer 7 to the total thickness of all layers existing between the heat-sealable resin layer 4 is, for example, about 60 to 100%, preferably about 70 to 100%. , preferably 80 to 100%, more preferably about 90 to 100%.

In addition, when two or more layers satisfying the indentation elastic modulus of 1.0 GPa to 5.0 GPa are laminated between the metal layer 3 and the heat-fusible resin layer 4, the two or more layers Specific combinations of resins constituting each of them include PET and OPP, PET and ON, PET and PBT, PET and PEN, PET and PET, ON and OPP, ON and PBT, ON and PEN, ON and ON, and OPP. and PBT, OPP and PEN, and OPP and OPP, and the like. In the laminated structure, it is preferable to laminate so that the layer of olefin resin such as OPP having high solvent resistance (electrolyte resistance) is positioned on the heat-fusible resin layer side.

[Adhesion layer 5b]
In the electrical storage device packaging material 10 of the present disclosure, the adhesive layer 5b (second adhesive layer) is provided between the intermediate layer 7 and the heat-fusible resin layer 4, if necessary, in order to firmly bond them. It is a layer that may be provided.

The adhesive layer 5 b that may be provided between the intermediate layer 7 and the heat-fusible resin layer 4 is made of an adhesive capable of bonding the intermediate layer 7 and the heat-fusible resin layer 4 together. As the resin used to form the adhesive layer 5b, the same adhesive as that used to form the adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7 can be used. The thickness can also be set in the same manner as the adhesive layer 5a provided between the metal layer 3 and the intermediate layer 7 described above.

[Heat-fusible resin layer 4]
In the power storage device packaging material of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and functions to seal the power storage device element by heat-sealing the heat-fusible resin layers to each other when assembling the power storage device. It is a layer (sealant layer) that exhibits

The resin used for the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but resins containing polyolefin skeletons such as polyolefins and acid-modified polyolefins are preferred. The inclusion of a polyolefin skeleton in the resin forming the heat-fusible resin layer 4 can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Further, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers of 1760 cm ⁻¹ and 1780 cm ⁻¹ . In the case where the heat-fusible resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid denaturation is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymer; homopolypropylene, block copolymer of polypropylene (eg, propylene and ethylene block copolymers), random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; ethylene-butene-propylene terpolymers, and the like. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin-based resins may be used alone or in combination of two or more.

Also, the polyolefin may be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins that are constituent monomers of the cyclic polyolefins include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting cyclic polyolefins include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the above polyolefin, a copolymer obtained by copolymerizing the above polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as crosslinked polyolefin can be used. Examples of acid components used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride and itaconic anhydride, and anhydrides thereof.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. Acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin in place of the acid component, or by block-polymerizing or graft-polymerizing the acid component to the cyclic polyolefin. be. The acid-modified cyclic polyolefin is the same as described above. The acid component used for acid modification is the same as the acid component used for modification of polyolefin.

Preferred acid-modified polyolefins include carboxylic acid- or anhydride-modified polyolefins, carboxylic acid- or anhydride-modified polypropylenes, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

The heat-fusible resin layer 4 may be formed of one type of resin alone, or may be formed of a blend polymer in which two or more types of resin are combined. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

Moreover, the heat-fusible resin layer 4 may contain a lubricant or the like as necessary. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the electrical storage device packaging material can be improved. The lubricant is not particularly limited, and known lubricants can be used. Lubricants may be used singly or in combination of two or more.

The thickness of the heat-fusible resin layer 4 is not particularly limited as long as it functions as a heat-fusible resin layer. About 15 to 40 μm can be mentioned.

The indentation elastic modulus of the heat-fusible resin layer 4 is not particularly limited. In the electrical storage device packaging material 10 of the present disclosure, since the intermediate layer 7 having a specific indentation elastic modulus is provided between the heat-fusible resin layer 4 and the metal layer 3, the electrical storage device packaging material 10 The bending resistance of the intermediate layer 7 during the bending process is excellent. Therefore, even if cracks occur in the heat-fusible resin layer 4 during the bending process, the intermediate layer 7 blocks the electrolyte that has entered through the cracks in the heat-fusible resin layer 4 and contacts the metal layer 3 . can be prevented. Therefore, the heat-fusible resin layer 4 does not require bending resistance when the electrical storage device packaging material 10 is bent. Therefore, the indentation modulus of the heat-fusible resin layer 4 is the ratio of the indentation modulus of the heat-fusible resin layer 4 to the indentation modulus of the substrate layer 1 (indentation modulus of the heat-fusible resin layer 4/ The indentation modulus of the substrate layer 1) is the ratio of the indentation modulus of the intermediate layer 7 to the indentation modulus of the substrate layer 1 (indentation modulus of the intermediate layer 7/indentation modulus of the substrate layer 1). .3 to 2.9. As an example of a case where the ratio of the indentation modulus of the heat-fusible resin layer 4 exceeds the range of 0.3 to 2.9, the resin constituting the heat-fusible resin layer 4 is the above-described polyolefin or cyclic polyolefin. A case is mentioned.

[Surface coating layer 6]
In the electrical storage device packaging material of the present disclosure, for the purpose of improving design, electrolyte resistance, scratch resistance, moldability, etc., the outer side of the base layer 1 (the metal of the base layer 1 A surface coating layer 6 may be provided on the side opposite to the layer 3, if necessary. When providing the surface coating layer 6, the surface coating layer 6 becomes the outermost layer of the electrical storage device packaging material.

The surface coating layer 6 can be made of, for example, polyvinylidene chloride, polyester, urethane resin, acrylic resin, epoxy resin, or the like. Among these, the surface coating layer 6 is preferably formed of a two-liquid curing resin. Examples of the two-liquid curing resin forming the surface coating layer 6 include two-liquid curing urethane resin, two-liquid curing polyester, and two-liquid curing epoxy resin. Further, the surface coating layer 6 may contain additives.

Examples of the additive include fine particles having an average particle size of about 0.5 nm to 5 μm. The material of the additive is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, organic substances, and the like. Also, the shape of the additive is not particularly limited, but examples thereof include spherical, fibrous, plate-like, amorphous, scale-like, and the like. Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, oxide Antimony, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, crosslinked Acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel and the like. These additives may be used singly or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability, cost, and the like. Moreover, the additive may be subjected to various surface treatments such as insulation treatment and high-dispersion treatment.

The content of the additive in the surface coating layer 6 is not particularly limited, but is preferably about 0.05 to 1.0 mass %, more preferably about 0.1 to 0.5 mass %.

A method for forming the surface coating layer 6 is not particularly limited, but for example, a method of coating the outer surface of the substrate layer 1 with a two-liquid curing resin that forms the surface coating layer can be used. When an additive is blended, the additive may be added to the two-liquid curing resin, mixed, and then applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above functions as the surface coating layer 6, and is, for example, approximately 0.5 to 10 μm, preferably approximately 1 to 5 μm.

3. Method for producing electrical storage device packaging material The method for producing the electrical storage device packaging material of the present disclosure is not particularly limited as long as a laminate obtained by laminating each layer having a predetermined composition is obtained. It comprises a step of obtaining a laminate by laminating a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, wherein the intermediate layer has an indentation elastic modulus of 1.0 GPa. A method using a material having a pressure of 5.0 GPa or less can be mentioned.

A specific example of the method for manufacturing the packaging material for an electricity storage device of the present disclosure is as follows. First, as a method of forming a laminate by laminating a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, for example, (a) A laminate (hereinafter sometimes referred to as "laminate A") in which a substrate layer 1, an adhesive layer 2 provided as necessary, and a metal layer 3 are laminated in order, and an intermediate layer 7, if necessary An adhesive layer 5b provided on the substrate and a laminate (hereinafter sometimes referred to as "laminate B") in which the heat-fusible resin layer 4 is laminated in order are formed, respectively, and the laminate A and the laminate B are formed. A method of lamination can be mentioned.

Specifically, the laminate A is formed by applying an adhesive used for forming the adhesive layer 2 to the base material layer 1 or the metal layer 3 by a coating method such as gravure coating or roll coating. After drying, the metal layer 3 or the substrate layer 1 is laminated and the adhesive layer 2 is cured by a dry lamination method.

Specifically, the laminate B is formed by: (1) applying an adhesive used for forming the adhesive layer 5b to the intermediate layer 7 or the heat-fusible resin layer 4 by gravure coating, roll coating, or the like; (2) a dry lamination method in which the intermediate layer 7 or the heat-fusible resin layer 4 is laminated and the adhesive layer 5b is cured after coating and drying by a method; (3) A method of laminating by co-extrusion the adhesive used for forming the adhesive layer 5b and the heat-fusible resin layer 4 on the intermediate layer 7 (co-extrusion lamination method). (4) co-extrusion of the intermediate layer 7 and the heat-fusible resin layer 4, and the like.

As a method for laminating the laminate A and the laminate B, an adhesive layer 5a is provided on the metal layer 3 of the laminate A or the intermediate layer 7 of the laminate B, and the metal layer 3 side of the laminate A and the laminate B and the intermediate layer 7 side. As a method for providing the adhesive layer 5a on the metal layer 3, for example, the resin component constituting the adhesive layer 5a is applied onto the metal layer 3 of the laminate A or the intermediate layer 7 of the laminate B by a gravure coating method or a roll coating method. , an extrusion lamination method, or the like. After that, the laminate A and the laminate B can be laminated by a dry lamination method or a thermal lamination method. Further, as a method for laminating the laminate A and the laminate B, the melted adhesive layer 5a is poured between the metal layer 3 of the laminate A and the intermediate layer 7 of the laminate B, and the adhesive layer is A method of laminating the laminate A and the laminate B via 5a (sandwich lamination method) can also be used.

Next, as another method of forming a laminate by laminating a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order, for example, After forming a laminate (laminate A) in which the substrate layer 1, the adhesive layer 2 provided as necessary, and the metal layer 3 are laminated in this order in the same manner as described above, the metal layer 3 side of the laminate A Alternatively, the intermediate layer 7, the adhesive layer 5b provided as necessary, and the heat-fusible resin layer 4 are laminated in this order via the adhesive layer 5a.

When providing the surface coating layer 6 , the surface coating layer is laminated on the surface of the substrate layer 1 opposite to the metal layer 3 . The surface coating layer can be formed, for example, by coating the surface of the substrate layer 1 with the above-described resin for forming the surface coating layer. The order of the step of laminating the metal layer 3 on the surface of the substrate layer 1 and the step of laminating the surface coating layer on the surface of the substrate layer 1 is not particularly limited. For example, after forming a surface coating layer on the surface of the substrate layer 1, the metal layer 3 may be formed on the surface of the substrate layer 1 opposite to the surface coating layer.

Surface coating layer 6/base layer 1/optional adhesive layer 2/metal layer 3/adhesive layer 5a/intermediate layer 7/optionally provided as described above A laminate consisting of the adhesive layer 5b/the heat-fusible resin layer 4 is formed. , near- or far-infrared heat treatment.

In the electrical storage device packaging material of the present disclosure, each layer that constitutes the laminate is improved or stabilized in film formability, lamination processing, final product secondary processing (pouching, embossing) aptitude, etc. as necessary. For this purpose, surface activation treatment such as corona treatment, blasting treatment, oxidation treatment, and ozone treatment may be applied.

4. Use of Electrical Storage Device Packaging Material The electrical storage device packaging material of the present disclosure is used for a packaging body for sealingly containing electrical storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an electricity storage device can be obtained by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed by the electricity storage device packaging material of the present disclosure.

Specifically, an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is placed in the packaging material for an electricity storage device of the present disclosure in a state in which metal terminals connected to the positive electrode and the negative electrode protrude outward. , covering the periphery of the electricity storage device element so as to form a flange portion (area where the heat-fusible resin layers contact each other), and heat-sealing the heat-fusible resin layers of the flange portion to seal. provides an electricity storage device using the electricity storage device packaging material. In addition, when housing an electricity storage device element in a package formed by the electricity storage device packaging material of the present disclosure, the heat-fusible resin portion of the electricity storage device packaging material of the present disclosure is on the inside (surface in contact with the electricity storage device element ) to form a package.

The power storage device to which the power storage device packaging material of the present disclosure is applied may be either a primary power storage device or a secondary power storage device, preferably a secondary power storage device. The type of secondary power storage device to which the power storage device packaging material of the present disclosure is applied is not particularly limited. - Cadmium storage devices, nickel/iron storage devices, nickel/zinc storage devices, silver/zinc oxide storage devices, metal air storage devices, polyvalent cation storage devices, capacitors, capacitors, etc., preferably lithium ion storage devices mentioned. In addition, the packaging material for an electricity storage device of the present disclosure is applied to any electricity storage device such as an electrolyte electricity storage device such as a non-aqueous electrolyte electricity storage device, an aqueous electrolyte electricity storage device, and an ionic liquid electricity storage device, and a polymer electricity storage device. be able to. Since the electrical storage device packaging material of the present disclosure includes an intermediate layer that has a specific indentation elastic modulus and is excellent in corrosion resistance after bending, among these electrical storage devices, electrolyte electrical storage devices and polymer electrical storage devices It is preferably applied, and particularly preferably applied to an electrolyte storage device.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. However, the invention is not limited to the examples.

<Manufacturing of packaging materials for power storage devices>
Example 1-4 and Comparative Example 1-2
A packaging material for an electricity storage device shown in Table 1 was produced. The prepared electrical storage device packaging material has a layer structure shown in FIG. First, a biaxially stretched nylon film having a thickness shown in Table 1 was prepared as the substrate layer 1 . Also, a metal layer 3 composed of an aluminum foil (JIS H4160:1994 A8021H-O, thickness 35 μm) provided with an acid-resistant film was prepared. The acid-resistant film on the aluminum foil was formed by coating both sides of the aluminum foil with a solution containing a chromium fluoride compound. A metal layer 3 provided with an acid-resistant film was laminated on the surface of the substrate layer 1 by a dry lamination method. Specifically, a two-component urethane adhesive (polyester polyol compound and aromatic isocyanate compound) is applied to one side of the aluminum foil to form an adhesive layer 2 (having a thickness of 2 μm after curing), which is acid-resistant. A metal layer 3 with a protective coating was deposited. Next, the laminate of the adhesive layer 2 on the metal layer 3 provided with the acid-resistant coating and the base material layer 1 is subjected to an aging treatment to obtain a base layer 1/adhesive layer 2/acid-resistant coating. A laminate A of the metal layer 3 was produced.

Next, an adhesive (having a thickness of 2 μm after curing) composed of an acid-modified polypropylene and a compound having an epoxy group is applied to the metal layer 3 of the obtained laminate A, and dried to form an adhesive layer 5a, Next, after laminating the intermediate layer 7 having the resin type and thickness shown in Table 1, an adhesive (having a thickness of 2 μm after curing) consisting of a modified polypropylene and an epoxy resin compound was applied on the intermediate layer 7, It was dried to form an adhesive layer 5b, and an unstretched polypropylene film having the thickness shown in Table 1 was laminated thereon. Next, by subjecting the obtained laminate to an aging treatment, the base layer 1/adhesive layer 2/metal layer 3/adhesive layer 5a/intermediate layer 7/adhesive layer 5b/thermal fusion layer resin layer 4 is changed to this An electric storage device packaging material 10 laminated in order was obtained.

<Measurement of indentation modulus>
In order to measure the indentation modulus, in accordance with ISO 14577, a Vickers indenter (a regular square pyramid with a facing angle of 136 ° A method of measuring the indentation elastic modulus using a microhardness tester equipped with a diamond indenter) was used. Specifically, the outer periphery of the sample was fixed with a curable resin-based adhesive, the fixed sample was cut in the thickness direction with a diamond knife, and an indenter was pushed into the exposed cross section of the sample for measurement. The measurement was performed in an environment of 23° C. and 60% RH, with an indentation speed of 0.1 μm/sec, an indentation depth of 2 μm, a retention time of 5 seconds, and a withdrawal speed of 0.1 μm/sec. As the microhardness tester, an ultra microload hardness tester Picodenter HM500 (manufactured by Fisher Instruments) was used. Five samples were measured under one measurement condition, and the average of the measured values was used as the measured value of the indentation modulus under the measurement condition.

<Method for measuring tensile modulus>
For measuring the tensile modulus, in accordance with JIS K7161-1:2014 (Plastics-Determination of tensile properties-Part 1: General rule), the electrical storage device packaging material 10 is cut into a rectangle with a width of 15 mm and a length of 120 mm. After creating a test piece, in an environment of 23 ° C. and 55% humidity, using a tensile tester, the distance between chucks is 100 mm, the tensile speed is 100 mm / min, and a reserve force is used. was used. As a tensile tester, Instron 5565 (manufactured by Instron Japan) was used. The reserve force is stress σ0 and elastic modulus Et (if the appropriate elastic modulus and stress for the reserve force are unknown, conduct a test in advance to obtain the predicted values of elastic modulus and stress), ( Et/10000)≦σ0≦(Et/3000). Since the value of the tensile elastic modulus may vary depending on the in-plane direction of the electrical storage device packaging material 10, the in-plane average value was used as the value of the tensile elastic modulus. Specifically, the test piece of the electrical storage device packaging material 10 was sampled so that the in-plane direction was shifted by about 22.5 degrees and the eight in-plane directions were the longitudinal directions. The average of the measured values was taken as the in-plane average value.

<Evaluation of bending resistance>
Regarding the bending resistance of the electrical storage device packaging material 10, the following water vapor barrier properties (g/m ² ·24 hours) were measured before and after folding the test piece of the electrical storage device packaging material 10. and evaluated the extent of the difference.

(Preparation of test piece)
The electrical storage device packaging material 10 was cut into a rectangle of 120 mm width×120 mm length to obtain a test piece before bending. The test piece was bent to a width of 60 mm and a length of 120 mm, and further bent to a width of 60 mm and a length of 60 mm to obtain a bent test piece.

(Measurement of water vapor barrier properties)
The water vapor barrier properties of the test pieces before and after bending of the electrical storage device packaging material 10 obtained above were measured according to JIS K7129-B: 2008 (Plastics - film and sheet - method for determining water vapor permeability (instrumental measurement method ), Appendix B: Infrared sensor method), and measured as follows. Specifically, the outside of the outer packaging material (the side where the metal layer 3 of the electrical storage device packaging material 10 is arranged) was measured using a water vapor permeability measuring device under the conditions of a temperature of 40 ° C. and a humidity of 90% RH (condition 3). ) is on the high humidity side (water vapor supply side), and the measurement is performed under the condition of a permeation area of 50 cm ² . Permatran-3/33G+ (manufactured by US company MOCON) was used as a water vapor transmission rate measuring device. NIST film #3 was used as a standard specimen. At least three samples were measured for each condition, and the average of these measurements was taken as the water vapor barrier property value for that condition.

(evaluation)
Regarding the measured water vapor barrier property (g/m ² ·24 hours), the difference between before and after bending the test piece was determined, and the bending resistance was evaluated based on the following criteria.
A: Difference in water vapor barrier properties before and after bending is 0.02 g/m ² ·24 hours or less ○: Difference in water vapor barrier properties before and after bending is 0.02 g/m ² ·24 hours or more and 0.1 g/m ² - 24 hours or less △: Difference in water vapor barrier properties before and after bending is 0.1 g/m ² ·24 hours or more and 0.5 g/m ² ·24 hours or less ×: Difference in water vapor barrier properties before and after bending is 0.5 g/m 2 ·24 hours or less. 5 g/m ² over 24 hours

<Evaluation of electrolyte resistance before bending>
Regarding the electrolytic solution resistance before bending of the electrical storage device packaging material 10, the peel strength (initial) between the metal layer and the intermediate layer of the electrical storage device packaging material 10 and the electrical storage device packaging material 10 are evaluated as follows. The degree of difference in peel strength between the metal layer and the intermediate layer after being exposed to the electrolyte (after immersion in the electrolyte) was evaluated.

(Preparation of test piece)
Each of the electrical storage device packaging materials was cut into 60 mm (MD direction, vertical direction)×150 mm (TD direction, horizontal direction) as shown in the schematic diagram of FIG. 5 (FIG. 5(a)). Next, the cut packaging material for electrical storage devices was folded in half so that the heat-fusible resin layers faced each other at the position where the length in the TD direction was divided into two (FIG. 5(b)). Next, one side E in the MD direction and one side F of a pair of sides in the TD direction are heat-sealed (the width of the heat-sealed portion S is 7 mm), and the other side in the TD direction is opened ( Fig. 5(c) Opening G) A bag-like packaging material for an electricity storage device was produced. The heat welding conditions were a temperature of 190° C., a surface pressure of 1.0 MPa, and a heating/pressurizing time of 3 seconds. Next, as shown in FIG. 5(d), 3 g of electrolytic solution H was injected through the opening G. Then, as shown in FIG. Next, the opening G was thermally welded with a width of 7 mm under the same conditions as above (FIG. 5(e)). Electrolytic solution H was obtained by mixing a solution in which ethylene carbonate: diethyl carbonate: dimethyl carbonate was mixed at a volume ratio of 1:1:1 so as to contain 1 mol/L of lithium hexafluorophosphate. It is.

Next, the electrical storage device packaging material was allowed to stand in a constant temperature layer at 85° C. for 24 hours with the opening G facing upward (state shown in FIG. 5(e)). After standing still, the electrical storage device packaging material is taken out from the constant temperature layer, and as shown in FIG. The packaging material was opened and the electrolytic solution H was taken out (Fig. 5(g)). Next, a portion with a width W of 15 mm in the TD direction of the electrical storage device packaging material was cut into strips (broken line in FIG. 5(h)) to obtain a test piece T (FIG. 5(I)).

(Measurement of peel strength)
The intermediate layer and the metal layer of the obtained test piece T were separated by about 30 mm in the length direction. Using a tensile tester (trade name AGS-50D manufactured by Shimadzu Corporation), the intermediate layer and the metal layer of the peeled part are measured at normal temperature (23 ° C.) and normal humidity (50% RH). The peel strength (N/15 mm) of the test piece was measured by pulling it at 50 mm and 180 degree peeling at a rate of 50 mm/min (peeling strength after immersion). On the other hand, the peel strength (N/15 mm) was similarly measured for a test piece T obtained by cutting the electrical storage device packaging material not exposed to the electrolytic solution H into a width of 15 mm (initial peel strength). Three samples were measured in the same manner, and the average value of the obtained measured values was taken as the peel strength. When the intermediate layer and the metal layer are separated, the adhesive layer positioned between these layers is in a state of being laminated on either or both of the intermediate layer and the metal layer.

(evaluation)
The initial peel strength and the peel strength after immersion were measured, and the electrolytic solution resistance was evaluated based on the following criteria.
○: Both the initial peel strength and the peel strength after immersion are 3 N / 15 mm or more ×: Both the initial peel strength and the peel strength after immersion are less than 3 N / 15 mm

<Evaluation of corrosion resistance after bending>
Regarding the post-bending corrosion resistance of the electrical storage device packaging material 10, the presence or absence of the following corrosion reaction was tested for the post-bending test piece of the electrical storage device packaging material 10. FIG.

(Preparation of test piece)
On the metal layer 3, an adhesive (having a thickness of 2 μm after curing) made of modified polypropylene and an epoxy resin compound for forming the adhesive layer 5a is applied and dried, and then the resin type and thickness shown in Table 1 are applied. After laminating the intermediate layer 7 having a metal layer 3 / adhesive layer A laminate was produced in which 5a/intermediate layer 7/adhesive layer 5b/heat-fusible resin layer 4 were laminated in this order.

Each of the prepared laminates was cut into a rectangle of 15 mm×50 mm as shown in the schematic diagram of FIG. 6 (FIG. 6(a)). Next, the cut electrical storage device packaging material 10 is folded in four so that the heat-sealable resin layer is on the inside (FIGS. 6(b) to 6(c)), and the folded state (FIG. 6(d) )), a surface pressure of 0.71 MPa/cm ² was applied to the entire surface including the crease for 2 seconds. The electrical storage device packaging material 10 was unfolded (FIG. 6(e)), and the end faces around the electrical storage device packaging material 10 except for one longitudinal end and its vicinity of the electrical storage device packaging material 10 were protected with PPa. At this time, the intersection of the folds f formed on the surface of the electrical storage device packaging material 10 was exposed. A test piece was thus produced.

(Measurement of corrosion reaction)
An electricity storage device using the prepared test piece as an electrode was constructed in the following manner.
1. A beaker cell was prepared, and the test piece and the Li metal piece were fixed with alligator clips.
2. Into the beaker cell, an electrolytic solution obtained by mixing lithium hexafluorophosphate at a volume ratio of 1:1:1 with a volume ratio of ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1:1:1 was added. The test piece was immersed so that the intersection of f was immersed.
3. The working electrode (anode) of the potentiostat was connected to the terminal on the side of the test piece, and the counter electrode (cathode) was connected to the terminal of the Li metal piece.
4. The potentiostat voltage was set to 0.1 V and left for 24 hours.
5. A current value flowing between both terminals was measured.

(evaluation)
If the intermediate layer of the test piece is completely insulated, current will not flow, but when the electrolytic solution comes into contact with the metal layer through the intermediate layer of the test piece, the metal layer, that is, aluminum and Li ions react (corrosion reaction), Alloying of Li—Al progresses, and current flows. Therefore, the corrosion resistance after bending was evaluated based on the following criteria.
○: Current did not flow ×: Current flowed

<Pinhole resistance evaluation after molding>
Each of the electrical storage device packaging materials 10 was cut into a rectangle of 90 mm×150 mm. The sample was set in a molding machine and molded at a presser pressure of 0.9 Mpa and a predetermined depth. After molding, light was applied with a penlight in a dark room to confirm the presence or absence of light transmission (pinholes in the metal layer). The molding depth at which there is no pinhole in the metal layer of each sample is used as an evaluation index for pinhole resistance, and the deeper the molding depth, the better the pinhole resistance. The molding depth (mm) was calculated as an average value of N=10, and the pinhole resistance was evaluated by classifying the average value based on the following criteria.

+++ 11.5 mm or more ++ 10.5 mm or more and less than 11.5 mm
+ 9.5 mm or more and less than 10.5 mm
- 8.5 mm or more and less than 9.5 mm -- less than 8.5 mm

In Table 1, ALM is aluminum foil, OPP is oriented polypropylene film, PET is polyethylene terephthalate, PBT is polybutylene terephthalate, ON is oriented nylon film, PPa is maleic anhydride-modified polypropylene, Miktron is Toray aramid film, and CPP is It means an unstretched polypropylene film. Also, the numerical value after the material constituting each layer means the thickness (μm) of each layer, for example, “OPP20” means a 20 μm thick stretched polypropylene film.

As is clear from the results shown in Table 2, the electrical storage device packaging material of Comparative Example 1 in which an intermediate layer having an indentation elastic modulus of less than 1.0 GPa was provided between the metal layer and the heat-sealable resin layer However, due to the imbalance between the indentation elastic modulus of the intermediate layer and the indentation elastic modulus of the base layer, the metal layer interposed between the two layers could not have sufficient pinhole resistance. In addition, in the electrical storage device packaging material of Comparative Example 1, by making the thickness of the intermediate layer non-dominant with respect to the thickness of the base material layer, the indentation elastic modulus of the base material layer that causes pinhole resistance is different. The imbalance should have been substantially mitigated, but it is still not at a level that can achieve the desired pinhole resistance, and even the corrosion resistance after folding is not sufficient due to the inability to secure a sufficient thickness of the intermediate layer. It was an unsatisfactory result. The electrical storage device packaging material of Comparative Example 2, in which an intermediate layer having an indentation elastic modulus exceeding 5.0 GPa was provided between the metal layer and the heat-fusible resin layer, had no bending resistance (water vapor before and after bending Since the difference in barrier properties was 6.1 g/m ² for 24 hours), corrosion resistance after bending could not be obtained, and the pinhole resistance was further deteriorated (molding depth was only 3 mm).

On the other hand, in the electrical storage device packaging materials of Examples 1 to 4, by providing an intermediate layer having an indentation elastic modulus of 1.0 GPa to 5.0 GPa between the metal layer and the heat-fusible resin layer, , excellent post-bending corrosion resistance and pinhole resistance were obtained. Among these, the electrical storage device packaging materials of Examples 1 to 3, in which the intermediate layer is a polyolefin resin or a polyester resin, were excellent in swelling resistance of the intermediate layer to the electrolyte even in the electrolyte resistance test before folding. , the electrolyte resistance of the intermediate layer is much more excellent, and it was found that it can be used particularly preferably in an electrolyte electricity storage device. Further, among the electrical storage device packaging materials of Examples 1 to 3, it was found that the electrical storage device packaging material of Example 1, in which the intermediate layer was made of polyolefin resin, was extremely excellent in pinhole resistance. Furthermore, among the electrical storage device packaging materials of Examples 2 and 3, in which the intermediate layer is a polyester resin, the electrical storage device packaging material of Example 3, in which the intermediate layer is polybutylene terephthalate, has the indentation elastic modulus of polybutylene terephthalate However, it was found that better balance with the indentation elastic modulus of the base material layer results in better pinhole resistance.

DESCRIPTION OF SYMBOLS 1... Base material layer 2... Adhesive layer 3... Metal layer 4... Heat-fusible resin layer 5a... Adhesive layer (first adhesive layer)
5b... Adhesive layer (second adhesive layer)
6... Surface coating layer 7... Intermediate layer 10... Packaging material for electrical storage device

Claims (11)

At least, it is composed of a laminate comprising a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order,
A packaging material for an electrical storage device, wherein the intermediate layer has an indentation modulus of 1.0 GPa or more and 5.0 GPa or less. The electrical storage device packaging material according to claim 1, wherein a ratio of the indentation elastic modulus of the intermediate layer to the indentation elastic modulus of the base material layer is 0.3 or more and 2.9 or less. The electrical storage device packaging material according to claim 1 or 2, having a tensile modulus of 4.0 GPa or more and 10.0 GPa or less. The electrical storage device packaging material according to any one of claims 1 to 3, wherein the intermediate layer is composed of at least one resin film selected from the group consisting of polyolefin, polyester, and aliphatic polyamide. The electrical storage device packaging material according to any one of claims 1 to 4, wherein the intermediate layer has a thickness of 5 µm or more and 50 µm or less. The electrical storage device packaging material according to any one of claims 1 to 5, wherein the heat-fusible resin layer has a thickness of 10 µm or more and 100 µm or less. The electricity storage device according to any one of claims 1 to 6, wherein the heat-fusible resin layer is composed of at least one selected from the group consisting of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin. packaging material for The electrical storage device packaging material according to any one of claims 1 to 7, wherein a peak derived from maleic anhydride is detected when the heat-fusible resin layer is analyzed by infrared spectroscopy. The packaging material for an electricity storage device according to any one of claims 1 to 8, which is used for an electrolyte electricity storage device. A step of obtaining a laminate by laminating at least a substrate layer, a metal layer, an adhesive layer, an intermediate layer, and a heat-fusible resin layer in this order,
A method for producing a packaging material for an electricity storage device, wherein the intermediate layer has an indentation modulus of 1.0 GPa or more and 5.0 GPa or less. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is accommodated in a package formed of the electricity storage device packaging material according to any one of claims 1 to 9.

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