Exterior material for power storage device, manufacturing method thereof, and power storage device

Abstract

To provide an exterior material for a power storage device, which has excellent formability, effectively suppresses corrosion of an aluminum alloy foil when electricity is applied while an electrolytic solution is adhered to the foil, and has improved insulating properties.SOLUTION: An exterior material for a power storage device includes at least a laminate including a substrate layer, a barrier layer, an adhesive layer, and a heat-fusible resin layer in this order, and the barrier layer contains an aluminum alloy foil satisfying a composition of Fe: 0.2% by mass to 2.0% by mass and Mg: 0.1% by mass to 5.0% by mass, and the adhesive layer is formed by a cured product of a resin composition containing a curable resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an electricity storage device, a method for producing the same, and an electricity storage device. [Background technology]

[0002] Various types of electricity storage devices have been developed, but in all of them, packaging materials (exterior materials) are essential components for sealing the electricity storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

[0003] Meanwhile, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., electricity storage devices are being required to have a variety of shapes as well as to be thinner and lighter in weight. However, the metallic exterior materials for electricity storage devices that have been widely used in the past have the drawbacks of being difficult to keep up with the diversification of shapes and also having limitations on how much they can be made lighter.

[0004] Therefore, in recent years, a film-like packaging material in which a substrate / aluminum alloy foil layer / thermally adhesive resin layer are sequentially laminated has been proposed as a packaging material for an electricity storage device that can be easily processed into various shapes and can be made thinner and lighter (see, for example, Patent Document 1).

[0005] In such film-like packaging materials, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolyte are placed in the spaces formed by the recesses. The heat-sealable resin layers are then heat-sealed together to obtain an energy storage device in which the energy storage device elements are housed inside the packaging material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-287971 Summary of the Invention [Problem to be solved by the invention]

[0007] From the viewpoint of increasing the energy density of an electricity storage device, it is required that deep recesses be formed in a film-like packaging material by molding, and therefore, the aluminum alloy foil used in the packaging material for an electricity storage device is required to have high formability.

[0008] As an aluminum alloy foil having excellent formability, an Al-Fe alloy-based soft aluminum alloy foil is known. Specific examples of such soft aluminum alloy foil include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O.

[0009] On the other hand, during the molding process of the electrical storage device packaging material, the process of housing an electrical storage device element in the electrical storage device packaging material and heat-sealing it, or the process of folding the heat-sealed portion, if a short circuit occurs between the external terminal and the aluminum alloy foil of the electrical storage device packaging material via a foreign object, or if uneven pressure during heat-sealing causes the external terminal and the aluminum alloy foil of the electrical storage device packaging material to come into close proximity or contact with each other, and if fine cracks or pinholes occur in the innermost heat-sealing resin layer, current may flow between the aluminum alloy foil of the electrical storage device packaging material and the external terminal via the electrolyte that has permeated the heat-sealing resin layer, potentially causing alloy corrosion of the aluminum alloy foil with lithium ions in the electrolyte (particularly, if the aluminum alloy foil and the negative electrode terminal are short-circuited via the electrolyte, the aluminum alloy foil is likely to corrode). Corrosion of the aluminum alloy foil can cause problems such as expansion of the aluminum alloy foil, leading to deterioration of the performance of the electrical storage device.

[0010] Furthermore, when sealing an electricity storage device element, a heat-sealable resin layer is heat-sealed by applying high temperature and high pressure to the electricity storage device exterior material using a metal plate, etc. However, applying high temperature and high pressure to the electricity storage device exterior material causes a problem in that the insulating properties of the electricity storage device exterior material are reduced.

[0011] Under these circumstances, an object of the present disclosure is to provide an exterior packaging material for an electricity storage device, which is formed by laminating at least a base material layer, a barrier layer including an aluminum alloy foil layer, and a heat-sealable resin layer in this order, and which has excellent formability, effectively suppresses corrosion of the aluminum alloy foil when current is passed through the material with an electrolyte attached, and further has improved insulation properties. [Means for solving the problem]

[0012] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. Specifically, they conducted extensive research on the composition of aluminum alloy foil used in the barrier layer of a packaging material for an electricity storage device, and found that by setting the Mg and Fe contents within a predetermined range, high formability of the packaging material for an electricity storage device can be ensured and corrosion can be effectively suppressed when electricity is passed through the packaging material with an electrolyte attached. Furthermore, the inventors of the present disclosure also found that insulating properties can be improved by using the aluminum alloy foil for the barrier layer and laminating an adhesive layer formed from a cured product of a resin composition containing a curable resin between the barrier layer and the heat-sealable resin layer.

[0013] The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects. The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the barrier layer contains an aluminum alloy foil having a composition of Fe: 0.2% by mass or more and 2.0% by mass or less, and Mg: 0.1% by mass or more and 5.0% by mass or less, The adhesive layer is formed from a cured product of a resin composition containing a curable resin. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide an electrical storage device packaging material having at least a base material layer, a barrier layer including an aluminum alloy foil layer, and a heat-sealable resin layer laminated in this order, which has excellent formability, effectively suppresses corrosion of the aluminum alloy foil when current is passed through the material with an electrolyte solution attached, and has improved insulation. The present disclosure can also provide a method for manufacturing the electrical storage device packaging material, and an electrical storage device. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 2] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 3] 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 4] FIG. 2 is a schematic diagram for explaining a method for evaluating corrosion resistance in the examples. [Figure 5] FIG. 2 is a schematic diagram showing crystal grains and second-phase particles in a cross section of an aluminum alloy foil in the thickness direction. [Figure 6] 1 is a microscope image of the surface of an aluminum alloy foil observed after evaluation of corrosion resistance, showing an example in which corrosion is suitably suppressed. [Figure 7] 1 is a microscope image of the surface of an aluminum alloy foil observed after evaluating corrosion resistance, showing an example in which corrosion is not sufficiently suppressed. [Figure 8] FIG. 1 is a diagram showing the planar shape of a square punch used in a limit forming height test in an example of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] The packaging material for an electricity storage device of the present disclosure is composed of a laminate having at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the barrier layer containing an aluminum alloy foil satisfying a composition of Fe: 0.2% by mass to 2.0% by mass and Mg: 0.1% by mass to 5.0% by mass, and the adhesive layer is formed of a cured product of a resin composition containing a curable resin. The packaging material for an electricity storage device of the present disclosure has this configuration, which provides excellent formability, effectively suppresses corrosion of the aluminum alloy foil when current is applied with an electrolyte solution attached, and also improves insulation.

[0017] The exterior packaging material for an electricity storage device, its manufacturing method, and the electricity storage device of the present disclosure will be described in detail below. In this specification, a numerical range indicated by "to" means "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0018] 1. Exterior materials for energy storage devices As shown in FIG. 1 , for example, the electrical storage device packaging material 10 of the present disclosure is composed of a laminate including a base material layer 1, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin layer 4 in this order. In the electrical storage device packaging material 10, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electrical storage device using the electrical storage device packaging material 10 and an electrical storage device element, the electrical storage device element is housed in a space formed by heat-sealing the peripheral portions of the electrical storage device packaging material 10 with the heat-sealable resin layers 4 of the electrical storage device packaging material 10 facing each other. In the laminate constituting the electrical storage device packaging material 10 of the present disclosure, with the barrier layer 3 as the reference, the heat-sealable resin layer 4 side relative to the barrier layer 3 is the inner side, and the base material layer 1 side relative to the barrier layer 3 is the outer side.

[0019] The barrier layer 3 of the electrical storage device packaging material of the present disclosure contains aluminum alloy foil. That is, the barrier layer 3 of the electrical storage device packaging material of the present disclosure can be composed of aluminum alloy foil. An electrical storage device packaging material of the present disclosure using aluminum alloy foil satisfying a predetermined composition described below has excellent formability and effectively suppresses corrosion of the aluminum alloy foil. Furthermore, the adhesive layer of the electrical storage device packaging material of the present disclosure is formed from a cured product of a resin composition containing a curable resin. The electrical storage device packaging material of the present disclosure can improve the insulation properties of the electrical storage device packaging material due to the synergistic effect of the adhesive layer 5 and the barrier layer (aluminum alloy foil).

[0020] 1 to 3, the packaging material 10 for an electricity storage device may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of increasing the adhesion between these layers. Furthermore, as shown in FIG. 3, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-sealable resin layer 4 side), if necessary.

[0021] The thickness of the laminate constituting the electricity storage device packaging material 10 is not particularly limited, but from the viewpoint of cost reduction, improving energy density, etc., it is, for example, 190 μm or less, preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the electricity storage device packaging material to protect the electricity storage device elements, the thickness of the laminate constituting the electricity storage device packaging material 10 is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the laminate constituting the packaging material 10 for an electricity storage device include, for example, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, with about 60 to 155 μm being particularly preferred.

[0022] In the electrical storage device packaging material 10, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 (which is provided as needed), the barrier layer 3, the adhesive layer 5, the heat-sealable resin layer 4, and the surface coating layer 6 (which is provided as needed) to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device packaging material 10 of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0023] In the packaging material for an electricity storage device, the MD (Machine Direction) and TD (Transverse Direction) of the barrier layer 3 described below can usually be determined during the manufacturing process. When the barrier layer 3 is made of an aluminum alloy foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Furthermore, during the manufacturing process of a laminate, the MD of the laminate usually coincides with the RD of the metal foil, so the MD of the laminate can be identified by observing the surface of the metal foil of the laminate and identifying the rolling direction (RD) of the metal foil. Furthermore, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be identified.

[0024] Furthermore, when the MD of the electrical storage device packaging material cannot be identified due to the rolling marks on the aluminum alloy foil, it can be identified by the following method. One method for confirming the MD of an electrical storage device packaging material is to observe the cross section of the heat-sealable resin layer of the electrical storage device packaging material using an electron microscope to confirm the sea-island structure. In this method, the direction parallel to the cross section in which the average diameter of the island shapes in the direction perpendicular to the thickness direction of the heat-sealable resin layer is the largest can be determined as the MD. Specifically, the sea-island structure is confirmed by observing the longitudinal cross section of the heat-sealable resin layer and each cross section at an angle of 10 degrees from the direction parallel to the longitudinal cross section (a total of 10 cross sections) using an electron microscope. Next, the shape of each individual island is observed in each cross section. For each island shape, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealable resin layer to the rightmost end in the perpendicular direction is defined as the diameter y. For each cross section, the average of the diameters y of the top 20 island shapes in descending order of diameter y is calculated. The direction parallel to the cross section where the average diameter y of the island shape was the largest was determined to be the MD.

[0025] Each layer that forms the exterior material for an electricity storage device [Base material layer 1] In the present disclosure, the substrate layer 1 is a layer provided for the purpose of allowing the packaging material for an electricity storage device to function as a substrate. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

[0026] There are no particular limitations on the material forming the base layer 1, as long as it functions as a base, i.e., has at least insulating properties. The base layer 1 can be formed using, for example, a resin, which may contain additives described below.

[0027] When the base layer 1 is formed of a resin, the base 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. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Examples of methods for applying a resin include roll coating, gravure coating, and extrusion coating.

[0028] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins or a modified version of the copolymer. Furthermore, it may also be a mixture of these resins.

[0029] Of these, preferred resins for forming the base layer 1 include polyester and polyamide.

[0030] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

[0031] 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; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain structural units derived from terephthalic acid and / or isophthalic acid; and aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); polyamides copolymerized with a lactam component or an isocyanate component such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and polyamides such as copolymers of these copolymers. These polyamides may be used singly or in combination of two or more.

[0032] The base layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably includes at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably includes at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and even more preferably includes at least one of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polybutylene terephthalate film, a biaxially oriented nylon film, and a biaxially oriented polypropylene film.

[0033] The base material layer 1 may be a single layer, or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base material layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base material layer 1.

[0034] Specific examples of laminates of two or more resin films in the base layer 1 include laminates of polyester film and nylon film, laminates of two or more nylon films, and laminates of two or more polyester films. Preferably, laminates of stretched nylon film and stretched polyester film, laminates of two or more stretched nylon films, and laminates of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred. 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. Furthermore, when the base layer 1 is a laminate of two or more resin films, it is preferred that the polyester resin film be located as the outermost layer of the base layer 1, because polyester resins are less likely to discolor when an electrolyte solution adheres to their surface.

[0035] When the base layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include the same adhesives as those exemplified for adhesive layer 2 described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, a polyurethane adhesive is preferably used as the adhesive. In this case, the thickness of the adhesive may be, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film before lamination. Examples of the anchor coat layer include the same adhesives as those exemplified for adhesive layer 2 described below. In this case, the thickness of the anchor coat layer may be, for example, about 0.01 to 1.0 μm.

[0036] Furthermore, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and the interior of the base material layer 1. Only one type of additive may be used, or two or more types may be mixed and used.

[0037] In the present disclosure, from the viewpoint of improving the formability of the exterior material for an electrical storage device, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, and N,N'-distearyl sebacic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide. Specific examples of fatty acid ester amides include stearamidoethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

[0038] When a lubricant is present on the surface of the base layer 1, the amount of the lubricant is not particularly limited, but is preferably about 3 mg / m 2 or more, more preferably 4 to 15 mg / m 2 approximately, more preferably 5 to 14 mg / m 2 The degree of

[0039] The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1.

[0040] The thickness of the base layer 1 is not particularly limited as long as it functions as a base, but may be, for example, about 3 to 50 μm, and preferably about 10 to 35 μm. When the base 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.

[0041] [Adhesive layer 2] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as needed for the purpose of increasing the adhesion between them.

[0042] The adhesive layer 2 is formed from an adhesive capable of bonding the base material layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot pressure type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

[0043] Specific examples of adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin-based resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected appropriately from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional groups of the adhesive components.

[0044] Examples of polyurethane adhesives include polyurethane adhesives containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, as the polyol compound, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit. Forming the adhesive layer 2 from a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, preventing peeling of the base layer 1 even when the electrolyte adheres to the side surface.

[0045] Furthermore, in the case of an all-solid-state battery exterior material, the adhesive layer 2 is preferably formed of a cured product of a resin composition containing at least one of polyester and polycarbonate, and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound, similar to the adhesive layer 5 described below. This prevents delamination between the base layer and the barrier layer in a high-temperature environment in the all-solid-state battery exterior material. Details of the resin composition in the adhesive layer 2 are the same as those in the adhesive layer 5.

[0046] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. When the adhesive layer 2 contains a colorant, the exterior material for an electricity storage device can be colored. Known colorants such as pigments and dyes can be used as the colorant. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0047] The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments, while examples of inorganic pigments include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and other examples include finely powdered mica and fish scale foil.

[0048] Among colorants, carbon black is preferred in order to give the exterior appearance of the electrical storage device packaging material a black color, for example.

[0049] The average particle size of the pigment is not particularly limited and may be, for example, about 0.05 to 5 μm, and preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured with a laser diffraction / scattering particle size distribution measuring device.

[0050] The content of the pigment in the adhesive layer 2 is not particularly limited as long as it colors the packaging material for an electricity storage device, and may be, for example, about 5 to 60 mass %, and preferably 10 to 40 mass %.

[0051] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3 together, but the lower limit is, for example, about 1 μm or more, or about 2 μm or more, and the upper limit is about 10 μm or less, or about 5 μm or less, and preferred ranges are about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, or about 2 to 5 μm.

[0052] [Colored layer] The colored layer is a layer (not shown) that is provided between the base material layer 1 and the barrier layer 3 as needed. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Alternatively, a colored layer may be provided on the outside of the base material layer 1. By providing a colored layer, the packaging material for an electricity storage device can be colored.

[0053] The colored layer can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1, the surface of the adhesive layer 2, or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

[0054] Specific examples of the colorant contained in the colored layer include the same as those exemplified in the section [Adhesive layer 2].

[0055] [Barrier layer 3] In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the penetration of moisture.

[0056] The barrier layer 3 of the packaging material for an electricity storage device according to the present disclosure contains an aluminum alloy foil.

[0057] The aluminum alloy foil includes an aluminum alloy foil that satisfies the composition of Fe (iron): 0.2% by mass to 2.0% by mass and Mg (magnesium): 0.1% by mass to 5.0% by mass. The main component of the aluminum alloy foil is Al (aluminum), and for example, 92.10% by mass or more is constituted by aluminum. The aluminum alloy foil preferably contains Si (silicon). The silicon content is preferably about 0.50% by mass or less.

[0058] The aluminum alloy foil may contain other components in addition to Fe, Mg, and Al. Examples of the other components include inevitable impurities such as Si (silicon), Mn (manganese), Cu (copper), Cr (chromium), and Zn (zinc). The inevitable impurities in the aluminum alloy foil are, for example, 0.10% by mass or less individually and 0.40% by mass or less in total. The other components may be one type or two or more types.

[0059] In aluminum alloy foil, Fe crystallizes as Al-Fe intermetallic compounds during casting. If the size of these compounds is large, they become recrystallization sites during annealing, thereby refining the recrystallized grains. If the Fe content is below the lower limit (0.2 mass%), the distribution density of coarse intermetallic compounds decreases, the grain refinement effect is reduced, and the final grain size distribution becomes non-uniform. If the Fe content exceeds the upper limit (2.0 mass%), the grain refinement effect saturates or even decreases. Furthermore, the size of the Al-Fe intermetallic compounds formed during casting becomes too large, resulting in reduced elongation and rollability of the aluminum alloy foil. For these reasons, the Fe content is set to the above range of 0.2 mass% to 2.0 mass%. For the same reasons, the Fe content is preferably set to a lower limit of 0.5 mass%, and more preferably to a lower limit of 1.0 mass% and an upper limit of 1.8 mass%.

[0060] In aluminum alloy foils, Mg dissolves in aluminum and can increase the strength of the foil through solid-solution strengthening. Furthermore, because Mg dissolves readily in aluminum, even when Mg is added together with Fe, there is little risk of coarsening intermetallic compounds and reducing formability and rollability. If the Mg content is below the lower limit (0.1% by mass), the strength improvement is insufficient. If the Mg content exceeds the upper limit (5.0% by mass), the aluminum alloy foil becomes hard, resulting in reduced rollability and formability. A particularly preferred lower limit is 0.5% by mass. If the Mg content exceeds 5.0% by mass, the aluminum alloy foil becomes hard and its formability and rollability deteriorate, but an aluminum alloy foil with extremely high strength can be obtained. It is desirable to set the Mg content in the range of more than 0.5% by mass to 4.5% by mass. Furthermore, adding Mg improves the corrosion resistance of the exterior material for an electric storage device to the electrolyte. Although the details of the mechanism are not clear, the greater the amount of Mg added, the less likely the aluminum alloy foil is to react with lithium and other elements in the electrolyte, thereby suppressing pulverization and the formation of through-holes in the aluminum alloy foil.

[0061] Although trace amounts of Si are sometimes added to aluminum alloy foils to increase their strength, in the present disclosure, a Si content of 0.5% by mass or less reduces the size of Al-Fe-Si intermetallic compounds formed during casting, thereby improving the elongation and formability of the aluminum alloy foil. Therefore, even when the aluminum alloy foil is thin, fracture originating from the intermetallic compounds is less likely to occur, and rollability is improved. Furthermore, by not adding a large amount of Si to an alloy with a high Mg content, the amount of Mg-Si precipitates formed is reduced, which reduces the likelihood of a decrease in rollability or the amount of Mg dissolved, thereby preventing a decrease in strength. For the same reason, it is desirable to limit the Si content to 0.2% by mass or less. The lower limit of the Si content is preferably 0.001% by mass, more preferably 0.005% by mass. Note that a lower Si content tends to improve formability, rollability, grain refinement, and ductility.

[0062] Aluminum alloy foil may contain inevitable impurities such as Cu and Mn. The content of each of these impurities is preferably, for example, 0.1% by mass or less. Note that, in the present disclosure, the upper limit of the content of the inevitable impurities is not limited to the above-mentioned numerical values. However, since Mn is difficult to dissolve in aluminum, unlike Mg, it is not expected to significantly increase the strength of the aluminum alloy foil by solid solution strengthening. Furthermore, adding a large amount of Mn to an alloy with a high Fe content increases the risk of coarsening of intermetallic compounds and the formation of giant Al-Fe-Mn intermetallic compounds, which may result in reduced rollability and formability. Therefore, the Mn content is preferably 0.1% by mass or less. The Mn content is more preferably 0.08% by mass or less. The lower limit of the Mn content is preferably 0.001% by mass, more preferably 0.005% by mass.

[0063] In the present disclosure, from the viewpoint of providing an exterior material for an electricity storage device that has excellent formability and that is effectively inhibited from corrosion when current is passed through it with an electrolyte attached, the aluminum alloy foil preferably satisfies a composition of Mn (manganese): 0.1 mass % or less, more preferably a composition of Mn: 0.01 mass % or more and 0.1 mass % or less, and even more preferably a composition of Mn: 0.01 mass % or more and 0.08 mass % or less.

[0064] The preferred composition and properties of the aluminum alloy foil will now be described in more detail.

[0065] ·Fe: 0.2 mass% or more and 2.0 mass% or less Fe crystallizes as Al-Fe intermetallic compounds during casting, and if the size of these compounds is large, they become recrystallization sites during annealing, thereby refining the recrystallized grains. If the Fe content is below the lower limit, the distribution density of coarse intermetallic compounds decreases, the effect of grain refinement is reduced, and the final grain size distribution becomes non-uniform. If the Fe content exceeds the upper limit, the effect of grain refinement saturates or even decreases, and the size of the Al-Fe intermetallic compounds formed during casting becomes very large, resulting in reduced elongation and rollability of the foil. For this reason, the Fe content is set within the above range. For the same reasons, the lower limit of the Fe content is preferably 0.5% by mass, and for the same reasons, the lower limit of the Fe content is more preferably 1.0% by mass and the upper limit is more preferably 1.8% by mass.

[0066] ·Mg: 0.1 mass% or more and 5.0 mass% or less Mg dissolves in aluminum and can increase the strength of soft foils through solid-solution strengthening. Furthermore, because Mg dissolves easily in aluminum, even when it is contained together with Fe, there is little risk of coarsening intermetallic compounds and reducing formability and rollability. If the Mg content is below the lower limit, the improvement in strength becomes insufficient, while if it exceeds the upper limit, the aluminum alloy foil becomes hard, resulting in reduced rollability and formability. A particularly preferred range is 0.5% by mass or more and 5.0% by mass or less. It has also been confirmed that adding Mg improves corrosion resistance against the electrolyte of lithium-ion secondary batteries. Although the details of the mechanism are not clear, the more Mg added, the less likely the aluminum alloy foil is to react with lithium in the electrolyte, which can prevent the aluminum alloy foil from pulverizing and the formation of through holes. Although formability is slightly reduced, a lower Mg limit of 0.5 mass% is desirable, especially when a clear improvement in corrosion resistance is expected.

[0067] Preferably, Si: 0.5 mass% or less Although trace amounts of Si may be added to enhance foil strength, in the present disclosure, a content of 0.5% or less reduces the size of Al-Fe-Si intermetallic compounds generated during casting, improving foil elongation and formability. Even when the foil is thin, fracture originating from the intermetallic compounds is unlikely to occur, improving rollability. Therefore, a content of 0.5% by mass or less is preferred. Furthermore, not adding a large amount of Si reduces the amount of Mg-Si precipitates generated, making it less likely to cause a decrease in rollability or the amount of Mg in solid solution, and therefore less likely to result in a decrease in strength. For the same reason, it is desirable to limit the Si content to 0.2% by mass or less. The lower the Si content, the better the formability, rollability, grain refinement, and ductility tend to be.

[0068] Inevitable impurities In addition, unavoidable impurities such as Cu and Mn may be contained. The content of these impurities is preferably 0.1 mass% or less. However, in the present disclosure, the upper limit of the content of the unavoidable impurities is not limited to the above numerical values. However, because Mn is difficult to dissolve in aluminum, unlike Mg, it cannot be expected to significantly increase the strength of soft foils through solid solution strengthening. Furthermore, adding large amounts of Mn to alloys with a high Fe content increases the risk of coarsening of intermetallic compounds and the formation of large Al-Fe-Mn intermetallic compounds, which can lead to reduced rollability and formability. Therefore, it is desirable to limit the Mn content to 0.1% by mass or less.

[0069] The texture has an orientation density of 15 or less for the copper orientation and R orientation. The texture has a significant effect on the mechanical properties and formability of the foil. To achieve good formability, it is desirable to keep the density of the copper orientation and the R orientation below 15, and more preferably below 10.

[0070] The surface Mg concentration is 5.0 atomic percent or more and the oxide film thickness is 80 Å or more (Mg: 0.1 mass% to 1.5 mass%) Although the details of the mechanism are unclear, it has been confirmed that the Mg concentration and oxide film thickness on the foil surface contribute to corrosion resistance against the electrolyte of lithium-ion secondary batteries. A high Mg concentration on the foil surface and the formation of a thick oxide film improve corrosion resistance. For this reason, when the Mg content is 0.1% by mass or more and 1.5% by mass or less, it is desirable for the Mg concentration on the aluminum foil surface to be 5.0 atomic percent or more and the oxide film thickness to be 80 Å or more. More preferably, the surface Mg concentration is 15.0 atomic percent or more and the oxide film thickness is 200 Å or more. Even more preferably, the surface Mg concentration is 20.0 atomic percent or more.

[0071] The Mg concentration on the surface is 15.0 atomic percent or more, and the oxide film thickness is 120 Å or more (Mg: more than 1.5 mass% and 5.0 mass% or less) As mentioned above, although the details of the mechanism are unclear, it has been confirmed that the Mg concentration and oxide film thickness on the foil surface contribute to corrosion resistance against the electrolyte of lithium-ion secondary batteries. A high Mg concentration on the foil surface and the formation of a thick oxide film improve corrosion resistance. Therefore, when the Mg content is greater than 1.5 mass% and less than or equal to 5.0 mass%, it is desirable for the Mg concentration on the aluminum foil surface to be 15.0 atomic percent or more and the oxide film thickness to be 120 Å or more. More preferably, the surface Mg concentration is 20.0 atomic percent or more and the oxide film thickness is 220 Å or more. Even more preferably, the surface Mg concentration is 25.0 atomic percent or more.

[0072] When the length of a high-angle grain boundary per unit area measured by backscattered electron diffraction is L1 and the length of a low-angle grain boundary is L2, L1 / L2>3.0 The ratio of high-angle grain boundaries (HAGBs) to low-angle grain boundaries (LAGBs) in the recrystallized grain structure after annealing affects the elongation and formability of the foil. Reducing the ratio of LAGBs in the recrystallized grain structure after final annealing suppresses localized deformation and improves elongation and formability. Therefore, by increasing the ratio of HAGBs with L1 / L2 > 3.0, high elongation and good formability can be expected. More preferably, L1 / L2 > 5.0.

[0073] Tensile strength: 110 MPa to 180 MPa (Mg: 0.1% to 1.5% by mass) When Mg is 0.1% by mass or more and 1.5% by mass or less, a tensile strength of 110 MPa or more is required to dramatically improve impact resistance and puncture strength compared to existing foils such as JIS A8079 and 8021. A tensile strength of 180 MPa or less is preferred. Tensile strength can be achieved by composition selection and optimization of grain size.

[0074] Tensile strength: 180 MPa or more (Mg: over 1.5% by mass and up to 5.0% by mass) When the Mg content is more than 1.5% by mass and not more than 5.0% by mass, a tensile strength of 180 MPa or more is preferable in order to dramatically improve impact resistance and puncture strength compared to existing foils such as JIS A8079 and 8021. For the same reason, a tensile strength of 200 MPa or more is desirable. However, since formability decreases as the tensile strength increases, it is better to keep the tensile strength low when formability is important. As mentioned above, tensile strength can be achieved by optimizing composition and grain size.

[0075] Breaking elongation: 10% or more (Mg: 0.1% by mass or more and 1.5% by mass or less) The effect of elongation on formability varies greatly depending on the forming method, and formability is not determined solely by elongation. In the stretching process often used for aluminum packaging materials, the higher the elongation of the aluminum alloy foil, the better the formability. When the Mg content is 0.1% by mass or more and 1.5% by mass or less, it is desirable for the aluminum alloy foil to have an elongation of 10% or more. The elongation properties can be achieved by selecting the composition and by reducing the grain size.

[0076] Breaking elongation: 15% or more (Mg: over 1.5% by mass and up to 5.0% by mass) As mentioned above, the effect of elongation on formability varies greatly depending on the forming method, and formability is not determined solely by elongation. However, in the stretching process that is often used for aluminum packaging materials, the higher the elongation of the aluminum alloy foil, the more advantageous the formability is. When the Mg content is more than 1.5% by mass and not more than 5.0% by mass, it is desirable for the aluminum alloy foil to have an elongation of 15% or more. As mentioned above, the elongation properties can be achieved by selecting the composition and by refining the grain size.

[0077] ·Average grain size: 25μm or less The fine grain size of soft aluminum alloy foil can suppress surface roughness during deformation, and high elongation and therefore high formability can be expected. The effect of grain size becomes greater as the foil thickness becomes thinner. To achieve high elongation properties and the resulting high formability, it is desirable for the average grain size to be 25 μm or less. The average crystal grain size can be achieved by selecting the composition and optimizing the manufacturing conditions such as homogenization treatment and cold rolling reduction.

[0078] Preferred compositions of the aluminum alloy foil include those satisfying the compositions of the following specific examples 1 and 2.

[0079] Example 1 Si: 0.1% by mass or more and 0.5% by mass or less, Fe: 0.2% by mass or more and 2.0% by mass or less, Mg: 0.1% by mass or more and 5.0% by mass or less, Mn: 0.05% by mass or more and 0.1% by mass or less, Cu: 0.0% by mass or more and 0.1% by mass or less, Cr: 0.0% by mass or more and 0.1% by mass or less, Zr: 0.0% by mass or more and 0.1% by mass or less, other unavoidable impurities are each 0.05% by mass or less and 0.15% by mass or less in total, and the balance is Al.

[0080] Example 2 More preferably, the aluminum alloy foil contains 0.1% by mass or more and 0.5% by mass or less of Si, 0.2% by mass or more and 2.0% by mass or less of Fe, 0.1% by mass or more and 5.0% by mass or less of Mg, 0.1% by mass or more and 0.05% by mass or less of Mn, 0.1% by mass or more and 0.05% by mass or less of Cr, 0.0% by mass or less of Zr, and other unavoidable impurities each containing 0.05% by mass or less and 0.15% by mass or less in total, with the balance being Al. Also, the aluminum alloy foil contains 0.5% by mass or less of Si, 0.2% by mass or more and 2.0% by mass or less of Fe, 0.1% by mass or more and 5.0% by mass or less of Mg, 0.1% by mass or more and 0.05% by mass or less of Cr, 0.0% by mass or less of Zr, and other unavoidable impurities each containing 0.05% by mass or less and 0.15% by mass or less in total, with the balance being Al.

[0081] To dramatically improve impact resistance and puncture strength compared to existing aluminum alloy foils such as JIS A8079 and 8021, the tensile strength of the aluminum alloy foil is preferably 100 MPa or more, more preferably 200 MPa or more. The upper limit of the tensile strength is preferably 350 MPa. Furthermore, the tensile strength is preferably 200 MPa or more and 350 MPa or less, more preferably 200 MPa or more and 310 MPa or less. However, since formability decreases as the tensile strength increases, it is better to keep the tensile strength low when formability is important. From the viewpoint of improving the formability of the exterior material for an electric storage device, the aluminum alloy foil preferably has a tensile strength of 100 MPa or more and 180 MPa or less, as measured on a JIS No. 5 test piece in accordance with JIS Z2241:2011. Specifically, the tensile strength is measured by the method described in the Examples. The tensile strength of the aluminum alloy foil can be achieved by selecting the composition and optimizing the crystal grain size.

[0082] The effect of elongation on the formability of aluminum alloy foil varies greatly depending on the forming method, and formability is not determined solely by elongation. When stretching aluminum alloy foil for packaging materials, the higher the elongation of the aluminum alloy foil, the more advantageous the forming. The aluminum alloy foil has a breaking elongation measured on a JIS No. 5 test piece in accordance with JIS Z2241:2011, preferably 10% or more, more preferably 15% or more. The upper limit of breaking elongation is preferably 40%, more preferably 30%. Furthermore, breaking elongation is preferably 0% to 40%, more preferably 15% to 40%, and even more preferably 15% to 30%. Specifically, the breaking elongation is measured by the method described in the Examples. The elongation characteristics of aluminum alloy foil can be achieved by selecting the composition and refining the crystal grain size.

[0083] An aluminum alloy foil satisfying the above-described composition and properties can be produced by adjusting the composition based on an aluminum alloy having a composition in the A5000 series of alloy numbers in JIS H4000:2014, and then performing the steps of melting, homogenization, hot rolling, cold rolling, intermediate annealing, cold rolling, and final annealing, similar to known methods for producing aluminum alloy foils. Regarding the production conditions of the aluminum alloy foil, reference can be made to the description in, for example, JP 2005-163077 A. Furthermore, the chemical components contained in the aluminum alloy foil are analyzed by analytical tests specified in JIS H4160-1994.

[0084] For example, an aluminum alloy ingot having a composition of 0.2% by mass or more and 2.0% by mass or less of Fe and 0.1% by mass or more and 5.0% by mass or less of Mg is cast by a conventional method such as semi-continuous casting, and the obtained ingot is subjected to a homogenization treatment at 480 to 540°C for 6 to 12 hours.

[0085] Generally, homogenization treatment of aluminum materials is carried out at 400 to 600°C for a long period of time (for example, about 12 hours), but considering the grain refinement achieved by adding Fe as in the present disclosure, heat treatment at 480 to 540°C for 6 hours or more is desirable. Temperatures below 480°C result in insufficient grain refinement, while temperatures above 540°C lead to grain coarsening. Treatment times of less than 6 hours result in insufficient homogenization.

[0086] After the homogenization treatment, the aluminum alloy sheet is hot-rolled to obtain a desired thickness. Hot-rolling can be performed by a conventional method, but the coiling temperature in the hot-rolling is preferably equal to or higher than the recrystallization temperature, specifically, 300°C or higher. Temperatures below 300°C are undesirable because they cause precipitation of fine Al-Fe intermetallic compounds of 0.3 μm or less, and also cause recrystallized grains and fibrous grains to coexist after hot-rolling, resulting in non-uniform grain sizes after intermediate annealing and final annealing, which may result in reduced elongation properties.

[0087] After the hot rolling, cold rolling, intermediate annealing, and final cold rolling are performed to reduce the thickness to 5 to 100 μm, thereby obtaining the aluminum alloy foil of the present disclosure. The final cold rolling reduction is preferably 90% or more.

[0088] Intermediate annealing during cold rolling is not necessary, but may be performed in some cases. There are two types of intermediate annealing: batch annealing, in which the coil is placed in a furnace and held there for a certain period of time, and continuous annealing line (hereafter referred to as CAL annealing), in which the material is rapidly heated and cooled. When intermediate annealing is added, either method is acceptable, but CAL annealing is preferred if the aim is to refine the crystal grains and increase strength, and batch annealing is preferred if formability is prioritized.

[0089] For example, in batch annealing, conditions such as 300 to 400°C for 3 hours or more can be adopted, and in CAL annealing, conditions such as a temperature rise rate of 10 to 250°C / sec, a heating temperature of 400 to 550°C, no holding time or a holding time of 5 seconds or less, and a cooling rate of 20 to 200°C / sec can be adopted. However, the present disclosure is not limited to specific conditions such as whether intermediate annealing is performed or not.

[0090] After foil rolling, final annealing is performed to produce a soft foil. Final annealing after foil rolling is generally performed at 250°C to 400°C. However, to further enhance the corrosion resistance effect of Mg, it is desirable to hold the foil at a high temperature of 350°C or higher for 5 hours or more.

[0091] If the final annealing temperature is too low, the softening will be insufficient, and the Mg will not be concentrated sufficiently on the foil surface, which may result in reduced corrosion resistance. If the temperature exceeds 400°C, the Mg will be excessively concentrated on the foil surface, causing discoloration of the foil and changes in the properties of the oxide film, resulting in microcracks and reduced corrosion resistance. If the final annealing time is less than 5 hours, the effect of the final annealing will be insufficient.

[0092] A preferred method for preparing the aluminum alloy foil will be described in more detail below. An aluminum alloy ingot having a composition containing 0.2 to 2.0 mass% Fe, 0.1 to 5.0 mass% Mg, the balance being Al and unavoidable impurities, and optionally 0.1 mass% or less Mn, is cast by a conventional method such as semi-continuous casting, and the resulting ingot is subjected to a homogenization treatment at 480 to 540°C for 6 to 12 hours.

[0093] Homogenization: 450~540℃ The homogenization process aims to eliminate microsegregation within the ingot and adjust the distribution of intermetallic compounds, and is a very important process for ultimately obtaining the desired crystal grain structure. Generally, homogenization of aluminum materials is carried out at 400 to 600°C for a long period of time, but in the present invention, it is necessary to take into consideration the refinement of crystal grains by adding Fe. In homogenization treatment, temperatures below 450°C result in insufficient Fe precipitation, leading to grain coarsening during final annealing and an increased rate of in-situ recrystallization, resulting in an increased rate of LAGB, a decrease in L1 / L2, and concerns about reduced formability due to an increase in the orientation density of the copper and R orientations. Furthermore, temperatures above 550°C result in significant growth of precipitates, leading to grain coarsening during final annealing and reduced formability. The homogenization treatment time must be at least 3 hours. Precipitation is insufficient at temperatures below 3 hours, resulting in a decrease in the density of fine intermetallic compounds. A temperature of 480 to 520°C and a time of 5 hours or more are desirable.

[0094] After the homogenization treatment, the aluminum alloy sheet is hot-rolled to obtain a desired thickness. Hot-rolling can be performed by a conventional method, but the coiling temperature in the hot-rolling is preferably equal to or higher than the recrystallization temperature, specifically, 300°C or higher. Temperatures below 300°C are undesirable because they cause precipitation of fine Al-Fe intermetallic compounds of 0.3 μm or less, and also cause recrystallized grains and fibrous grains to coexist after hot-rolling, resulting in non-uniform grain sizes after intermediate annealing and final annealing, which may result in reduced elongation properties.

[0095] After the hot rolling, cold rolling, intermediate annealing, and final cold rolling are carried out to a thickness of 5 to 100 μm, thereby obtaining the aluminum alloy foil of the present invention. There are two types of intermediate annealing: batch annealing, in which the coil is placed in a furnace and held there for a certain period of time, and continuous annealing line (hereafter referred to as CAL annealing), in which the material is rapidly heated and cooled. Either method is acceptable when intermediate annealing is applied, but CAL annealing is preferable if the goal is to refine the crystal grains and increase strength. However, there is a concern that the texture will develop after the final cold rolling and final annealing, increasing the density of the copper orientation and R orientation and reducing formability, so if formability is a priority, batch annealing is preferable. For example, in batch annealing, conditions such as 300 to 400°C for 3 hours or more can be adopted, and in CAL annealing, conditions such as a temperature rise rate of 10 to 250°C / sec, a heating temperature of 400 to 550°C, no holding time or a holding time of 5 seconds or less, and a cooling rate of 20 to 200°C / sec can be adopted. However, the present invention is not limited to specific conditions such as whether intermediate annealing is performed or not.

[0096] Final cold rolling reduction: 84.0% to 97.0% The higher the final cold-rolling reduction from intermediate annealing to final thickness, the greater the amount of strain accumulated in the material, resulting in finer recrystallized grains after final annealing. This also has the effect of suppressing in-situ recrystallization, and improved formability is expected as the L1 / L2 ratio increases. Specifically, a final cold-rolling reduction of 84.0% or greater is desirable. However, if the final cold-rolling reduction is too high, there is concern that formability will decrease due to an increase in the orientation density of copper and R orientations even after final annealing. This also results in a decrease in L1 / L2. Therefore, a final cold-rolling reduction of 97.0% or less is desirable. Furthermore, if the final cold-rolling reduction is too low, there is concern that formability will decrease due to grain coarsening and a decrease in L1 / L2. For similar reasons, a more desirable final cold-rolling reduction range is 90.0% to 93.0%.

[0097] After the foil rolling, final annealing is performed to produce a soft foil. Final annealing after foil rolling is generally performed at 250°C to 400°C. However, to enhance the corrosion resistance effect of Mg, it is preferable to hold the foil at a high temperature of 300°C or higher for 5 hours or more, and 350°C to 400°C is even more preferable. If the final annealing temperature is low, softening will be insufficient, raising concerns about a decrease in L1 / L2 and an increase in the orientation density of the copper and R orientations. There is also concern that magnesium will not concentrate on the foil surface and the oxide film will not grow sufficiently, resulting in reduced corrosion resistance. If the temperature exceeds 400°C, magnesium will concentrate excessively on the foil surface, causing discoloration of the foil and changes in the properties of the oxide film, resulting in microcracks and reduced corrosion resistance. If the final annealing time is less than 5 hours, the effect of the final annealing will be insufficient.

[0098] The obtained aluminum alloy foil has a tensile strength of 110 MPa or more and 180 MPa or less and a breaking elongation of 10% or more when the Mg content is 0.1% by mass or more and 1.5% by mass or less, and a tensile strength of 180 MPa or more and a breaking elongation of 15% or more when the Mg content is more than 1.5% by mass and 5.0% by mass or less, at room temperature. The average crystal grain size is 25 μm or less.

[0099] In the present disclosure, as shown in the schematic diagram of Fig. 5, when any 100 second-phase particles 3b within the field of view of an optical microscope are examined in a cross section of the aluminum alloy foil (barrier layer 3) in the thickness direction, and the linear distance connecting the leftmost end of each second-phase particle 3b in the direction perpendicular to the thickness direction to the rightmost end in the direction perpendicular to the thickness direction is defined as diameter y, the average diameter y of the top 20 second-phase particles 3b in descending order of diameter y is preferably 10.0 µm or less. This makes it possible to provide an exterior material for an electricity storage device with excellent formability when the aluminum alloy foil is laminated on the exterior material for an electricity storage device and molded, even though the aluminum alloy foil is very thin, for example, having a thickness of about 85 µm or less, further about 50 µm or less, or even about 40 µm or less. Furthermore, in the present disclosure, the average diameter y of the second phase particles 3b in the aluminum alloy foil (barrier layer 3) is 10.0 μm or less, so that even when the thickness of the aluminum alloy foil is, for example, about 85 μm or less, further about 50 μm or less, or even about 40 μm or less, and the total thickness of the exterior material for an electricity storage device is as thin as the aforementioned thickness, pinholes and cracks are unlikely to occur during molding, and the exterior material has excellent moldability.

[0100] From the viewpoint of further improving moldability, the average diameter y is more preferably about 1.0 to 8.0 μm, and even more preferably about 1.0 to 6.0 μm. Note that, since Fig. 5 is a schematic diagram, the drawing is omitted and not all 100 second-phase particles 3b are drawn.

[0101] In the present disclosure, the second phase particles contained in the aluminum alloy foil refer to intermetallic compound particles present in the aluminum alloy, and are crystallized phase particles separated by rolling or precipitated phase particles precipitated during homogenization treatment or annealing.

[0102] When a cross section of an aluminum alloy foil in the thickness direction is observed with a scanning electron microscope (SEM), crystal grains usually have boundaries where multiple crystals meet. In contrast, second-phase particles usually have boundaries that form a single crystal. Furthermore, because the crystal grains and second-phase particles are in different phases, they are characterized by different colors in SEM images. Furthermore, when a cross section of an aluminum alloy foil layer in the thickness direction is observed with an optical microscope, only the second-phase particles appear black due to the difference in phase between the crystal grains and the second-phase particles, making observation easier.

[0103] From the viewpoint of further improving formability, the average crystal grain size in the aluminum alloy foil is preferably 25.0 μm or less, more preferably 20.0 μm or less, even more preferably 10.0 μm or less, and is preferably 1.0 μm or more, 3.0 μm or more, and more preferably 9.0 μm or more. Preferred ranges for the average crystal grain size include about 1.0 to 25.0 μm, about 1.0 to 20.0 μm, about 1.0 to 10.0 μm, about 3.0 to 25.0 μm, about 3.0 to 20.0 μm, about 3.0 to 10.0 μm, about 9.0 to 25.0 μm, about 9.0 to 20.0 μm, and about 9.0 to 10.0 μm. When the average crystal grain size in the aluminum alloy foil is 25.0 μm or less and the diameter y of the second-phase particles 3b is within the above range, the formability of the packaging material for an electricity storage device, which will be described later, can be further improved.

[0104] In the present disclosure, the average crystal grain size in an aluminum alloy foil is determined by observing a cross section of the aluminum alloy foil in the thickness direction with a scanning electron microscope (SEM), and for 100 aluminum alloy crystal grains 3a located within the field of view, the maximum diameter x is defined as the linear distance connecting the leftmost end of each crystal grain in the direction perpendicular to the thickness direction to the rightmost end of each crystal grain in the direction perpendicular to the thickness direction, as shown in the schematic diagram of Figure 5. Note that, because Figure 5 is a schematic diagram, the drawing of all 100 crystal grains 3a is omitted, and the drawing of all 100 crystal grains 3a is not performed.

[0105] The thickness of the aluminum alloy foil in the packaging material for an electricity storage device may be such that it at least functions as a barrier layer that prevents moisture from penetrating, with the lower limit being about 9 μm or more and the upper limit being about 200 μm or less. From the viewpoint of reducing the thickness of the exterior material for an electricity storage device, the upper limit of the thickness of the aluminum alloy foil is, for example, preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 45 μm or less, and particularly preferably about 40 μm or less; the lower limit is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more; and preferred ranges for the thickness include about 10 to 85 μm, about 10 to 50 μm, about 10 to 45 μm, about 10 to 40 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 45 μm, about 20 to 40 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 45 μm, and about 25 to 40 μm.

[0106] Furthermore, it is preferable that at least one side of the aluminum alloy foil be provided with a corrosion-resistant coating to inhibit dissolution and corrosion of the aluminum alloy foil. The aluminum alloy foil may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film formed on the surface of the aluminum alloy foil by, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing treatment, a nickel or chromium plating treatment, or a corrosion prevention treatment such as applying a coating agent, to provide the aluminum alloy foil with corrosion resistance. The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, the aluminum alloy foil may be formed in a single layer or in multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the metal foil surface is dissolved by a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Furthermore, when an aluminum alloy foil is provided with a corrosion-resistant coating, the corrosion-resistant coating is also included in the aluminum alloy foil.

[0107] The corrosion-resistant coating prevents delamination between the aluminum alloy foil and the base layer during molding of the exterior material for an electricity storage device, prevents dissolution and corrosion of the aluminum alloy foil surface and dissolution and corrosion of aluminum oxide present on the aluminum alloy foil surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and improves the adhesion (wettability) of the aluminum alloy foil surface, thereby preventing delamination between the base layer and the aluminum alloy foil during heat sealing and between the base layer and the aluminum alloy foil during molding.

[0108] Various corrosion-resistant coatings formed by chemical conversion treatments are known, including corrosion-resistant coatings containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution primarily composed of a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, or Zn (zinc) phosphate, or a mixture of these metal salts, or a treatment solution primarily composed of a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, using a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may be a polymer such as a phenolic resin or an acrylic resin, or may be a chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4): In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, an acrylic acid methacrylic acid ester copolymer, an acrylic acid maleic acid copolymer, an acrylic acid styrene copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. A derivative of polyacrylic acid, such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid, is particularly preferred. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, or an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. 1 and R 2 are the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. 1 and R 2Examples of the alkyl group represented by X and R include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. 1 and R 2 Examples of the hydroxyalkyl group represented by the formula (1) include a linear or branched alkyl group having 1 to 4 carbon atoms substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. 1 and R 2 The alkyl group and hydroxyalkyl group represented by the formula (1) may be the same or different. In the 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 the formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be prepared, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the formula (1) or (3), and then polycondensing the polymer with formaldehyde and an amine (R 1 R 2 NH) to the functional group (-CHNR 1 R 2 The aminated phenol polymers can be used singly or in combination of two or more.

[0114] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. The coating agent may further contain phosphoric acid or a phosphate salt, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol has rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the perspective of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant coating can be used alone or in combination of two or more. The liquid dispersion medium for the rare earth element oxide sol can be various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes composed of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of a compound having a functional group selected from an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphoric acid salt is preferably a condensed phosphoric acid or a condensed phosphate salt.

[0115] An example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of a barrier layer and baking the coating at 150°C or higher.

[0116] The corrosion-resistant coating may have a laminated structure, if necessary, by further laminating at least one of a cationic polymer and an anionic polymer, such as those mentioned above.

[0117] The composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

[0118] The amount of corrosion-resistant film formed on the surface of the aluminum alloy foil in the chemical conversion treatment is not particularly limited. For example, in the case of a coating-type chromate treatment, the amount of the corrosion-resistant film formed on the surface of the aluminum alloy foil is 2 It is desirable that the chromate compound is contained in an amount, in terms of chromium, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, the phosphorus compound in terms of phosphorus, and the aminated phenol polymer in an amount, in terms of phosphorus, of about 1.0 to 200 mg, preferably about 5.0 to 150 mg, per unit area.

[0119] The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesive strength with the barrier layer or the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry can reveal the thickness of the corrosion-resistant coating, for example, by measuring the thickness of the coating with secondary ions consisting of Ce, P, and O (e.g., Ce2PO4 + , CePO4 - At least one of the following ions may be present: Cr, P, and O secondary ions (e.g., CrPO2 + , CrPO4 - Peaks derived from at least one of the above are detected.

[0120] The chemical conversion treatment is carried out by applying a solution containing a compound used to form a corrosion-resistant coating to the surface of an aluminum alloy foil by bar coating, roll coating, gravure coating, immersion, or other methods, and then heating the aluminum alloy foil to a temperature of approximately 70 to 200°C. Furthermore, before subjecting the aluminum alloy foil to the chemical conversion treatment, the aluminum alloy foil may be subjected to a degreasing treatment using an alkali immersion method, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or other methods. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the aluminum alloy foil can be carried out more efficiently. Furthermore, by using an acid degreasing agent prepared by dissolving a fluorine-containing compound in an inorganic acid for the degreasing treatment, not only the metal foil can be degreased but also a passive metal fluoride can be formed. In such cases, only the degreasing treatment may be performed.

[0121] [Thermofusible resin layer 4] In the packaging material for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 corresponds to the innermost layer and is a layer (sealant layer) that exhibits the function of sealing the electricity storage device elements by heat-sealing the heat-sealable resin layers to each other when assembling the electricity storage device.

[0122] The resin constituting the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but resins containing a polyolefin skeleton, such as polyolefin and acid-modified polyolefin, are preferred. The presence of a polyolefin skeleton in the resin constituting the heat-sealable resin layer 4 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Furthermore, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak derived from maleic anhydride is detected at a wavenumber of 1760 cm. -1 Near and wave number 1780cm -1A peak derived from maleic anhydride is detected around . When the thermally adhesive resin layer 4 is a layer made of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0123] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0124] The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, preferred are cyclic alkenes, and more preferred are norbornene.

[0125] Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the above-mentioned polyolefins, copolymers of the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, and crosslinked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0126] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerizing or graft polymerizing an acid component onto the cyclic polyolefin. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

[0127] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0128] The thermally adhesive resin layer 4 may be formed of one type of resin alone or may be formed of a blend polymer of two or more types of resins. Furthermore, the thermally adhesive 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.

[0129] Furthermore, the packaging material 1 for an electricity storage device according to the present disclosure can be suitably used as a packaging material for an all-solid-state battery, and the melting point of the heat-sealable resin layer 4 of the packaging material for an all-solid-state battery is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and still more preferably 200 to 250°C.

[0130] Furthermore, examples of resins contained in the heat-sealable resin layer 4 of the all-solid-state battery exterior packaging material include the above-mentioned polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polyesters such as polyethylene terephthalate and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the all-solid-state battery exterior packaging material, the heat-sealable resin layer 4 is preferably formed from a polybutylene terephthalate film. Note that the polybutylene terephthalate film forming the heat-sealable resin layer 4 may be formed by laminating a previously prepared polybutylene terephthalate film with the adhesive layer 5, or the resin forming the polybutylene terephthalate film may be melt-extruded to form a film and then laminated with the adhesive layer 5.

[0131] The polybutylene terephthalate film may be a stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and is preferably an unstretched polybutylene terephthalate film.

[0132] The polybutylene terephthalate film preferably further contains an elastomer in addition to polybutylene terephthalate. The elastomer serves to ensure the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. Preferred elastomers include at least one thermoplastic elastomer selected from polyesters, polyamides, polyurethanes, polyolefins, polystyrenes, and polyethers, or thermoplastic elastomer copolymers thereof. The content of the elastomer in the polybutylene terephthalate film is not particularly limited as long as it ensures the durability of the polybutylene terephthalate film in high-temperature environments while increasing its flexibility. For example, the content is about 0.1% by mass or more, preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more, and even more preferably about 3.0% by mass or more. The content may be, for example, about 10.0% by mass or less, about 8.0% by mass or less, or about 5.0% by mass or less. Preferred ranges for the content include about 0.1 to 10.0 mass%, about 0.1 to 8.0 mass%, about 0.1 to 5.0 mass%, about 0.5 to 10.0 mass%, about 0.5 to 8.0 mass%, about 0.5 to 5.0 mass%, about 1.0 to 10.0 mass%, about 1.0 to 8.0 mass%, about 1.0 to 5.0 mass%, about 3.0 to 10.0 mass%, about 3.0 to 8.0 mass%, and about 3.0 to 5.0 mass%, etc.

[0133] In the all-solid-state battery packaging material, when the heat-sealable resin layer 4 is formed of two or more layers, at least one layer is formed of a polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the all-solid-state battery packaging material. Furthermore, the layer bonded to the adhesive layer 5 is preferably a polybutylene terephthalate film. When the heat-sealable resin layer 4 is formed of two or more layers, the layer not formed of a polybutylene terephthalate film may be formed of, for example, a polyolefin such as polypropylene or polyethylene, or an acid-modified polyolefin such as acid-modified polypropylene or acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments than polybutylene terephthalate, in the all-solid-state battery packaging material, the heat-sealable resin layer 4 is preferably formed solely of a polybutylene terephthalate film.

[0134] Furthermore, the heat-sealable resin layer 4 may contain a lubricant, etc., as necessary. When the heat-sealable 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. The lubricants may be used alone or in combination of two or more.

[0135] The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of the lubricant include those exemplified for the base layer 1. The lubricant may be used alone or in combination of two or more.

[0136] When a lubricant is present on the surface of the heat-sealable resin layer 4, the amount of the lubricant present is not particularly limited, but from the viewpoint of improving the formability of the packaging material for an electricity storage device, it is preferably 10 to 50 mg / m 2 about 15 to 40 mg / m 2 The degree of

[0137] The lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin constituting the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

[0138] The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it can heat-seal the heat-sealable resin layers to each other and function to seal the electricity storage device element, but may be, for example, about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-sealable resin layer 4 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0139] [Adhesive layer 5] In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 5 is a layer provided between the barrier layer 3 (or acid-resistant film) and the heat-sealable resin layer 4 in order to firmly bond them together.

[0140] The adhesive layer 5 is formed from a cured product of a resin composition containing a curable resin. The term "curable resin" refers to a resin that has curability, such as a thermosetting resin or an ionizing radiation-curable resin, and is, for example, one that does not have a clear melting peak temperature after curing. The resin composition used to form the adhesive layer 5 can be the same as the resin composition used in the adhesive exemplified for the adhesive layer 2. The adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-fusible resin layer 4. The presence of a polyolefin skeleton in the cured product of the resin composition constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry, and the analysis method is not particularly limited. Furthermore, when the cured product of the resin composition constituting the adhesive layer 5 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak at a wavenumber of 1760 cm is detected. -1 Near and wave number 1780cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0141] To more effectively exert the effects of the present invention, the adhesive layer 5 is preferably formed from a cured product of a resin composition containing an acid-modified polyolefin. Particularly preferred examples of the acid-modified polyolefin include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0142] Furthermore, from the viewpoint of more suitably exhibiting the effects of the present invention, the adhesive layer 5 is more preferably a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. In this case, the acid-modified polyolefin and the curing agent constitute a curable resin. Preferred examples of the acid-modified polyolefin include those listed above.

[0143] The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an 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. The adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, more preferably polyurethane and epoxy resin. A preferred polyester is, for example, an amide ester resin. Amide ester resins are generally produced by the reaction of a carboxyl group with an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. In addition, if unreacted compounds of curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, and epoxy resins remain in the adhesive layer 5, the presence of the unreacted compounds can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), etc.

[0144] Furthermore, from the viewpoint of further enhancing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C═N bond, and a COC bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C═N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a COC bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethane. Whether the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

[0145] The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates.

[0146] The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0147] The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Examples of commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0148] The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, in the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0149] An example of a compound having an epoxy group is an epoxy resin. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the 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 2,000, more preferably about 100 to 1,000, and even more preferably about 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0150] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. One type of epoxy resin may be used alone, or two or more types may be used in combination.

[0151] The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

[0152] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of two-component curing polyurethane.

[0153] The proportion of polyurethane in adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting adhesive layer 5. This effectively improves the adhesion between barrier layer 3 and adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as an electrolyte solution.

[0154] In addition, when the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0155] Furthermore, when the packaging material for an electricity storage device is a packaging material for an all-solid-state battery, the adhesive layer is preferably formed from a cured product of a resin composition containing at least one of a polyester and a polycarbonate and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound, whereby the packaging material for an all-solid-state battery is able to suppress delamination between the barrier layer and the heat-fusible resin layer in a high-temperature environment and also to exhibit high seal strength.

[0156] The polyester is preferably a polyester polyol. The polyester polyol is not particularly limited as long as it has an ester bond in the polymer main chain and a plurality of hydroxyl groups at the terminal or side chain. The polycarbonate is preferably a polycarbonate polyol. The polyester polyol is not particularly limited as long as it has a carbonate bond in the polymer main chain and a plurality of hydroxyl groups at the terminal or side chain. The polyester is preferably, for example, a polyester obtained by previously reacting a polyester polyol with a polyisocyanate (e.g., diisocyanate) to extend the urethane chain, or a polycarbonate obtained by previously reacting a polycarbonate polyol with a polyisocyanate (e.g., diisocyanate) to extend the urethane chain. The polyester and polycarbonate contained in the resin composition forming the adhesive layer may each be one type or two or more types.

[0157] The alicyclic isocyanate compound is not particularly limited as long as it is a compound having an alicyclic structure and an isocyanate group. The alicyclic isocyanate compound preferably has two or more isocyanate groups. Specific examples of the alicyclic isocyanate compound include isophorone diisocyanate (IPDI), bis(4-isocyanatocyclohexyl)methane, 1,3-bis(isocyanatomethyl)cyclohexane, methylenebis(4,1-cyclohexylene)diisocyanate, and the like, as well as their polymers or nurates, mixtures thereof, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates. The alicyclic isocyanate compound is preferably a polyol-modified polyisocyanate obtained by reacting an alicyclic isocyanate with a polyol (e.g., polyester polyol) in advance. The resin composition for forming the adhesive layer may contain one or more types of alicyclic isocyanate compounds.

[0158] The aromatic isocyanate compound is not particularly limited as long as it is a compound having an aromatic ring and an isocyanate group. Preferably, the aromatic isocyanate compound has two or more isocyanate groups. Specific examples of aromatic isocyanate compounds include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), their polymers or nurates, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates. Preferably, the aromatic isocyanate compound is a polyol-modified polyisocyanate obtained by reacting an aromatic isocyanate with a polyol (e.g., polyester polyol) in advance. The aromatic isocyanate compound contained in the resin composition forming the adhesive layer 5 may be one type or two or more types.

[0159] The resin composition forming the adhesive layer may, for example, contain an alicyclic isocyanate compound but not contain an aromatic isocyanate compound, or may, for example, contain an aromatic isocyanate compound but not contain an alicyclic isocyanate compound, or may, for example, contain both an alicyclic isocyanate compound and an aromatic isocyanate compound. The resin composition forming the adhesive layer 32 preferably contains an aromatic isocyanate compound.

[0160] The content of the alicyclic isocyanate compound and aromatic isocyanate compound in the adhesive layer is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, respectively, in the resin composition constituting the adhesive layer 5. Furthermore, when the adhesive layer 5 contains both an alicyclic isocyanate compound and an aromatic isocyanate compound, the total content thereof in the resin composition constituting the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %.

[0161] The upper limit of the thickness of adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less, and the lower limit is preferably about 0.1 μm or more, or about 0.5 μm or more, and the thickness range is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of an adhesive such as those exemplified for adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when a resin exemplified for the heat-fusible resin layer 4 is used, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is an adhesive exemplified for the adhesive layer 2 or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. When a resin exemplified for the heat-fusible resin layer 4 is used, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed, for example, by extrusion molding.

[0162] [Surface coating layer 6] The packaging material for an electricity storage device according to the present disclosure may have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) as needed, for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the packaging material for an electricity storage device when an electricity storage device is assembled using the packaging material for an electricity storage device.

[0163] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0164] When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0165] Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Forming the surface coating layer 6 from polyurethane provides the electrical storage device exterior material with excellent electrolyte resistance.

[0166] The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and / or inside of the surface coating layer 6, as needed, depending on the functionality to be imparted to the surface of the surface coating layer 6. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured with a laser diffraction / scattering particle size distribution analyzer.

[0167] The additive may be either inorganic or organic. The shape of the additive is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and scaly shapes.

[0168] 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, antimony oxide, 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, acrylate resin, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoints of dispersion stability, cost, and the like. The additives may also be subjected to various surface treatments, such as insulation treatment and high-dispersibility treatment.

[0169] The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin to form the surface coating layer 6. When an additive is blended into the surface coating layer 6, a resin mixed with the additive may be applied.

[0170] The thickness of the surface coating layer 6 is not particularly limited as long as the surface coating layer 6 exhibits the above-mentioned functions, and may be, for example, about 0.5 to 10 μm, and preferably about 1 to 5 μm.

[0171] 2. Manufacturing method for exterior materials for energy storage devices The method for producing the electrical storage device packaging material is not particularly limited as long as it can produce a laminate in which the layers of the electrical storage device packaging material of the present disclosure are stacked, and examples include a method comprising a step of stacking at least a substrate layer 1, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin 4 in this order. As described above, an aluminum alloy foil having the above-mentioned predetermined composition can be used as the barrier layer 3. The adhesive layer 5 is formed from a cured product of a resin composition containing a curable resin.

[0172] An example of a method for manufacturing an exterior material for an electricity storage device according to the present disclosure is as follows: First, a laminate (hereinafter, sometimes referred to as "laminate A") is formed in which a base layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form adhesive layer 2 is applied to base layer 1 or to barrier layer 3, the surface of which has been chemically treated as necessary, by a coating method such as gravure coating or roll coating, and then dried, followed by laminating the barrier layer 3 or base layer 1 and curing the adhesive layer 2.

[0173] Next, a heat-sealable resin layer 4 is laminated on the barrier layer 3 of the laminate A. For example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them onto the barrier layer 3 of the laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and laminating this on the barrier layer 3 of the laminate A by a thermal lamination method, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this on the heat-sealable resin layer 4 by a thermal lamination method, or (3) a laminate (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A, followed by drying or baking, and then laminating the heat-sealable resin layer 4, which has been previously formed into a sheet, on the adhesive layer 5, and the like.

[0174] When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin for forming the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

[0175] As described above, a laminate is formed which includes the optional surface coating layer 6, the base material layer 1, the optional adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-sealable resin layer 4 in this order. In order to strengthen the adhesion of the optional adhesive layer 2 and the adhesive layer 5, the laminate may be further subjected to a heat treatment.

[0176] In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc., as needed to improve processability. For example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to corona treatment, the printability of ink on the surface of the base layer 1 can be improved.

[0177] 3. Applications of exterior materials for energy storage devices The exterior packaging material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. That is, an electricity storage device can be formed by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the exterior packaging material for an electricity storage device according to the present disclosure.

[0178] Specifically, an electricity storage device using the electricity storage device packaging material is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure in a state in which metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) can be formed around the periphery of the electricity storage device element, and heat-sealing the heat-sealable resin layers of the flange portion to form a hermetic seal. Note that when an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inside (the surface in contact with the electricity storage device element).

[0179] The exterior material for an electricity storage device according to the present disclosure can be suitably used in electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior material for an electricity storage device according to the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior material for an electricity storage device according to the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material for an electricity storage device according to the present disclosure. [Example]

[0180] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0181] <Production of aluminum alloy foil> Aluminum alloy ingots having the compositions shown in Table 1 (the balance being Al and other unavoidable impurities) were prepared, homogenized under the conditions shown in the table, and then hot-rolled to a finishing temperature of 330°C to form 3 mm thick plates. Subsequently, the ingots underwent cold rolling, intermediate annealing, and final cold rolling to produce aluminum alloy foil samples having a thickness of 40 μm and a width of 1200 mm. The method of intermediate annealing is shown in Table 1. The cold rolling item in Table 1 shows the plate thickness immediately before intermediate annealing and the cold rolling reduction ratio to reach that thickness.

[0182] The aluminum alloy foils thus produced were subjected to the following tests or measurements, and the results are shown in Table 1.

[0183] Tensile strength and elongation at break of aluminum alloy foil Both tensile strength and elongation at break were measured by tensile testing. The tensile test conformed to JIS Z2241:2011. JIS No. 5 test pieces were cut from the samples so that elongation in the 0° direction relative to the rolling direction could be measured. Tests were performed using a universal tensile testing machine (Shimadzu Corporation, AGS-X 10kN) at a tensile speed of 2mm / min. Elongation refers to elongation at break, and the elongation percentage was calculated as follows. First, before the test, two lines were marked perpendicular to the longitudinal center of the test piece, spaced 50mm apart (the gauge length). After the test, the fracture surfaces of the aluminum alloy foil were butted together to measure the distance between the marks. The gauge length (50mm) was then subtracted from this to obtain the elongation (mm), and the resulting value was divided by the gauge length (50mm) to obtain the elongation percentage (%). The elongation of the aluminum alloy foil was the total elongation at break (the sum of the elastic and plastic elongations of the extensometer) and expressed as a percentage of the extensometer gauge length.

[0184] ·Average grain size The surface of the aluminum alloy foil was electropolished using a mixed solution of 20% by volume perchloric acid and 80% by volume ethanol at a voltage of 20 V, and then anodized in Barker's solution at a voltage of 30 V. After the treatment, the crystal grains of the test material were observed using an optical microscope. The average crystal grain size was calculated from the photographs taken using the intercept method.

[0185] L1 (HAGB length) / L2 (LAGB length) After electrolytic polishing the foil surface, crystal orientation analysis was performed using SEM-EBSD to observe high-angle grain boundaries (HAGBs) with a misorientation between crystal grains of 15° or more, and low-angle grain boundaries with a misorientation between 2° and less than 15°. Four fields of view, each 170 x 340 μm in size, were measured at a magnification of 500x, and the lengths of the HAGBs and LAGBs within the fields of view were determined, and the ratio was calculated. The calculated ratio is shown in Table 2 as L1 / L2.

[0186] Crystal orientation Copper orientation is {112} <111> , R direction is {123} <634> The orientation density of each was obtained by measuring the incomplete pole figures of {111}, {200}, and {220} using X-ray diffraction, and then calculating the crystal orientation distribution function (ODF) using the results.

[0187] ·Surface analysis The Mg concentration on the foil surface was estimated using XPS (X-ray Photoelectron Spectroscopy). The narrow spectrum obtained by narrow scan measurement was subjected to waveform separation, and the atomic concentration of each element was quantified. For Mg, the Mg2p spectrum was used. The XPS equipment used was Quantera SMX manufactured by ULVAC-PHI. The analysis conditions were an X-ray source of 100 W, pass energy of 26 eV, and step 0.05 eV, analysis area (beam diameter) 100 μm × 1.4 mm, detection angle 45°.

[0188] Oxide film thickness measurement The oxide film thickness was measured using an FE-EPMA (Electron Probe Micro Analyzer) rather than XPS. The oxide film thickness of the sample was calculated using a calibration curve of X-ray intensity obtained from an oxide film sample with a known thickness. The FE-EPMA used was a JEOL JXA-8530F. The analysis conditions were an accelerating voltage of 10 kV, a probe current of 100 nA, and a beam diameter of 50 μm.

[0189] -Puncture strength A needle with a diameter of 1.0 mm and a tip radius of 0.5 mm was pierced into a 40 μm thick aluminum alloy foil at a speed of 50 mm / min, and the maximum load (N) until the needle penetrated the foil was measured. Here, a piercing strength of 9.0 N or more was considered to be good piercing resistance, and a piercing strength of less than 9.0 N was evaluated as good.

[0190] Limit forming height The forming height was evaluated using a rectangular tube forming test. The test was performed using a universal sheet metal forming tester (Erichsen Model 142 / 20) with a 40 μm thick aluminum alloy foil and a rectangular punch (side length D = 37 mm, corner chamfer diameter R = 4.5 mm) as shown in Figure 8. The test conditions were a wrinkle suppression force of 10 kN, a punch ascent speed (forming speed) scale of 1, and mineral oil lubricant on one side of the foil (the side that the punch contacts). The foil was formed by the punch rising from the bottom of the device. The maximum punch elevation height that could be achieved without cracks or pinholes after three consecutive forming runs was defined as the limit forming height (mm) for that material. The punch height was varied in 0.5 mm increments. A protrusion height of 7.0 mm or greater was considered good formability, with a rating of ○, and a rating of × for a protrusion less than 7.0 mm.

[0191] Corrosion evaluation 152 g of lithium hexafluorophosphate was dissolved in 1 L of propylene carbonate / diethylene carbonate (volume ratio: 1 / 1) to prepare a 1 mol / L electrolyte. Next, each aluminum alloy foil used in the Examples and Comparative Examples was placed on the positive electrode of a 200 mL bipolar beaker cell, metallic lithium was placed on the negative electrode, and the aforementioned electrolyte was added. A potential difference of 0.1 V was applied for 1 hour and 3 hours, and the aluminum alloy foil surface was then visually observed under a microscope. As shown in the micrographs (observation magnification: 200x) in Figures 6 and 7, surfaces that were corroded (Figure 7) were evaluated as ×, and those that remained unchanged (Figure 6) were evaluated as ○. Surfaces that were only partially changed were evaluated as △, indicating that they were practically acceptable but had slightly poor corrosion resistance. The corroded aluminum alloy foil surface (evaluated as ×) was observed to have formed a compound with lithium, resulting in a raised surface due to volume expansion. The results for each test material are shown in Table 2.

[0192] <Manufacturing of exterior materials for electricity storage devices> (Example 1 and Comparative Examples 1 and 2) A laminated film was prepared in which a polyethylene terephthalate film (12 μm) was laminated as a substrate layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), thickness 3 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order. Next, a barrier layer made of the aluminum alloy foil (having the composition shown in Table 1 and a thickness of 40 μm) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (thickness 15 μm) of the substrate layer by dry lamination. Specifically, acid-resistant coatings (coatings formed by chromate treatment, with a chromium content of 30 mg / m) were formed on both sides. 2 A two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which the adhesive layer had been formed, forming an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, the adhesive layer on the aluminum alloy foil and a biaxially oriented nylon film were laminated together, and then an aging treatment was performed to produce a laminate of a substrate layer / adhesive layer / barrier layer.

[0193] Next, an unstretched polypropylene film (80 μm thick) was laminated on the barrier layer of the obtained laminate by dry lamination. Specifically, a two-component curing adhesive (acid-modified polypropylene and epoxy compound) was applied to form an adhesive layer (2 μm thick after curing) on ​​the aluminum alloy foil. Next, an aging treatment was performed to obtain an exterior material for an electricity storage device, in which a polyethylene terephthalate film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (2 μm) / heat-sealable resin layer (80 μm) were laminated in this order.

[0194] Example 2 A polyethylene terephthalate film (25 μm) was prepared as a substrate layer. Next, a barrier layer made of the aluminum alloy foil (having the composition shown in Table 1 and a thickness of 40 μm) with acid-resistant coatings formed on both sides was laminated on the substrate layer by dry lamination. Specifically, the acid-resistant coatings (coatings formed by chromate treatment with a chromium content of 30 mg / m) were formed on both sides. 2 A two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which the barrier layer had been formed, forming an adhesive layer (thickness 3 μm after curing) on ​​the aluminum alloy foil. Next, the adhesive layer on the aluminum alloy foil and the substrate layer were laminated together, and then an aging treatment was performed to produce a substrate layer / adhesive layer / barrier layer laminate.

[0195] Next, an unstretched polybutylene terephthalate film (50 μm thick) was laminated on the barrier layer of the obtained laminate by dry lamination. Specifically, a two-component curing adhesive (acid-modified polypropylene and epoxy compound) was applied to form an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, an aging treatment was performed to obtain an exterior material for an electricity storage device, in which a polyethylene terephthalate film (25 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (3 μm) / polybutylene terephthalate film (50 μm) were laminated in this order.

[0196] Example 3 A laminated film was prepared in which a polyethylene terephthalate film (12 μm) was laminated as a substrate layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), thickness 3 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order. Next, a barrier layer made of the aluminum alloy foil (having the composition shown in Table 1 and a thickness of 40 μm) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (thickness 15 μm) of the substrate layer by dry lamination. Specifically, acid-resistant coatings (coatings formed by chromate treatment, with a chromium content of 30 mg / m) were formed on both sides. 2 A two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which the adhesive layer had been formed, forming an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, the adhesive layer on the aluminum alloy foil and a biaxially oriented nylon film were laminated together, and then an aging treatment was performed to produce a laminate of a substrate layer / adhesive layer / barrier layer.

[0197] Next, an unstretched polypropylene film (80 μm thick) was laminated on the barrier layer of the obtained laminate by dry lamination. Specifically, a two-component curing adhesive (a polyester polyol compound and an alicyclic isocyanate compound) was applied to form an adhesive layer (2 μm thick after curing) on ​​the aluminum alloy foil. Next, an aging treatment was performed to obtain an exterior material for an electricity storage device, in which a polyethylene terephthalate film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (2 μm) / heat-sealable resin layer (80 μm) were laminated in this order.

[0198] (Comparative Example 3) A laminated film was prepared in which a polyethylene terephthalate film (12 μm) was laminated as a substrate layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), thickness 3 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order. Next, a barrier layer made of the aluminum alloy foil (having the composition shown in Table 1 and a thickness of 40 μm) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (thickness 15 μm) of the substrate layer by dry lamination. Specifically, acid-resistant coatings (coatings formed by chromate treatment, with a chromium content of 30 mg / m) were formed on both sides. 2 A two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one side of the aluminum alloy foil on which the adhesive layer had been formed, forming an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, the adhesive layer on the aluminum alloy foil and a biaxially oriented nylon film were laminated together, and then an aging treatment was performed to produce a laminate of a substrate layer / adhesive layer / barrier layer.

[0199] Next, a maleic anhydride-modified polypropylene (40 μm thick) as an adhesive layer and a polypropylene (40 μm thick) as a heat-sealable resin layer were co-extruded onto the barrier layer of the obtained laminate, thereby laminating an adhesive layer / heat-sealable resin layer on the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior packaging material for an electricity storage device, in which a polyethylene terephthalate film (12 μm) / adhesive layer (3 μm) / biaxially oriented nylon film (15 μm) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (40 μm) / heat-sealable resin layer (40 μm) were laminated in this order.

[0200] Erucic acid amide was present as a lubricant on both sides of the electrical storage device packaging material to form a lubricant layer.

[0201] <Evaluation of corrosion resistance of aluminum alloy foil to electrolyte> Each aluminum alloy foil used in the examples and comparative examples was cut into a rectangle measuring 45 mm long and 15 mm wide. Next, rectangular polyethylene films measuring 50 mm long and 20 mm wide were attached and heat-sealed to the front and back surfaces of the aluminum alloy foil, leaving a 1 cm diameter exposed area on one side of the foil. These films were then used to prepare test samples. The corrosion resistance of the test samples was evaluated using the 1 cm diameter exposed portion of the aluminum alloy foil AL. The end of the test sample not immersed in the electrolyte was left exposed for connection to a working electrode. Next, as shown in the schematic diagram of Figure 4, the test sample AL was set as the working electrode, and metallic lithium Li (disk-shaped, 15 mm diameter x 0.35 mm thick) was set as the counter electrode. The test samples were then immersed in an electrolyte consisting of 1 mol / L LiPF6 and a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (volume ratio 1:1:1). In this state, a voltage of 0.1 V was applied for 1 hour in an environment of 20°C, and then the surface of the aluminum alloy foil was observed. Surfaces that were corroded, as shown in Figure 7, were given a rating of C, while surfaces that remained unchanged, as shown in Figure 6, were given a rating of A. The results are shown in Table 2. It can be seen that compounds with lithium are formed on the corroded aluminum alloy foil surface, and the surface is raised due to volume expansion.

[0202] <Corrosion resistance of aluminum alloy foil against all-solid-state electrolytes> In a glove box, a solid electrolyte (Li2S-P2S5 (75:25)) with a thickness of 800 μm and a diameter of 10 mm was prepared by powder compaction. Next, indium foil (0.3 mm thick x 9 mm diameter), lithium foil (0.2 mm thick x 8 mm diameter), and indium foil (0.1 mm thick x 9 mm diameter) were placed on top of the solid electrolyte, with the indium foil (0.1 mm thick) facing the solid electrolyte side, and the foil was restrained and left overnight. The restraint was then released, and each aluminum alloy foil used in the Examples and Comparative Examples was punched out to a diameter of 9 mm and laminated on the solid electrolyte on the opposite side of the foil. The resulting laminate was restrained and sealed in a leaded glass cell. The laminate was removed from the glove box and left for 1 hour to stabilize. In this state, a voltage of -0.53 V was applied for 3 hours at 25°C, and the quantity of electricity per unit area was calculated. The quantity of electricity was 4 C / cm 2 If it is less than 4C / cm, it is rated A. 2 If the result was above this, the evaluation was C. The results are shown in Table 3.

[0203] <Evaluation of formability> Each of the resulting electrical storage device packaging materials was cut into a rectangle measuring 90 mm in length (MD) and 150 mm in width (TD) to prepare a test sample. The MD of the electrical storage device packaging material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the electrical storage device packaging material corresponds to the TD of the aluminum alloy foil. The test sample was placed in a 25°C environment in a forming die (female die, surface has a maximum height roughness (nominal value of Rz) of 3.2 μm, corner R2.0 mm, ridge R1.0 mm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Annex 1 (Reference)) with a rectangular opening of 31.6 mm (MD) x 54.5 mm (TD). The forming die was then pressed into a corresponding forming die (male die, surface has a maximum height roughness (nominal value of Rz) of 3.2 μm, corner R2.0 mm, ridge R1.0 mm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Annex 1 (Reference)). The maximum height roughness (nominal Rz value) of the comparative surface roughness standard specimen, as specified in Table 2, was 1.6 μm. Using a corner radius of 2.0 mm and a ridge radius of 1.0 mm, a pressing pressure (surface pressure) of 0.25 MPa was applied to ten samples, varying the forming depth from 0.5 mm in 0.5 mm increments. The test samples were placed on a female mold with the heat-sealable resin layer facing the male mold. The clearance between the male and female molds was 0.3 mm. After cold forming, the samples were illuminated with a penlight in a darkroom to check for pinholes or cracks in the aluminum alloy foil. The maximum forming depth at which no pinholes or cracks occurred in any of the ten samples was determined as the limit forming depth P mm. When the limit forming depth was 4.0 mm or more, it was given an evaluation of A, when it was 3.5 mm, it was given an evaluation of B, and when it was 3.0 mm or less, it was given an evaluation of C. The results are shown in Table 3.

[0204] <Insulation evaluation> Each of the electrical storage device packaging materials obtained in the Examples and Comparative Examples was cut to a length (MD) of 100 mm and a width (TD) of 40 mm. Additionally, a 100 mm x 30 mm, 1 mm thick aluminum plate was prepared, and a 50 μm diameter aluminum wire was fixed to the aluminum plate with double-sided tape. The positive terminal of a megaohm tester (HIOKI 3154 DIGITAL MΩ HiTESTER) was contacted to the aluminum plate, and the negative terminal was connected so that the jig was in contact with the barrier layer of the electrical storage device packaging material. The heat-sealable resin layer side of the electrical storage device packaging material was placed over the wire side of the aluminum plate. In this state, the electrical storage device packaging material was heat-sealed from above using a 7 mm wide seal bar (sealing conditions: 190°C, 0.1 MPa). The time required for the heat-sealable resin layer to penetrate the wire, the wire to reach the barrier layer, and the resistance between the electrical storage device packaging material and the aluminum plate to fall below 200 MΩ at 100 V was measured. A time of 15 seconds or more was given an evaluation of A, and a time of less than 15 seconds was given an evaluation of C. The results are shown in Table 3.

[0205] [Table 1]

[0206] [Table 2]

[0207] [Table 3]

[0208] In Table 3, acid-modified PP refers to acid-modified polypropylene.

[0209] The electrical storage device packaging materials of Examples 1 to 3 are composed of a laminate having at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, the barrier layer containing an aluminum alloy foil having a composition of 0.2 to 2.0 mass% Fe and 0.1 to 5.0 mass% Mg, and the adhesive layer is formed of a cured product of a resin composition containing a curable resin. The electrical storage device packaging materials of Examples 1 to 3 have excellent formability, effectively suppress corrosion of the aluminum alloy foil when current is passed through with an electrolyte attached, and also have improved insulation properties.

[0210] As described above, the present disclosure provides the following aspects of the invention. Item 1. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the barrier layer contains an aluminum alloy foil having a composition of Fe: 0.2% by mass or more and 2.0% by mass or less, and Mg: 0.1% by mass or more and 5.0% by mass or less, The adhesive layer is formed from a cured product of a resin composition containing a curable resin. Item 2. The packaging material for an electricity storage device according to Item 1, wherein the aluminum alloy foil has a composition satisfying Mn: 0.1 mass % or less. Item 3. The packaging material for an electricity storage device according to Item 1 or 2, wherein the aluminum alloy foil has a tensile strength of 100 MPa or more and a breaking elongation of 10% or more, as measured using a JIS No. 5 test piece in accordance with JIS Z2241:2011. Item 4. The packaging material for an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer is formed from a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Item 5. The packaging material for an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer is formed from a cured product of a resin composition containing at least one of polyester and polycarbonate, and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound. Item 6. The packaging material for an electricity storage device according to any one of Items 1 to 5, wherein the base layer contains polyester. Item 7. The packaging material for an electricity storage device according to any one of Items 1 to 6, wherein the heat-sealable resin layer contains polyester. Item 8. The packaging material for an electricity storage device according to any one of Items 1 to 7, wherein the aluminum alloy foil has a composition of Si: 0.5 mass % or less. Section 9. Item 9. The exterior material for an electricity storage device according to any one of items 1 to 8, wherein the aluminum alloy foil has a ratio of a length L1 of a high-angle grain boundary per unit area to a length L2 of a low-angle grain boundary per unit area measured by electron backscatter diffraction that satisfies the relationship L1 / L2>3.0. Item 10. The composition of the aluminum alloy foil satisfies Mg: 0.1 mass% or more and 1.5 mass% or less, Item 10. The aluminum alloy foil contains 5.0 atomic percent or more of Mg on at least one surface thereof, and the aluminum alloy foil has an oxide film having a thickness of 80 Å or more on at least one surface thereof. Item 10. The exterior material for a storage battery device according to Item 9. Item 11. The composition of the aluminum alloy foil satisfies Mg: 0.1 mass% or more and 1.5 mass% or less, Item 11. The packaging material for an electricity storage device according to Item 9 or 10, wherein the aluminum alloy foil has a tensile strength of 110 MPa or more and 180 MPa or less and an elongation at break of 10% or more. Item 12. The composition of the aluminum alloy foil satisfies Mg: more than 1.5 mass% and 5.0 mass% or less, Item 10. The aluminum alloy foil contains 15.0 atomic percent or more of Mg on at least one surface thereof, and the aluminum alloy foil has an oxide film having a thickness of 120 Å or more on at least one surface thereof. Item 10. The exterior material for a storage battery device according to Item 9. Item 13. The composition of the aluminum alloy foil satisfies Mg: more than 1.5 mass% and 5.0 mass% or less, Item 13. The packaging material for an electricity storage device according to Item 9 or 12, wherein the aluminum alloy foil has a tensile strength of 180 MPa or more and an elongation at break of 15% or more. Item 14. The packaging material for an electricity storage device according to any one of Items 9 to 13, wherein the aluminum alloy foil has a texture in which the orientation densities of the Copper orientation and the R orientation are each 15 or less. Item 15. The packaging material for an electricity storage device according to any one of Items 9 to 14, wherein the aluminum alloy foil has an average crystal grain size of 25 μm or less. Item 16. The packaging material for an electricity storage device according to any one of Items 9 to 15, wherein the aluminum alloy foil has a composition in which unavoidable impurities include Mn: 0.1 mass % or less. Item 17. The packaging material for an electricity storage device according to any one of Items 9 to 16, wherein the aluminum alloy foil has a composition satisfying the following: Si: 0.5 mass % or less. Item 18. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an electricity storage device according to any one of Items 1 to 17. Item 19. The method includes a step of laminating at least a base layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate, the barrier layer contains an aluminum alloy foil having a composition of Fe: 0.2% by mass or more and 2.0% by mass or less, and Mg: 0.1% by mass or more and 5.0% by mass or less, The method for producing an exterior material for an electricity storage device, wherein the adhesive layer is formed from a cured product of a resin composition containing a curable resin. [Explanation of symbols]

[0211] 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices

Claims

1. The laminate is composed of at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order, the barrier layer contains an aluminum alloy foil that satisfies a composition of Fe: 1.0% by mass or more and 2.0% by mass or less, Mg: 0.1% by mass or more and 5.0% by mass or less, and inevitable impurities each being 0.10% by mass or less and totaling 0.40% by mass or less; The adhesive layer is formed from a cured product of a resin composition containing a curable resin.

2. The packaging material for an electricity storage device according to claim 1 , wherein the aluminum alloy foil has a composition satisfying Mn: 0.1 mass % or less.

3. 3. The exterior material for an electricity storage device according to claim 1 or 2, wherein the aluminum alloy foil has a tensile strength of 100 MPa or more and a breaking elongation of 10% or more, as measured on a JIS No. 5 test piece in accordance with JIS Z2241:2011.

4. The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein the adhesive layer is formed from a cured product of a resin composition containing an acid-modified polyolefin and a curing agent.

5. The electrical storage device packaging material according to any one of claims 1 to 3, wherein the adhesive layer is formed from a cured product of a resin composition containing at least one of polyester and polycarbonate, and at least one of an alicyclic isocyanate compound and an aromatic isocyanate compound.

6. The packaging material for an electricity storage device according to any one of claims 1 to 5, wherein the base material layer contains polyester.

7. The packaging material for an electricity storage device according to any one of claims 1 to 6, wherein the heat-sealable resin layer contains polyester.

8. The packaging material for an electricity storage device according to any one of claims 1 to 7, wherein the aluminum alloy foil has a composition of Si: 0.5 mass% or less.

9. The aluminum alloy foil has a ratio of a length L1 of a high-angle grain boundary per unit area to a length L2 of a low-angle grain boundary per unit area measured by electron backscatter diffraction, satisfying the relationship L1 / L2>3.

0. The exterior material for an electricity storage device according to any one of claims 1 to 8.

10. The composition of the aluminum alloy foil satisfies Mg: 0.1 mass% or more and 1.5 mass% or less, 10. The exterior packaging material for an electricity storage device according to claim 9, wherein at least one surface of the aluminum alloy foil contains 5.0 atomic percent or more of Mg, and at least one surface of the aluminum alloy foil has an oxide film having a thickness of 80 Å or more.

11. The composition of the aluminum alloy foil satisfies Mg: 0.1 mass% or more and 1.5 mass% or less, The packaging material for an electricity storage device according to claim 9 or 10, wherein the aluminum alloy foil has a tensile strength of 110 MPa or more and 180 MPa or less and an elongation at break of 10% or more.

12. The composition of the aluminum alloy foil satisfies Mg: more than 1.5 mass% and 5.0 mass% or less, At least one surface of the aluminum alloy foil is coated with 15.0 atomic percent or more of Mg and an oxide film having a thickness of 120 Å or more on at least one surface of the aluminum alloy foil.

13. The composition of the aluminum alloy foil satisfies Mg: more than 1.5 mass% and 5.0 mass% or less, The packaging material for an electricity storage device according to claim 9 or 12, wherein the aluminum alloy foil has a tensile strength of 180 MPa or more and an elongation at break of 15% or more.

14. The packaging material for an electricity storage device according to any one of claims 9 to 13, wherein the aluminum alloy foil has a texture in which the orientation densities of the Copper orientation and the R orientation are each 15 or less.

15. The packaging material for an electricity storage device according to any one of claims 9 to 14, wherein the aluminum alloy foil has an average crystal grain size of 25 µm or less.

16. The packaging material for an electricity storage device according to any one of claims 9 to 15, wherein the aluminum alloy foil has a composition containing 0.1 mass% or less of Mn as inevitable impurities.

17. The packaging material for an electricity storage device according to any one of claims 9 to 16, wherein the composition of the aluminum alloy foil satisfies Si: 0.5 mass% or less.

18. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of claims 1 to 17.

19. The method includes a step of laminating at least a base layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order to obtain a laminate, the barrier layer contains an aluminum alloy foil that satisfies a composition of Fe: 1.0% by mass or more and 2.0% by mass or less, Mg: 0.1% by mass or more and 5.0% by mass or less, and inevitable impurities each being 0.10% by mass or less and totaling 0.40% by mass or less; The method for producing an exterior material for an electricity storage device, wherein the adhesive layer is formed from a cured product of a resin composition containing a curable resin.

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