Exterior material for energy storage devices, method for manufacturing the same, and energy storage device

Abstract

To provide an outer package material for power storage devices which sequentially comprises at least a base material layer, a barrier layer including an aluminum alloy foil layer and a thermally fusible resin layer in this order, effectively suppresses corrosion of the aluminum alloy foil when electric conduction occurs in such a state that an electrolyte adheres thereto, and has the high mechanical strength and high moldability.SOLUTION: There is provided an outer package material 10 for power storage devices, the outer package material being composed of a multilayer body which sequentially comprises at least a base material layer 1, a barrier layer 3 and a thermally fusible resin layer 4 in this order, wherein: the barrier layer contains an aluminum alloy foil that has a composition containing 0.2% by mass to 2.0% by mass of Fe and 0.1% by mass to 5.0% by mass of Mg; and with respect to this aluminum alloy foil, the ratio of the length L1 of a high angle grain boundary to the length L2 of a low angle grain boundary per unit area as determined by a back scattering electron diffraction method satisfies the relational expression of L1 / L2>3.0.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to an exterior material for an energy storage device, a method for manufacturing the same, and an energy storage device. [Background technology]

[0002] While various types of energy storage devices have been developed, packaging materials (outer packaging) are essential components for sealing energy storage device elements such as electrodes and electrolytes in all of them. Traditionally, metal outer packaging materials have been widely used for energy storage devices.

[0003] On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., energy storage devices are required to come in a variety of shapes, as well as be thinner and lighter. However, conventional metal casing materials for energy storage devices have the drawback of being unable to keep up with the diversification of shapes, and also having limitations in terms of weight reduction.

[0004] Therefore, in recent years, a film-like exterior material has been proposed for energy storage devices in which a base material, an aluminum alloy foil layer, and a heat-sealable resin layer are sequentially laminated, as it can be easily processed into various shapes and enables thinning and weight reduction (see, for example, Patent Document 1).

[0005] In such film-like exterior materials, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolytes are placed in the spaces formed by these recesses. By heat-sealing the heat-sealable resin layers together, an energy storage device is obtained in which the energy storage device elements are housed inside the exterior material. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-287971 [Overview of the project] [Problems that the invention aims to solve]

[0007] From the perspective of increasing the energy density of energy storage devices, it is necessary to form deep recesses in film-like exterior materials through molding. Therefore, high formability is required for aluminum alloy foil used as exterior material for energy storage devices.

[0008] As aluminum alloy foil with excellent formability, Al-Fe alloy-based soft aluminum alloy foil is known. Specific examples of such soft aluminum alloy foil include, for example, aluminum alloy foil having the 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 processes such as molding the exterior material for energy storage devices, housing the energy storage device elements in the exterior material and heat-sealing it, and bending the heat-sealed portion, a short circuit may occur between the external terminals and the aluminum alloy foil of the energy storage device exterior material via foreign matter, or due to uneven pressure during heat sealing causing the external terminals and the aluminum alloy foil of the energy storage device exterior material to come into close proximity or contact, and if fine cracks or pinholes occur in the heat-sealable resin layer located in the innermost layer, current may flow between the aluminum alloy foil of the energy storage device exterior material and the external terminals via the electrolyte that has penetrated the heat-sealable resin layer, potentially causing the aluminum alloy foil to corrode due to alloying with lithium ions in the electrolyte (in particular, if the aluminum alloy foil and the negative electrode terminal short-circuit via the electrolyte, the aluminum alloy foil is more susceptible to corrosion). When the aluminum alloy foil corrodes, problems such as expansion of the aluminum alloy foil occur, leading to a deterioration in the performance of the energy storage device.

[0010] Under such circumstances, the present disclosure provides an exterior material for a power storage device in which at least a base material layer, a barrier layer including an aluminum alloy foil layer, and a heat-sealable resin layer are laminated in this order, and corrosion of the aluminum alloy foil when energization occurs in a state where an electrolytic solution is attached is effectively suppressed, and further having high mechanical strength and high formability.

Means for Solving the Problems

[0011] The inventors of the present disclosure conducted intensive studies to solve the above problems. Specifically, regarding the composition and physical properties of the aluminum alloy foil used for the barrier layer of the exterior material for a power storage device, repeated studies were carried out, the contents of Mg and Fe were set within a predetermined range, and by controlling the ratio of the length L1 of large-angle grain boundaries per unit area and the length L2 of small-angle grain boundaries measured by the backscattered electron diffraction method, corrosion when energization occurs in a state where an electrolytic solution is attached was effectively suppressed, and further, high mechanical strength and high formability were imparted to the exterior material for a power storage device.

[0012] The present disclosure was completed by further studies based on these findings. That is, the present disclosure provides an invention in the following aspects. It is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, The barrier layer includes an aluminum alloy foil satisfying a composition of Fe: 0.2 mass% or more and 2.0 mass% or less, and Mg: 0.1 mass% or more and 5.0 mass% or less, The aluminum alloy foil is an exterior material for a power storage device in which the ratio of the length L1 of large-angle grain boundaries per unit area and the length L2 of small-angle grain boundaries measured by the backscattered electron diffraction method satisfies the relationship L1 / L2 > 3.0.

Effects of the Invention

[0013] According to the present disclosure, there is provided an exterior material for a power storage device in which at least a base material layer, a barrier layer including an aluminum alloy foil layer, and a heat-sealable resin layer are laminated in this order, and corrosion of the aluminum alloy foil when energization occurs in a state where an electrolytic solution is adhered is effectively suppressed, and which further has high mechanical strength and high formability. Further, according to the present disclosure, a method for manufacturing the exterior material for a power storage device and a power storage device can also be provided.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 2] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 3] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 4] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 5] It is a diagram showing a planar shape of a square punch used in a limiting drawing height test in an embodiment of the present disclosure. [Figure 6] It is a micrograph showing the surface of an aluminum alloy foil used for evaluation of corrosiveness. (a) is a surface without corrosion, and (b) is a surface with corrosion. [Figure 7] It is a schematic diagram for explaining a method for measuring a logarithmic decrement ΔE by a rigid pendulum measurement. [Figure 8] It is a schematic diagram for explaining a protruding portion formed inside a heat-sealed portion of a heat-sealable resin layer.

Modes for Carrying Out the Invention

[0015] The exterior material for energy storage devices of this disclosure comprises a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in that order, wherein the barrier layer contains aluminum alloy foil satisfying a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass, and the aluminum alloy foil is characterized in that the ratio of the length of the large-angle grain boundary L1 to the length of the small-angle grain boundary L2 per unit area, as measured by backscattered electron diffraction, satisfies the relationship L1 / L2 > 3.0. With the exterior material for energy storage devices of this disclosure, the corrosion of the aluminum alloy foil when current is applied while electrolyte is attached is effectively suppressed, and furthermore, it has high mechanical strength and high moldability.

[0016] The following details the exterior material for energy storage devices, its manufacturing method, and the energy storage device described herein. In this specification, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to." For example, the notation 2~15mm means 2mm or more and 15mm or less.

[0017] 1. Exterior materials for energy storage devices The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising, for example, a base layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in that order, as shown in Figures 1 to 4. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an energy storage device using the exterior material 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-sealing the peripheral edges of the heat-sealable resin layers 4 of the exterior material 10 facing each other.

[0018] The barrier layer 3 of the exterior material for energy storage devices of this disclosure includes aluminum alloy foil. That is, the barrier layer 3 of the exterior material for energy storage devices of this disclosure can be composed of aluminum alloy foil. The exterior material for energy storage devices of this disclosure using aluminum alloy foil that satisfies predetermined composition and properties described later effectively suppresses corrosion of the aluminum alloy foil and also exhibits excellent mechanical strength and formability.

[0019] The exterior material 10 for the energy storage device may, for example, have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as needed, for the purpose of improving the adhesion between these layers, as shown in Figures 2 to 4. Also, as shown in Figures 3 and 4, an adhesive layer 5 may, as needed, have an adhesive layer 5 between the barrier layer 3 and the heat-fusible resin layer 4, for the purpose of improving the adhesion between these layers. Furthermore, as shown in Figure 4, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (opposite the heat-fusible resin layer 4 side), as needed.

[0020] The thickness of the laminate constituting the exterior material 10 for energy storage devices is not particularly limited, but from the viewpoint of cost reduction and improvement of energy density, for example, it can be 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 exterior material for energy storage devices, which is to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 10 for energy storage devices can be 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 outer casing material 10 for the energy storage device include, for example, approximately 35-190 μm, 35-180 μm, 35-155 μm, 35-120 μm, 45-190 μm, 45-180 μm, 45-155 μm, 45-120 μm, 60-190 μm, 60-180 μm, 60-155 μm, and 60-120 μm, with approximately 60-155 μm being particularly preferred.

[0021] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3, the adhesive layer 5 (optionally provided), the heat-fusible resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. For example, if the exterior material 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0022] Furthermore, in the case of exterior materials for energy storage devices, the Machine Direction (MD) and Transverse Direction (TD) of the barrier layer 3 described later can usually be determined during the manufacturing process. When the barrier layer 3 is made of 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. Also, in the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and determining the rolling direction (RD) of the metal foil. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

[0023] Furthermore, if the MD of the exterior material for energy storage devices cannot be identified by the rolling marks of the aluminum alloy foil, it can be identified by the following method. One method for confirming the MD of the exterior material for energy storage devices is to observe the cross-section of the heat-fusible resin layer of the exterior material of the energy storage device with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing electron microscope images of each of the cross-sections in the longitudinal direction of the heat-fusible resin layer and each of the cross-sections (a total of 10 cross-sections) from the direction parallel to the longitudinal cross-section, changing the angle by 10 degrees at a time, up to the direction perpendicular to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For each island shape, the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost point perpendicular to that point is defined as the diameter y. In each cross-section, the average of the top 20 diameters y of the island shapes, in descending order of diameter y, is calculated. The direction parallel to the cross-section where the average of the relevant diameter y of the island's shape was largest is determined to be the MD (Movement Direction).

[0024] Each layer forming the exterior material for energy storage devices [Base material layer 1] In this disclosure, the base material layer 1 is a layer provided for purposes such as enabling it to function as a base material for the exterior material of an energy storage device. The base material layer 1 is located on the outer layer side of the exterior material for the energy storage device.

[0025] The material forming the base layer 1 is not particularly limited, as long as it has the function of a base material, that is, at least insulating properties. The base layer 1 can be formed using, for example, a resin, and the resin may contain additives described later.

[0026] When the base layer 1 is formed of resin, the base layer 1 may be, for example, a resin film formed of resin, or a film formed by coating with 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 a biaxially stretched film include sequential biaxial stretching, inflation stretching, and simultaneous biaxial stretching. Examples of resin coating methods include roll coating, gravure coating, and extrusion coating.

[0027] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. Furthermore, the resin forming the base layer 1 may be a copolymer of these resins, or a modified version of such copolymer. It may also be a mixture of these resins.

[0028] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0029] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (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 individually or in combination of two or more types.

[0030] Furthermore, 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 constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0031] The base layer 1 preferably contains at least one of polyester film, polyamide film, and polyolefin film, preferably at least one of stretched polyester film, stretched polyamide film, and stretched polyolefin film, more preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, and stretched polypropylene film, and even more preferably at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

[0032] The base layer 1 may be a single layer or may consist of two or more layers. If the base layer 1 consists of two or more layers, the base layer 1 may be a laminate formed by laminating resin films with an adhesive, or it may be a laminate of two or more resin films formed by co-extruding resin. Furthermore, the laminate of two or more resin films formed by co-extruding resin may be used as the base layer 1 in its unstretched state, or it may be used as the base layer 1 after uniaxial stretching or biaxial stretching.

[0033] Specific examples of a laminate of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate 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, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film be located in the outermost layer of the base layer 1.

[0034] If the base layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in adhesive layer 2 described later. The method for laminating the two or more resin films 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, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and then laminated. The anchor coat layer may be the same type of adhesive as exemplified in adhesive layer 2 described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0035] Furthermore, at least one of the surface and interior of the base layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. Only one type of additive may be used, or two or more types may be mixed and used.

[0036] In this disclosure, from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide 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 stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide. The lubricant may be used alone or in combination of two or more types.

[0037] If a lubricant is present on the surface of the substrate layer 1, the amount present is not particularly limited, but preferably about 3 mg / m². 2 More preferably 4-15 mg / m² 2 To a certain extent, more preferably 5-14 mg / m² 2 The degree can be described as follows.

[0038] The lubricant present on the surface of the base layer 1 may be a lubricant contained in the resin constituting the base layer 1 that has seeped out, or a lubricant may be applied to the surface of the base layer 1.

[0039] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 to 50 μm, preferably about 10 to 35 μm. If the base layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer can be preferably about 2 to 25 μm.

[0040] [Adhesive layer 2] In the exterior material for energy storage devices of this disclosure, the adhesive layer 2 is a layer provided between the substrate layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0041] The adhesive layer 2 is formed by an adhesive capable of bonding the substrate layer 1 and the barrier layer 3. The adhesive used to form the adhesive layer 2 is not limited, but may be a chemical reaction type, solvent evaporation type, heat melt type, hot pressure type, etc. It may also be a two-component curing adhesive (two-part adhesive), a one-component curing adhesive (one-part adhesive), or a resin that does not undergo a curing reaction. Furthermore, the adhesive layer 2 may be a single layer or a multi-layer layer.

[0042] Specifically, adhesive components included in adhesives include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, copolymerized polyamides; polyolefin 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 individually or in combination of two or more. Among these adhesive components, polyurethane adhesives are particularly preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected appropriately from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components.

[0043] Examples of polyurethane adhesives include polyurethane adhesives comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, a two-component curing type polyurethane adhesive is used, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is the main component and an aromatic or aliphatic polyisocyanate is the curing agent. Furthermore, as the polyol compound, it is preferable to use a polyester polyol that has hydroxyl groups not only at the ends of the repeating units but also in the side chains. Because the adhesive layer 2 is formed of a polyurethane adhesive, the exterior material for the energy storage device is given excellent electrolyte resistance, and peeling of the base material layer 1 is suppressed even if electrolyte adheres to the side surface.

[0044] Furthermore, in the case of an exterior material for an all-solid-state battery, the adhesive layer 2 is preferably 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, similar to the adhesive layer 5 described later. This suppresses delamination between the substrate layer and the barrier layer in high-temperature environments for the exterior material for the all-solid-state battery. The details of the resin composition in the adhesive layer 2 are the same as those for the adhesive layer 5.

[0045] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may include colorants, thermoplastic elastomers, tackifiers, fillers, etc. The inclusion of a colorant in the adhesive layer 2 allows for the coloring of the exterior material for energy storage devices. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0046] The type of pigment is not particularly limited, as long as it does not impair the adhesion of adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0047] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance.

[0048] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0049] The pigment content in the adhesive layer 2 is not particularly limited as long as the exterior material for the energy storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0050] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the substrate layer 1 and the barrier layer 3. For example, the lower limit can be about 1 μm or more, or about 2 μm or more, and the upper limit can be about 10 μm or less, or about 5 μm or less. Preferred ranges can be about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, or about 2 to 5 μm.

[0051] [Colored layer] The colored layer is a layer provided between the base layer 1 and the barrier layer 3 as needed (not shown in the figure). If an adhesive layer 2 is present, the colored layer may be provided between the base layer 1 and the adhesive layer 2, and between the adhesive layer 2 and the barrier layer 3. Alternatively, the colored layer may be provided on the outside of the base layer 1. By providing a colored layer, the exterior material for the energy storage device can be colored.

[0052] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer 1, the adhesive layer 2, or the barrier layer 3. Known coloring agents such as pigments and dyes can be used. In addition, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0053] Specific examples of colorants included in the colored layer are the same as those exemplified in the [Adhesive Layer 2] section.

[0054] [Barrier layer 3] In the exterior material for energy storage devices, the barrier layer 3 is a layer that at least prevents the intrusion of moisture.

[0055] The barrier layer 3 of the exterior material for the energy storage device disclosed herein includes an aluminum alloy foil. The characteristics of the aluminum alloy foil in this disclosure are described below.

[0056] ·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, thus having the effect of refining the recrystallized grains. If the Fe content falls 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 content exceeds the upper limit, the effect of grain refinement saturates or even decreases, and the size of the Al-Fe intermetallic compounds generated during casting becomes very large, reducing the elongation and rollability of the foil. For this reason, the Fe content is set within the above range. For the same reason, it is preferable to set the Fe content to a lower limit of 0.5 mass%, and for the same reason, it is even more preferable to set the Fe content to a lower limit of 1.0 mass% and an upper limit of 1.8 mass%.

[0057] ·Mg: 0.1 mass% or more and 5.0 mass% or less Mg dissolves in aluminum, and solid solution strengthening can increase the strength of soft foils. Furthermore, because Mg readily dissolves in aluminum, even when included with Fe, there is little risk of intermetallic compound coarsening and a decrease in formability and rollability. If the Mg content falls below the lower limit, the improvement in strength will be insufficient, and if the Mg content exceeds the upper limit, the aluminum alloy foil will become hard, leading to a decrease in rollability and formability. The particularly preferable range for Mg content is 0.5% by mass or more and 5.0% by mass or less. It was also confirmed that adding Mg improves the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Although the detailed mechanism is not clear, the more Mg added, the less likely the aluminum alloy foil is to react with lithium in the electrolyte, thereby suppressing the pulverization of the aluminum alloy foil and the formation of through-holes. While moldability is slightly reduced, it is desirable to set the lower limit of the Mg content to 0.5 mass%, especially when a clear improvement in corrosion resistance is expected.

[0058] Preferably, Si: 0.5% by mass or less While silicon (Si) is sometimes added in small amounts to increase the strength of the foil, in this disclosure, a Si content of 0.5% or less is preferred because it reduces the size of Al-Fe-Si intermetallic compounds formed during casting, improving the elongation and formability of the foil. It also makes fracture originating from intermetallic compounds less likely, even when the foil is thin, and improves rollability. Furthermore, by not adding large amounts of Si, the amount of Mg-Si precipitates formed is reduced, making it less likely for rollability and Mg solid solution to decrease, thus reducing strength. For similar reasons, it is desirable to keep the Si content to 0.2% or less. Lower Si levels tend to result in better formability, rollability, grain refinement, and ductility.

[0059] Inevitable impurities In addition, unavoidable impurities such as Cu and Mn may be included. It is desirable that the amount of each element of these unavoidable impurities be 0.1% by mass or less. However, this disclosure does not mean that the upper limit of the content of the aforementioned unavoidable impurities is limited to the above values. However, since Mn does not readily dissolve in aluminum, unlike Mg, it cannot be expected to significantly increase the strength of soft foil 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 may lead to a decrease in rollability and formability. For this reason, it is desirable to keep the Mn content below 0.1% by mass.

[0060] • The azimuthal density of the Copper and R directions of the collective organization is 15 or less. Texture significantly affects the mechanical properties and formability of the foil. If the density of either the Copper or R orientation exceeds 15, there is a concern that uniform deformation may not occur during molding, resulting in reduced formability. To obtain good formability, it is desirable to keep the density of both the Copper and R orientations below 15. More preferably, the density of each orientation should be 10 or less.

[0061] • Surface Mg concentration of 5.0 atomic percent or more, and oxide film thickness of 80 Å or more (when Mg: 0.1 mass% to 1.5 mass%) Although the detailed mechanism is not clear, it has been confirmed that the Mg concentration on the foil surface and the thickness of the oxide film contribute to the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Corrosion resistance is improved when the Mg concentration on the foil surface is high and a thick oxide film is formed. For this reason, when the Mg content is between 0.1% by mass and 1.5% by mass, it is desirable to have an Mg concentration of 5.0 atomic percent or more on the aluminum foil surface and an oxide film thickness of 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. Here, the surface Mg concentration is the Mg concentration of the surface portion from the outermost surface to a depth of 8 nm, and the Mg concentration is the amount relative to 100 atomic percent of the total of all elements.

[0062] • Surface Mg concentration of 15.0 atomic percent or more, and oxide film thickness of 120 Å or more (when Mg: greater than 1.5 mass% and 5.0 mass% or less) As mentioned above, although the details of the mechanism are not clear, it has been confirmed that the Mg concentration on the foil surface and the thickness of the oxide film contribute to the corrosion resistance of lithium-ion secondary batteries to the electrolyte. Corrosion resistance is improved when the Mg concentration on the foil surface is high and a thick oxide film is formed. For this reason, when the Mg: greater than 1.5 mass% and less than or equal to 5.0 mass%, it is desirable to have an Mg concentration of 15.0 atomic percent or more on the aluminum foil surface and an oxide film thickness of 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.

[0063] When L1 is the length of the large-angle grain boundary per unit area measured by backscattered electron diffraction, and L2 is the length of the small-angle grain boundary, then L1 / L2 > 3.0 The ratio of high-angle grain boundaries (HAGB) to low-angle grain boundaries (LAGB) in the recrystallized grain structure after annealing affects the elongation and formability of the foil. If the proportion of LAGB is high in the recrystallized grain structure after final annealing, deformation localization is more likely to occur, reducing elongation and formability. Therefore, by increasing the proportion of HAGB by setting L1 / L2 > 3.0, high elongation and good formability can be expected. More preferably, L1 / L2 > 5.0.

[0064] • Tensile strength: 110 MPa to 180 MPa (when Mg: 0.1% by mass to 1.5% by mass) When the Mg content is between 0.1% and 1.5% by mass, a tensile strength of 110 MPa or higher is required to dramatically improve impact resistance and puncture strength compared to existing foils such as JIS A8079 and 8021. In particular, when moldability is important, it is preferable to have a tensile strength of 180 MPa or lower. Tensile strength can be achieved by selecting the composition and optimizing the grain size.

[0065] • Tensile strength: 180 MPa or higher (when Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass) For Mg content exceeding 1.5% by mass and 5.0% by mass or less, a tensile strength of 180 MPa or higher is preferable 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 higher is desirable. However, higher tensile strength reduces moldability, so if moldability is a priority, it is better to keep the tensile strength lower. As mentioned above, tensile strength can be achieved by selecting the composition and optimizing the crystal grain size.

[0066] • Elongation at break: 10% or more (when 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 molding method, and formability is not determined solely by elongation. In the stretching process commonly used for aluminum packaging materials, higher elongation of the aluminum alloy foil is advantageous for formability, and it is desirable to have an elongation of 10% or more when the Mg content is between 0.1% and 1.5% by mass. The elongation properties can be achieved through careful composition selection and refinement of the crystal grain size.

[0067] • Elongation at break: 15% or more (when Mg: greater than 1.5% by mass and less than or equal to 5.0% by mass) As mentioned above, the effect of elongation on formability varies greatly depending on the molding method, and formability is not determined solely by elongation. However, in the stretching process commonly used for aluminum packaging materials, higher elongation of the aluminum alloy foil is advantageous for formability, and it is desirable to have an elongation of 15% or more when the Mg content is between 1.5% and 5.0% by mass. As mentioned above, the elongation characteristics can be achieved by selecting the composition and refining the crystal grain size.

[0068] ·Average grain size: 25μm or less Soft aluminum alloy foils, with their finer crystal grains, can suppress surface roughness during deformation, resulting in high elongation and consequently high formability. The effect of crystal grain size becomes greater as the foil thickness decreases. To achieve high elongation and the resulting high formability, an average crystal grain size of 25 μm or less is desirable. The average grain size can be achieved through careful selection of the composition and optimization of manufacturing conditions, including homogenization treatment and cold rolling ratio.

[0069] The following describes the method for preparing aluminum alloy foil. Aluminum alloy ingots are cast using conventional methods such as semi-continuous casting. The aluminum alloy ingots have a composition containing Fe: 0.2% to 2.0% by mass, Mg: 0.1% to 5.0% by mass, with the remainder being Al and unavoidable impurities, and optionally Mn: 0.1% by mass or less. The resulting ingots are subjected to a homogenization treatment at 480-540°C for 6-12 hours.

[0070] • Homogenization process: 450~550℃ Homogenization treatment aims to eliminate microsegregation within the ingot and adjust the distribution of intermetallic compounds, and is a crucial process for ultimately obtaining the desired grain structure. Generally, homogenization of aluminum materials is performed at 400-600°C for a long period of time, but in this invention, it is necessary to consider grain refinement by adding Fe. In homogenization treatment, temperatures below 450°C result in insufficient Fe precipitation, raising concerns about grain coarsening during final annealing. Furthermore, an increase in the proportion of LAGB due to in-situ recrystallization leads to a decrease in L1 / L2 ratio. Increased density in both the Copper and R orientations also raises concerns about reduced formability. Above 550°C, crystallized material grows significantly, leading to grain coarsening and reduced formability during final annealing. A minimum of 3 hours is required for homogenization treatment. Less than 3 hours results in insufficient precipitation and a decrease in the density of fine intermetallic compounds. Ideally, the temperature should be between 480 and 520°C for 5 hours or more.

[0071] After homogenization treatment, hot rolling is performed to obtain an aluminum alloy sheet of the desired thickness. Hot rolling can be carried out by conventional methods, but it is desirable that the coiling temperature during hot rolling be above the recrystallization temperature, specifically above 300°C. Below 300°C, fine Al-Fe intermetallic compounds of 0.3 μm or less will precipitate. Furthermore, after hot rolling, recrystallized grains and fiber grains may be mixed, leading to concerns that the grain size will become non-uniform after intermediate and final annealing, resulting in a decrease in elongation properties, which is undesirable.

[0072] After hot rolling, cold rolling, intermediate annealing, and final cold rolling are performed to obtain the aluminum alloy foil of the present invention, with a thickness of 5 to 100 μm. There are two methods for intermediate annealing: batch annealing, in which coils are placed in a furnace and held for a certain period of time, and continuous annealing line (CAL annealing), which rapidly heats and cools the material. When applying intermediate annealing, either method is acceptable, but CAL annealing is preferable when aiming to refine the crystal grains and increase strength. However, after CAL annealing, there is a concern that the texture will develop after the final cold rolling and final annealing, increasing the density of copper and R orientations and reducing formability. For this reason, batch annealing is preferable if formability is a priority. For example, in batch annealing, conditions of 300-400°C for 3 hours or more can be used. In CAL annealing, conditions such as heating rate: 10-250°C / second, heating temperature: 400-550°C, holding time: none or holding time: 5 seconds or less, and cooling rate: 20-200°C / second can be used. However, the present invention is not limited to specific conditions regarding the presence or absence of intermediate annealing, or the conditions under which intermediate annealing is performed.

[0073] • Final cold rolling ratio: 84.0% to 97.0% The higher the final cold rolling ratio from intermediate annealing to the final thickness, the greater the amount of strain accumulated in the material, resulting in finer recrystallized grains after final annealing. It also has the effect of suppressing in-situ recrystallization, and an improvement in formability due to the increase in L1 / L2 can be expected. Specifically, it is desirable to set the final cold rolling ratio to 84.0% or higher. However, if the final cold rolling ratio is too high, there is a concern that formability will decrease due to an increase in the density of each orientation, Copper orientation and R orientation, even after final annealing. As a result, a decrease in L1 / L2 will also occur, so specifically, it is desirable to set the final cold rolling ratio to 97.0% or lower. If the final cold rolling ratio is too low, there is a concern that formability will decrease due to grain coarsening and a decrease in L1 / L2. For similar reasons, an even more desirable range for the final cold rolling ratio is 90.0% to 93.0%.

[0074] After foil rolling, a final annealing is performed to create a soft foil. Generally, the final annealing after foil rolling can be carried out at 250°C to 400°C. However, to enhance the corrosion resistance effect of Mg, it is desirable to hold the foil at a high temperature of 300°C or higher for 5 hours or more, and a temperature of 350°C to 400°C is even more desirable. If the final annealing temperature is too low, softening will be insufficient, raising concerns about a decrease in L1 / L2 ratio and an increase in density in both the copper and R orientations. Furthermore, insufficient concentration of Mg on the foil surface and insufficient growth of the oxide film may lead to reduced corrosion resistance. Above 400°C, excessive concentration of Mg on the foil surface may cause discoloration, alter the properties of the oxide film, and create microscopic cracks, resulting in reduced corrosion resistance. A final annealing time of less than 5 hours is insufficient for effective annealing.

[0075] The resulting aluminum alloy foil, at room temperature, exhibits, for example, a tensile strength of 110 MPa to 180 MPa and a fracture elongation of 10% or more when the Mg content is between 0.1% and 1.5% by mass, and a tensile strength of 180 MPa or more and a fracture elongation of 15% or more when the Mg content is between 1.5% and 5.0% by mass. Furthermore, the average grain size is 25 μm or less. The average grain size can be determined by the cutting method specified in JIS G0551.

[0076] The thickness of the aluminum alloy foil in the exterior material for energy storage devices only needs to function as a barrier layer that at least prevents moisture from entering, with a lower limit of approximately 9 μm or more and an upper limit of approximately 200 μm or less. From the viewpoint of reducing the thickness of the exterior material for energy storage devices, the thickness of the aluminum alloy foil can be such that, for example, the upper limit is 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, and 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 the preferred range of the thickness can be such as 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.

[0077] Furthermore, it is preferable that the aluminum alloy foil has a corrosion-resistant coating on at least one side to suppress the dissolution and corrosion of the aluminum alloy foil. The aluminum alloy foil may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance to the aluminum alloy foil by performing treatments on the surface of the aluminum alloy foil, such as hydrothermal modification treatments like boehmite treatment, chemical conversion treatments, anodizing treatments, plating treatments with nickel or chromium, or corrosion prevention treatments such as coating agents. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers rather than just one layer. Furthermore, among these treatments, hydrothermal modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Also, if the aluminum alloy foil has a corrosion-resistant coating, the aluminum alloy foil includes the corrosion-resistant coating.

[0078] The corrosion-resistant coating prevents delamination between the aluminum alloy foil and the substrate layer during the molding of exterior materials for energy storage devices, prevents dissolution and corrosion of the aluminum alloy foil surface due to hydrogen fluoride generated by the reaction of electrolyte and water, prevents dissolution and corrosion of aluminum oxide present on the aluminum alloy foil surface, improves the adhesion (wettability) of the aluminum alloy foil surface, and exhibits the effect of preventing delamination between the substrate layer and the aluminum alloy foil during heat sealing and molding.

[0079] Various corrosion-resistant coatings are known to be formed by chemical conversion treatments, mainly including corrosion-resistant coatings containing at least one of the following: phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include 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, acetyl acetate chromate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphate. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. This coating-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., aluminum alloy foil) using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation. Then, a treatment solution mainly composed of metal phosphate salts such as chromium phosphate, titanium phosphate, zirconium phosphate, and zinc phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphates and mixtures thereof, or a treatment solution consisting of a mixture of these with synthetic resins, etc., is applied to the degreased surface using a well-known coating method such as roll coating, gravure printing, or immersion, and then dried. Various solvents can be used as the treatment solution, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Furthermore, examples of resin components used in this process include polymers such as phenolic resins and acrylic resins, and examples of chromate treatment using an amination phenol polymer having repeating units represented by the following general formulas (1) to (4). In this amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included individually or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, acrylate methacrylate copolymer, acrylate maleic acid copolymer, acrylate styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, or amine salts. Derivatives of polyacrylic acid, such as ammonium salts, sodium salts, or amine salts of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid means a polymer of acrylic acid. Furthermore, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride, and also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group, etc. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by General 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 is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating units represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 ). The aminated phenol polymer is used alone or in combination of two or more.

[0085] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are 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 viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0086] One example of a corrosion-resistant coating is one formed by dispersing metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or fine particles of barium sulfate, in phosphoric acid, applying this mixture to the surface of a barrier layer, and then baking it at a temperature of 150°C or higher.

[0087] The corrosion-resistant coating may, if necessary, be a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic and anionic polymers include those mentioned above.

[0088] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0089] There are no particular restrictions on the amount of corrosion-resistant coating formed on the surface of the aluminum alloy foil during chemical conversion treatment, but for example, in the case of coating-type chromate treatment, the amount of coating applied to the surface of the aluminum alloy foil is 1 m 2 It is desirable that the product contains, for example, about 0.5 to 50 mg of chromium-based chromium, preferably about 1.0 to 40 mg of phosphorus-based chromium

[0090] The thickness of the corrosion-resistant coating is not particularly limited, but from the viewpoint of the cohesive force of the coating and the adhesion force with the barrier layer and the heat-fusible resin layer, it 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. 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 beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions consisting of Ce, P, and O (e.g., Ce2PO4) can be identified. + CePO4 - (at least one of the above), or, for example, a secondary ion consisting of Cr, P, and O (e.g., CrPO2) + , CrPO4 - Peaks originating from at least one of the following are detected.

[0091] The chemical conversion treatment is carried out by applying a solution containing compounds used to form a corrosion-resistant film to the surface of the aluminum alloy foil using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the aluminum alloy foil to a temperature of approximately 70-200°C. Alternatively, before applying the chemical conversion treatment to the aluminum alloy foil, it may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. This degreasing treatment makes it possible to perform the chemical conversion treatment on the surface of the aluminum alloy foil more efficiently. Furthermore, by using an acid degreasing agent, which is a fluorine-containing compound dissolved in an inorganic acid, it is possible to not only degrease the metal foil but also form a fluoride of the passive metal; in such cases, only the degreasing treatment may be performed.

[0092] [Thermofusible resin layer 4] In the exterior material for energy storage devices of this disclosure, the heat-sealable resin layer 4 is the innermost layer and is a layer (sealant layer) that performs the function of sealing the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device.

[0093] The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, are preferred. The presence of a polyolefin backbone in the resin constituting the heat-fusible resin layer 4 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable to detect a peak originating from maleic anhydride. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1A peak derived from maleic anhydride is detected in the vicinity. If the heat-fusible resin layer 4 is composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0094] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. These polyolefin resins may be used individually or in combination of two or more.

[0095] Furthermore, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0096] Acid-modified polyolefins are polymers obtained by modifying polyolefins through block polymerization or graft polymerization with an acid component. Examples of polyolefins that can be acid-modified include the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or their anhydrides, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0097] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin with an acid component, or by block polymerization or graft polymerization of an acid component to a cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

[0098] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0099] The heat-sealable resin layer 4 may be formed by a single resin or by a blended polymer of two or more resins. Furthermore, the heat-sealable resin layer 4 may be formed as a single layer or as two or more layers of the same or different resins.

[0100] Furthermore, the exterior material 1 for energy storage devices of this disclosure can be suitably used as an exterior material for all-solid-state batteries, and the melting point of the heat-fusible resin layer 4 of the exterior material for all-solid-state batteries is preferably 150 to 270°C, preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C.

[0101] Furthermore, the resins included in the heat-sealable resin layer 4 of the casing material for all-solid-state batteries include polyolefins such as polypropylene and polyethylene, as well as 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 casing material for all-solid-state batteries, the heat-sealable resin layer 4 is preferably formed from a polybutylene terephthalate film. The polybutylene terephthalate film forming the heat-sealable resin layer 4 may be formed by laminating a pre-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.

[0102] The polybutylene terephthalate film may be an stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and an unstretched polybutylene terephthalate film is preferred.

[0103] The polybutylene terephthalate film preferably contains an elastomer in addition to polybutylene terephthalate. The elastomer plays a role in enhancing the flexibility of the polybutylene terephthalate film while ensuring its durability in high-temperature environments. Preferred elastomers include at least one thermoplastic elastomer selected from polyester, polyamide, polyurethane, polyolefin, polystyrene, and polyether types, or thermoplastic elastomers that are copolymers thereof. In the polybutylene terephthalate film, there are no particular restrictions on the elastomer content, as long as it is sufficient to enhance the flexibility of the polybutylene terephthalate film while ensuring its durability in high-temperature environments. For example, it 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. Alternatively, the content may be 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 approximately 0.1 to 10.0 mass%, 0.1 to 8.0 mass%, 0.1 to 5.0 mass%, 0.5 to 10.0 mass%, 0.5 to 8.0 mass%, 0.5 to 5.0 mass%, 1.0 to 10.0 mass%, 1.0 to 8.0 mass%, 1.0 to 5.0 mass%, 3.0 to 10.0 mass%, 3.0 to 8.0 mass%, and 3.0 to 5.0 mass%.

[0104] In the case of an outer casing material for an all-solid-state battery, if the heat-sealable resin layer 4 is formed of two or more layers, at least one layer is preferably made of polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the outer casing material for the all-solid-state battery. Furthermore, the layer that adheres to the adhesive layer 5 is preferably made of polybutylene terephthalate film. If the heat-sealable resin layer 4 is formed of two or more layers, the layer not made of polybutylene terephthalate film may be made of, for example, polyolefins such as polypropylene and polyethylene, or acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments compared to polybutylene terephthalate, it is preferable that the heat-sealable resin layer 4 in the outer casing material for an all-solid-state battery is made only of polybutylene terephthalate film.

[0105] Furthermore, the heat-fusible resin layer 4 may contain a lubricant or the like as needed. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more types.

[0106] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in base layer 1. The lubricant may be used alone or in combination of two or more types.

[0107] When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount present is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably 10 to 50 mg / m². 2 To a certain extent, more preferably 15-40 mg / m² 2 The degree can be described as follows.

[0108] The lubricant present on the surface of the heat-fusible resin layer 4 may be a lubricant contained in the resin constituting the heat-fusible resin layer 4 that has seeped out, or a lubricant may be applied to the surface of the heat-fusible resin layer 4.

[0109] Furthermore, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device elements, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described later is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0110] Furthermore, the following second embodiment is also preferred for the heat-fusible resin layer. In the second embodiment, the heat-fusible resin layer 4 is composed of a single layer or multiple layers, and of the heat-fusible resin layer 4, the first heat-fusible resin layer 41 constitutes the surface of the laminate. Therefore, when assembling the energy storage device, the first heat-fusible resin layer 41 is heat-fused to seal the energy storage device elements. Furthermore, the second embodiment is characterized in that the logarithmic decay rate ΔE of the first heat-fusible resin layer 41 at 140°C in rigid pendulum measurement is 0.25 or less.

[0111] When the heat-fusible resin layer 4 is composed of a single layer, the heat-fusible resin layer 4 constitutes the first heat-fusible resin layer 41.

[0112] Furthermore, if the heat-sealable resin layer 4 is composed of multiple layers, the laminate constituting the exterior material 10 for the energy storage device includes, in order from the surface side, at least a first heat-sealable resin layer 41 and a second heat-sealable resin layer 42.

[0113] When the heat-fusible resin layer 4 is composed of multiple layers, in addition to the first heat-fusible resin layer 41 and the second heat-fusible resin layer 42, the heat-fusible resin layer 4 may also have a third heat-fusible resin layer, a fourth heat-fusible resin layer, etc., on the barrier layer 3 side of the second heat-fusible resin layer 42. When the heat-fusible resin layer 4 is composed of multiple layers, it is preferable that the heat-fusible resin layer 4 is composed of two layers: the first heat-fusible resin layer 41 and the second heat-fusible resin layer 42.

[0114] In the second embodiment, the logarithmic decay rate ΔE at 140°C is 0.25 or less, which effectively suppresses crushing when the first heat-sealable resin layer 41 is heat-sealed, and the synergistic effect with the barrier layer (aluminum alloy foil) makes it possible to improve the insulation properties of the exterior material for the energy storage device.

[0115] In the second embodiment, the logarithmic decay rate at 140°C in rigid pendulum measurement is an indicator of the hardness of the resin in a high-temperature environment of 140°C, and a smaller logarithmic decay rate means that the resin is harder. The temperature at which the heat-fusible resin layer is heat-fused is high, and in the heat-fused portion formed by heat-fusing the heat-fusible resin layer, the heat-fusible resin layer may protrude significantly into the inside of the heat-fused portion (the side where the energy storage device element is housed). When the heat-fusible resin layer 4 protrudes significantly into the inside of the heat-fused portion, cracks can occur in the heat-fusible resin layer 4 starting from this protrusion (so-called poly-retention), and the insulating properties tend to decrease. Figure 8 shows a schematic cross-sectional view in which a protrusion A is formed inside the heat-fused portion of the heat-fusible resin layer 4. As shown in this cross-sectional view, the protrusion A has endpoints A1 and A2, and these endpoints A1 and A2 are structurally prone to becoming the starting points for cracks. Therefore, if the heat-fusible resin layer 4 protrudes significantly into the heat-fusible portion, forming a protrusion, the insulation performance is likely to decrease due to cracking. For this reason, it is important to control the shape of the heat-fusible portion, and for this purpose, the hardness of the heat-fusible resin layer at high temperatures is important. For this reason, the present invention employs a logarithmic attenuation rate at a high temperature of 140°C. In rigid pendulum measurement, the attenuation rate of the pendulum is measured when the temperature of the resin is increased from a low temperature to a high temperature. In rigid pendulum measurement, the edge portion is generally brought into contact with the surface of the object to be measured, and the pendulum is made to move in the left-right direction to impart vibration to the object to be measured. In the exterior material for energy storage devices of the present invention, by arranging a hard first heat-fusible resin layer 41 with a logarithmic attenuation rate of 0.25 or less in a high-temperature environment of 140°C on the surface of the exterior material for energy storage devices, crushing (thinning) of the first heat-fusible resin layer 41 during heat fusion of the exterior material for energy storage devices is suppressed. By suppressing the collapse of the first heat-fusible resin layer 41, the heat-fusible resin layer is prevented from protruding significantly inward into the heat-fussed portion formed by heat-fussing the heat-fusible resin layer, thereby effectively suppressing the decrease in the insulating properties of the exterior material for the energy storage device due to heat fusion.

[0116] The logarithmic decay rate ΔE is calculated using the following formula. ΔE=[ln(A1 / A2)+ln(A2 / A3)+...ln(An / An+1)] / n A: Amplitude n: wavenumber

[0117] In a second embodiment, from the viewpoint of effectively suppressing the collapse of the first heat-fusible resin layer 41 when the first heat-fusible resin layer 41 is heat-fussed and improving its insulating properties, the logarithmic attenuation rate ΔE at 140°C is preferably about 0.10 or more, more preferably about 0.11 or more, even more preferably about 0.12 or more, and also preferably about 0.20 or less, more preferably about 0.18 or less, even more preferably about 0.15 or less, and even more preferably about 0.13 or less. Preferred ranges include approximately 0.10-0.25, 0.10-0.20, 0.10-0.18, 0.10-0.15, 0.10-0.13, 0.11-0.25, 0.11-0.20, 0.11-0.18, 0.11-0.15, 0.11-0.13, 0.12-0.25, 0.12-0.20, 0.12-0.18, 0.12-0.15, and 0.12-0.13.

[0118] The logarithmic decay rate ΔE of the first heat-fusible resin layer 41 can be adjusted, for example, by the melt mass flow rate (MFR), molecular weight, melting point, softening point, molecular weight distribution, and degree of crystallinity of the resin constituting the first heat-fusible resin layer 41.

[0119] In measuring the logarithmic decay rate ΔE, a commercially available rigid pendulum-type physical property tester was used. A cylindrical cylinder edge was used as the edge pressed against the first heat-fusible resin layer 41, the initial amplitude was 0.3 degrees, and the rigid pendulum physical property test was performed on the first heat-fusible resin layer 41 under the conditions of a temperature range of 30°C to 200°C with a heating rate of 3°C / min (see Figure 7). Based on the logarithmic decay rate at 140°C, a standard for suppressing deformation exhibited by the first heat-fusible resin layer 41, as described later, was established. For the first heat-fusible resin layer 41 for which the logarithmic decay rate ΔE is measured, the exterior material for the energy storage device was immersed in 15% hydrochloric acid to dissolve the base layer and barrier layer, and the sample was thoroughly dried before being used for measurement. If the exterior material for the energy storage device has an adhesive layer 5, as described later, the laminate of the adhesive layer 5 and the heat-fusible resin layer 4 was used as the sample.

[0120] Furthermore, the exterior material for the energy storage device can be obtained from the energy storage device, and the logarithmic decay rate ΔE of the first heat-sealable resin layer 41 can be measured. When obtaining the exterior material for the energy storage device from the energy storage device and measuring the logarithmic decay rate ΔE of the first heat-sealable resin layer 41, a sample is cut from the top surface of the exterior material for the energy storage device that has not been stretched by molding and used as the measurement target.

[0121] In a second embodiment, the heat-sealable resin layers of a laminate constituting the exterior material for an energy storage device are placed facing each other and heated and pressurized in the lamination direction under the conditions of a temperature of 190°C, a surface pressure of 2.0 MPa, and a time of 3 seconds. Preferably, the remaining percentage of the total thickness of the two first heat-sealable resin layers 41 is about 30% or more, preferably about 32% or more, and preferably about 34% or more. Preferred ranges include 30-60%, 32-60%, 34-60%, 30-50%, 32-50%, and 34-50%. The upper limit of the remaining percentage of thickness is, for example, about 60% and about 50%. The remaining percentage of thickness is a value measured by the following method. To set the remaining percentage of thickness, for example, the type, composition, molecular weight, etc. of the resin constituting the first heat-sealable resin layer 41 are adjusted.

[0122] <Measurement of the remaining thickness of the first heat-fusible resin layer> A test sample is prepared by cutting an outer casing material for an energy storage device to a length of 150 mm and a width of 60 mm. Next, the first heat-sealable resin layers 41 of the test sample are placed facing each other. Then, in this state, a 7 mm wide metal plate is used to heat and pressurize the test sample from both sides in the lamination direction at a temperature of 190°C, a surface pressure of 0.5 MPa, and for a time of 3 seconds, to heat-seal the first heat-sealable resin layers 41. Next, the heat-sealed portion of the test sample is cut in the lamination direction using a microtome, and the total thickness of the two heat-sealable resin layers 41 that are heat-sealed to each other is measured on the exposed cross-section. The same procedure is followed for the test sample before heat sealing, where it is cut in the lamination direction using a microtome, and the thickness of the two first heat-sealable resin layers 41 is measured on the exposed cross-section. The ratio of the total thickness of the two first heat-fusible resin layers 41 after heat fusion to the total thickness of the two first heat-fusible resin layers 41 before heat fusion is calculated to determine the remaining percentage (%) of the total thickness of the two first heat-fusible resin layers 41. The thickness of the two first heat-fusible resin layers 41 at the heat-fussed portion is measured in areas where the thickness of the exterior material for the energy storage device is constant.

[0123] Furthermore, it is also possible to obtain the exterior material for the energy storage device from the energy storage device and measure the remaining percentage of the total thickness of the two first heat-fusible resin layers 41. When obtaining the exterior material for the energy storage device from the energy storage device and measuring the remaining percentage of the total thickness of the two first heat-fusible resin layers 41, a sample is cut from the top surface of the exterior material for the energy storage device that has not been stretched by molding and used as the target for measurement.

[0124] In the second embodiment, the resin constituting the first heat-fusible resin layer 41 is not particularly limited, as long as it is heat-fusible and the logarithmic decay rate ΔE of the first heat-fusible resin layer 41 is 0.25 or less, and examples of resins forming the heat-fusible resin layer include those described above.

[0125] The first heat-fusible resin layer 41 constituting the surface preferably contains polyolefin. For example, in the exterior material 10 for energy storage devices of this disclosure, if the heat-fusible resin layer 4 comprises a first heat-fusible resin layer 41 and a second heat-fusible resin layer 42, it is preferable that the first heat-fusible resin layer 41 constituting the surface contains polyolefin and the second heat-fusible resin layer 42 contains acid-modified polyolefin. Furthermore, in the exterior material 10 for energy storage devices of this disclosure, if an adhesive layer 5 is provided, it is preferable that the first heat-fusible resin layer 41 constituting the surface contains polyolefin and the adhesive layer 5 contains acid-modified polyolefin. It is also preferable that the adhesive layer 5 contains acid-modified polyolefin, the first heat-fusible resin layer contains polyolefin, and the second heat-fusible resin layer contains polyolefin, and it is more preferable that the adhesive layer 5 contains acid-modified polypropylene, the first heat-fusible resin layer contains polypropylene, and the second heat-fusible resin layer contains polypropylene.

[0126] Furthermore, the first heat-sealable resin layer 41 may contain a lubricant or the like as needed. When the first heat-sealable resin layer 41 contains a lubricant, the moldability of the exterior material for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more types.

[0127] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in base layer 1. The lubricant may be used alone or in combination of two or more types.

[0128] When a lubricant is present on the surface of the first heat-fusible resin layer 41, the amount present is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably 10 to 50 mg / m². 2 To a certain extent, more preferably 15-40 mg / m² 2The degree can be described as follows. Furthermore, even if a lubricant is present on the surface of the first heat-fusible resin layer 41, the first heat-fusible resin layer 41, including the lubricant, constitutes the surface of the exterior material 10 for the energy storage device.

[0129] The lubricant present on the surface of the first heat-fusible resin layer 41 may be a lubricant contained in the resin constituting the first heat-fusible resin layer 41 that has seeped out, or a lubricant may be applied to the surface of the first heat-fusible resin layer 41.

[0130] Furthermore, the thickness of the first heat-sealable resin layer 41 is not particularly limited as long as the heat-sealable resin layer performs the function of sealing the energy storage device element through heat fusion.

[0131] In a second embodiment, from the viewpoint of effectively suppressing crushing when the first heat-fusible resin layer 41 is heat-fussed and improving insulation, the thickness of the first heat-fusible resin layer 41 is preferably about 100 μm or less, about 85 μm or less, about 60 μm or less, and also 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, and the preferred range is Examples include 5-100 μm, 5-85 μm, 5-60 μm, 10-100 μm, 10-85 μm, 10-60 μm, 20-100 μm, 20-85 μm, 20-60 μm, 30-100 μm, 30-85 μm, 30-60 μm, 40-100 μm, 40-85 μm, and 40-60 μm.

[0132] Specifically, from the viewpoint of effectively suppressing crushing when the first heat-fusible resin layer 41 is heat-fussed and improving insulation, when the heat-fusible resin layer 4 is composed of a single layer of the first heat-fusible resin layer 41, the thickness of the first heat-fusible resin layer 41 is preferably about 100 μm or less, about 85 μm or less, about 60 μm or less, or about 25 μm or less, and also preferably 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. The ranges include approximately 5-100 μm, 5-85 μm, 5-60 μm, 5-25 μm, 10-100 μm, 10-85 μm, 10-60 μm, 10-25 μm, 20-100 μm, 20-85 μm, 20-60 μm, 20-25 μm, 30-100 μm, 30-85 μm, 30-60 μm, 40-100 μm, 40-85 μm, and 40-60 μm.

[0133] Furthermore, in a second embodiment, from the viewpoint of effectively suppressing crushing when the first heat-fusible resin layer 41 is heat-fussed, improving insulation, and enhancing the sealing performance of the exterior material for the energy storage device, when the heat-fusible resin layer 4 comprises a first heat-fusible resin layer 41 and a second heat-fusible resin layer 42, the thickness of the first heat-fusible resin layer 41 is preferably about 85 μm or less, about 60 μm or less, about 25 μm or less, and also 5 μm The above-mentioned ranges include 10 μm or more, 20 μm or more, 30 μm or more, and 40 μm or more, while preferred ranges include approximately 5-85 μm, 5-60 μm, 5-25 μm, 10-85 μm, 10-60 μm, 10-25 μm, 20-85 μm, 20-60 μm, 20-25 μm, 30-85 μm, 30-60 μm, 40-85 μm, and 40-60 μm.

[0134] In a second embodiment, when the heat-fusible resin layer 4 comprises a second heat-fusible resin layer 42, the resin constituting the second heat-fusible resin layer 42 is preferably a resin containing a polyolefin backbone, such as polyolefin or acid-modified polyolefin. These resins are the same as those described for the first heat-fusible resin layer 41. The presence of a polyolefin backbone in the resin constituting the second heat-fusible resin layer 42 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the second heat-fusible resin layer 42 is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak derived from maleic anhydride is detected in the vicinity. If the second heat-fusible resin layer 42 is composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0135] In a second embodiment, the second heat-fusible resin layer 42 preferably contains polyolefin. In particular, when the heat-fusible resin layer 4 comprises a first heat-fusible resin layer 41 and a second heat-fusible resin layer 42, and includes the adhesive layer 5 described later, the second heat-fusible resin layer 42 preferably contains polyolefin. Furthermore, as described above, in the exterior material 10 for energy storage devices of this disclosure, when the heat-fusible resin layer 4 comprises a first heat-fusible resin layer 41 and a second heat-fusible resin layer 42, and does not include the adhesive layer 5 described later, it is preferable that the first heat-fusible resin layer 41 constituting the surface contains polyolefin, and the second heat-fusible resin layer 42 contains acid-modified polyolefin.

[0136] In the second embodiment, the thickness of the second heat-fusible resin layer 42 is not particularly limited as long as the heat-fusible resin layer 4 heat-fusses and performs the function of sealing the energy storage device element.

[0137] In the second embodiment, from the viewpoint of effectively suppressing crushing when the first heat-fusible resin layer 41 is heat-fusible, improving insulation, and enhancing the sealing performance of the exterior material for the energy storage device, it is preferable that the thickness of the second heat-fusible resin layer 42 is greater than the thickness of the first heat-fusible resin layer 41. The first heat-fusible resin layer 41 is preferably made of a resin that flows easily at high temperatures to provide excellent heat-fusibility. By having such a thickness relationship, the insulation performance of the exterior material for the energy storage device can be increased by making the first heat-fusible resin layer 41, which is part of the heat-fusible resin layer 4 and is made of a resin that flows easily, thinner. By appropriately adjusting the MFR, melting point, molecular weight, etc. of the resin constituting the first heat-fusible resin layer 41, it is possible to make the first heat-fusible resin layer 41 a resin layer that flows easily at high temperatures.

[0138] In a second embodiment, from the viewpoint of effectively suppressing crushing when the first heat-fusible resin layer 41 is heat-fussed, improving insulation, and enhancing the sealing performance of the exterior material for the energy storage device, the thickness of the second heat-fusible resin layer 42 is preferably about 100 μm or less, about 85 μm or less, or about 60 μm or less, and also 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Preferred ranges include approximately 5-100 μm, 5-85 μm, 5-60 μm, 10-100 μm, 10-85 μm, 10-60 μm, 20-100 μm, 20-85 μm, 20-60 μm, 30-100 μm, 30-85 μm, 30-60 μm, 40-100 μm, 40-85 μm, and 40-60 μm.

[0139] In a second embodiment, the heat-fusible resin layer 4 may include, in addition to the first heat-fusible resin layer 41 and the second heat-fusible resin layer 42, other heat-fusible resin layers such as a third heat-fusible resin layer and a fourth heat-fusible resin layer on the barrier layer 3 side of the second heat-fusible resin layer 42. Examples of resins constituting the other heat-fusible resin layers are the same as those described for the first heat-fusible resin layer 41. Examples of the thickness of the other heat-fusible resin layers are the same as the thickness described for the second heat-fusible resin layer 42.

[0140] In the second aspect, the total thickness of the heat-fusible resin layer 4 is preferably about 100 μm or less, about 85 μm or less, or about 60 μm or less, and also 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Preferred ranges include about 5 to 100 μm, about 5 to 85 μm, about 5 to 60 μm, about 10 to 100 μm, about 10 to 85 μm, about 10 to 60 μm, about 20 to 100 μm, about 20 to 85 μm, about 20 to 60 μm, about 30 to 100 μm, about 30 to 85 μm, about 30 to 60 μm, about 40 to 100 μm, about 40 to 85 μm, and about 40 to 60 μm.

[0141] [Adhesive layer 5] In the exterior material for energy storage devices of this disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or acid-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0142] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. Preferably, the adhesive layer 5 is formed of a cured product of a resin composition containing a curable resin. A 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. As the resin used to form the adhesive layer 5, for example, the same type as the adhesive exemplified in the adhesive layer 2 can be used. Furthermore, it is preferable that the resin used to form the adhesive layer 5 contains a polyolefin skeleton, such as the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4 mentioned above. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry, and the analytical method is not particularly limited. In addition, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, it is preferable that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1A peak originating from maleic anhydride is detected in the vicinity. However, if the degree of acid denaturation is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0143] From the viewpoint of firmly bonding the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred as the acid-modified polyolefin are polyolefins modified with a carboxylic acid or its anhydride, polypropylenes modified with a carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0144] Furthermore, from the viewpoint of reducing the thickness of the exterior material for energy storage devices while providing excellent shape stability after molding, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing acid-modified polyolefin and a curing agent. In this case, the acid-modified polyolefin and the curing agent constitute the curable resin. Preferably, the acid-modified polyolefin is one of the aforementioned examples.

[0145] Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, amide ester resin is preferred. Amide ester resin is generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition comprising at least one of these resins and the acid-modified polyolefin. Furthermore, if unreacted compounds containing isocyanate groups, compounds containing oxazoline groups, or curing agents such as epoxy resin remain in the adhesive layer 5, the presence of these unreacted compounds can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, or time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0146] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups, curing agents having epoxy groups, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0147] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. 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), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, burettes, and isocyanurates are also examples.

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

[0149] Compounds containing an oxazoline group are not particularly limited as long as they have an oxazoline skeleton. Specific examples of compounds containing an oxazoline group include those with a polystyrene main chain and those with an acrylic main chain. Commercially available examples include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0150] The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0151] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably around 50 to 2000, more preferably around 100 to 1000, and even more preferably around 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0152] 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, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0153] The proportion of epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0154] 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 a two-component polyurethane.

[0155] The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere where components that induce corrosion of the barrier layer, such as electrolytes, are present.

[0156] Furthermore, if the adhesive layer 5 is a cured product of a resin composition containing at least one compound selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups each function as curing agents.

[0157] Furthermore, when the exterior material for the energy storage device is an exterior material for an all-solid-state battery, it is preferable that the adhesive layer be 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. This suppresses delamination between the barrier layer and the heat-sealable resin layer in high-temperature environments, and also allows the exterior material for the all-solid-state battery to exhibit high sealing strength.

[0158] The polyester is preferably a polyester polyol. The polyester polyol is not particularly limited as long as it has ester bonds in the polymer main chain and multiple hydroxyl groups in the terminal or side chains. The polycarbonate is preferably a polycarbonate polyol. The polyester polyol is not particularly limited as long as it has carbonate bonds in the polymer main chain and multiple hydroxyl groups in the terminal or side chains. The polyester may also preferably be, for example, a polyester obtained by reacting a polyester polyol with a polyisocyanate (e.g., diisocyanate) in advance to extend the urethane chain, or a polycarbonate obtained by reacting a polycarbonate polyol with a polyisocyanate (e.g., diisocyanate) in advance 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.

[0159] The alicyclic isocyanate compound is not particularly limited as long as it is a compound having an alicyclic structure and an isocyanate group. It is preferable that the alicyclic isocyanate compound has two or more isocyanate groups. Specific examples of alicyclic isocyanate compounds include isophorone diisocyanate (IPDI), bis(4-isocyanate cyclohexyl)methane, 1,3-bis(isocyanate methyl)cyclohexane, methylenebis(4,1-cyclohexylene)diisocyanate, polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, burettes, and isocyanurates are also examples. Furthermore, it is preferable that the alicyclic isocyanate compound is a polyol-modified polyisocyanate obtained by reacting an alicyclic isocyanate with a polyol (e.g., polyester polyol) beforehand. The resin composition forming the adhesive layer may contain one or more types of alicyclic isocyanate compounds.

[0160] Furthermore, the aromatic isocyanate compound is not particularly limited as long as it is a compound having an aromatic ring and an isocyanate group. It is preferable that the aromatic isocyanate compound has two or more isocyanate groups. Specific examples of aromatic isocyanate compounds include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Also, adducts, burettes, and isocyanurates are also examples. It is also preferable that the aromatic isocyanate compound is a polyol-modified polyisocyanate obtained by reacting an aromatic isocyanate with a polyol (e.g., polyester polyol) beforehand. The aromatic isocyanate compound contained in the resin composition forming the adhesive layer 5 may be one type or two or more types.

[0161] The resin composition forming the adhesive layer may, for example, contain an alicyclic isocyanate compound but not an aromatic isocyanate compound, or it may contain an aromatic isocyanate compound but not an alicyclic isocyanate compound, or it may contain both an alicyclic isocyanate compound and an aromatic isocyanate compound. It is preferable that the resin composition forming the adhesive layer 5 contains an aromatic isocyanate compound.

[0162] The content of alicyclic isocyanate compounds and aromatic isocyanate compounds in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, respectively, in the resin composition constituting the adhesive layer 5. Furthermore, if the adhesive layer 5 contains both alicyclic isocyanate compounds and aromatic isocyanate compounds, the total content of these compounds is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5.

[0163] The thickness of the 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, and about 5 μm or less for the upper limit, and preferably about 0.1 μm or more and about 0.5 μm or more for the lower limit, and the range of the thickness 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, and about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2, or the cured product of acid-modified polyolefin and curing agent, it is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified in 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. Also, when using the resin exemplified in the heat-fusible resin layer 4, it can be formed, for example, by extrusion molding of the heat-fusible resin layer 4 and the adhesive layer 5.

[0164] [Surface coating layer 6] The exterior material for energy storage devices of this disclosure may optionally include a surface coating layer 6 on the base layer 1 (on the side opposite to the barrier layer 3 of the base layer 1) for the purpose of improving at least one of the following: aesthetics, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the exterior material for energy storage devices when the energy storage device is assembled using the exterior material for energy storage devices.

[0165] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0166] If the resin forming the surface coating layer 6 is a curable resin, it 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.

[0167] Examples of two-component curable polyurethanes include polyurethanes comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are used with a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the main component and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. The surface coating layer 6 being formed of polyurethane provides excellent electrolyte resistance to the exterior material for energy storage devices.

[0168] The surface coating layer 6 may contain, as necessary, additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents in at least one of its surface and interior, depending on the functionality to be provided to the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0169] The additive may be an inorganic or organic substance. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0170] 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, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used individually or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0171] The method for forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin to form the surface coating layer 6 can be used. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0172] The thickness of the surface coating layer 6 is not particularly limited as long as it performs the above-mentioned functions as a surface coating layer 6, and for example, it can be about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0173] 2. Method for manufacturing exterior materials for energy storage devices The method for manufacturing the exterior material for energy storage devices is not particularly limited, as long as a laminate is obtained by laminating the layers of the exterior material for energy storage devices of this disclosure. At a minimum, a method can be described that includes the step of laminating the base layer 1, the barrier layer 3, and the heat-fusible resin 4 in this order. As described above, an aluminum alloy foil satisfying the predetermined composition described above can be used as the barrier layer 3.

[0174] An example of a method for manufacturing the exterior material for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated laminate A") is formed by sequentially laminating a base layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form the adhesive layer 2 is applied to the base layer 1 or, if necessary, to the barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured.

[0175] Next, a heat-fusible resin layer 4 is laminated onto the barrier layer 3 of laminate A. When the heat-fusible resin layer 4 is directly laminated onto the barrier layer 3, the heat-fusible resin layer 4 can be laminated onto the barrier layer 3 of laminate A by methods such as thermal lamination or extrusion lamination. When an adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-fusible resin layer 4 by extrusion onto the barrier layer 3 of laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of forming a laminate in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated separately, and then laminating this onto the barrier layer 3 of laminate A by thermal lamination, or a method of forming a laminate in which the adhesive layer 5 is laminated onto the barrier layer 3 of laminate A, and then laminating this with the heat-fusible resin layer 4 by thermal lamination. (3) A method of lamination by pouring a molten adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 which has been previously formed into a sheet, thereby bonding the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5 (sandwich lamination method); (4) A method of lamination by applying an adhesive solution to the barrier layer 3 of the laminate A to form the adhesive layer 5, drying it, or even baking it, and then laminating the heat-fusible resin layer 4 which has been previously formed into a sheet, onto this adhesive layer 5.

[0176] When a surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the resin used to form the surface coating layer 6 to the surface of the base layer 1. The order of the steps of laminating the barrier layer 3 to the surface of the base layer 1 and laminating the surface coating layer 6 to the surface of the base layer 1 is not particularly limited. For example, the surface coating layer 6 may be formed on the surface of the base layer 1, and then the barrier layer 3 may be formed on the surface of the base layer 1 opposite to the surface coating layer 6.

[0177] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0178] In exterior materials for energy storage devices, the processability of each layer constituting the laminate may be improved by subjecting it to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as needed. For example, by applying corona treatment to the surface of the substrate layer 1 opposite to the barrier layer 3, the printability of ink on the surface of the substrate layer 1 can be improved.

[0179] 3. Applications of exterior materials for energy storage devices The exterior material for energy storage devices of this disclosure is used in packaging for sealing and housing energy storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an energy storage device can be formed by housing energy storage device elements, which include at least a positive electrode, a negative electrode, and an electrolyte, in packaging formed from the exterior material for energy storage devices of this disclosure.

[0180] Specifically, an energy storage device is provided by covering an energy storage device element, which comprises at least a positive electrode, a negative electrode, and an electrolyte, with the energy storage device exterior material of this disclosure, such that a flange portion (an area where heat-sealable resin layers come into contact) is formed around the periphery of the energy storage device element, with the metal terminals connected to the positive electrode and negative electrode respectively protruding outward, and then heat-sealing the heat-sealable resin layers of the flange portion to seal it. When housing the energy storage device element in a package formed from the energy storage device exterior material of this disclosure, the package is formed such that the heat-sealable resin portion of the energy storage device exterior material of this disclosure faces inward (the surface in contact with the energy storage device element).

[0181] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the casing material for energy storage devices disclosed herein can be 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, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. [Examples]

[0182] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0183] Aluminum alloy ingots were prepared with the compositions shown in Tables 1 and 2 (the remainder being Al and unavoidable impurities). Homogenization treatment was performed under the conditions shown in Tables 1 and 2, and then hot rolling was performed at a finishing temperature of 330°C to produce 3 mm thick plates. Subsequently, aluminum alloy foil samples with a thickness of 40 μm and a width of 1200 mm were prepared through cold rolling, intermediate annealing, final cold rolling, and final annealing. The conditions for intermediate and final annealing are shown in Tables 1 and 2. In Example 11, CAL annealing was performed as the intermediate annealing. CAL was performed under the following conditions: heating rate: 70°C / sec, heating temperature: 420°C, holding time: 0 seconds, cooling rate: 50°C / sec. The cold rolling column in Tables 1 and 2 shows the plate thickness immediately before intermediate annealing and the cold rolling rate up to that plate thickness. The following tests or measurements were performed on the prepared aluminum alloy foil, and the results are shown in Tables 1 to 4.

[0184] • Tensile strength, elongation at break Both tensile strength and elongation at break were measured by tensile testing. The tensile testing was conducted in accordance with JIS Z2241, using JIS No. 5 test specimens taken from the sample to measure elongation in the 0° direction relative to the rolling direction. The tests were performed on a universal tensile testing machine (Shimadzu Corporation AGS-X 10kN) at a tensile speed of 2 mm / min. The elongation was the elongation at fracture and was calculated using the following method. First, before the test, two lines were marked perpendicular to the length of the specimen at a distance of 50 mm from the center of the specimen. After the test, the fracture surfaces of the aluminum alloy foil were joined together and the distance between the marks was measured. The elongation (mm) was calculated by subtracting the gauge length (50 mm) from the distance between the marks, and the elongation (%) was obtained by dividing the elongation by the gauge length (50 mm).

[0185] ·Average grain size The surface of an aluminum alloy foil was electropolished using a mixed solution of 20% perchloric acid and 80% ethanol at a voltage of 20V. Subsequently, it was anodized in Barker's solution at a voltage of 30V. The crystal grains of the treated specimens were observed using an optical microscope. The average crystal grain size was calculated from the photographs taken using the sectioning method specified in JIS G0551.

[0186] L1 (HAGB length) / L2 (LAGB length) The foil surface was electropolished, and then the crystal orientation was analyzed using a SEM-EBSD apparatus to observe large-angle grain boundaries (HAGBs) with an orientation difference of 15° or more, and small-angle grain boundaries (LAGBs) with an orientation difference of 2° or more and less than 15°. Four fields of view were measured at a magnification of ×500 with a field of view size of 170 × 340 μm. The length of HAGBs (L1) and LAGBs (L2) per unit area within the field of view were determined, and their ratio was calculated. The calculated ratio, L1 / L2, is shown in Tables 3 and 4.

[0187] • Crystal orientation Copper direction is {112} <111> The R direction is {123} <634> The following orientations were designated as representative orientations. The orientation densities for each orientation were obtained by the following method: Incomplete pole figures for {111}, {200}, and {220} were measured by X-ray diffraction. Using these results, the crystal orientation distribution function (ODF) was determined, and the orientation densities for the Copper orientation and the R orientation were obtained.

[0188] ·Surface analysis The Mg concentration on the foil surface was estimated using XPS (X-ray Photoelectron Spectroscopy). Narrow spectra obtained from narrow-scan measurements in the surface region from the outermost surface to a depth of 8 nm were separated by waveform analysis, and the atomic concentrations of each element were quantified. For the quantification of Mg, the Mg2p spectrum was used. Details of the analytical conditions are as follows. Measurement device: ULVAC-FI PHI5000-VersaProbeIII Incident X-ray: Al Kα monochromatic X-ray, hν=1486.6ev X-ray source output: 100W, 20kV, 5.8mA Pass energy: 26 eV Step: 0.05eV Analysis area (beam diameter): 100μm x 1.4mm Detection angle: 45° Photoelectron capture angle: 45 degrees Measurement area: 100 μm in diameter, 1.4 mm in the X direction. Peak shift correction: Correction is performed so that the CC peak is 285.0 eV at the C1s peak. Charge neutralization: Charge neutralization using a dual beam of Ar ions and electron beams.

[0189] • Measurement of oxide film thickness The oxide film thickness was measured using an FE-EPMA (Electron Probe Micro Analyzer) instrument. The oxide film thickness of the sample was calculated using a calibration curve of X-ray intensity obtained from oxide film samples with known thicknesses. The FE-EPMA instrument used was the JXA-8530F from JEOL Ltd. The analysis conditions were an acceleration voltage of 10kV, an irradiation current of 100nA, and a beam diameter of 50μm.

[0190] • Piercing strength A needle with a diameter of 1.0 mm and a tip radius of 0.5 mm was used to pierce a 40 μm thick aluminum alloy foil at a speed of 50 mm / min. The maximum load (N) required for the needle to penetrate the foil was measured as the puncture strength. Here, a puncture strength of 9.0 N or higher was judged to be good puncture resistance and was indicated as "○" (good) in Tables 3 and 4. A puncture strength of less than 9.0 N was judged to be poor puncture resistance and was indicated as "×" (poor) in Tables 3 and 4.

[0191] • Limit forming height The forming height was evaluated using a rectangular tube forming test. The test was conducted using a universal thin sheet forming tester (ERICHSEN Model 142 / 20), and a rectangular punch with the shape shown in Figure 5 (side length D=37mm, corner chamfer diameter R=4.5mm) was used on a 40μm thick aluminum alloy foil. The test conditions were a wrinkle-suppressing force of 10kN, a punch rising speed (forming speed) scale set to 1, and mineral oil applied as a lubricant to one side of the foil (the side that the punch strikes). The punch rising from the bottom of the device struck the foil, forming it. The maximum punch rising height at which no cracks or pinholes were produced during three consecutive forming tests was defined as the limit forming height (mm) for that material. The punch height was varied in 0.5mm increments. Here, a forming height of 7.0mm or more was judged to be good formability and is indicated as "○" (good) in Tables 3 and 4. If the molding height was less than 7.0 mm, it was judged to have poor moldability and was indicated as "×" (poor) in Tables 3 and 4.

[0192] • Evaluation of corrosiveness 152 g of lithium hexafluorophosphate was dissolved in 1 L of a propylene carbonate / diethylene carbonate solution (volume ratio) to prepare a 1 mol / L electrolyte. Next, the aluminum alloy foils used in the examples and comparative examples were placed as the positive electrode of a 200 mL two-electrode beaker cell, metallic lithium was placed as the negative electrode, and the aforementioned electrolyte was added. In this state, a potential difference of 0.1 V was applied for 1 hour and 3 hours. After that, the surface of the aluminum alloy foil was observed visually with a microscope. As shown in the microscope image in Figure 6 (observation magnification 200x), those with corroded surfaces were judged to have poor corrosion resistance and are indicated as "×" (poor) in Tables 3 and 4. Those with no surface change were judged to have good corrosion resistance and are indicated as "○" (good) in Tables 3 and 4. Furthermore, those with only a small portion of the surface changed were judged to have no practical problems but slightly low corrosion resistance and are indicated as "△" (fair) in Tables 3 and 4. On the surface of the corroded aluminum alloy foil (Judgment: ×), a compound of aluminum and lithium was observed to have formed, causing the surface to bulge due to volume expansion. The results for each test material are shown in Tables 3 and 4.

[0193] [Table 1]

[0194] [Table 2]

[0195] [Table 3]

[0196] [Table 4]

[0197] <Manufacturing of exterior materials for energy storage devices> (Examples 1-19, 21-40, 42; Comparative Examples 1-6, 8-13) A laminated film was prepared by sequentially laminating a polyethylene terephthalate film (12 μm) as the base layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), 3 μm thick), and a biaxially oriented nylon film (15 μm thick). Next, a barrier layer made of the aforementioned aluminum alloy foil (having the composition shown in Tables 1 and 2 and the properties shown in Tables 3 and 4, and 40 μm thick) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (15 μm thick) of the base layer by dry lamination. Specifically, the coatings on both sides were acid-resistant (a coating formed by chromate treatment, with a chromium content of 30 mg / m²). 2A two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of an aluminum alloy foil that had a smear pattern formed on it, to form an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, a laminate of a substrate layer / adhesive layer / barrier layer was fabricated by laminating the adhesive layer on the aluminum alloy foil with a biaxially oriented nylon film and then performing an aging treatment. Next, a laminate of a substrate layer / adhesive layer / barrier layer was fabricated on the barrier layer of the obtained laminate by co-extruding maleic anhydride-modified polypropylene (40 μm thick) as an adhesive layer and polypropylene (40 μm thick) as a heat-fusible resin layer. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device in which 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 ((first heat-sealable resin layer) 40 μm) were laminated in this order. The first heat-sealable resin layer in Examples 1-19, 22-40 and Comparative Examples 1-6, 8-13 is common to all and has the logarithmic decay rate ΔE at 140°C (value measured using a rigid pendulum type physical property tester) as described in Table 7. Also, the first heat-sealable resin layer in Examples 21 and 42 is common to all and has the logarithmic decay rate ΔE at 140°C (value measured using a rigid pendulum type physical property tester) as described in Table 7.

[0198] Furthermore, erucic acid amide was present as a lubricant on both sides of the exterior material for the energy storage device to form a lubricant layer.

[0199] (Examples 20, 41 and Comparative Examples 7, 14) A laminated film was prepared by sequentially laminating a polyethylene terephthalate film (12 μm) as the base layer, an adhesive layer (two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound), 3 μm thick), and a biaxially oriented nylon film (15 μm thick). Next, a barrier layer made of the aforementioned aluminum alloy foil (having the composition shown in Tables 1 and 2 and the properties shown in Tables 3 and 4, and 40 μm thick) with acid-resistant coatings formed on both sides was laminated on the biaxially oriented nylon film (15 μm thick) of the base layer by dry lamination. Specifically, the coatings on both sides were acid-resistant (a coating formed by chromate treatment, with a chromium content of 30 mg / m²). 2 A two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of an aluminum alloy foil that had a smear pattern formed on it, to form an adhesive layer (3 μm thick after curing) on ​​the aluminum alloy foil. Next, the adhesive layer on the aluminum alloy foil was laminated with a biaxially oriented nylon film, and then an aging treatment was performed to create a laminate of a base layer / adhesive layer / barrier layer.

[0200] Next, by co-extruding maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick), random polypropylene as a second heat-fusible resin layer (20 μm thick), and random polypropylene as a first heat-fusible resin layer (10 μm thick) onto the barrier layer of each laminate obtained above, an adhesive layer / second heat-fusible resin layer / first heat-fusible resin layer was laminated on the barrier layer, resulting in an exterior material for an energy storage device in which 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 (20 μm) / second heat-fusible resin layer (20 μm) / first heat-fusible resin layer (10 μm) were laminated in this order. The first heat-sealable resin layers of Examples 20, 41 and Comparative Examples 7, 14 each have the logarithmic decay rate ΔE at 140°C (measured using a rigid pendulum type physical property tester) as described in Table 7.

[0201] Furthermore, erucic acid amide was present as a lubricant on both sides of the exterior material for the energy storage device to form a lubricant layer. <Evaluation of corrosion resistance of aluminum alloy foil> Each aluminum alloy foil used in the examples and comparative examples was cut into a rectangle measuring 45 mm in length and 15 mm in width. Next, a rectangular polyethylene film measuring 50 mm in length and 20 mm in width was heat-sealed and attached to the front and back surfaces of the aluminum alloy foil, so that a 1 cm diameter exposed area was formed on one side of the front and back surfaces of the aluminum alloy foil, to create the test sample. The corrosion resistance of the test sample was evaluated on the 1 cm diameter exposed portion of the aluminum alloy foil AL, and the end of the test sample that was not immersed in the electrolyte was left exposed for connection to the working electrode. Next, the test sample AL was set as the working electrode and metallic lithium Li (15 mm in diameter and 0.35 mm thick, in disc shape) as the counter electrode, and it was immersed in the electrolyte (consisting of 1 mol / l LiPF6 and a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (volume ratio 1:1:1)). Under these conditions, the aluminum alloy foil surface was observed after applying a voltage of 0.1V for 1 hour at 20°C. As shown in Figure 6, surfaces that showed corrosion were rated C, and those that remained unchanged were rated A. The results are shown in Tables 5 and 6. On the corroded aluminum alloy foil surface, compounds with lithium were formed, and it was observed that the surface was raised due to volume expansion.

[0202] <Evaluation of moldability> Each of the exterior materials for energy storage devices obtained above was cut into rectangles with a length (MD) of 90 mm and a width (TD) of 150 mm to prepare test samples. The MD of the exterior material for energy storage devices corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for energy storage devices corresponds to the TD of the aluminum alloy foil. The test samples were subjected to a molding die (female mold, surface: maximum height roughness (nominal value of Rz) of 3.2 μm, corner R2.0 mm, edge R1.0 mm) with a rectangular bore of 31.6 mm (MD) x 54.5 mm (TD) in a 25°C environment, and a corresponding molding die (male mold, surface: JIS B 0659-1:2002 Annex 1 (Reference) Table 2 of the comparative surface roughness standard specimens) The maximum height roughness (nominal value of Rz) is 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimens. Using corner radius R2.0 mm and edge radius R1.0 mm, cold forming (single-stage pull-in forming) was performed on 10 samples each, varying the forming depth in 0.5 mm increments from a forming depth of 0.5 mm at a pressing pressure (surface pressure) of 0.25 MPa. At this time, the test sample was placed on the female mold so that the heat-fusible resin layer side was located on the male mold side before forming. The clearance between the male and female molds was set to 0.3 mm. After cold forming, the samples were examined in a dark room using a penlight to check for pinholes or cracks in the aluminum alloy foil by light transmission. The deepest forming depth at which no pinholes or cracks occurred in any of the 10 samples was defined as the limit forming depth P mm. A limit molding depth of 4.0 mm or more was rated A, 3.5 mm was rated B, and 3.0 mm or less was rated C. The results are shown in Tables 5 and 6.

[0203] <Puncture strength of exterior materials for energy storage devices> For each of the exterior materials for energy storage devices obtained above, the puncture strength was measured from the base layer side using a method compliant with JIS Z1707:1997. Specifically, in a measurement environment of 23±2℃ and relative humidity (50±5)%, the test specimen was fixed with a 115mm diameter stand and a clamping plate with a 15mm opening in the center, and a semicircular needle with a diameter of 1.0mm and a tip radius of 0.5mm was punctured at a speed of 50±5mm per minute, and the maximum stress until the needle penetrated was measured. Five test specimens were used, and the average value was calculated. If there were not enough test specimens to measure five, the number of measurable specimens was measured, and the average value was calculated. The puncture strength measuring device used was the ZP-50N (force gauge) and MX2-500N (measuring stand) manufactured by IMADA Corporation. A puncture strength exceeding 30N was evaluated as A, and a puncture strength of 30N or less was evaluated as C. The results are shown in Tables 5 and 6.

[0204] <Measurement of the logarithmic decay rate ΔE of the first heat-fusible resin layer> The exterior materials for energy storage devices obtained in Examples 1, 20, 21, 22, 41, 42 and Comparative Examples 1, 4, 7, 8, 11, 14 were cut into rectangles with a width (TD: Transverse Direction) of 15 mm and a length (MD: Machine Direction) of 45 mm to prepare test samples (exterior material 10 for energy storage devices). The MD of the exterior material for energy storage devices corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for energy storage devices corresponds to the TD of the aluminum alloy foil. The rolling direction (RD) of the aluminum alloy foil can be determined by the rolling marks. If the MD of the exterior material for energy storage devices cannot be determined by the rolling marks of the aluminum alloy foil, it can be determined by the following method. As a method for confirming the MD of the exterior material for energy storage devices, the cross-section of the heat-fusible resin layer of the exterior material for energy storage devices is observed with an electron microscope to confirm the sea-island structure, and the direction parallel to the cross-section where the average diameter of the island shape in the direction perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing electron microscope images of each of the following cross-sections of the heat-fusible resin layer: a cross-section along the length of the heat-fusible resin layer, and each of the following cross-sections (a total of 10 cross-sections) by changing the angle by 10 degrees from a direction parallel to the length of the heat-fusible resin layer to a direction perpendicular to the length of the layer. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, the diameter y is defined as the straight-line distance between the leftmost point perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost point perpendicular to that point. In each cross-section, the average of the top 20 diameters y of the island shapes, in descending order of diameter y, is calculated. The direction parallel to the cross-section with the largest average diameter y of the island shapes is determined to be the MD (Marginal Distortion). A schematic diagram illustrating the method for measuring the logarithmic attenuation rate ΔE using rigid pendulum measurement is shown in Figure 7. A rigid pendulum-type physical property tester (model number: RPT-3000W, manufactured by A&D Co., Ltd.) was used. The frame of the pendulum 30 was made of FRB-100, the cylindrical cylinder edge 30a of the edge portion was made of RBP-060, the thermal block 31 was made of CHB-100, and a vibration displacement detector 32 and a weight 33 were also used. The initial amplitude was set to 0.3 degrees. The measurement surface (first heat-fusible resin layer) of the test sample was placed on the thermal block 31 with the measurement surface facing upwards, and the cylindrical cylinder edge 30a with the pendulum 30 attached was positioned so that its axis direction was perpendicular to the MD direction of the test sample.Furthermore, to prevent the test sample from floating or warping during measurement, tape was applied to areas of the test sample that would not affect the measurement results and fixed to the cooling block 31. The cylindrical cylinder edge 30a was brought into contact with the surface of the first heat-fusible resin layer. Next, the logarithmic decay rate ΔE of the first heat-fusible resin layer was measured using the cooling block 31 at a heating rate of 3°C / min in the temperature range of 30°C to 200°C. The logarithmic decay rate ΔE of the first heat-fusible resin layer of the test sample (exterior material 10 for energy storage device) when the surface temperature reached 140°C was adopted. (The test sample that had been measured once was not used, and the average value of three measurements (N=3) using newly cut samples was used.) For the first heat-fusible resin layer, each exterior material for energy storage device obtained above was immersed in 15% hydrochloric acid to dissolve the base material layer and aluminum foil, and the test sample, which consisted only of the adhesive layer and heat-fusible resin layer, was thoroughly dried and the logarithmic decay rate ΔE was measured. The logarithmic decay rates ΔE at 140°C are shown in Table 7. The logarithmic decay rate ΔE is calculated using the following formula. ΔE=[ln(A1 / A2)+ln(A2 / A3)+...+ln(An / An+1)] / n A: Amplitude n: wavenumber

[0205] <Measurement of the remaining thickness of the first heat-fusible resin layer> Each exterior material for energy storage devices obtained in Examples 1, 20, 21, 22, 41, 42 and Comparative Examples 1, 4, 7, 8, 11, 14 was cut to a length of 150 mm × width of 60 mm to prepare test samples (exterior material for energy storage devices 10). Next, the first heat-sealable resin layers of the test samples made from the same exterior material for energy storage devices were placed facing each other. Then, in this state, a 7 mm wide metal plate was used to heat and pressurize both sides of the test sample in the lamination direction at a temperature of 190°C, the surface pressures (MPa) listed in Table 1, and for a time of 3 seconds, to heat-seal the first heat-sealable resin layers. Next, the heat-sealed portion of the test sample was cut in the lamination direction using a microtome, and the thickness of the two heat-sealable resin layers that were heat-sealed to each other was measured on the exposed cross-section. Similarly, the test samples before heat fusion were cut in the lamination direction using a microtome, and the thickness of the two first heat-fusible resin layers was measured on the exposed cross-section. The ratio of the total thickness of the two first heat-fusible resin layers after heat fusion to the total thickness of the two first heat-fusible resin layers before heat fusion was calculated, and the remaining percentage of the total thickness of the two first heat-fusible resin layers was measured for each. The results are shown in Table 7.

[0206] <Evaluation of insulating properties of exterior materials for energy storage devices> The exterior materials for each energy storage device obtained in Examples 1, 20, 21, 22, 41, 42 and Comparative Examples 1, 4, 7, 8, 11, 14 were cut into rectangles with a length (MD) of 120 mm and a width (TD) of 60 mm. The heat-sealable resin layers were brought together and folded in the MD direction, then sealed with a seal width of 3 mm (conditions: 190°C, 2 MPa, 3 seconds). After that, the material was cut to a width (TD) of 15 mm to prepare the test samples. 152 g of lithium hexafluorophosphate was dissolved in 1 L of propylene carbonate / diethylene carbonate (volume ratio) to prepare a 1 mol / L electrolyte. Next, the 15 mm wide test sample was set on the positive electrode of a 200 mL two-electrode beaker cell with the seal open, metallic lithium was set on the negative electrode, and the aforementioned electrolyte was added. At this time, the test sample was folded in the MD direction so that the heat-sealable resin layers of the test sample faced each other, and the folded portion was heat-sealed. Next, the end of the test sample was opened 180°, taking care not to damage the heat-sealed portion. Then, the end of the test sample was clamped with an alligator clip, and the alligator clip was brought to the aluminum alloy foil of the test sample, electrically connecting the alligator clip and the aluminum alloy foil. In this state, a potential difference of 1V was applied for 12 hours and 24 hours, and the formation of lithium aluminum alloy (black foreign matter) in the heat-sealed portion was visually observed. This allowed evaluation of whether cracks formed from the side of the resin reservoir formed in the heat-sealed portion of the test sample, allowing the electrolyte to penetrate and cause corrosion (formation of black foreign matter). Samples in which black foreign matter formed within 12 hours were classified as C, those in which black foreign matter formed between 12 and 24 hours were classified as B, and those in which no black foreign matter formed after 24 hours were classified as A. The results are shown in Table 7.

[0207] [Table 5]

[0208] [Table 6]

[0209] [Table 7]

[0210] The exterior materials for energy storage devices of Examples 1 to 42 are each composed of a laminate comprising, in this order, at least a base layer, a barrier layer, and a heat-fusible resin layer. The barrier layer contains aluminum alloy foil satisfying a composition of Fe: 0.2% to 2.0% by mass and Mg: 0.1% to 5.0% by mass. The aluminum alloy foil satisfies the relationship L1 / L2 > 3.0, where L1 is the ratio of the length of the large-angle grain boundary L1 to the length of the small-angle grain boundary L2 per unit area, as measured by backscattered electron diffraction. The exterior materials for energy storage devices of Examples 1 to 42 effectively suppress corrosion of the aluminum alloy foil when current is applied while electrolyte is present, and also possess high mechanical strength and high moldability.

[0211] As described above, this disclosure provides inventions in the following embodiments. Item 1. The laminate comprises at least a base layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer comprises aluminum alloy foil satisfying the composition of Fe: 0.2% to 2.0% by mass, Mg: 0.1% to 5.0% by mass, with the remainder being Al and unavoidable impurities. The aforementioned aluminum alloy foil is an outer covering material for energy storage devices, wherein the ratio of the length of large-angle grain boundaries L1 to the length of small-angle grain boundaries L2 per unit area, as measured by backscattered electron diffraction, satisfies the relationship L1 / L2 > 3.0. Item 2. The composition of the aluminum alloy foil shall satisfy Mg: 0.1% by mass or more and 1.5% by mass or less. The exterior material for an energy storage device according to claim 1, 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 with a thickness of 80 Å or more. Item 3. The composition of the aluminum alloy foil shall satisfy Mg: 0.1% by mass or more and 1.5% by mass or less. The aluminum alloy foil is an outer covering material for energy storage devices as described in item 1 or 2, having a tensile strength of 110 MPa or more and an elongation at break of 10% or more. Item 4. The composition of the aluminum alloy foil satisfies the requirement that Mg: greater than 1.5% by mass and 5.0% by mass or less. The exterior material for an energy storage device according to claim 1, wherein at least one surface of the aluminum alloy foil contains 15.0 atomic percent or more of Mg, and at least one surface of the aluminum alloy foil has an oxide film with a thickness of 120 Å or more. Item 5. The composition of the aluminum alloy foil satisfies the requirement that Mg: greater than 1.5% by mass and 5.0% by mass or less. The aluminum alloy foil has a tensile strength of 180 MPa or more and an elongation at break of 15% or more, as an outer covering material for energy storage devices according to item 1 or 4. Item 6. The aluminum alloy foil is an exterior material for an energy storage device according to any one of items 1 to 5, wherein the orientation density of the copper orientation and R orientation of the texture is 15 or less. Item 7. The aluminum alloy foil is an exterior material for an energy storage device according to any one of items 1 to 6, wherein the average crystal grain size is 25 μm or less. Item 8. The aluminum alloy foil contains Mn: 0.1% by mass as the unavoidable impurity, as described in any one of items 1 to 7, for use as an exterior material for an energy storage device. Item 9. The aluminum alloy foil has a composition of Si: 0.5% by mass or less, and is an exterior material for an energy storage device according to any one of items 1 to 8. Item 10. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer casing material for energy storage devices as described in any one of items 1 to 9. Item 11. The process includes at least a step of obtaining a laminate by laminating a base layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer contains aluminum alloy foil satisfying the composition of Fe: 0.2% to 2.0% by mass, and Mg: 0.1% to 5.0% by mass. The aluminum alloy foil is manufactured in a manner that satisfies the relationship L1 / L2 > 3.0, where the ratio of the length of the large-angle grain boundary L1 to the length of the small-angle grain boundary L2 per unit area, as measured by backscattered electron diffraction, is L1 / L2. [Explanation of Symbols]

[0212] 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. It is composed of a laminate comprising, at least, a base layer, a barrier layer, and a heat-sealable resin layer in this order. The barrier layer comprises an aluminum alloy foil satisfying the following composition: Fe: 0.2% to 2.0% by mass, Mg: 0.1% to 5.0% by mass, and the remainder being Al and unavoidable impurities. The aluminum alloy foil satisfies the relationship L1 / L2 > 3.0, where the ratio of the length L1 of the large-angle grain boundary to the length L2 of the small-angle grain boundary per unit area, as measured by backscattered electron diffraction, The composition of the aluminum alloy foil satisfies the following: Mg: greater than 1.5% by mass and 5.0% by mass or less. The aluminum alloy foil is an outer casing material for energy storage devices, having a tensile strength of 180 MPa or more and an elongation at break of 15% or more.

2. The exterior material for an energy storage device according to claim 1, wherein at least one surface of the aluminum alloy foil contains 15.0 atomic percent or more of Mg, and at least one surface of the aluminum alloy foil has an oxide film with a thickness of 120 Å or more.

3. The aluminum alloy foil has a texture density of 15 or less in both the Copper orientation and the R orientation, as described in claim 1 or 2, for exterior material for energy storage devices.

4. The aluminum alloy foil has an average crystal grain size of 25 μm or less, as described in claim 1 or 2, for use as an outer casing material for an energy storage device.

5. The aluminum alloy foil contains Mn: 0.1% by mass or less as the unavoidable impurity, as described in claim 1 or 2, for the exterior material of an energy storage device.

6. The exterior material for an energy storage device according to claim 1 or 2, wherein the composition of the aluminum alloy foil satisfies Si: 0.5% by mass or less.

7. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the outer material for energy storage devices described in claim 1 or 2.

8. The process includes at least a step of obtaining a laminate by laminating a base layer, a barrier layer, and a heat-sealable resin layer in this order, The barrier layer comprises an aluminum alloy foil satisfying the 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 aluminum alloy foil satisfies the relationship L1 / L2 > 3.0, where the ratio of the length L1 of the large-angle grain boundary to the length L2 of the small-angle grain boundary per unit area, as measured by backscattered electron diffraction, The composition of the aluminum alloy foil satisfies the following: Mg: greater than 1.5% by mass and 5.0% by mass or less. The aluminum alloy foil has a tensile strength of 180 MPa or more and an elongation at break of 15% or more, and is a method for manufacturing an exterior material for an energy storage device.

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