Exterior material for energy storage devices, method for manufacturing the same, resin composition, elastic particles, and energy storage device

Abstract

Provided is an exterior material for a power storage device, the exterior material comprising exceptional molding properties.　This exterior material for a power storage device is configured from a laminate provided with at least a base material layer, a barrier layer, and a thermally fusible resin layer in order from the outer side. At least one layer included in the laminate constitutes a molding properties improvement layer that contains elastic particles.

Description

[Technical Field]

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

[0002] While various types of energy storage devices have been developed, casing materials are essential components for sealing the device elements, such as electrodes and electrolytes, in all of them. Traditionally, metal casing 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, and mobile phones, 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 laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated has been proposed as an exterior material for energy storage devices that can be easily processed into various shapes and can achieve thinning and weight reduction (see, for example, Patent Document 1).

[0005] In such an exterior material for energy storage devices, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolytes are placed in the space formed by the recesses. By heat-sealing a heat-sealable resin layer, an energy storage device is obtained in which the energy storage device elements are housed inside the exterior material for the energy storage device. [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] In recent years, there has been a demand for thinner film-like exterior materials. Furthermore, from the perspective of further increasing the energy density of energy storage devices, there is also a demand for forming deep recesses in the exterior materials.

[0008] However, when forming a film-like outer material for energy storage devices to create recesses that house the energy storage device elements, there is a problem that cracks and pinholes are prone to occur.

[0009] Under these circumstances, the primary objective of this disclosure is to provide an exterior material for energy storage devices that has excellent moldability. [Means for solving the problem]

[0010] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that an exterior material for an energy storage device, which is composed of a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, and in which at least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles, has excellent moldability.

[0011] This disclosure was completed by further consideration based on such novel findings. Specifically, this disclosure provides inventions in the following embodiments. An exterior material for an energy storage device, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, wherein at least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide an exterior material for an electricity storage device that has excellent moldability. Further, according to the present disclosure, it is also possible to provide a method for producing the exterior material for an electricity storage device, an electricity storage device using the exterior material for an electricity storage device, a resin composition for use in the exterior material for an electricity storage device, and elastic particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. [Figure 3] FIG. 3 is a schematic diagram illustrating an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. [Figure 4] FIG. 4 is a schematic diagram illustrating an example of a cross-sectional structure of an exterior material for an electricity storage device according to the present disclosure. [Figure 5] FIG. 5 is a schematic diagram for explaining a method of housing an electricity storage device element in a package formed of the exterior material for an electricity storage device according to the present disclosure. [Figure 6] FIG. 6 is a schematic diagram of primary particles and secondary particles. DESCRIPTION OF EMBODIMENTS

[0014] The exterior material for an electricity storage device of the present disclosure is constituted by a laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order from the outer side, and at least one layer contained in the laminate constitutes a moldability improving layer containing elastic particles. The exterior material for an electricity storage device of the present disclosure has excellent moldability.

[0015] The exterior materials for energy storage devices described herein will be described in detail below. 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. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Alternatively, upper and lower limits, upper and lower limits, or lower limits described separately may be combined to form numerical ranges. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0016] 1. Laminated structure of exterior material for energy storage devices The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order, as shown in Figure 1, for example. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-fusible 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-fussing the peripheral edges of the heat-fusible resin layers 4 of the exterior material 10 facing each other. In the laminate constituting the exterior material 10 for energy storage devices of this disclosure, with respect to the barrier layer 3, the heat-fusible resin layer 4 side is inward of the barrier layer 3, and the base layer 1 side is outward of the barrier layer 3.

[0017] 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.

[0018] At least one of the layers in the laminate constituting the exterior material 10 for energy storage devices constitutes a moldability-enhancing layer containing elastic particles. In this disclosure, the moldability-enhancing layer means a layer that, by containing elastic particles, improves the moldability of the exterior material for energy storage devices compared to a layer that does not contain elastic particles. The mechanism is thought to be that, because the moldability-enhancing layer contains elastic particles, it relieves the stress applied during the molding of the exterior material for energy storage devices and disperses the force applied to the barrier layer, thereby suppressing the occurrence of pinholes and cracks in the barrier layer.

[0019] In the exterior material 10 for energy storage devices, the layer constituting the moldability-improving layer is not particularly limited as long as it can contain elastic particles. For example, the surface coating layer 6, base material layer 1, adhesive layer 2, coloring layer, adhesive layer 5, and heat-fusible resin layer 4, which will be described later, are suitable. Among these, it is preferable that at least one of the adhesive layer 2 and adhesive layer 5 constitutes the moldability-improving layer, and it is particularly preferable that the adhesive layer 2 constitutes the moldability-improving layer.

[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. Furthermore, even if the exterior material 10 for energy storage devices of this disclosure is a laminate comprising a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0022] 2. Each layer forming the exterior material for the energy storage device [Moldability improving layer] In the exterior material 10 for energy storage devices of this disclosure, the moldability-improving layer is a layer containing elastic particles. Of the layers included in the laminate constituting the exterior material 10 for energy storage devices, at least one layer constitutes the moldability-improving layer containing elastic particles. As described above, the exterior material for energy storage devices of this disclosure can improve the moldability of the exterior material for energy storage devices compared to the case in which elastic particles are not included, because the moldability-improving layer contains elastic particles. The mechanism is thought to be that, because the moldability-improving layer contains elastic particles, it relieves the stress applied during the molding of the exterior material for energy storage devices and disperses the force applied to the barrier layer, thereby suppressing the occurrence of pinholes and cracks in the barrier layer.

[0023] In the exterior material 10 for the energy storage device, the layer constituting the moldability-improving layer is not particularly limited as long as it can contain elastic particles. For example, the surface coating layer 6, base layer 1, adhesive layer 2, coloring layer, adhesive layer 5, and heat-fusible resin layer 4, which will be described later, are suitable. Among these, it is preferable that at least one of the adhesive layer 2 and adhesive layer 5 constitutes the moldability-improving layer, and it is particularly preferable that the adhesive layer 2 constitutes the moldability-improving layer.

[0024] In this disclosure, elastic particles refer to particles that have undergone a change in shape or volume due to an external force, but which return to their original state when the force is removed. Examples include particles containing rubber.

[0025] The elastic particles are not particularly limited as long as they improve the moldability of the exterior material for energy storage devices, and examples include particles containing synthetic rubber such as butadiene rubber, acrylic rubber, styrene rubber, and silicone rubber. The synthetic rubber contained in the elastic particles may be one type or two or more types.

[0026] Furthermore, it is preferable that the elastic particles have a core-shell structure. Preferably, the elastic particles having a core made of rubber and a shell made of resin are used. By adopting such a configuration, elastic particles are obtained that combine the elasticity of the core with the high dispersibility of the shell in resin.

[0027] As elastic particles having a core-shell structure, for example, core-shell type rubber particles described in Japanese Patent No. 6061837 can be used. That is, such elastic particles having a core-shell structure are granular materials having a structure with at least two layers: a rubbery core layer and a shell layer. The core layer refers to the inner part of the elastic particle and can form domains inside the elastic particle. The core layer can be any rubbery substance, and is typically an elastomer, preferably consisting of a polymer formed by the polymerization of conjugated dienes and / or lower alkyl acrylates, a copolymer formed by copolymerizing these with monomers copolymerizable thereto, or polysiloxane rubber. When elastic particles having a core-shell structure are dispersed in a base resin, it is preferable that the core layer is insoluble in the base resin; for example, if the base resin is an epoxy resin, it is preferable that the core layer is insoluble in the epoxy resin. The base resin (dispersion medium) for dispersing the elastic particles can be any material in which the elastic particles are dispersed. Examples include polyester, polyolefin, polyurethane, polyurea, polyamide, polystyrene, polycarbonate, polyacetal, polyvinyl alcohol, epoxy resin, phenolic resin, acrylic resin, amino resin, and imide resin, as well as mixtures or copolymers of two or more of these. Epoxy resin is preferred as the base resin. Furthermore, if the shell has high affinity (compatibility) with the solvent, it can be dispersed in the solvent rather than just using a resin as the dispersant. When dispersed in a dispersion medium such as a base resin, it becomes unnecessary to handle the elastic particles in powder form, allowing for quicker mixing. Additionally, if the base resin has a composition that is compatible with the core-shell structure, when mixed with other resin compositions, it becomes possible to maintain the rubber particles in a more dispersed state compared to when mixed in powder form. The core layer can also be made of synthetic rubbers such as the aforementioned butadiene-based rubber, acrylic-based rubber, styrene-based rubber, and silicone-based rubber.

[0028] Examples of conjugated dienes include butadiene, isoprene, and chloroprene. Among these, butadiene is particularly preferred because it is inexpensive to obtain, the resulting polymer has good rubber properties, and polymerization is easy. Examples of lower alkyl acrylates include ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate. Among these, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred because the resulting polymer has good rubber properties and polymerization is easy.

[0029] Examples of monomers copolymerizable with conjugated dienes or alkyl acrylates include aromatic vinyls such as styrene, vinyltoluene, vinylnaphthalene, and α-methylstyrene; aromatic vinylidene, vinyl cyanide / vinylidene cyanide such as acrylonitrile and methacrylonitrile; alkyl methacrylates such as methyl methacrylate and butyl methacrylate; aromatic (meth)acrylates such as benzyl (meth)acrylate, phenoxyethyl acrylate, ethyl (meth)acrylate, and butyl methacrylate; vinyl acetate; and vinyl chloride. Monomers having functional groups such as epoxy groups, carboxyl groups, hydroxyl groups, and amino groups can also be copolymerized. For example, monomers having epoxy groups include glycidyl methacrylate; monomers having carboxyl groups include methacrylic acid, acrylic acid, maleic acid, and itaconic acid; and monomers having hydroxyl groups include 2-hydroxymethacrylate and 2-hydroxyacrylate. Furthermore, crosslinkable monomers (polyfunctional monomers) such as divinylbenzene, butanediol di(meth)acrylate, triallyl (iso)cyanurate, allyl (meth)acrylate, diallyl itaconicate, and diallyl phthalate, as well as graft monomers such as diallyl maleate, monoallyl fumarate, and allyl methacrylate, which have two or more unsaturated sites with unequal reactivity and at least one of the reaction sites being non-conjugated, can also be used as components constituting the core. When such crosslinkable monomers or graft monomers are used in small amounts, preferably 10% by mass or less of the total elastic particles having a core-shell structure, interlayer bonding is achieved, and the particles become less prone to deformation even when heated. Furthermore, silicone rubber can also be used as a monomer copolymerizable with conjugated dienes or alkyl acrylates. In addition, polysiloxane rubber composed of alkyl or allyl disubstituted silyloxy units such as dimethylsilyloxy, methylphenylsilyloxy, and diphenylsilyloxy can be used instead of, or in combination with, such conjugated dienes or alkyl acrylate copolymerizable monomers.When using such polysiloxane rubber, it is preferable to introduce a crosslinked structure into the polysiloxane beforehand, either by partially using a polyfunctional alkoxysilane compound during polymerization as needed, or by radically reacting a silane compound with a vinyl-reactive group.

[0030] On the other hand, in elastic particles having a core-shell structure, the shell layer forms the outermost layer of the elastic particle and has affinity (compatibility) with the resin. The material constituting this shell layer is not particularly limited as long as it is a material that does not exhibit elasticity, but it is preferably a polymer obtained by polymerizing methyl methacrylate and / or styrene monomers, or a copolymer obtained by copolymerizing monomers copolymerized with these. These are inexpensive and readily available, and can enable both good graft polymerization and affinity with the resin, and exhibit good adhesive strength over a wide temperature range.

[0031] Examples of monomers copolymerizable with methyl methacrylate or styrene include alkyl acrylates such as ethyl acrylate and butyl acrylate, alkyl methacrylates such as ethyl methacrylate and butyl methacrylate, aromatic vinyls such as vinyltoluene, α-methylstyrene, monochlorostyrene, 3,4-dichlorostyrene, and bromostyrene, aromatic vinylidene, vinyl acetate, vinyl chloride, vinyl cyanide such as acrylonitrile and methacrylonitrile, and vinylidene cyanide, which are vinyl polymerizable monomers. Ethyl acrylate or acrylonitrile are preferred among these.

[0032] Furthermore, it is also possible to modify the shell layer surface with epoxy groups and / or functional groups that react with epoxy groups by copolymerizing monomers having epoxy groups and / or functional groups that react with epoxy groups, such as carboxyl groups, hydroxyl groups, and amino groups, as monomers copolymerizable with methyl methacrylate or styrene. For example, monomers having epoxy groups include glycidyl methacrylate, monomers having carboxyl groups include methacrylic acid, acrylic acid, maleic acid, and itaconic acid, and monomers having hydroxyl groups include 2-hydroxymethacrylate and 2-hydroxyacrylate.

[0033] Furthermore, when chemical reactivity is desired in the shell layer, copolymers obtained by copolymerizing one or more components selected from the group of monomers consisting of (meth)acrylic acid esters having reactive side chains such as hydroxyalkyl (meth)acrylate and epoxyalkyl (meth)acrylate, epoxyalkyl vinyl ether, (meth)acrylamide (including N-substituted products), α,β-unsaturated acid, α,β-unsaturated acid anhydride, and maleimide derivatives are more preferable. Specifically, examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, styrene, α-methylstyrene, (meth)acrylonitrile, (meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycidyl vinyl ether, (meth)acrylamide, maleic acid anhydride, and maleic acid imide. It is also possible to enhance reactivity by incorporating reactive groups, such as glycidyl groups provided by monomers such as glycidyl methacrylate, into the shell layer.

[0034] Furthermore, the shell layer is preferably grafted and / or crosslinked to the core layer, and it is also possible to use a crosslinkable monomer or graft monomer in an amount of 10% by mass or less as a monomer copolymerizable with methyl methacrylate or styrene. This is because interlayer bonding is achieved and the particles are less likely to deform when heated. Examples of crosslinkable monomers include aromatic divinyl compounds such as divinylbenzene, alkane polyol polyacrylates such as hexanediol diacrylate, butylene glycol dimethacrylate, and norbornene dimethylol dimethacrylate, and examples of graft monomers include unsaturated carboxylic acid allyl esters such as allyl methacrylate.

[0035] Elastic particles having such a core-shell structure are not particularly limited in their manufacturing method, and commercially available products can be used. Elastic particles having a core-shell structure can be used by dispersing them in a base resin such as epoxy resin. For example, when the adhesive layer 2 or adhesive layer 5 described later is to be used as a moldability-improving layer, the adhesive (resin composition) used to form the adhesive layer 2 or adhesive layer 5 can be mixed with a resin composition containing elastic particles and a base resin to form the adhesive layer 2 or adhesive layer 5, thereby creating a moldability-improving layer.

[0036] Furthermore, the preferred core / shell ratio (mass ratio) of elastic particles having a core-shell structure is in the range of 50 / 50 to 95 / 5, and more preferably in the range of 60 / 40 to 90 / 10.

[0037] From the viewpoint of suitably exhibiting the effects of the present invention, the primary particle diameter of the elastic particles is preferably about 1 nm to 3 μm, more preferably about 1 to 900 nm, even more preferably about 20 to 600 nm, and even more preferably about 50 to 300 nm.

[0038] Furthermore, the secondary particle diameter of the elastic particles can be, for example, about 0.1 to 5 μm, preferably about 0.2 to 2 μm.

[0039] In this disclosure, the primary particle diameter and secondary particle diameter of the elastic particles contained in the moldability-enhancing layer are measured by the following methods, respectively.

[0040] <Measurement of primary and secondary particle diameters of elastic particles> The primary and secondary particle diameters of the elastic particles contained in the moldability-enhancing layer are measured on a cross-section of the moldability-enhancing layer of the exterior material for energy storage devices, under the following pretreatment and observation conditions. The primary particle diameter refers to the average value of the diameter x and diameter y of each primary particle, obtained by selecting 10 primary particles from the largest visible particles within the field of view using image analysis at the magnification of the primary particle diameter measurement described in the observation conditions below, measuring the diameter x and diameter y in a total of 6 field of view locations (3 in the field of view in the cross-section parallel to MD and 3 in the field of view in the cross-section parallel to TD), and averaging all the obtained measurement data. The diameter x of each primary particle refers to the straight-line distance between the leftmost point perpendicular to the thickness direction and the rightmost point perpendicular to the thickness direction of each primary particle. The diameter y of each primary particle refers to the straight-line distance between the uppermost point parallel to the thickness direction and the lowermost point parallel to the thickness direction of each primary particle. If there are not 10 particles in the field of view, the diameters x and diameter y of all primary particles present in the field of view are measured and the average value is calculated.

[0041] As shown in the schematic diagram in Figure 6, secondary particles are aggregates of primary particles. If there is a distance of at least the primary particle diameter calculated as an average value above between the outer circumference of any one particle a and the outer circumference of the adjacent particle b at the shortest distance, then particles a and b are considered to belong to different secondary particles. If a particle c is adjacent to any one particle a at a distance less than the primary particle diameter, then it is considered to belong to the same secondary particle as particle a. The secondary particle diameter is defined as the average value of all measurement data obtained by selecting five secondary particles in order from the largest apparent major axis diameter within the field of view at one location at the magnification for secondary particle diameter measurement described below, treating the secondary particles as a single ellipse, and measuring the major axis diameter and minor axis diameter at a total of two or more locations within the field of view of a cross section parallel to MD and within the field of view of a cross section parallel to TD.

[0042] <Pre-treatment> The exterior material for the energy storage device will be fixed as a sample. The fixation method will be embedding fixation using room-temperature curing resin. The sample will be cut using a microtome (e.g., Leica UC7), and the cross-section will be finished using a knife (e.g., Diamond Ultra35). The cutting thickness when finishing the cross-section will be 100 nm, which is the cutting thickness for ultrathin section finishing (100 nm). Staining will be done with Os (osmium tetroxide) staining, the sample will be in the form of a section, and the staining time will be 30 minutes. The conductive treatment conditions will be PtPd (irradiation time: 20 seconds).

[0043] <Observation conditions> Ultrathin sections will be observed using a SEM transmission detector (STEM observation). A commercially available observation device (e.g., Hitachi High-Technologies SU9000) will be used. The mode will be TE (signal selection: BF-STEM), the probe current will be normal, the acceleration voltage will be 30.0kV, the emission current will be 10μA, the WD will be 0mm, the tilt will be 0°, and the STEM observation magnification will be ×20k and ×100k (the reference observation magnification during imaging will be Polaroid 545). Primary particle size will be measured on the device at ×100k (field of view: approximately 1250nm × approximately 950nm). Secondary particle size will be measured on the device at ×20k (field of view: approximately 6.4μm × approximately 4.8μm).

[0044] 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. For example, when the barrier layer 3 is composed of metal foil such as aluminum alloy foil or stainless steel 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 identifying 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.

[0045] Furthermore, if the MD of the exterior material for energy storage devices cannot be identified by the rolling marks of metal foils such as aluminum alloy foil or stainless steel 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 each of the cross-sections (a total of 10 cross-sections) in the longitudinal direction of the heat-fusible resin layer, and each of the cross-sections perpendicular to the longitudinal direction, by changing the angle by 10 degrees from the direction parallel to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, 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. For each cross-section, the average of the top 20 diameters y of the island shape, ordered from largest to smallest, is calculated. The direction parallel to the cross-section with the largest average diameter y of the island shape is determined to be the MD (Movement Direction).

[0046] From the viewpoint of suitably exhibiting the effects of the present invention, the content of elastic particles in the moldability-improving layer is preferably 0.25% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Also, from the same viewpoint, the content of elastic particles in the moldability-improving layer is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. A preferred range for the content of elastic particles in the moldability-improving layer is 0.25 to 25% by mass. When colorants such as pigments or fillers are added to the layers constituting the exterior material for energy storage devices, the moldability tends to decrease, but when elastic particles are added to the layer, the decrease in moldability is suppressed and excellent moldability is obtained.

[0047] [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.

[0048] In the exterior material 10 for energy storage devices, the base layer 1 may be a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the base layer 1 is a moldability-improving layer, elastic particles are included in the base layer 1. When the base layer is a moldability-improving layer, stress distribution becomes possible in the base layer 1, so that localized forces are not applied to the barrier layer 3 during molding, cracks can be suppressed, and moldability is improved.

[0049] 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.

[0050] 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.

[0051] 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. These resins may be copolymers of these resins, or modified copolymers of these resins. Furthermore, they may be mixtures of these resins.

[0052] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0053] 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.

[0054] Furthermore, specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 laminated. The anchor coat layer is similar to the adhesive 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 or about 35 to 50 μm. If the base layer 1 is a laminate of two or more resin films, the thickness of the resin films constituting each layer can be preferably about 2 to 25 μm, 2 to 20 μm, or 20 to 30 μm, respectively.

[0064] [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 (or corrosion-resistant film) as needed, for the purpose of improving the adhesion between them.

[0065] In the exterior material 10 for energy storage devices, it is preferable that the adhesive layer 2 be a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the adhesive layer 2 is a moldability-improving layer, elastic particles are included in the adhesive layer 2. When the adhesive layer 2 is a moldability-improving layer, it is provided between the base material layer 1 and the barrier layer 3 (or corrosion-resistant film), so it can follow both the elongation of the base material layer 1 and the elongation of the barrier layer 3 caused by molding, thereby relieving stress and improving moldability.

[0066] As described above, elastic particles having a core-shell structure, for example, can be dispersed in a base resin such as epoxy resin and used. More specifically, for example, an adhesive (resin composition) used to form the adhesive layer 2 can be mixed with a resin composition containing elastic particles and epoxy resin to form the adhesive layer 2, which can then be used as a moldability-improving layer.

[0067] 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.

[0068] 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.

[0069] Examples of polyurethane adhesives include polyurethane adhesives comprising a first agent containing a polyol compound and a second 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 used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent are aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also, polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are used. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. The adhesive layer 2 is formed from a polyurethane adhesive, which provides excellent electrolyte resistance to the exterior material for energy storage devices, preventing peeling of the substrate layer 1 even if electrolyte adheres to the sides.

[0070] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. The presence of a colorant in the adhesive layer 2 allows the exterior material for energy storage devices to be colored. Known colorants such as pigments and dyes can be used. In addition, only one type of colorant may be used, or two or more types may be mixed and used. Adding colorants such as pigments or fillers to the adhesive layer or colored layer tends to reduce moldability, but adding elastic particles to the layer suppresses the reduction in moldability and provides excellent moldability.

[0071] 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.

[0072] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance.

[0073] 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.

[0074] 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.

[0075] 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, but for example, it is about 1 μm or more and about 2 μm or more. Also, the thickness of the adhesive layer 2 is, for example, about 10 μm or less and about 5 μm or less. Furthermore, preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0076] [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.

[0077] In the exterior material 10 for the energy storage device, it is preferable that the colored layer be a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the colored layer is a moldability-improving layer, elastic particles are included in the colored layer.

[0078] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer 1 or the surface of 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.

[0079] Specific examples of colorants included in the colored layer are the same as those exemplified in the [Adhesive Layer 2] section.

[0080] [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.

[0081] Examples of barrier layer 3 include metal foil, vapor-deposited film, and resin layer with barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as barrier layer 3. Multiple layers of barrier layer 3 may be provided. It is preferable that barrier layer 3 includes a layer made of a metal material. Specific examples of metal materials constituting barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0082] From the viewpoint of improving the formability of the exterior material for energy storage devices, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is more preferably an aluminum alloy foil containing iron. In an iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior material for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material for energy storage devices with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments.

[0083] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0084] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0085] In the case of metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer that prevents moisture from penetrating, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 3 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 3 include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, when the barrier layer 3 is made of aluminum alloy foil, from the viewpoint of providing high formability and high rigidity to the exterior material 10 for the energy storage device, the thickness of the barrier layer 3 is preferably about 45 μm or more, more preferably about 50 μm or more, more preferably about 55 μm or more, preferably about 85 μm or less, more preferably 75 μm or less, and even more preferably 70 μm or less. Preferred ranges include about 45-85 μm, about 45-75 μm, about 45-70 μm, about 50-85 μm, about 50-75 μm, about 50-70 μm, about 55-85 μm, about 55-75 μm, and about 55-70 μm. By providing the exterior material 10 for the energy storage device with high formability, deep drawing can be facilitated, which can contribute to increasing the capacity of the energy storage device. Furthermore, as the capacity of the energy storage device increases, the weight of the energy storage device also increases. However, by increasing the rigidity of the exterior material 10 for the energy storage device, it is possible to contribute to the high sealing performance of the energy storage device. In particular, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more.Furthermore, preferred thickness ranges for stainless steel foil include approximately 10-60 μm, 10-50 μm, 10-40 μm, 10-30 μm, 10-25 μm, 15-60 μm, 15-50 μm, 15-40 μm, 15-30 μm, and 15-25 μm.

[0086] Furthermore, if the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. 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 instead of just one. Furthermore, among these treatments, hot water 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. These processes may also be included in the definition of chemical conversion treatment. Furthermore, if barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0087] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of exterior materials for energy storage devices. It also prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolyte and water, particularly the dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil. Furthermore, it improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0088] 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.

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] 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 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 and tert-butyl group. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by include linear or branched C1-C4 alkyl groups substituted with one hydroxy group, 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 and 4-hydroxybutyl group. In general formulas (1) to (4), X, R 1 and R 2 The alkyl group and hydroxyalkyl group represented by may each be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably, for example, about 500 to 1,000,000, 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 with formaldehyde to produce a polymer consisting of the repeating unit represented by the above general formula (1) or general formula (3), followed by formaldehyde and an amine (R 1 R 2 NH) to introduce a functional group (-CH2NR 1 R 2 ) into the polymer obtained above. The aminated phenol polymer may be used alone or in combination of two or more thereof.

[0094] 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.

[0095] An 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.

[0096] 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.

[0097] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0098] The amount of corrosion-resistant film to be formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of coating-type chromate treatment, the surface of the barrier layer 3 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

[0099] 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.

[0100] 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 barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70-200°C. Alternatively, before applying the chemical conversion treatment to the barrier layer, 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 barrier layer 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.

[0101] [Thermal adhesive 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.

[0102] In the exterior material 10 for energy storage devices, the heat-fusible resin layer 4 may be used as a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the heat-fusible resin layer 4 is used as a moldability-improving layer, elastic particles are included in the heat-fusible resin layer 4. When the heat-fusible resin layer 4 is used as a moldability-improving layer, stress distribution becomes possible in the heat-fusible resin layer 4, so that localized forces are not applied to the barrier layer 3 during molding, cracks can be suppressed, and moldability is improved. When the heat-fusible resin layer is multilayered, if elastic particles are not added to the innermost heat-fusible resin layer, but elastic particles are added to at least one of the layers other than the innermost layer, moldability can be improved while maintaining high sealing performance.

[0103] 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 -1 A 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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 made of the same or different resins.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] [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 corrosion-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0116] In the exterior material 10 for energy storage devices, it is preferable that the adhesive layer 5 be a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the adhesive layer 5 is a moldability-improving layer, elastic particles are included in the adhesive layer 5. When the adhesive layer 5 is a moldability-improving layer, it is provided between the heat-fusible resin layer 4 and the barrier layer 3 (or corrosion-resistant film), so it can follow both the elongation of the base material layer 1 and the elongation of the barrier layer 3 caused by molding, thereby relieving stress and improving moldability.

[0117] As described above, elastic particles having a core-shell structure, for example, can be dispersed in a base resin such as epoxy resin and used. More specifically, for example, an adhesive (resin composition) used to form the adhesive layer 5 can be mixed with a resin composition containing elastic particles and epoxy resin to form the adhesive layer 5, which can then be used as a moldability-improving layer.

[0118] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. The resin used to form the adhesive layer 5 can be the same as the adhesive exemplified in the adhesive layer 2. Furthermore, from the viewpoint of firmly bonding the adhesive layer 5 to the heat-fusible resin layer 4, the resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, their anhydrides, acrylic acid, and methacrylic acid, but maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the viewpoint of heat resistance for the exterior material of the energy storage device, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

[0119] The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be analyzed by methods such as infrared spectroscopy and gas chromatography-mass spectrometry, and the analytical method is not particularly limited. Furthermore, the presence of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined, for example, by measuring maleic anhydride-modified polyolefin using infrared spectroscopy, at a wavenumber of 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A 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.

[0120] Furthermore, from the viewpoint of ensuring durability such as heat resistance and resistance to contents of the exterior material for energy storage devices, as well as ensuring moldability while keeping the thickness thin, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. The above-mentioned products are examples of the acid-modified polyolefin.

[0121] 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, ester resins produced by the reaction of epoxy groups and maleic anhydride groups, and amide ester resins produced by the reaction of oxazoline groups and maleic anhydride groups are preferred. If unreacted curing agents such as compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins remain in the adhesive layer 5, the presence of unreacted substances can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0122] 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 and curing agents having epoxy groups. 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).

[0123] 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, biuretes, and isocyanurates are also examples.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0134] 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, or about 5 μm or less. Alternatively, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more, or about 0.5 μm or more. The range of the thickness of the adhesive layer 5 is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2, or the cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when 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.

[0135] [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.

[0136] In the exterior material 10 for energy storage devices, the surface coating layer 6 may be a moldability-improving layer. Details of the moldability-improving layer are as described above, and when the surface coating layer 6 is used as a moldability-improving layer, elastic particles are included in the surface coating layer 6. When the surface coating layer 6 is used as a moldability-improving layer, stress distribution becomes possible in the surface coating layer 6, so that localized forces are not applied to the base material layer 1 or barrier layer 3 during molding, thereby suppressing cracking and splitting of the base material and improving moldability.

[0137] The surface coating layer 6 may be made of resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, or phenolic resin, or modified versions of these resins. It may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins. The resin is preferably a curable resin. That is, the surface coating layer 6 is preferably composed of a cured product of a resin composition containing a curable resin.

[0138] 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.

[0139] Examples of two-component curable polyurethanes include polyurethanes comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, two-component curable polyurethanes include those comprising a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the first agent and an aromatic or aliphatic polyisocyanate as the second agent. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and a polyol compound. Examples of polyurethanes include polyurethanes cured by reacting a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. Furthermore, aliphatic isocyanate compounds refer to isocyanates that have an aliphatic group and no aromatic ring, alicyclic isocyanate compounds refer to isocyanates that have an alicyclic hydrocarbon group, and aromatic isocyanate compounds refer to isocyanates that have an aromatic ring.The surface coating layer 6 is formed of polyurethane, which provides the exterior material for energy storage devices with excellent electrolyte resistance.

[0140] 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.

[0141] The additive may be either inorganic or organic. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0142] 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.

[0143] The method for forming the surface coating layer 6 is not particularly limited, and one example is to apply a resin to form the surface coating layer 6. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0144] 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.

[0145] 3. 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 stacking the layers of the exterior material for energy storage devices of the present invention. At a minimum, the method includes a step of stacking the base layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order.

[0146] An example of a method for manufacturing the exterior material for energy storage devices of the present invention is as follows. First, a laminate (hereinafter sometimes referred to as "laminated body A") is formed by sequentially laminating a base material 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 material 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 material layer 1 is laminated and the adhesive layer 2 is cured.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 4. 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.

[0152] 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). The packaging can be formed by overlapping the heat-sealable resin layers of two energy storage device casing materials facing each other and heat-sealing the periphery of the overlapped casing materials. Alternatively, as shown in the example in Figure 5, one energy storage device casing material can be folded and overlapped, and the periphery can be heat-sealed to form the packaging. When folding and overlapping, as shown in the example in Figure 5, the edges other than the folded edge can be heat-sealed to form a three-sided seal, or the edges can be folded to form a flange and then sealed on all four sides. Furthermore, the energy storage device casing material may have a recess for housing the energy storage device element formed by deep drawing or stretch molding. As shown in the example in Figure 5, one energy storage device casing material may have a recess while the other does not, or the other energy storage device casing material may also have a recess.

[0153] 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 types of secondary batteries to which the casing material for energy storage devices disclosed herein can be applied are 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.

[0154] 5. Resin composition for use as an exterior material for energy storage devices The resin composition for use in exterior materials for energy storage devices described herein is a resin composition for use in exterior materials for energy storage devices, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, and is a resin composition containing elastic particles and resin. More specifically, it is a resin composition used to form a moldability-improving layer for exterior materials for energy storage devices.

[0155] In the resin composition, the elastic particles are as described in the section on [Moldability-enhancing layer]. Examples of the resin include the resin that forms the adhesive layer 2 and the resin that forms the adhesive layer 5.

[0156] 6. Elastic particles for use in exterior materials for energy storage devices The elastic particles for use in the exterior material for energy storage devices of this disclosure are a resin composition for use in the exterior material for energy storage devices, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer. More specifically, they are elastic particles used to form a moldability-improving layer for the exterior material for energy storage devices.

[0157] The elastic particles are as described in the [Moldability Improvement Layer] section. [Examples]

[0158] 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.

[0159] The details of the adhesive resins 1-3 and additives 1-3 containing elastic particles used in the examples and comparative examples are as follows. • Adhesive resin 1: A two-component polyurethane adhesive using a polyester polyol and an aromatic isocyanate compound. • Adhesive resin 2: A resin different from adhesive resin 1, which is a two-component polyurethane adhesive using a polyester polyol and an aromatic isocyanate compound. • Adhesive resin 3: An adhesive resin mainly used for bonding between the barrier layer and the heat-sealable resin layer of exterior materials for energy storage devices, which is a two-component polyolefin adhesive using acid-modified polypropylene and an ether-based compound. • Additive 1: An epoxy resin composition containing polybutadiene-based rubber particles (rubber particle content is 25% by mass). The polybutadiene-based rubber particles have a core-shell structure, with the core composed of polybutadiene-based rubber. When Additive 1 is measured by gas chromatography-mass spectrometry (GC-MS) as described in the measurement method below, 4-vinylcyclohexene derived from polybutadiene with a retention time of 4.771 min, styrene with a retention time of 6.558 min, methyl methacrylate with a retention time of 2.483 min, and glycidyl methacrylate with a retention time of 10.996 min are observed. • Additive 2: An epoxy resin composition containing styrene-butadiene rubber particles (rubber particle content is 25% by mass). The styrene-butadiene rubber particles have a core-shell structure, with the core composed of styrene-butadiene rubber. Additive 3: An epoxy resin composition containing silicone rubber particles (rubber particle content is 25% by mass). The silicone rubber particles have a core-shell structure, with the core being composed of silicone rubber.

[0160] GC-MS measurement method A Shimadzu QP2010 was used as the instrument. The pretreatment, measurement mode, and measurement conditions are as follows. <Pre-treatment> Sampling was performed using a scalpel. <Measurement Mode> The method used was thermal decomposition (electric furnace type). <Measurement conditions> A column manufactured by UA-5 FRONTIER LAB (stationary phase 5% diphenyl-95% dimethylpolysiloxane, inner diameter 0.25 mm, length 30 m, film thickness 0.25 μm) was used. The oven temperature (column temperature) was maintained at 50°C for 5 minutes, then increased by 10°C over 1 minute to 320°C. The ionization method was electron collision ionization (EI). A quadrupole detector was used, and the thermal decomposition temperature was set to 600°C.

[0161] <Manufacturing of exterior materials for energy storage devices> Examples 1-4 and Comparative Example 1 As base layers, stretched polyethylene terephthalate (PET) film (12 μm thick) and stretched nylon (ONy) film (15 μm thick) were prepared. Using a two-component urethane adhesive (polyol compound and aromatic isocyanate compound), the PET film and ONy film were bonded via the adhesive layer so that the thickness of the adhesive layer after curing was 3 μm. In addition, aluminum foil (JIS H4160:1994 A8021H-O (each with a thickness of 40 μm as described in Table 1)) was prepared as a barrier layer. Next, the aforementioned adhesive resin 1 and additives 1 to 3 containing elastic particles were mixed so that the adhesive forming the adhesive layer had the composition described in Table 1 to prepare the adhesive. Next, using the obtained adhesive, the aluminum foil and the base layer (ONy film side) were laminated by dry lamination so that the thickness of the adhesive layer after curing was 3 μm, and then an aging treatment was performed to create a laminate of base layer / adhesive layer / barrier layer. Both sides of the aluminum foil were treated with chemical conversion treatment. The chemical conversion treatment of aluminum foil involves a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was achieved by applying the coating to both sides of the aluminum foil using the roll-coating method and then baking it to achieve the desired (dry mass).

[0162] Next, maleic anhydride-modified polypropylene as an adhesive layer and random polypropylene as a heat-fusible resin layer were melt-extruded onto the barrier layer of each laminate obtained above, thereby laminating an adhesive layer (40 μm thick) and a heat-fusible resin layer (40 μm thick) on the barrier layer, and an exterior material for energy storage devices was obtained in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in that order.

[0163] Examples 5-6 and Comparative Example 2 Except for mixing the aforementioned adhesive resin 2 and additive 1 containing elastic particles so that the adhesive forming the adhesive layer has the composition shown in Table 2, an exterior material for an energy storage device was obtained in the same manner as in Examples 1-4 and Comparative Example 1. In Example 6, when the primary and secondary particle diameters were measured, the primary particle diameter was approximately 90 nm and the secondary particle diameter was approximately 0.8 μm. The method for measuring the primary and secondary particle diameters of elastic particles is described below.

[0164] Example 7 and Comparative Example 3 Except for the addition of carbon black as a pigment to the adhesive forming the adhesive layer, exterior materials for energy storage devices were obtained in the same manner as in Example 3 and Comparative Example 1 (Table 3).

[0165] Examples 8-10 and Comparative Example 4 Except for using a single layer of stretched nylon (ONy) film (25 μm thick) as the base layer, and preparing the adhesive by mixing the aforementioned adhesive resin 2 and additive 1 containing elastic particles so that the adhesive forming the adhesive layer had the composition shown in Table 4, an exterior material for an energy storage device was obtained in the same manner as in Examples 1-4 and Comparative Example 1.

[0166] Example 11 and Comparative Example 5 A stretched nylon (ONy) film (25 μm thick) was prepared as the base layer. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick, as described in Table 1)) was prepared as the barrier layer. A two-component urethane adhesive (polyol compound and aromatic isocyanate compound) was used to create a laminate of the base layer / adhesive layer / barrier layer by dry lamination, with the adhesive layer thickness after curing being 3 μm. An aging treatment was then performed. Both sides of the aluminum foil were treated with a chemical conversion solution. The chemical conversion treatment of the aluminum foil involved a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was achieved by applying the coating to both sides of the aluminum foil using the roll-coating method and then baking it to achieve the desired (dry mass).

[0167] Next, an unstretched polypropylene film (40 μm thick) was prepared as the heat-sealable resin layer. Furthermore, the aforementioned adhesive resin 3 and additive 1 containing elastic particles were mixed to prepare an adhesive so that the adhesive forming the adhesive layer had the composition shown in Table 5. Next, using the obtained adhesive, the barrier layer side of each laminate obtained above and the unstretched polypropylene film as the heat-sealable resin layer were laminated by dry lamination so that the thickness of the adhesive layer after curing was 3 μm. After aging treatment, an adhesive layer (3 μm thick) and a heat-sealable resin layer (40 μm thick) were laminated on top of the barrier layer, resulting in an exterior material for an energy storage device in which the base layer, adhesive layer, barrier layer, adhesive layer, and heat-sealable resin layer were laminated in that order.

[0168] <Measurement of primary and secondary particle diameters of elastic particles> The primary and secondary particle diameters of the elastic particles contained in the moldability-enhancing layer were measured on the cross-section of the moldability-enhancing layer of the exterior material for energy storage devices, under the following pretreatment and observation conditions. The primary particle diameter refers to the average value of the diameter x and diameter y of each primary particle, obtained by selecting 10 primary particles from the largest visible particles within the field of view using image analysis at the magnification of the primary particle diameter measurement described in the observation conditions below, measuring the diameter x and diameter y in a total of 6 field of view locations (3 in the cross-section parallel to MD and 3 in the cross-section parallel to TD), and averaging all the obtained measurement data. The diameter x of each primary particle refers to the straight-line distance between the leftmost point perpendicular to the thickness direction and the rightmost point perpendicular to the thickness direction of each primary particle. The diameter y of each primary particle refers to the straight-line distance between the uppermost point parallel to the thickness direction and the lowermost point parallel to the thickness direction of each primary particle. If there were not 10 particles in the field of view, the diameters x and diameter y of all primary particles present in the field of view were measured and the average value was calculated.

[0169] <Pre-treatment> Exterior material for energy storage devices was fixed as a sample. The fixation method was embedding with room-temperature curing resin. The sample was cut using a microtome (Leica UC7), and the cross-section was finished with a knife (Diamond Ultra35). The cutting thickness when finishing the cross-section was set to 100 nm, which is the cutting thickness for ultra-thin sectioning (100 nm). Staining was performed with Os (osmium tetroxide) staining, the sample was in the form of a section, and the staining time was 30 minutes. The conductive treatment conditions were PtPd (irradiation time: 20 seconds).

[0170] <Observation conditions> Ultrathin sections were observed using a SEM transmission detector (STEM observation). The observation device used was a Hitachi High-Technologies SU9000. The mode was set to TE (signal selection: BF-STEM), the probe current was set to normal, the acceleration voltage to 30.0kV, the emission current to 10μA, the working width (WD) to 0mm, the tilt to 0°, and the STEM observation magnification to ×20k and ×100k (the reference observation magnification during imaging was Polaroid 545). Primary particle size was measured on the device at ×100k (field of view: approximately 1250nm × approximately 950nm). Secondary particle size was measured on the device at ×20k (field of view: approximately 6.4μm × approximately 4.8μm).

[0171] <Evaluation of moldability> Each exterior material for the energy storage device was cut into a rectangle with a length (MD) of 80 mm and a width (TD) of 120 mm to create a test sample. The MD of the exterior material for the energy storage device corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for the energy storage device corresponds to the TD of the aluminum alloy foil. This sample was subjected to the following experiment at 25°C: a rectangular molding die with a bore diameter of 31.6 mm (MD) × 54.5 mm (TD) (female mold, surface has a maximum height roughness (nominal value Rz) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002; corner radius R2.0 mm, edge radius R1.0 mm) and a molding die with a clearance of 0.3 mm (male mold, edge surface has a maximum height roughness (nominal value Rz) of 1.6 μm as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002; surface other than the edge is as specified in Annex 1 (Reference) of JIS B 0659-1:2002 The maximum height roughness (nominal value of Rz) is 3.2 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 0.37 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. After cold forming, the samples were examined in a dark room using a penlight to check for pinholes or cracks in the aluminum foil by light transmission. The deepest forming depth at which no pinholes or cracks occurred in any of the 10 samples was defined as A mm, and the number of samples at the shallowest forming depth at which pinholes or cracks occurred was defined as B, which was defined as the limit forming depth for the exterior material of the energy storage device. The results are shown in Tables 1 to 5. Limit molding depth = A mm + (0.5 mm / 10 pieces) × (10 pieces - B pieces)

[0172] <Evaluation of interlayer delamination in high-temperature, high-humidity environments> The exterior material for the energy storage device obtained above was cut to create strips measuring 120 mm (TD) x 80 mm (MD), which were used as test samples. Four test samples were prepared for each type. As mentioned above, the MD of the exterior material for the energy storage device corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for the energy storage device corresponds to the TD of the aluminum alloy foil. Furthermore, the direction perpendicular to the same plane as MD and RD is TD. The rolling direction of the aluminum alloy foil can be confirmed by the rolling marks on the aluminum alloy foil. The mold used consisted of a rectangular male mold measuring 31.6 mm (MD) x 54.5 mm (TD) (with a maximum height roughness (nominal value Rz) of 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002; corner radius 2.0 mm, edge radius 1.0 mm) and a female mold with a clearance of 0.3 mm from the male mold (with a maximum height roughness (nominal value Rz) of 3.2 μm, as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002; corner radius 2.0 mm, edge radius 1.0 mm). The test sample was placed on the female mold so that the heat-fusible resin layer side was positioned on the male mold side. Each test sample was cold-formed (single-stage pull-in forming) at 25°C under a surface pressure of 0.37 MPa, with a molding depth of 5 mm to prevent cracks or pinholes during molding. Next, the cold-formed samples were placed in a constant temperature and humidity chamber at 80°C and 90% RH and left to stand for 37 days. The molded samples were removed from the constant temperature and humidity chamber and visually inspected to see if any delamination (peeling of the base layer) had occurred between the base layer and the aluminum alloy foil. Tables 1 and 2 show the percentage of samples in which delamination (peeling of the base layer) occurred (number of delaminations / total number) from four locations per sample (16 locations in total for four test samples) when lines extending perpendicularly from the center of each side of the molded section measuring 31.6 mm (MD) × 54.5 mm (TD) were drawn, i.e., four locations per sample.

[0173] [Table 1]

[0174] As shown in Table 1, the exterior materials for energy storage devices in Examples 1 to 4 have an adhesive layer 2 containing elastic particles that constitutes a moldability-enhancing layer. Compared to Comparative Example 1, which does not contain elastic particles in the adhesive layer, the exterior materials for energy storage devices in Examples 1 to 4 have superior moldability and exhibit the excellent effect of being less prone to delamination in high-temperature and high-humidity environments.

[0175] [Table 2]

[0176] As shown in Table 2, the exterior materials for energy storage devices in Examples 5 and 6 have an adhesive layer 2 containing elastic particles that constitutes a moldability-enhancing layer. Compared to Comparative Example 2, which does not contain elastic particles in the adhesive layer, the exterior materials for energy storage devices in Examples 5 and 6 also exhibit superior moldability and the excellent effect of being less prone to delamination in high-temperature and high-humidity environments.

[0177] [Table 3]

[0178] As shown in Table 3, the exterior material for the energy storage device in Example 7 has an adhesive layer 2 containing elastic particles that constitutes a moldability-enhancing layer. Despite the inclusion of carbon black in the adhesive layer, which tends to reduce moldability, the exterior material for the energy storage device in Example 7 exhibits superior moldability compared to Comparative Example 3, which does not contain elastic particles in the adhesive layer.

[0179] [Table 4]

[0180] As shown in Table 4, the exterior materials for energy storage devices in Examples 8 to 10 have an adhesive layer 2 containing elastic particles that constitutes a moldability-enhancing layer. The exterior materials for energy storage devices in Examples 8 to 10 have superior moldability compared to Comparative Example 4, which does not contain elastic particles in the adhesive layer.

[0181] [Table 5]

[0182] As shown in Table 5, the exterior material for the energy storage device in Example 11 has an adhesive layer 5 containing elastic particles that constitutes a moldability-enhancing layer. The exterior material for the energy storage device in Example 11 has superior moldability compared to Comparative Example 5, which does not contain elastic particles in the adhesive layer.

[0183] In Tables 1-5, ONy refers to stretched nylon film, and PET / ONy refers to a laminate of stretched polyethylene terephthalate film and stretched nylon film.

[0184] As described above, this disclosure provides inventions in the following embodiments. Item 1. The laminate is composed of, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer. An exterior material for an energy storage device, wherein at least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles. Item 2. The exterior material for an energy storage device according to Item 1, wherein the primary particle diameter of the elastic particles is 1 nm or more and 3 μm or less. Item 3. The exterior material for an energy storage device according to Item 1 or 2, wherein the elastic particles include at least one selected from the group consisting of butadiene rubber, acrylic rubber, styrene rubber, and silicone rubber. Item 4. The elastic particles are an outer covering material for an energy storage device according to any one of items 1 to 3, having a core-shell structure. Item 5. An adhesive layer is provided between the base material layer and the barrier layer, The exterior material for an energy storage device according to any one of claims 1 to 4, wherein the adhesive layer constitutes the moldability-improving layer. Item 6. An adhesive layer is provided between the barrier layer and the heat-fusible resin layer, The exterior material for an energy storage device according to any one of claims 1 to 5, wherein the adhesive layer constitutes the moldability-improving layer. Item 7. A resin composition for use in an exterior material for an energy storage device, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, The resin composition is used to form at least one moldability-improving layer included in the laminate. A resin composition comprising elastic particles and resin. Item 8. The resin composition according to item 7, comprising an adhesive layer between the base material layer and the barrier layer, wherein the adhesive layer constitutes the moldability improving layer. Item 9. The resin composition according to item 7 or 8, comprising an adhesive layer between the barrier layer and the heat-fusible resin layer, wherein the adhesive layer constitutes the moldability-improving layer. Item 10. Elastic particles for use in an exterior material for an energy storage device, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, The elastic particles are elastic particles used to form at least one moldability-improving layer contained in the laminate. Item 11. The process includes obtaining a laminate in which, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated, A method for manufacturing an exterior material for an energy storage device, wherein at least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles. Item 12. 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 an energy storage device as described in any one of items 1 to 6. [Explanation of Symbols]

[0185] 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, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer. At least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles, An adhesive layer is provided between the substrate layer and the barrier layer. The adhesive layer constitutes the moldability improving layer, The elastic particles have a core-shell structure and are an outer material for an energy storage device.

2. An adhesive layer is provided between the barrier layer and the heat-fusible resin layer. The exterior material for an energy storage device according to claim 1, wherein the adhesive layer constitutes the moldability improving layer.

3. It is composed of a laminate comprising, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer. At least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles, An adhesive layer is provided between the barrier layer and the heat-fusible resin layer. The adhesive layer constitutes the moldability improving layer, The elastic particles have a core-shell structure and are an outer material for an energy storage device.

4. An adhesive layer is provided between the substrate layer and the barrier layer. The exterior material for an energy storage device according to claim 3, wherein the adhesive layer constitutes the moldability-improving layer.

5. The exterior material for an energy storage device according to any one of claims 1 to 4, wherein the primary particle diameter of the elastic particles is 1 nm or more and 3 μm or less.

6. The exterior material for an energy storage device according to any one of claims 1 to 5, wherein the elastic particles include at least one selected from the group consisting of butadiene rubber, acrylic rubber, styrene rubber, and silicone rubber.

7. A resin composition for use in an exterior material for an energy storage device, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, The resin composition is used to form at least one moldability-improving layer contained in the laminate. An adhesive layer is provided between the base material layer and the barrier layer, and the adhesive layer constitutes the moldability improving layer. It contains elastic particles and resin, The elastic particles are a resin composition having a core-shell structure.

8. The resin composition according to claim 7, wherein an adhesive layer is provided between the barrier layer and the heat-fusible resin layer, and the adhesive layer constitutes the moldability-improving layer.

9. A resin composition for use in an exterior material for an energy storage device, comprising a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, The resin composition is used to form at least one moldability-improving layer contained in the laminate. An adhesive layer is provided between the barrier layer and the heat-fusible resin layer, and the adhesive layer constitutes the moldability-improving layer. It contains elastic particles and resin, The elastic particles are a resin composition having a core-shell structure.

10. The resin composition according to claim 9, wherein an adhesive layer is provided between the base material layer and the barrier layer, and the adhesive layer constitutes the moldability improving layer.

11. The process includes obtaining a laminate in which, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated. At least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles, An adhesive layer is provided between the base material layer and the barrier layer, and the adhesive layer constitutes the moldability improving layer. The elastic particles have a core-shell structure, and this is a method for manufacturing an exterior material for an energy storage device.

12. The process includes obtaining a laminate in which, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated. At least one layer included in the laminate constitutes a moldability-enhancing layer containing elastic particles, An adhesive layer is provided between the barrier layer and the heat-fusible resin layer, and the adhesive layer constitutes the moldability-improving layer. The elastic particles have a core-shell structure, and this is a method for manufacturing an exterior material for an energy storage device.

13. 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 material for an energy storage device according to any one of claims 1 to 6.

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