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

Abstract

To provide an exterior material for a power storage device in which the occurrence of cracking and peeling of a surface coating layer due to molding of the exterior material for the power storage device is suppressed.SOLUTION: An exterior material for a power storage device is composed of a laminate having at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealing resin layer from the outside, and the surface coating layer contains a resin and particles, and in an environment in which the temperature is 23°C, the hardness of the resin of the surface coating layer measured by the nanoindentation method with respect to the cross section in the thickness direction of the surface coating layer is 420.4 MPa or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] While various types of energy storage devices have been developed, 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 exterior materials 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 these recesses. A heat-sealable resin layer is then heat-fused (heat-sealed) to the recesses, thereby obtaining an energy storage device in which the energy storage device elements are housed inside the exterior material. [Prior art documents] [Patent Documents]

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

[0007] In exterior materials for energy storage devices composed of a film-like laminate, a surface coating layer containing particles may be provided on the outside of the base material layer in order to give the outer surface a matte finish.

[0008] However, as mentioned above, since the exterior materials for energy storage devices are subjected to molding, excellent moldability is required for exterior materials for energy storage devices that have a surface coating layer containing particles. Specifically, it is necessary to suppress the occurrence of cracks and peeling of the surface coating layer during the molding of the exterior materials for energy storage devices.

[0009] Under these circumstances, the main objective of this disclosure is to provide an exterior material for energy storage devices in which the occurrence of cracking and peeling of the surface coating layer due to molding of the exterior material for energy storage devices is suppressed. [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, comprising a laminate comprising, in order from the outside, at least a surface coating layer, a base layer, a barrier layer, and a heat-fusible resin layer, wherein the surface coating layer contains resin and particles, and the hardness of the resin in the surface coating layer, measured by nanoindentation in a cross-section in the thickness direction of the surface coating layer at a 23°C environment, is 420.4 MPa or less, suppresses the occurrence of cracking and peeling of the surface coating layer due to molding of the exterior material for an energy storage device.

[0011] This disclosure is the result of further consideration based on these findings. Specifically, this disclosure provides inventions in the following embodiments. It is composed of a laminate comprising, in order from the outside in, at least a surface coating layer, a base layer, a barrier layer, and a heat-fusible resin layer. The aforementioned surface coating layer contains resin and particles, In an environment of 23°C, for the cross-section in the thickness direction of the surface coating layer, the hardness of the resin of the surface coating layer measured by the nanoindentation method is 420.4 MPa or less, which is an exterior material for a power storage device.

Advantages of the Invention

[0012] According to the present disclosure, it is possible to provide an exterior material for a power storage device in which cracks and peeling of the surface coating layer due to molding of the exterior material for a power storage device are suppressed. Further, according to the present disclosure, it is also possible to provide a method for manufacturing the exterior material for a power storage device and a power storage device using the exterior material for a power storage device.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 2] It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 3] It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure.

Embodiments for Carrying Out the Invention

[0014] The exterior material for a power storage device of the present disclosure is composed of a laminate including at least a surface coating layer, a base material layer, a barrier layer, and a heat-sealable resin layer in order from the outside. The surface coating layer contains a resin and particles. In an environment of 23°C, for the cross-section in the thickness direction of the surface coating layer, the hardness of the resin of the surface coating layer measured by the nanoindentation method is 420.4 MPa or less. The exterior material for a power storage device of the present disclosure has this configuration, so that cracks and peeling of the surface coating layer due to molding of the exterior material for a power storage device are suppressed.

[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.

[0016] 1. Laminated structure and physical properties of exterior materials for energy storage devices The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising, for example, a surface coating layer 6, a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4, in order from the outside, as shown in Figures 1 to 3. In the exterior material 10 for energy storage devices, the surface coating layer 6 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 surface coating layer 6 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 purposes such as improving the adhesion between these layers, as shown in Figures 2 to 3. Although not shown, a colored layer may also be present between the base layer 1 and the barrier layer 3. Furthermore, as shown in Figure 3, for example, an adhesive layer 5 may be present between the barrier layer 3 and the heat-fusible resin layer 4, as needed, for purposes such as improving the adhesion between these layers.

[0018] 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 energy density improvement, preferred thicknesses include approximately 180 μm or less, approximately 160 μm or less, approximately 155 μm or less, approximately 140 μm or less, approximately 130 μm or less, and approximately 120 μm or less. From the viewpoint of maintaining the function of the exterior material for energy storage devices, which is to protect the energy storage device elements, preferred thicknesses include approximately 35 μm or more, approximately 45 μm or more, approximately 60 μm or more, and approximately 80 μm or more. For example, preferred ranges include approximately 35 to 180 μm, approximately 35 to 160 μm, and 3 Examples of particle sizes include approximately 5-155 μm, 35-140 μm, 35-130 μm, 35-120 μm, 45-180 μm, 45-160 μm, 45-155 μm, 45-140 μm, 45-130 μm, 45-120 μm, 60-180 μm, 60-160 μm, 60-155 μm, 60-140 μm, 60-130 μm, 60-120 μm, 80-180 μm, 80-160 μm, 80-155 μm, 80-140 μm, 80-130 μm, and 80-120 μm. Among these, approximately 80-130 μm is particularly preferred.

[0019] In the exterior material 10 for energy storage devices disclosed herein, the hardness of the resin of the surface coating layer 6, measured by nanoindentation in a cross-sectional area in the thickness direction of the surface coating layer 6 at a 23°C environment, is 420.4 MPa or less. In the exterior material 10 for energy storage devices, the hardness of the surface coating layer 6 at a 23°C environment suppresses the occurrence of cracking and peeling of the surface coating layer due to molding of the exterior material for energy storage devices at room temperature.

[0020] From the viewpoint of more effectively suppressing the occurrence of cracks and peeling of the surface coating layer due to molding of the exterior material for energy storage devices, the exterior material 10 for energy storage devices of this disclosure has a hardness of the resin of the surface coating layer 6 measured by nanoindentation method in a cross-section in the thickness direction of the surface coating layer 6 in a 23°C environment, preferably about 350.4 MPa or less, more preferably about 310.4 MPa or less, and also preferably about 20.0 MPa or more, more preferably about 22.5 MPa or more, even more preferably about 25.5 MPa or more, even more preferably about 50.0 MPa or more, even more preferably about 100.0 MPa or more, and even more preferably about 150.0 MPa or more, and the preferred range is Examples include approximately 20.0-420.4 MPa, 20.0-350.4 MPa, 20.0-310.4 MPa, 22.5-420.4 MPa, 22.5-350.4 MPa, 22.5-310.4 MPa, 25.5-420.4 MPa, 25.5-350.4 MPa, 25.5-310.4 MPa, 50.0-420.4 MPa, 50.0-350.4 MPa, 50.0-310.4 MPa, 100.0-420.4 MPa, 100.0-350.4 MPa, 100.0-310.4 MPa, 150.0-420.4 MPa, 150.0-350.4 MPa, and 150.0-310.4 MPa. Among these, a range of approximately 150.0 to 310.4 MPa is particularly preferred. In this invention, excellent moldability means, more specifically, that the matte finish of the surface coating layer is not impaired when the exterior material 10 for the energy storage device is molded, and that cracks and peeling of the surface coating layer due to room temperature molding are suppressed. The hardness measured by the nanoindentation method in a 23°C environment is measured as follows.

[0021] [Hardness measured by nanoindentation method in a 23°C environment] The hardness is measured using a nanoindenter (e.g., the "TI950 TriboIndenter" manufactured by HYSITRON). A Berkovich indenter (e.g., TI-0039) is used as the indenter for the nanoindenter. First, in an environment of 50% relative humidity and 23°C, the indenter is applied to the surface of the surface coating layer of the exterior material for the energy storage device (the surface where the surface coating layer is exposed and parallel to the thickness direction of each layer) from a direction perpendicular to the thickness direction. The indenter is pressed into the surface coating layer with a load of 50 μN from the surface over 10 seconds, held in that position for 5 seconds, and then unloaded over 10 seconds. The average value of N=5 measurements taken at different measurement locations is taken as the hardness. The surface into which the indenter is pressed is the resin portion where the cross-section of the surface coating layer is exposed, obtained by cutting the exterior material for the energy storage device in the thickness direction, passing through the center. The cutting is performed using a commercially available rotary microtome. Furthermore, when obtaining exterior material for energy storage devices from energy storage devices to prepare test samples, the exterior material is obtained from areas of the energy storage device that are less affected by molding, such as the top or sides of the device.

[0022] The hardness measured by nanoindentation in a 23°C environment can be adjusted by the composition (type and content of resin), curing conditions, molecular weight, number of functional groups, crosslinking density, and bulk height of substituents of the resin composition forming the surface coating layer 6.

[0023] 2. Each layer forming the exterior material for the energy storage device [Surface coating layer 6] The exterior material 10 for energy storage devices of this disclosure has a surface coating layer 6 on the outside of the base layer 1 for purposes such as providing a matte finish to the outer surface of the exterior material 10 for energy storage devices. The surface coating layer 6 is the outermost layer of the exterior material 10 for energy storage devices when an energy storage device is assembled using the exterior material 10 for energy storage devices.

[0024] The surface coating layer 6 contains resin and particles. Examples of particles include inorganic particles and organic particles. The particles contained in the surface coating layer 6 may be of one type or two or more types. It is also preferable to use inorganic particles and organic particles in combination. Furthermore, there are no particular restrictions on the shape of the particles, and examples include spherical, fibrous, plate-like, irregular, and flaky shapes.

[0025] The average particle diameter is not particularly limited, but from the viewpoint of giving the exterior material 10 for the energy storage device a matte finish, for example, it can be about 0.01 to 5 μm. The average particle diameter is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer. The average particle diameter is preferably less than or equal to the thickness of the surface coating layer 6.

[0026] The inorganic particles are not particularly limited as long as the surface coating layer 6 can be made matte. Examples include silica, talc, 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, gold, aluminum, copper, and nickel. Among these, silica particles are particularly preferred.

[0027] Furthermore, the organic particles are not particularly limited as long as the surface coating layer 6 can be made matte, and examples include nylon, polyacrylate, polystyrene, styrene-acrylic copolymer, polyethylene, benzoguanamine, or crosslinked products thereof.

[0028] In the measurement of hardness measured by the nanoindentation method in a 23°C environment described above, the hardness of organic particles contained in the surface coating layer 6 can also be measured by cutting the surface into which the indenter is pressed in the thickness direction, passing through the center of the exterior material for the energy storage device, and using the location where organic particles are present with an exposed cross-section of the surface coating layer. From the viewpoint of more effectively suppressing the occurrence of cracks and peeling of the surface coating layer due to molding of the exterior material for energy storage devices, the hardness of the organic particles measured in this way is preferably about 300.0 MPa or more, more preferably about 400.0 MPa or more, and also preferably about 1500.4 MPa or less, more preferably about 1000.4 MPa or less, and even more preferably about 600.4 MPa or less. Preferred ranges include about 300.0 to 1500.4 MPa, about 300.0 to 1000.4 MPa, about 300.0 to 600.4 MPa, about 400.0 to 1500.4 MPa, about 400.0 to 1000.4 MPa, and about 400.0 to 600.4 MPa, among these, about 400.0 to 600.4 MPa is particularly preferred.

[0029] The particle content in the surface coating layer 6 is not particularly limited, as long as the hardness measured by nanoindentation in a 23°C environment is 420.4 MPa or less. Preferably, it is about 3 parts by mass or more, more preferably about 10 parts by mass or more, and also preferably about 30 parts by mass or less, more preferably about 20 parts by mass or less, per 100 parts by mass of resin in the resin composition forming the surface coating layer 6. Preferred ranges include about 3 to 30 parts by mass, about 3 to 20 parts by mass, about 10 to 30 parts by mass, and about 10 to 20 parts by mass.

[0030] If there are too many particles in the surface coating layer 6, the adhesion between the resin and the particles will be weak, and cracks will easily form at the boundary. Therefore, it is preferable to adjust the particle content to a small amount.

[0031] The resin included in the resin composition forming the surface coating layer 6 is not particularly limited, as long as the hardness measured by nanoindentation at a 23°C environment is 420.4 MPa or less, but it 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 and particles. Specific examples of the resin include, for example, polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified products of these resins. It may also be a copolymer of these resins, or a modified product of a copolymer. Furthermore, it may be a mixture of these resins. The resin is preferably a curable resin.

[0032] The curable resin may be either a one-component or two-component curable resin, but a two-component curable resin is preferred. 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.

[0033] Examples of two-component curable polyurethanes include polyurethanes comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are those in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is the main component and an aromatic or aliphatic polyisocyanate is the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. Examples of curing agents 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). Furthermore, examples include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Polyisocyanate compounds can also be used as polymers (e.g., trimers). Examples of such polymers include adducts, biuretes, and nulates. It should be noted that aliphatic isocyanate compounds refer to isocyanates having aliphatic groups and no aromatic rings, alicyclic isocyanate compounds refer to isocyanates having alicyclic hydrocarbon groups, and aromatic isocyanate compounds refer to isocyanates having aromatic rings.

[0034] In a resin composition that forms the surface coating layer 6, if the resin is a polyurethane comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound, the hardness measured by nanoindentation in a 23°C environment can be adjusted, for example, by adjusting the ratio of the main component to the curing agent.

[0035] The surface and interior of the surface coating layer 6 may further contain additives such as lubricants, colorants, antiblocking agents, flame retardants, antioxidants, tackifiers, antistatic agents, and waxes, as needed, depending on the functionality to be provided to the surface coating layer 6 and its surface.

[0036] If the surface coating layer 6 contains a coloring agent, known coloring agents such as pigments and dyes can be used. Furthermore, only one type of coloring agent may be used, or two or more types may be mixed. Specific examples of coloring agents included in the surface coating layer 6 are the same as those exemplified in the [Adhesive Layer 2] section. The preferred content of coloring agents included in the surface coating layer 6 is also the same as that described in the [Adhesive Layer 2] section.

[0037] The method for forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin composition for forming the surface coating layer 6 can be used. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0038] If the amount of additives present in the surface coating layer 6 is too high, the adhesion between the resin and the attachment will be weak, and cracks will easily form at the boundary. Therefore, it is preferable to adjust the amount of additives to the minimum necessary.

[0039] The thickness of the surface coating layer 6 is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of more effectively suppressing the occurrence of cracks and peeling of the surface coating layer due to the molding of the exterior material for the energy storage device. Preferred ranges include approximately 0.5 to 10 μm, approximately 0.5 to 5 μm, approximately 1 to 10 μm, and approximately 1 to 5 μm.

[0040] 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 surface coating layer 6. 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.

[0041] If a lubricant is present on the surface of the surface coating layer 6, 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.

[0042] The lubricant present on the surface of the surface coating layer 6 may be a lubricant that has seeped out of the surface coating layer 6, or a lubricant that has been applied to the surface of the surface coating layer 6.

[0043] [Base material layer 1] In this disclosure, the base material layer 1 is a layer provided for purposes such as enabling the base material to function as a base material for the exterior material of an energy storage device. The base material layer 1 is located between the surface coating layer 6 and the barrier layer 3 of the exterior material 10 for the energy storage device. If an adhesive layer 2 is present, the base material layer 1 is located between the surface coating layer 6 and the adhesive layer 2.

[0044] 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.

[0045] 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.

[0046] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. Furthermore, the resin forming the base layer 1 may be a copolymer of these resins, or a modified version of such copolymer. It may also be a mixture of these resins.

[0047] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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, or a laminate of two or more stretched polyester films is 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 on the outermost layer of the base layer 1.

[0053] 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.

[0054] 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.

[0055] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but examples include approximately 3 to 50 μm, 3 to 35 μm, and 3 to 25 μm. If the base layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer is preferably approximately 2 to 25 μm.

[0056] [Adhesive layer 2] In the exterior material for energy storage devices of this disclosure, the adhesive layer 2 is a layer provided between the substrate layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0057] 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.

[0058] 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.

[0059] Examples of polyurethane adhesives include polyurethane adhesives comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curing polyurethane adhesives are used, with a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the main component and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. Examples of curing agents 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). Furthermore, examples include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Polyisocyanate compounds can also be used as polymers (e.g., trimers). Such polymers include adducts, biuretes, and nurates. The adhesive layer 2 is formed from a polyurethane adhesive, providing excellent electrolyte resistance to the exterior material for energy storage devices, and preventing the substrate layer 1 from peeling off even if electrolyte adheres to the sides.

[0060] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, particles, etc. The inclusion of a colorant in the adhesive layer 2 allows for the coloring of the exterior material for energy storage devices. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0061] 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.

[0062] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance.

[0063] 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.

[0064] 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.

[0065] 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 examples include approximately 1 μm or more and approximately 2 μm or more. Alternatively, the thickness of the adhesive layer 2 may be approximately 10 μm or less and approximately 5 μm or less. Furthermore, preferred ranges for the thickness of the adhesive layer 2 include approximately 1 to 10 μm, approximately 1 to 5 μm, approximately 2 to 10 μm, and approximately 2 to 5 μm.

[0066] [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. A colored adhesive layer 2 and a colored layer may be provided between the base layer 1 and the barrier layer 3.

[0067] 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.

[0068] Specific examples of colorants included in the colored layer are the same as those exemplified in the [Adhesive Layer 2] section.

[0069] [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.

[0070] 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.

[0071] From the viewpoint of suppressing the occurrence of pinholes and cracks during the molding of the exterior material for energy storage devices, it is more preferable that the aluminum alloy foil be a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of more effectively suppressing the occurrence of pinholes and cracks during molding, it is preferable that the aluminum alloy foil contains iron. In the iron-containing aluminum alloy foil (100 mass%), the iron content is preferably 0.1 to 9.0 mass%, and more preferably 0.5 to 2.0 mass%. By having an iron content of 0.1 mass% or more, an exterior material for energy storage devices can be obtained in which the occurrence of pinholes and cracks during molding is effectively suppressed. By having an iron content of 9.0 mass% or less, an exterior material for energy storage devices with superior 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.

[0072] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of suppressing the occurrence of pinholes and cracks during the molding of the exterior material for energy storage devices, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0073] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS301 or SUS304 being particularly preferred among these.

[0074] 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, and can be approximately 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. Alternatively, the thickness of the barrier layer 3 can be preferably about 10 μm or more, even more preferably about 20 μm or more, and even more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 3 include approximately 10-85 μm, 10-50 μm, 10-40 μm, 10-35 μm, 20-85 μm, 20-50 μm, 20-40 μm, 20-35 μm, 25-85 μm, 25-50 μm, 25-40 μm, and 25-35 μm, with 25-40 μm being particularly preferred among these. When the barrier layer 3 is made of aluminum alloy foil, the above range is particularly preferred. Furthermore, 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 particularly preferably about 25 μm or less. Furthermore, 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.

[0075] 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 to the barrier layer by performing a corrosion prevention treatment on the surface of the barrier layer, such as a hot water modification treatment like boehmite treatment, a chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or coating agent application. 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. Note that these treatments may also be included in the definition of chemical conversion treatment. Also, if the barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0076] 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.

[0077] 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.

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc. Also, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group, etc. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by General Formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating units represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 NH). The aminated phenol polymer is used alone or in combination of two or more.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0087] 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

[0088] 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.

[0089] 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.

[0090] [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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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 occurrence of pinholes and cracks during molding of the exterior material for the energy storage device can be suppressed. 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.

[0099] 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.

[0100] 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 suppressing the occurrence of pinholes and cracks during the molding 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.

[0101] 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.

[0102] 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.

[0103] [Adhesive layer 5] In the exterior material for energy storage devices of this disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or acid-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0104] 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. Preferably, the resin used to form the adhesive layer 5 contains a polyolefin skeleton, such as the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4. 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, when the resin constituting the adhesive layer 5 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 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.

[0105] From the viewpoint of firmly bonding the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred as the acid-modified polyolefin are polyolefins modified with a carboxylic acid or its anhydride, polypropylenes modified with a carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0106] Furthermore, from the viewpoint of reducing the thickness of the exterior material for energy storage devices while providing excellent shape stability after molding, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Examples of acid-modified polyolefins include those mentioned above.

[0107] Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, amide ester resin is preferred. Amide ester resin is generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition comprising at least one of these resins and the acid-modified polyolefin. Furthermore, if unreacted compounds containing isocyanate groups, compounds containing oxazoline groups, or curing agents such as epoxy resin remain in the adhesive layer 5, the presence of these unreacted compounds can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, or time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0108] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups, curing agents having epoxy groups, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0109] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, burettes, and isocyanurates are also examples.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 this 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.

[0114] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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. For example, when the adhesive layer 5 is formed from an acid-modified polyolefin, the thickness of the adhesive layer 5 is preferably about 2 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more. Also, when the adhesive layer 5 is formed from an acid-modified polyolefin, the thickness of the adhesive layer 5 is preferably about 50 μm or less, more preferably 40 μm or less. Also, when the adhesive layer 5 is formed from an acid-modified polyolefin, the preferred range for the thickness of the adhesive layer 5 is about 2 to 50 μm, about 2 to 40 μm, about 5 to 50 μm, about 5 to 40 μm, about 8 to 50 μm, and about 8 to 40 μm. Note that 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 or the like. Furthermore, 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.

[0120] 3. Method for manufacturing exterior materials for energy storage devices The method for manufacturing an 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. One example is a method that includes the step of obtaining a laminate in which, in order from the outside, at least a surface coating layer 6, a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 are stacked. Specifically, the method for manufacturing an exterior material for energy storage devices of the present disclosure includes the step of obtaining a laminate in which, in order from the outside, at least a surface coating layer 6, a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 are stacked, the surface coating layer 6 contains resin and particles, and the hardness of the outer surface of the surface coating layer 6, measured by nanoindentation in a 23°C environment, is 420.4 MPa or less.

[0121] 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.

[0122] 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.

[0123] Next, a surface coating layer 6 is laminated onto 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 above-mentioned resin composition for forming the surface coating layer 6 to the surface of the base layer 1 and curing it. The order of the steps of laminating the barrier layer 3 onto the surface of the base layer 1 and laminating the surface coating layer 6 onto the surface of the base layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the base layer 1, the barrier layer 3 may be formed on the surface of the base layer 1 opposite to the surface coating layer 6.

[0124] As described above, a laminate is formed comprising, in order from the outside in, a surface coating layer 6, a base material layer 1, an optional adhesive layer 2, a barrier layer 3, an optional adhesive layer 5, and a heat-fusible resin layer 4. However, to further strengthen the adhesion of the optional adhesive layer 2 and adhesive layer 5, the laminate may be subjected to heat treatment. Also, as described above, a colored layer may be provided between the base material layer 1 and the barrier layer 3.

[0125] 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.

[0126] 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).

[0127] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the casing material for energy storage devices disclosed herein can be applied is not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. [Examples]

[0128] 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.

[0129] <Manufacturing of exterior materials for energy storage devices> [Example 1] A stretched nylon (ONy) film (15 μm thick) was prepared as the base layer. Aluminum foil (JIS H4160:1994 A8021H-O (35 μm thick)) was prepared as the barrier layer. Next, the barrier layer and base layer were laminated using a dry lamination method with the adhesive described later (a two-component urethane adhesive containing a coloring agent), and then an aging treatment was performed to create a laminate of the base layer / adhesive layer / barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. 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).

[0130] Next, maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick) and random polypropylene as a heat-fusible resin layer (20 μm thick) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Furthermore, the following resin composition 1 was coated onto the surface of the base layer of the obtained laminate to a thickness of 3 μm, and cured under formation conditions of 3 days in an environment of 40°C to 100°C to form a matte surface coating layer, thereby obtaining an exterior material for an energy storage device consisting of a laminate (total thickness 96 μm) with the following layers laminated from the outside in: surface coating layer (3 μm) / base layer (15 μm thick) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm).

[0131] [Example 2] Except for using resin composition 2 instead of resin composition 1 in forming the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0132] [Example 3] Except for using resin composition 3 instead of resin composition 1 in forming the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0133] [Example 4] Except for using the resin composition 4 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0134] [Example 5] Except for using the resin composition 5 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0135] [Example 6] Except for using the resin composition 6 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0136] [Example 7] Except for using the resin composition 7 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0137] [Example 8] A stretched nylon (ONy) film (12 μm thick) was prepared as the base layer. A stainless steel foil (SUS301 (20 μm thick)) was prepared as the barrier layer. Next, the barrier layer and the base layer were laminated using a dry lamination method with the adhesive described later (a two-component urethane adhesive containing a coloring agent), and then an aging treatment was performed to create a laminate of the base layer / adhesive layer / barrier layer. Both sides of the stainless steel foil were treated with a chemical conversion treatment. The chemical conversion treatment of the stainless steel 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 stainless steel foil using the roll coating method and then baking it to achieve the desired (dry mass).

[0138] Next, the barrier layer and the heat-sealable resin layer of each laminate obtained above were bonded together by dry lamination using a modified olefin adhesive (the thickness of the bonded layer after curing was 3 μm), and the bonded layer and the heat-sealable resin layer were laminated on top of the barrier layer. An unstretched polypropylene film (thickness 23 μm) was used as the heat-sealable resin layer. Furthermore, the resin composition 2 described below was coated onto the surface of the base layer of the obtained laminate to a thickness of 3 μm, and cured under formation conditions of 3 days in an environment of 40°C to 100°C to form a matte surface coating layer, thereby obtaining an exterior material for an energy storage device consisting of a laminate (total thickness 64 μm) with the following layers laminated in order from the outside: surface coating layer (3 μm) / base layer (thickness 12 μm) / adhesive layer (3 μm) / barrier layer (20 μm) / adhesive layer (3 μm) / heat-sealable resin layer (23 μm).

[0139] [Example 9] Except for using the resin composition 9 described below instead of resin composition 2 in forming the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 8.

[0140] [Example 10] Except for using the resin composition 10 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0141] [Comparative Example 1] Except for using the resin composition 8 described below instead of resin composition 1 to form the surface coating layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1.

[0142] <Resin composition and formation conditions used for forming the surface coating layer> (Resin composition 1 (used in Example 1)) A resin composition comprising a resin (polyurethane formed from a mixture of two polyol compounds and an aromatic isocyanate compound), inorganic particles (silica particles, average particle size 1 μm), polystyrene-based organic particles (average particle size 2 μm), and an olefin-based wax.

[0143] (Resin composition 2 (used in Examples 2 and 8)) A resin composition comprising a resin (polyurethane formed from a mixture of two polyol compounds and an aliphatic isocyanate compound), inorganic particles (silica particles, average particle size 1 μm), polystyrene-based organic particles (average particle size 2 μm), and an olefin-based wax.

[0144] (Resin composition 3 (used in Example 3)) A resin composition comprising a resin (polyurethane formed from a mixture of two polyol compounds and an aromatic isocyanate compound (the blending ratio of the two polyol compounds is changed from that of resin composition 1)), inorganic particles (silica particles, average particle size 1 μm), polystyrene-based organic particles (average particle size 2 μm), and an olefin-based wax.

[0145] (Resin composition 4 (used in Example 4)) A resin composition comprising 100 parts by mass of resin (polyurethane formed from a mixture of one polyol compound and an aliphatic isocyanate compound), 10 parts by mass of inorganic particles (barium sulfate particles, average particle size 1 μm), polystyrene-based organic particles (average particle size 2 μm), and an olefin-based wax.

[0146] (Resin composition 5 (used in Example 5)) A resin composition in which the olefin wax content of the resin composition of Example 3 is reduced to 1 / 4.

[0147] (Resin composition 6 (used in Example 6)) A resin composition in which the olefin wax content of the resin composition of Example 3 is reduced to 1 / 8.

[0148] (Resin composition 7 (used in Example 7)) Resin composition of Example 3 that does not contain olefin-based wax

[0149] (Resin composition 8 (used in Comparative Example 1)) The same materials as in Example 1 were used, except that a different aromatic isocyanate compound was used.

[0150] (Resin composition 9 (used in Example 9)) A resin composition comprising a resin (polyurethane formed from a mixture of two polyol compounds and an aromatic isocyanate compound (the blending ratio of the two polyol compounds is changed from that of resin composition 1)), inorganic particles (silica particles, average particle size 1 μm), and polystyrene-based organic particles (average particle size 2 μm).

[0151] (Resin composition 10 (used in Example 10)) A resin composition comprising a resin (polyurethane formed from a mixture of two polyol compounds and an aromatic isocyanate compound (the blending ratio of the two polyol compounds is changed from that of resin composition 1)), inorganic particles (silica particles, average particle size 1 μm), and polystyrene-based organic particles (average particle size 2 μm).

[0152] [Hardness measured by nanoindentation method in a 23°C environment] The hardness was measured using a nanoindenter ("TI950 TriboIndenter" manufactured by HYSITRON). A Berkovich indenter (TI-0039) was used as the indenter for the nanoindenter. First, in an environment of 50% relative humidity and 23°C, the indenter was applied perpendicular to the thickness direction to the surface of the surface coating layer of the exterior material for the energy storage device (the surface where the surface coating layer is exposed and parallel to the thickness direction of each layer). The indenter was pressed into the surface coating layer with a load of 50 μN from the surface over 10 seconds, held in that position for 5 seconds, and then unloaded over 10 seconds. The average value of N=5 measurements taken at different measurement locations was taken as the hardness. The results are shown in Table 1. The surface to which the indenter was pressed was the resin portion where the cross-section of the surface coating layer was exposed, obtained by cutting the exterior material for the energy storage device in the thickness direction, passing through the center. Furthermore, in measuring the hardness of the surface coating layer, the indenter was pressed into the area of ​​the surface coating layer where no particles were present (the resin portion). The measurement results were rounded to two decimal places. The organic particles contained in the surface coating layers of Examples 1-10 and Comparative Example 1 were the same, and the hardness measured by pressing the indenter into the area where organic particles were present in the surface coating layers of Examples 2 and 10 was 496.1 MPa. Cutting was performed using a commercially available rotary microtome. The measurement results were rounded to two decimal places.

[0153] [Moldability] Each exterior material for the energy storage device was cut into a rectangle with a length (MD) of 90 mm and a width (TD) of 150 mm to serve as 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 test sample was subjected to the following conditions at 25°C: a rectangular molding die (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 2.0 mm, edge radius 1.0 mm) and a corresponding molding die (male mold, surface of the edge 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 has a maximum height roughness (nominal value Rz) of 1.6 μm. The maximum height roughness (nominal value of Rz) of the comparative surface roughness standard specimen is 3.2 μm. Ten test samples were cold-formed (single-stage pull-in molding) with a molding depth of 5 mm at a pressing pressure (surface pressure) of 0.22 MPa using corner radius R2.0 mm and edge radius R1.0 mm. At this time, the test samples were placed on the female mold so that the heat-fusible resin layer side was located on the male mold side, and molding was performed. The clearance between the male and female molds was set to 0.3 mm. The matte finish of each test sample after cold forming was evaluated according to the following criteria. The results are shown in Table 1. A: The matte finish was well maintained even after molding, and there were no cracks or peeling of the surface coating layer. B: After molding, no cracks or peeling occurred in the surface coating layer, but the surface of the surface coating layer became glossy, impairing the matte finish. C: After molding, the surface of the surface coating layer developed a glossy finish, damaging the matte appearance, and cracks and peeling of the surface coating layer also occurred.

[0154] [Table 1]

[0155] The exterior materials for energy storage devices in Examples 1-10 have a surface coating layer containing resin and particles, and the hardness of the outer surface of the surface coating layer, measured by nanoindentation in a 23°C environment, is 420.4 MPa or less. The exterior materials for energy storage devices in Examples 1-10 suppress the occurrence of cracking and peeling of the surface coating layer due to molding of the exterior material for energy storage devices. Furthermore, in Examples 5 and 6, where the amount of wax added to the surface coating layer was small, the occurrence of cracking and peeling of the surface coating layer was further suppressed, and in Examples 7, 9, and 10, where no wax was added to the surface coating layer, the occurrence of cracking and peeling of the surface coating layer was further suppressed.

[0156] As described above, this disclosure provides inventions in the following embodiments. Item 1. The laminate comprises, in order from the outside, at least a surface coating layer, a base layer, a barrier layer, and a heat-fusible resin layer. The aforementioned surface coating layer contains resin and particles, An exterior material for energy storage devices, wherein, in a 23°C environment, the hardness of the resin of the surface coating layer, measured by nanoindentation in the thickness direction of the surface coating layer, is 420.4 MPa or less. Item 2. The exterior material for energy storage devices according to Item 1, wherein, in a 23°C environment, the hardness of the particles of the surface coating layer, measured by nanoindentation in the thickness direction of the surface coating layer, is 300.0 MPa or more. Item 3. An exterior material for an energy storage device according to item 1 or 2, comprising an adhesive layer between the base material layer and the barrier layer. Item 4. The exterior material for an energy storage device according to Item 3, wherein the adhesive layer is colored. Item 5. An exterior material for an energy storage device according to any one of items 1 to 4, comprising a colored layer between the base material layer and the barrier layer. Item 6. A method for manufacturing an exterior material for an energy storage device, The process includes obtaining a laminate in which, in order from the outside in, at least a surface coating layer, a base material layer, a barrier layer, and a heat-fusible resin layer are laminated. The aforementioned surface coating layer contains resin and particles, A method for manufacturing an exterior material for an energy storage device, wherein, in a 23°C environment, the hardness of the resin of the surface coating layer, measured by nanoindentation in the thickness direction of the surface coating layer, is 420.4 MPa or less. Item 7. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer casing material for an energy storage device as described in any one of items 1 to 5. [Explanation of Symbols]

[0157] 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 surface coating layer, a base layer, a barrier layer, and a heat-fusible resin layer. The aforementioned surface coating layer contains resin and particles, The aforementioned particles include inorganic particles, The surface and at least one of the interior of the aforementioned surface coating layer contains a lubricant. An exterior material for an energy storage device, wherein, in a 23°C environment, the hardness of the resin of the surface coating layer, measured by nanoindentation in the thickness direction of the surface coating layer, is 420.4 MPa or less.

2. The exterior material for an energy storage device according to claim 1, wherein the lubricant is at least one selected from the group consisting of 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.

3. The exterior material for an energy storage device according to claim 1 or 2, wherein the inorganic particles are silica.

4. The exterior material for an energy storage device according to claim 1 or 2, wherein the inorganic particles are titanium oxide.

5. The exterior material for an energy storage device according to claim 1 or 2, wherein the inorganic particles are kaolin.

6. The surface coating layer is formed from a two-component curable polyurethane comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. The curing agent is an aromatic polyisocyanate, as described in any one of claims 1 to 5, for exterior material for energy storage devices.

7. An exterior material for an energy storage device according to any one of claims 1 to 6, wherein, in a 23°C environment, the hardness of the resin of the surface coating layer, as measured by nanoindentation in the thickness direction of the surface coating layer, is 25.5 MPa or more.

8. The barrier layer comprises stainless steel, as described in any one of claims 1 to 7, for exterior material for energy storage devices.

9. An exterior material for an energy storage device according to any one of claims 1 to 8, wherein a colored layer is provided between the base material layer and the barrier layer.

10. An adhesive layer is provided between the substrate layer and the barrier layer. An exterior material for an energy storage device according to any one of claims 1 to 9, wherein a colored layer is provided between the adhesive layer and the barrier layer.

11. A method for manufacturing an exterior material for an energy storage device, The process includes obtaining a laminate in which, in order from the outside in, at least a surface coating layer, a base material layer, a barrier layer, and a heat-fusible resin layer are laminated. The aforementioned surface coating layer contains resin and particles, The aforementioned particles include inorganic particles, The surface and at least one of the interior of the aforementioned surface coating layer contains a lubricant. A method for manufacturing an exterior material for an energy storage device, wherein, in a 23°C environment, the hardness of the resin of the surface coating layer, measured by nanoindentation in the thickness direction of the surface coating layer, is 420.4 MPa or less.

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 material for an energy storage device according to any one of claims 1 to 10.

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