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

Abstract

This exterior material for a power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order. The barrier layer includes an aluminum alloy foil. The thickness of the aluminum alloy foil is equal to or greater than 75 μm. The ratio of the thickness of the aluminum alloy foil when the thickness of the laminate is 100% is equal to or greater than 38%.

Description

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

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

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

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

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

[0005] In such an exterior material for energy storage devices, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolytes are placed in the space formed by the recesses. By heat-sealing a heat-sealable resin layer, an energy storage device is obtained in which the energy storage device elements are housed inside the exterior material for the energy storage device.

[0006] Japanese Patent Publication No. 2008-287971

[0007] In recent years, power storage devices using exterior materials for power storage devices formed from laminated films as described above are being used in in-vehicle applications, power storage system (ESS) applications, drone applications, and the like. Such power storage devices tend to be larger and have higher output. Since high-output power storage devices generate a large amount of heat during charging and discharging, it is important to quickly dissipate the heat generated inside the power storage device to the outside of the power storage device in order to ensure the quality of the power storage device. Therefore, high heat dissipation is also required for the exterior material for the power storage device.

[0008] Under such circumstances, the main object of the present disclosure is to provide an exterior material for a power storage device having excellent heat dissipation properties.

[0009] The inventors of the present disclosure have intensively studied to solve the above problems. As a result, in an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, after using an aluminum alloy foil for the barrier layer, the thickness of the aluminum alloy foil is set to a predetermined value or more, and by setting the ratio of the thickness of the aluminum alloy foil to the total thickness of the laminate constituting the exterior material for the power storage device to a predetermined value or more, it has been found that the exterior material for the power storage device exhibits high heat dissipation properties.

[0010] Based on these findings, the present disclosure has been completed through further study. That is, the present disclosure provides an invention in the following aspects. An exterior material for a power storage device, comprising a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside, the barrier layer includes an aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the total thickness of the laminate is 38% or more when the total thickness of the laminate is taken as 100%.

[0011] According to the present disclosure, it is possible to provide an exterior material for a power storage device having excellent heat dissipation properties. Further, according to the present disclosure, it is also possible to provide a method for manufacturing the exterior material for the power storage device and a power storage device using the exterior material for the power storage device.

[0012] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram illustrating a method for housing an energy storage device element in a package formed from the exterior material for energy storage devices of the present disclosure.

[0013] The exterior material for energy storage devices of this disclosure is characterized in that it is composed of a laminate comprising, at least from the outside, a base layer, a barrier layer, and a heat-fusible resin layer in that order, wherein the barrier layer includes an aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the thickness of the laminate is 100%) is 38% or more. The exterior material for energy storage devices of this disclosure can exhibit excellent heat dissipation due to having this configuration.

[0014] The exterior materials for energy storage devices described herein will be described in detail below. In this disclosure, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to". For example, the notation 2 to 15 mm means 2 mm or more and 15 mm or less. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Alternatively, upper and lower limits, upper and lower limits, or lower limits described separately may be combined to form numerical ranges. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0015] Furthermore, in the case of exterior materials for energy storage devices, the Machine Direction (MD) and Transfer Direction (TD) of the barrier layer 3 described later can usually be determined during the manufacturing process. For example, when the barrier layer 3 is composed of metal foil such as aluminum alloy foil or copper foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Also, in the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil of the laminate and determining the rolling direction (RD) of the metal foil. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

[0016] Furthermore, if the MD of the exterior material for energy storage devices cannot be identified by the rolling marks of metal foils such as aluminum alloy foil and copper foil, it can be identified by the following method. One method for confirming the MD of the exterior material for energy storage devices is to observe the cross-section of the heat-fusible resin layer of the exterior material for energy storage devices with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing each of the cross-sections (a total of 10 cross-sections) in the longitudinal direction of the heat-fusible resin layer, and each of the cross-sections perpendicular to the longitudinal direction, by changing the angle by 10 degrees from the direction parallel to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost point perpendicular to that point is defined as the diameter y. For each cross-section, the average of the top 20 diameters y of the island shape, ordered from largest to smallest, is calculated. The direction parallel to the cross-section with the largest average diameter y of the island shape is determined to be the MD (Mid-Depth Direction).

[0017] <Laminated Structure and Physical Properties of Exterior Material for Energy Storage Devices> The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising, for example, a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order from the outside, as shown in Figure 1. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling an energy storage device using the exterior material 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-fussing the peripheral edges of the heat-fusible resin layers 4 of the exterior material 10 facing each other. In the laminate constituting the exterior material 10 for energy storage devices of this disclosure, with respect to the barrier layer 3, the heat-fusible resin layer 4 side is inward of the barrier layer 3, and the base layer 1 side is outward of the barrier layer 3. As shown in Figures 2 to 4, the exterior material for energy storage devices may have an adhesive layer 2 as needed for the purpose of improving the adhesion between the base layer 1 and the barrier layer 3. Furthermore, as shown in Figure 4, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (opposite the side from the heat-fusible resin layer 4) as needed. In addition, as shown in Figures 3 and 4, an adhesive layer 5 may be provided as needed to improve the adhesion between the barrier layer 3 and the heat-fusible resin layer 4.

[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 improvement of energy density, for example, it can be about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior material for energy storage devices, which is to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 10 for energy storage devices can be preferably about 120 μm or more, about 140 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, the preferred range for the laminate constituting the outer material 10 for the energy storage device is, for example, approximately 120 to 300 μm, approximately 120 to 250 μm, approximately 120 to 210 μm, approximately 120 to 190 μm, approximately 120 to 180 μm, approximately 120 to 155 μm, approximately 140 to 300 μm, approximately 140 to 250 μm, approximately 140 to 210 μm, approximately 140 to 190 μm, approximately 140 to 180 μm, approximately 140 to 155 μm, Examples of particle sizes include approximately 155-300 μm, 155-250 μm, 155-210 μm, 155-190 μm, 155-180 μm, 190-300 μm, 190-250 μm, and 190-210 μm. In particular, when improving moldability, approximately 120-190 μm is preferred.

[0019] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3, the adhesive layer 5 (optionally provided), the heat-fusible resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Specifically, when the exterior material 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even if the exterior material 10 for energy storage devices of this disclosure is a laminate comprising a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0020] From the viewpoint of more favorably exhibiting the effects of the present invention, the thermal conductivity of the laminate constituting the exterior material 10 for the energy storage device is preferably about 0.24 W / (m·K) or more, more preferably 0.26 W / (m·K) or more, and even more preferably 0.27 W / (m·K) or more. The upper limit is, for example, 0.40 W / (m·K) or less, and preferred ranges include about 0.24 to 0.40 W / (m·K), about 0.26 to 0.40 W / (m·K), and about 0.27 to 0.40 W / (m·K).

[0021] <Layers forming the exterior material for energy storage devices> [Base layer 1] In this disclosure, the base layer 1 is a layer provided for purposes such as enabling it to function as a base material for the exterior material for energy storage devices. The base layer 1 is located on the outer layer side of the exterior material for energy storage devices.

[0022] From the viewpoint of more favorably exhibiting the effects of the present invention, the ratio of the total thickness of each layer outside the aluminum alloy foil (base layer 1, adhesive layer 2 provided as needed, etc.) when the thickness of the aluminum alloy foil included in the barrier layer 3 described later is taken as 100% is preferably about 69% or less, more preferably about 60% or less, and even more preferably about 50% or less. The lower limit can be, for example, about 10% or more, about 15% or more, about 20% or more, and preferred ranges can be about 10-69%, about 10-60%, about 10-50%, about 15-69%, about 15-60%, about 15-50%, about 20-69%, about 20-60%, and about 20-50%.

[0023] 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.

[0024] When the base layer 1 is formed of resin, the base layer 1 can be formed of, for example, a resin film. When the base layer 1 is formed of a resin film, a pre-formed resin film may be used as the base layer 1 when manufacturing the exterior material 10 for the energy storage device of this disclosure by laminating the base layer 1 with a barrier layer 3 or the like. Alternatively, the resin forming the base layer 1 may be formed into a film on the surface of the barrier layer 3 or the like by extrusion molding or coating, and the base layer 1 may be formed of a resin film. 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 method, and simultaneous biaxial stretching. Examples of methods for coating the resin include roll coating, gravure coating, and extrusion coating.

[0025] 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. The resin forming the base layer 1 may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins.

[0026] The base layer 1 preferably contains these resins as its main component, and more preferably contains polyester or polyamide as its main component. Here, "main component" means that among the resin components contained in the base layer 1, the content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the base layer 1 contains polyester or polyamide as its main component, it means that among the resin components contained in the base layer 1, the content of polyester or polyamide is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0027] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0028] 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). Furthermore, the polyester may be a copolymer of two or more polyesters selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate. These polyesters may be used individually or as a mixture of two or more.

[0029] Furthermore, examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0030] 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.

[0031] 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.

[0032] Specific examples of a laminate of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film is located in the outermost layer of the base layer 1. In a laminate of a polyester resin film and a polyamide resin film, the preferred thickness range of the polyester resin film is approximately 2-33 μm, 2-28 μm, 2-23 μm, 2-18 μm, 2-11 μm, 2-8 μm, 10-33 μm, 10-28 μm, 10-23 μm, 10-18 μm, 10-11 μm, 18-33 μm, and 18-28 μm. The thickness is approximately 18 to 23 μm. Preferred ranges for the thickness of the polyamide resin film include approximately 2 to 33 μm, 2 to 28 μm, 2 to 23 μm, 2 to 18 μm, 2 to 11 μm, 2 to 8 μm, 10 to 33 μm, 10 to 28 μm, 10 to 23 μm, 10 to 18 μm, 10 to 11 μm, 18 to 33 μm, 18 to 28 μm, and 18 to 23 μm.

[0033] If the base layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in adhesive layer 2 described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and then laminated. The anchor coat layer 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.

[0034] 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, antistatic agents, and colorants. Only one type of additive may be used, or two or more types may be mixed and used.

[0035] 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 at least one of the surface and interior of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0036] When the lubricant is present on the surface of the base material layer 1, the amount of its presence is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Also, as the amount of the lubricant present on the surface of the base material layer 1, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Also, the preferable range of the amount of the lubricant present on the surface of the base material layer 1 is about 3 to 15 mg / m 2 degree, about 3 to 14 mg / m 2 degree, about 3 to 10 mg / m 2 degree, about 4 to 15 mg / m 2 degree, about 4 to 14 mg / m 2 degree, about 4 to 10 mg / m 2 degree, about 5 to 15 mg / m 2 degree, about 5 to 14 mg / m 2 degree, about 5 to 10 mg / m 2 degree.

[0037] The lubricant present on the surface of the base material layer 1 may be one obtained by exuding the lubricant contained in the resin constituting the base material layer 1, or may be one obtained by applying the lubricant to the surface of the base material layer 1.

[0038] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 μm or more, preferably about 10 μm or more. Also, examples of the thickness of the base layer 1 can be about 100 μm or less, about 90 μm or less, about 70 μm or less, about 50 μm or less, preferably about 35 μm or less, about 11 μm or less, or about 8 μm or less. Furthermore, preferred thickness ranges for the base layer 1 include approximately 3 to 100 μm, 3 to 90 μm, 3 to 70 μm, 3 to 50 μm, 3 to 35 μm, 3 to 11 μm, 3 to 8 μm, 10 to 100 μm, 10 to 90 μm, 10 to 70 μm, 10 to 50 μm, 10 to 35 μm, and 10 to 11 μm. In particular, when making energy storage devices into lightweight thin films, thicknesses of approximately 3 to 35 μm, 3 to 11 μm, and 3 to 8 μm are preferred, and when improving moldability, thicknesses of approximately 35 to 50 μm are preferred. When the base layer 1 is a laminate of two or more resin films, the thickness of the resin film constituting each layer is not particularly limited, but examples include approximately 2 μm or more, preferably approximately 10 μm or more and approximately 18 μm or more, respectively. Furthermore, the thickness of the resin film constituting each layer can be, for example, about 33 μm or less, preferably about 28 μm or less, about 23 μm or less, about 18 μm or less, about 11 μm or less, or about 8 μm or less. In addition, preferred ranges for the thickness of the resin film constituting each layer can be about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, or about 18 to 23 μm.

[0039] The base layer 1 contains a coloring agent, which allows the exterior material for the energy storage device to be colored. 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 and used.

[0040] The type of pigment is not particularly limited, as long as it does not impair the function of the substrate layer 1 as a substrate. 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.

[0041] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0042] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0043] The amount of coloring agent in the base layer 1 is not particularly limited as long as the exterior material for the energy storage device is colored, and for example, it can be about 5 to 60% by mass, preferably about 10 to 40% by mass.

[0044] [Adhesive layer 2] In the exterior material for energy storage devices of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0045] 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.

[0046] Examples of adhesive components include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; 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.

[0047] Examples of polyurethane adhesives include polyurethane adhesives comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curing type polyurethane adhesive is used, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. As the second agent, aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds are used. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. The adhesive layer 2 is formed from a polyurethane adhesive, which provides excellent electrolyte resistance to the exterior material for the energy storage device, preventing the substrate layer 1 from peeling off even if electrolyte adheres to the sides.

[0048] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. The 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.

[0049] The type of pigment is not particularly limited, as long as it does not impair the adhesion of the 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.

[0050] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0051] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0052] The content of the coloring agent 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.

[0053] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the substrate layer 1 and the barrier layer 3, but for example, it is about 1 μm or more and about 2 μm or more. Alternatively, the thickness of the adhesive layer 2 is about 10 μm or less and about 5 μm or less. Preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0054] [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 there is an adhesive layer 2, 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.

[0055] 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.

[0056] Specific examples of colorants included in the colored layer are the same as those exemplified in the section for [Adhesive Layer 2].

[0057] [Barrier layer 3] In the exterior material 10 for the energy storage device, the barrier layer 3 is a layer that at least prevents moisture from entering.

[0058] In the exterior material 10 for energy storage devices, the barrier layer 3 includes aluminum alloy foil with a thickness of 75 μm or more. Furthermore, the ratio of the thickness of the aluminum alloy foil to the total thickness of the laminate constituting the exterior material 10 for energy storage devices is 38% or more. The exterior material for energy storage devices of this disclosure exhibits excellent heat dissipation by satisfying these characteristics. The exterior material for energy storage devices has a structure in which a barrier layer containing aluminum foil of 75 μm or more and a resin layer (base layer, heat-fusible resin layer) are laminated, and the heat dissipation of the exterior material for energy storage devices is easily affected by the thickness of the barrier layer, which has high thermal conductivity. Therefore, it is important to adjust the ratio of the thickness of the aluminum foil to the total thickness of the laminate.

[0059] The thickness of the aluminum alloy foil may be 75 μm or more, but from the viewpoint of more favorably exhibiting the effects of the present invention, it is preferably about 77 μm or more, more preferably about 80 μm or more, and also preferably about 105 μm or less, more preferably about 103 μm or less, and even more preferably about 100 μm or less. Preferred ranges include about 75 to 105 μm, about 75 to 103 μm, about 75 to 100 μm, about 77 to 105 μm, about 77 to 103 μm, about 77 to 100 μm, about 80 to 105 μm, about 80 to 103 μm, and about 80 to 100 μm.

[0060] Furthermore, the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate constituting the exterior material 10 for the energy storage device, when the thickness of the laminate is set to 100%, should be 38% or more. However, from the viewpoint of more favorably exhibiting the effects of the present invention, it is preferably about 43% or more, more preferably about 46% or more, and also preferably about 75% or less, more preferably about 70% or less, and even more preferably about 65% or less. Preferred ranges include approximately 38-75%, 38-70%, 38-65%, 43-75%, 43-70%, 43-65%, 46-75%, 46-70%, and 46-65%.

[0061] The barrier layer 3 may consist solely of aluminum alloy foil (as described later, a corrosion-resistant coating may be formed on at least one surface of the aluminum alloy foil), or it may further include other layers that can constitute the barrier layer 3 in addition to the aluminum alloy foil. Examples of other layers that can be included in the barrier layer 3 include metal foil with barrier properties (excluding aluminum alloy foil), vapor-deposited films, and resin layers. 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. Furthermore, the barrier layer 3 may also be a resin film having at least one of these vapor-deposited films and resin layers. As the metal material constituting the metal foil, metals with high thermal conductivity can be used, such as copper and tungsten.

[0062] In barrier layer 3, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include aluminum alloy or recycled steel sheet. For example, aluminum alloy foil may be composed of recycled aluminum alloy. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. Barrier layer 3 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0063] From the viewpoint of improving the formability of the exterior material for energy storage devices, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is more preferably an aluminum alloy foil containing iron. In an iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior material for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material for energy storage devices with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments.

[0064] In the case of metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer that suppresses the intrusion of moisture and improves heat dissipation, for example, about 75 to 200 μm. The thickness of the barrier layer 3 is preferably about 105 μm or less, more preferably about 103 μm or less, even more preferably about 100 μm or less, and particularly preferably about 95 μm or less, with preferred ranges being about 75 to 105 μm, about 75 to 103 μm, about 75 to 100 μm, and about 75 to 95 μm.

[0065] Furthermore, if the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one. Furthermore, among these treatments, hot water modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. These processes may also be included in the definition of chemical conversion treatment. Furthermore, if the barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0066] 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.

[0067] 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 (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, and zinc (Zn) phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphate salts 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. The treatment solution can be various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. 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.

[0068]

[0069]

[0070]

[0071]

[0072] 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 2 Examples of alkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. Also, X, R 1 and R 2Examples of hydroxyalkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxyl 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, and 4-hydroxybutyl group. In general formulas (1) to (4), X and R 1 and R 2 The alkyl group and hydroxyalkyl group shown may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a hydroxyalkyl group. The number-average molecular weight of the amination 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 amination phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by the above general formula (1) or general formula (3), and then mixing formaldehyde and amine (R 1 R 2 Using NH) the functional group (-CH2NR 1 R 2 It is produced by introducing ) into the polymer obtained above. The amination phenol polymer can be used alone or in a mixture of two or more types.

[0073] Another example of a corrosion-resistant film 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 film 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.

[0074] 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.

[0075] 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.

[0076] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0077] 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, about 0.5 to 50 mg of phosphorus-based chromium, preferably about 1.0 to 40 mg of phosphorus, and about 1.0 to 200 mg of aminophenol polymer, preferably about 5.0 to 150 mg.

[0078] 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 - A peak originating from at least one of the following is detected:

[0079] 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 to 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.

[0080] [Heat-fusible resin layer 4] In the exterior material for energy storage devices of this disclosure, the heat-fusible 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-fussing the heat-fusible resin layers together during the assembly of the energy storage device.

[0081] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, the ratio of the total thickness of each layer inside the aluminum alloy foil (heat-fusible resin layer 4, adhesive layer 5 provided as needed, etc.) when the thickness of the aluminum alloy foil included in the barrier layer 3 is taken as 100% is preferably about 99% or less, more preferably 90% or less, and even more preferably 81% or less. As for the upper limit, for example, 40% or more, 45% or more, 50% or more, etc., and as for the preferred range, examples include 40-99%, 40-90%, 40-81%, 45-99%, 45-90%, 45-81%, 50-99%, 50-90%, 50-81%, etc.

[0082] 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 that a peak originating from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby, wave frequency 1780 cm -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.

[0083] The heat-fusible resin layer 4 preferably contains a resin containing a polyolefin skeleton as its main component, more preferably contains polyolefin as its main component, and even more preferably contains polypropylene as its main component. Here, "main component" means a resin component in which the content of the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, if the heat-fusible resin layer 4 contains polypropylene as its main component, it means that the content of polypropylene in the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0084] 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.

[0085] 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.

[0086] Furthermore, the polyolefin may be an acid-modified polyolefin. An acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefin, copolymers obtained by copolymerizing the above-mentioned polyolefin with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins can also be used. 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.

[0087] 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.

[0088] 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.

[0089] 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 it may be formed as two or more layers of the same or different resins.

[0090] When manufacturing the exterior material 10 for the energy storage device of this disclosure by laminating the heat-fusible resin layer 4 with a barrier layer 3, an adhesive layer 5, etc., a pre-formed resin film may be used as the heat-fusible resin layer 4. Alternatively, the heat-fusible resin that forms the heat-fusible resin layer 4 may be formed into a film on the surface of the barrier layer 3, adhesive layer 5, etc. by extrusion molding or coating, and the heat-fusible resin layer 4 may be formed from a resin film.

[0091] Furthermore, the heat-fusible resin layer 4 may contain a lubricant or the like as needed. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used.

[0092] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in the base layer 1. The lubricant may be used alone or in combination of two or more types, with a combination of two or more being preferable.

[0093] 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 at least one of the surface and interior of the heat-fusible resin layer 4. 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, with a combination of two or more being preferable.

[0094] When a lubricant is present on the surface of the heat-fusible resin layer 4, there are no particular restrictions on the amount present, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably about 1 mg / m². 2 More preferably, about 3 mg / m² 2 More preferably, about 5 mg / m² 2 More preferably, about 10 mg / m² 2 More preferably, about 15 mg / m² 2 The above is true, and preferably about 50 mg / m² 2 More preferably, about 40 mg / m² 2 The following are preferred ranges, with a preferred range being 1 to 50 mg / m². 2 Degree, 1-40mg / m 2 Degree, 3-50mg / m 2 Degree, 3-40mg / m 2 degree, 5-50mg / m 2 degree, 5-40mg / m 2 degree, 10-50mg / m 2 degree, 10-40mg / m 2 degree, 15-50mg / m 2 degree, 15-40mg / m 2 The degree can be described as follows.

[0095] When a lubricant is present inside the heat-fusible resin layer 4, there are no particular restrictions on its amount. However, from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, even more preferably about 500 ppm or more, and also preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. When two or more types of lubricants are present inside the heat-fusible resin layer 4, the above amount of lubricant is the total amount of lubricant. Furthermore, when two or more types of lubricants are present inside the heat-fusible resin layer 4, the amount of the first type of lubricant is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, even more preferably about 500 ppm or more, and also preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. The amount of the second type of lubricant is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably about 50 ppm or more, more preferably about 100 ppm or more, even more preferably about 200 ppm or more, and also preferably about 1500 ppm or less, more preferably about 1000 ppm or less. Preferred ranges include about 50 to 1500 ppm, about 50 to 1000 ppm, about 100 to 1500 ppm, about 100 to 1000 ppm, about 200 to 1500 ppm, and about 200 to 1000 ppm.

[0096] 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.

[0097] 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 element. However, from the viewpoint of more favorably exhibiting the effects of the present invention, it is preferably about 45 μm or more, more preferably about 50 μm or more, even more preferably about 60 μm or more, and also preferably about 70 μm or less, more preferably about 60 μm or less, even more preferably about 50 μm or less. Preferred ranges include about 45 to 70 μm, about 45 to 60 μm, about 45 to 50 μm, about 50 to 70 μm, about 50 to 60 μm, and about 60 to 70 μm.

[0098] Furthermore, the thickness of each layer inside the aluminum alloy foil (heat-fusible resin layer 4, adhesive layer 5 provided as needed, etc.) is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device element. However, from the viewpoint of more favorably exhibiting the effects of the present invention, the thickness is preferably about 45 μm or more, more preferably about 50 μm or more, even more preferably about 60 μm or more, and also preferably about 70 μm or less, more preferably about 60 μm or less, even more preferably about 50 μm or less. Preferred ranges include about 45 to 70 μm, about 45 to 60 μm, about 45 to 50 μm, about 50 to 70 μm, about 50 to 60 μm, and about 60 to 70 μm.

[0099] Furthermore, if the exterior material 10 for the energy storage device further has an adhesive layer 5, described later, between the barrier layer 3 and the heat-fusible resin layer 4, it is preferable that the thickness of the adhesive layer 5 is 20 μm or more and 40 μm or less, and the thickness of the heat-fusible resin layer 4 is 20 μm or more and 40 μm or less, and it is more preferable that the thickness of the adhesive layer 5 is 25 μm or more and 35 μm or less, and the thickness of the heat-fusible resin layer 4 is 25 μm or more and 35 μm or less.

[0100] [Adhesive layer 5] In the exterior material for energy storage devices of the present disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or corrosion-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0101] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. As the resin used to form the adhesive layer 5, for example, the same type of adhesive as exemplified in the adhesive layer 2 can be used.

[0102] Furthermore, from the viewpoint of firmly bonding the adhesive layer 5 and the heat-fusible resin layer 4, it is preferable that the resin used to form the adhesive layer 5 contains a polyolefin skeleton, and examples include the polyolefins, acid-modified polyolefins, cyclic polyolefins, and acid-modified cyclic polyolefins exemplified in the heat-fusible resin layer 4 mentioned above. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid, but maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the viewpoint of heat resistance of the exterior material for energy storage devices, it is preferable that the olefin component is a polypropylene-based resin, and it is most preferable that the adhesive layer 5 contains maleic anhydride-modified polypropylene.

[0103] When the resin used to form the adhesive layer 5 contains a polyolefin skeleton, the adhesive layer 5 preferably contains a resin containing a polyolefin skeleton as its main component, more preferably contains acid-modified polyolefin as its main component, and even more preferably contains acid-modified polypropylene as its main component. Here, "main component" means a resin component whose content in the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the adhesive layer 5 contains acid-modified polypropylene as its main component, it means that the content of acid-modified polypropylene in the resin component of the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0104] The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be analyzed by methods such as infrared spectroscopy and gas chromatography-mass spectrometry, and the analytical method is not particularly limited. Furthermore, the presence of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be analyzed by measuring maleic anhydride-modified polyolefin using infrared spectroscopy, for example, at a wavenumber of 1760 cm⁻¹. -1 Nearby, wave frequency 1780 cm -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] Furthermore, from the viewpoint of ensuring durability such as heat resistance and resistance to contents of the exterior material for energy storage devices, as well as ensuring moldability while keeping the thickness thin, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. The above-mentioned products are examples of the acid-modified polyolefin.

[0106] Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, ester resins produced by the reaction of epoxy groups and maleic anhydride groups, and amide ester resins produced by the reaction of oxazoline groups and maleic anhydride groups are preferred. If unreacted curing agents such as compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins remain in the adhesive layer 5, the presence of unreacted substances can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0107] 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, heterocycles, C=N bonds, and C-O-C bonds. Examples of curing agents having heterocycles 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 C-O-C bonds include curing agents having oxazoline groups and curing agents having epoxy groups. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0108] 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 has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, biuretes, and isocyanurates are also examples.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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 about 50 to 2000, more preferably about 100 to 1000, and even more preferably about 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.

[0113] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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 a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

[0118] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0119] When manufacturing the exterior material 10 for the energy storage device according to this disclosure by laminating the adhesive layer 5 with a barrier layer 3, a heat-fusible resin layer 4, etc., a pre-formed resin film may be used as the adhesive layer 5. Alternatively, the heat-fusible resin that forms the adhesive layer 5 may be formed into a film on the surface of the barrier layer 3, the heat-fusible resin layer 4, etc. by extrusion molding or coating, and the adhesive layer 5 may be formed from a resin film.

[0120] 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 a cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified in the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating. Also, when using the resin exemplified in the heat-fusible resin layer 4, it can be formed, for example, by extrusion molding of the heat-fusible resin layer 4 and the adhesive layer 5.

[0121] [Surface coating layer 6] The exterior material for energy storage devices of the present disclosure may, if necessary, include a surface coating layer 6 on the base layer 1 (on the side opposite to the barrier layer 3 of the base layer 1) for the purpose of improving at least one of the following: design, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the exterior material for energy storage devices when the energy storage device is assembled using the exterior material for energy storage devices.

[0122] The surface coating layer 6 may be made of resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, or phenolic resin, or modified versions of these resins. It may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins. The resin is preferably a curable resin. That is, the surface coating layer 6 is preferably composed of a cured product of a resin composition containing a curable resin.

[0123] If the resin forming the surface coating layer 6 is a curable resin, it may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0124] Examples of two-component curable polyurethanes include polyurethanes comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are provided, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and a polyol compound. Examples of polyurethanes include polyurethanes obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. Furthermore, aliphatic isocyanate compounds refer to isocyanates that have an aliphatic group and no aromatic ring, alicyclic isocyanate compounds refer to isocyanates that have an alicyclic hydrocarbon group, and aromatic isocyanate compounds refer to isocyanates that have an aromatic ring.The surface coating layer 6 is formed of polyurethane, which provides the exterior material for energy storage devices with excellent electrolyte resistance.

[0125] The surface coating layer 6 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, and pigments in at least one of its surface and interior, depending on the functionality to be provided to the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0126] The additive may be either inorganic or organic. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0127] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used individually or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. Mica is also preferred from the viewpoint of heat dissipation from the energy storage device. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0128] As described above, the exterior material for energy storage devices of this disclosure has an aluminum alloy foil thickness of 75 μm or more, and the proportion of the thickness of the aluminum alloy foil is 38% or more, thus providing excellent heat dissipation. On the other hand, when sealing an energy storage device by heat-sealing the heat-sealable resins of the exterior material for energy storage devices, it is necessary to heat the exterior material for energy storage devices from the outside under high temperature and high pressure conditions using a metal heat sheet sealing bar. When the exterior material for energy storage devices is heated from the outside using a metal heat sheet sealing bar, the highly heat-dissipating exterior material for energy storage devices may cause the layers located outside the barrier layer 3 (e.g., the base layer, surface coating layer, etc.) to melt and adhere to the metal heat sheet sealing bar, which can be a problem. In particular, in recent years, the demand for energy storage devices has surged, the mass production speed has increased, and metal tabs have become thicker to meet the demand for higher capacity energy storage devices, so heat sealing at high temperature and high pressure is increasing. As a result, adhesion of the base layer and surface coating layer to the heat sealing bar has become more likely than before. Furthermore, because the exterior material for energy storage devices of this disclosure has a thick aluminum alloy foil, a higher temperature and pressure heat seal is required, which often leads to this problem. In such cases, the exterior material for energy storage devices of this disclosure is equipped with a surface coating layer 6, and if, for example, an inorganic additive is included in the surface coating layer 6, it is possible to suitably suppress the adhesion of the metal heat sheet seal bar to the surface coating layer. When polyurethane, epoxy resin, or acrylic resin is used as the material for the surface coating layer 6, adhesion to the heat seal bar can also be suitably suppressed.

[0129] From the viewpoint of effectively suppressing the adhesion of the metal heat sheet sealing bar to the surface coating layer 6, the inorganic content in the surface coating layer 6 is preferably about 1 part by mass or more, more preferably about 5 parts by mass or more, and preferably about 500 parts by mass or less, more preferably about 100 parts by mass or less, and even more preferably about 50 parts by mass or less, with preferred ranges including about 1 to 500 parts by mass, about 1 to 100 parts by mass, about 1 to 50 parts by mass, about 5 to 500 parts by mass, about 5 to 100 parts by mass, and about 5 to 50 parts by mass.

[0130] The method for forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin to form the surface coating layer 6 can be used. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0131] 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 at least one of the surface and interior 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, with a combination of two or more being preferable.

[0132] If a lubricant is present on the surface of the surface coating layer 6, there are no particular limitations on its amount, but for example, it may be about 3 mg / m². 2 Preferably about 4 mg / m² 2 Above, about 5mg / m 2 The above points are given. Furthermore, the amount of lubricant present on the surface of the surface coating layer 6 is, for example, about 15 mg / m². 2 Preferably about 14 mg / m² 2 Below, about 10mg / m 2 The following are examples. Furthermore, a preferred range for the amount of lubricant present on the surface of the surface coating layer 6 is 3 to 15 mg / m². 2 Degree, 3-14mg / m 2 Degree, 3-10mg / m 2 Degree, 4-15mg / m 2 Degree, 4-14mg / m 2 degree, 4-10mg / m 2 degree, 5-15mg / m 2 Degree, 5-14mg / m 2 degree, 5-10mg / m 2 The degree can be described as follows.

[0133] The lubricant present on the surface of the surface coating layer 6 may be a lubricant contained in the resin constituting the surface coating layer 6 that has seeped out, or a lubricant applied to the surface of the surface coating layer 6.

[0134] The surface coating layer 6 contains a coloring agent, which allows the exterior material for the energy storage device to be colored. 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.

[0135] The types of pigments are not particularly limited. 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.

[0136] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0137] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0138] The content of the coloring agent in the surface coating layer 6 is not particularly limited as long as the exterior material for the energy storage device is colored, and for example, it can be about 5 to 60% by mass, preferably about 10 to 40% by mass.

[0139] The thickness of the surface coating layer 6 is not particularly limited as long as it performs the above-mentioned functions as a surface coating layer 6, and for example, it can be about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0140] <Method for manufacturing exterior material for energy storage device> The method for manufacturing the exterior material for energy storage device is not particularly limited, as long as a laminate is obtained by laminating each layer of the exterior material for energy storage device of the present disclosure. At a minimum, a method is provided which involves laminating the base layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order.

[0141] An example of a method for manufacturing the exterior material for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated laminate A") is formed by sequentially laminating a base layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form the adhesive layer 2 is applied to the base layer 1 or, if necessary, a barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured.

[0142] Next, a heat-fusible resin layer 4 is laminated onto the barrier layer 3 of the 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 the laminate A by methods such as thermal lamination or extrusion lamination. Also, when an adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 and the heat-fusible resin layer 4 can be laminated by methods such as (1) extrusion lamination, (2) thermal lamination, (3) sandwich lamination, or (4) dry lamination. (1) An example of an extrusion lamination method is a method in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated by extrusion onto the barrier layer 3 of the laminate A (co-extrusion lamination method, tandem lamination method). Furthermore, (2) as a thermal lamination method, for example, a laminate is formed by separately laminating an adhesive layer 5 and a heat-fusible resin layer 4, and this is laminated onto the barrier layer 3 of the laminate A, or a laminate is formed by laminating an adhesive layer 5 on the barrier layer 3 of the laminate A, and this is laminated with the heat-fusible resin layer 4. Furthermore, (3) as a sandwich lamination method, for example, a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-fusible resin layer 4 that has been previously made into a sheet, thereby bonding the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5. Furthermore, (4) as a dry lamination method, for example, an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A and dried, or further laminated by baking, and a heat-fusible resin layer 4 that has been previously made into a sheet is laminated onto this adhesive layer 5.

[0143] When a surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the resin used to form the surface coating layer 6 to the surface of the base layer 1. The order of the steps of laminating the barrier layer 3 to the surface of the base layer 1 and laminating the surface coating layer 6 to the surface of the base layer 1 is not particularly limited. For example, the surface coating layer 6 may be formed on the surface of the base layer 1, and then the barrier layer 3 may be formed on the surface of the base layer 1 opposite to the surface coating layer 6.

[0144] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0145] In exterior materials for energy storage devices, the processability of each layer constituting the laminate may be improved by subjecting it to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as needed. For example, by applying corona treatment to the surface of the base layer 1 opposite to the barrier layer 3, the printability of ink on the surface of the base layer 1 can be improved.

[0146] <Applications of the Enclosure Material for Energy Storage Devices> The enclosure material for energy storage devices of this disclosure is used in packaging for sealing and housing energy storage device elements such as positive electrodes, negative electrodes, and electrolytes. That is, an energy storage device can be formed by housing an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in a packaging formed by the enclosure material for energy storage devices of this disclosure. In other words, an energy storage device can be formed by wrapping an energy storage device element with the enclosure material for energy storage devices of this disclosure.

[0147] Specifically, an energy storage device is provided by covering an energy storage device element, which comprises at least a positive electrode, a negative electrode, and an electrolyte, with the energy storage device exterior material of this disclosure, such that a flange portion (an area where heat-sealable resin layers come into contact) is formed around the periphery of the energy storage device element, with the metal terminals connected to the positive electrode and negative electrode respectively protruding outward, and then heat-sealing the heat-sealable resin layers of the flange portion to seal it. When housing the energy storage device element in a package formed from the energy storage device exterior material of this disclosure, the package is formed such that the heat-sealable resin portion of the energy storage device exterior material of this disclosure faces inward (the surface in contact with the energy storage device element). The packaging can be formed by overlapping the heat-sealable resin layers of two energy storage device casing materials facing each other and heat-sealing the periphery of the overlapped casing materials. Alternatively, as shown in the example in Figure 5, one energy storage device casing material can be folded and overlapped, and the periphery can be heat-sealed to form a packaging. When folding and overlapping, as shown in the example in Figure 5, the edges other than the folded edge can be heat-sealed to form a three-sided seal, or the edges can be folded to form a flange and then sealed on all four sides. Furthermore, if the innermost and outermost layers of the energy storage device casing material are heat-sealable resin layers, the packaging can be formed by heat-sealing the innermost heat-sealable resin layer and the outermost heat-sealable resin layer.

[0148] The energy storage device element may be sealed by a lid in addition to the energy storage device casing material. That is, the energy storage device casing material and the lid constitute an casing that seals the energy storage device element (an casing for the energy storage device). For example, the energy storage device element may be housed inside a cylindrical energy storage device casing material, and the opening may be closed with a lid. In another example, the energy storage device element, connected to a lid, may be housed inside a cylindrical energy storage device casing material that has an opening, and the opening may be closed with a lid. It is preferable that the lid and the energy storage device casing material are joined by any means. From the viewpoint of reducing dead space between the energy storage device element and the energy storage device casing material in order to improve the volumetric energy density of the energy storage device, it is preferable that the energy storage device casing material is wrapped around the energy storage device element and the lid.

[0149] The cover can be formed, for example, from a resin molded product, a metal molded product, an exterior material for an energy storage device, or a combination thereof. In this disclosure, when the cover is described as a resin molded product, the cover does not include embodiments in which the cover is composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the cover is a metal molded product, the metal terminals can be omitted as the cover also functions as a metal terminal. The cover may be composed of a resin material and a conductive material.

[0150] Furthermore, recesses for housing energy storage device elements may be formed in the exterior material for the energy storage device by deep drawing or stretch molding. As shown in the example in Figure 5, recesses may be provided in one exterior material for the energy storage device while not being provided in the other, or recesses may be provided in the other exterior material for the energy storage device as well.

[0151] The casing material for energy storage devices of this disclosure can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices of this disclosure can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The types of secondary batteries to which the casing material for energy storage devices of this disclosure can be applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, pseudo-solid-state batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, sodium-ion 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 of this disclosure.

[0152] 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.

[0153] <Manufacturing of exterior materials for energy storage devices> (Example 1) A stretched nylon (ONy) film (thickness 15 μm) was prepared as the base layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 80 μm)) was prepared as the barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil consisted of a treatment solution made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum foil using the roll coating method and then baking it to achieve the (dry mass) shown.

[0154] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0155] Next, maleic anhydride-modified homopolypropylene, which forms an adhesive layer (25 μm thick), and random polypropylene, which forms a heat-fusible resin layer (25 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. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in the order shown in Table 1.

[0156] (Example 2) An exterior material for an energy storage device was obtained in the same manner as in Example 1, except that a two-component curing urethane adhesive containing carbon black (CB) was used as the adhesive to form the adhesive layer (3 μm thick) that bonds the base material layer and the barrier layer. The laminate structure was as shown in Table 1, and the laminate consisted of a base material layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer laminated in this order.

[0157] (Example 3) Except for using a stretched nylon (ONy) film (25 μm thick) as the base layer, an exterior material for an energy storage device was obtained in the same manner as in Example 1, having the laminated structure shown in Table 1, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in this order.

[0158] (Example 4) Except for co-extruding maleic anhydride-modified homopolypropylene that forms an adhesive layer (35 μm thick) and random polypropylene that forms a heat-fusible resin layer (30 μm thick), an exterior material for an energy storage device was obtained in the same manner as in Example 1, having the laminated structure shown in Table 1, in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in this order.

[0159] (Example 5) An exterior material for an energy storage device was obtained in the same manner as in Example 1, consisting of a laminate in which a surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in the order shown in Table 1, except that after laminating an adhesive layer / heat-fusible resin layer on a barrier layer, a two-component curing urethane adhesive (silica content 45% by mass), which contains silica as an inorganic additive, was applied to the surface of the base layer to form a surface coating layer (thickness 3 μm).

[0160] (Example 6) An exterior material for an energy storage device was obtained in the same manner as in Example 5, except that a two-component curing urethane adhesive containing carbon black (CB) was used as the adhesive to form the adhesive layer (3 μm thick) that bonds the base layer and the barrier layer. The laminate structure was as shown in Table 1, and the laminate consisted of a surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer, laminated in this order.

[0161] (Example 7) Except for using a stretched nylon (ONy) film (25 μm thick) as the base layer, the same procedure as in Example 5 was followed to obtain an exterior material for an energy storage device, which consisted of a laminate having the laminated structure shown in Table 1, in which a surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order.

[0162] (Example 8) Except for co-extruding maleic anhydride-modified homopolypropylene that forms an adhesive layer (35 μm thick) and random polypropylene that forms a heat-fusible resin layer (30 μm thick), an exterior material for an energy storage device was obtained in the same manner as in Example 5, with the adhesive layer / heat-fusible resin layer laminated on top of the barrier layer, having the laminated structure shown in Table 1, in which a surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in this order.

[0163] (Example 9) As a base layer, a laminate was prepared in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 12 μm) and an oriented nylon (ONy) film (thickness 25 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 80 μm)) was prepared as a barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil consisted of a treatment solution made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum foil using the roll coating method and then baking it to achieve the (dry mass) shown.

[0164] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0165] Next, maleic anhydride-modified homopolypropylene, which forms an adhesive layer (30 μm thick), and random polypropylene, which forms a heat-fusible resin layer (30 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. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in the order shown in Table 1.

[0166] (Comparative Example 1) As a base layer, a laminate was prepared in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 12 μm) and an oriented nylon (ONy) film (thickness 15 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared as a barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil was performed using 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 carried out by applying the coating to both sides of the aluminum foil using the roll coating method and then baking it to achieve the (dry mass) shown.

[0167] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0168] Next, maleic anhydride-modified homopolypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 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. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in the order shown in Table 1.

[0169] (Comparative Example 2) Except for using a stretched nylon (ONy) film (thickness 25 μm) as the base layer and using aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) as the barrier layer, the same procedure as in Comparative Example 1 was used to obtain an exterior material for an energy storage device, which has the laminated structure shown in Table 1, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in this order.

[0170] (Comparative Example 3) A stretched nylon (ONy) film (thickness 25 μm) was prepared as the base layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared as the barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil consisted of a treatment solution made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum foil using the roll coating method and then baking it to achieve the (dry mass) shown.

[0171] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0172] Next, maleic anhydride-modified homopolypropylene, which forms an adhesive layer (22.5 μm thick), and random polypropylene, which forms a heat-fusible resin layer (22.5 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. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate with the laminate configuration shown in Table 1, in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in this order.

[0173] (Comparative Example 4) Except that an adhesive layer / heat-fusible resin layer was laminated on top of a barrier layer, and then a two-component curing urethane adhesive (silica content 45% by mass), which contains silica as an inorganic additive, was applied to the surface of the base layer to form a surface coating layer (thickness 3 μm), an exterior material for an energy storage device was obtained in the same manner as in Comparative Example 3, having the laminated structure shown in Table 1, in which a surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order.

[0174] (Comparative Example 5) As a base layer, a laminate was prepared in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 25 μm) and an oriented nylon (ONy) film (thickness 25 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 80 μm)) was prepared as a barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil consisted of a treatment solution made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum foil using the roll coating method and then baking it to achieve the (dry mass) shown.

[0175] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0176] Next, maleic anhydride-modified homopolypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 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. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in the order shown in Table 1.

[0177] <Measurement of Thermal Conductivity> For each exterior material for energy storage devices obtained in the examples and comparative examples, the thermal conductivity was measured using a thermal conductivity measuring device (TCM-1001 model manufactured by Resca) in accordance with the provisions of JIS H7903:2008 "Test Method for Thermal Conductivity of Porous Metals," under the conditions of a sample size TD20 mm × MD20 mm and a measurement temperature of 25°C. The results are shown in Table 1.

[0178] <Evaluation of Adhesion Suppression of the Outer Surface to Metal Heat Seal Bars> For each exterior material for energy storage devices (TD 60 mm, MD 120 mm) obtained in the examples and comparative examples, the adhesion suppression of the outer surface (the surface of the surface coating layer if one is present, or the surface of the base material layer if one is not present) to a metal seal bar heated to a high temperature was evaluated under the following conditions. The results are shown in Table 1. A copper foil (tough pitch copper C1100 TD60mm, MD60mm, thickness 100μm) was laminated to the outside of the exterior material for the energy storage device, with the MD direction of the copper foil aligned with the MD direction of the exterior material and the TD direction of the copper foil aligned with the TD direction of the energy storage device, and the MD edge of the copper foil aligned with the MD edge of the exterior material. The copper foil was heat-sealed to the surface of the base layer side of the exterior material for the energy storage device at a position 15 mm from the edge in the MD direction using a metal heat-sealing bar (width 7 mm) at a temperature of 195°C, a sealing time of 3 seconds, and a surface pressure of 1.5 MPa, in the TD direction. After 10 seconds, the exterior material for the energy storage device was peeled off by hand, using the unheat-sealed area as a starting point. Based on the resistance during peeling, the adhesion suppression of the outer surface of the exterior material for the energy storage device to the metal heat-sealing bar was evaluated according to the following evaluation criteria.

[0179] (Evaluation Criteria) A: No resistance is felt when peeling the outer material for the energy storage device from the copper foil, and it peels off easily from the copper foil. B: Resistance is felt when peeling the outer material for the energy storage device from the copper foil, but it peels off easily from the copper foil. C: There is a lot of resistance when peeling.

[0180]

[0181] In the representation of the laminate structure in Table 1, ONy represents stretched nylon film, PET represents polyethylene terephthalate film, DL represents an adhesive layer formed by dry lamination using a two-component curing urethane adhesive, DL-CB represents an adhesive layer formed by dry lamination using a two-component curing urethane adhesive containing carbon black, ALM represents aluminum alloy foil, PPa represents a maleic anhydride-modified polypropylene layer, PP represents a random polypropylene layer, and SC represents a surface coating layer. The numbers in parentheses indicate thickness (μm), and / indicates the boundary between layers.

[0182] The exterior material for energy storage devices of Examples 1-9 is composed of a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in that order, wherein the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the thickness of the laminate is 100%) is 38% or more. The exterior material for energy storage devices of Examples 1-9 is found to have high thermal conductivity and excellent heat dissipation.

[0183] Furthermore, the exterior material for energy storage devices in Examples 5-8 includes a surface coating layer containing silica, an inorganic additive. In addition, the exterior material for energy storage devices in Example 9 includes a polyethylene terephthalate film, which has superior heat resistance to the stretched nylon film, as a base layer on the outside of the stretched nylon film. As a result, adhesion of the outer surface to the metal heat seal bar is suitably suppressed in the exterior materials for energy storage devices in Examples 5-9.

[0184] As described above, this disclosure provides inventions in the following embodiments. Item 1. An exterior material for an energy storage device, comprising a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in that order from the outside, wherein the barrier layer includes an aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the thickness of the laminate is 100%) is 38% or more. Item 2. The exterior material for an energy storage device according to Item 1, wherein the ratio of the total thickness of each layer inside the aluminum alloy foil to the thickness of the aluminum alloy foil (when the thickness of the aluminum alloy foil is 100%) is 99% or less. Item 3. The exterior material for an energy storage device according to Item 1 or 2, wherein the ratio of the total thickness of each layer outside the aluminum alloy foil to the thickness of the aluminum alloy foil (when the thickness of the aluminum alloy foil is 100%) is 69% or less. Item 4. The exterior material for an energy storage device according to any one of Items 1 to 3, wherein the thickness of the aluminum alloy foil is 105 μm or less. Item 5. An exterior material for an energy storage device according to any one of items 1 to 4, wherein the total thickness of each layer inside the aluminum alloy foil is 45 μm or more and 70 μm or less. Item 6. An exterior material for an energy storage device according to any one of items 1 to 5, further comprising an adhesive layer between the base material layer and the barrier layer, wherein the adhesive layer contains a coloring agent. Item 7. An exterior material for an energy storage device according to any one of items 1 to 6, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer, wherein the thickness of the adhesive layer is 20 μm or more and 40 μm or less, and the thickness of the heat-fusible resin layer is 20 μm or more and 40 μm or less. Item 8. An exterior material for an energy storage device according to any one of items 1 to 7, further comprising a surface coating layer on the side of the base material layer opposite to the barrier layer side. Item 9. An exterior material for an energy storage device according to any one of items 1 to 8, wherein the thermal conductivity of the laminate is 0.24 W / (m·K) or more. Item 10. An exterior material for an energy storage device according to any one of claims 1 to 9, wherein the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate is 38% or more and 75% or less.Item 11. A method for manufacturing an exterior material for an energy storage device, comprising the step of obtaining a laminate in which a base layer, a barrier layer, and a heat-fusible resin layer are laminated in that order from the outside, wherein the barrier layer includes an aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the thickness of the laminate is 100%) is 38% or more. Item 12. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an energy storage device described in any one of Items 1 to 10.

[0185] 1. Base layer 2. Adhesive layer 3. Barrier layer 4. Heat-fusible resin layer 5. Adhesive layer 6. Surface coating layer 10. Exterior material for energy storage devices

Claims

1. An exterior material for an energy storage device, comprising a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in that order from the outside, wherein the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the total thickness of the laminate is 100%) is 38% or more.

2. The exterior material for an energy storage device according to claim 1, wherein the ratio of the total thickness of each layer inside the aluminum alloy foil to the thickness of the aluminum alloy foil (when the thickness of the aluminum alloy foil is set to 100%) is 99% or less.

3. The exterior material for an energy storage device according to claim 1 or 2, wherein the ratio of the total thickness of each layer outside the aluminum alloy foil to the thickness of the aluminum alloy foil being 100% is 69% or less.

4. The exterior material for an energy storage device according to claim 1 or 2, wherein the thickness of the aluminum alloy foil is 105 μm or less.

5. The exterior material for an energy storage device according to claim 1 or 2, wherein the total thickness of each layer inside the aluminum alloy foil is 45 μm or more and 70 μm or less.

6. The exterior material for an energy storage device according to claim 1 or 2, further comprising an adhesive layer between the base material layer and the barrier layer, wherein the adhesive layer contains a coloring agent.

7. The exterior material for an energy storage device according to claim 1 or 2, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer, wherein the thickness of the adhesive layer is 20 μm or more and 40 μm or less, and the thickness of the heat-fusible resin layer is 20 μm or more and 40 μm or less.

8. The exterior material for an energy storage device according to claim 1 or 2, further comprising a surface coating layer on the side of the base material layer opposite to the barrier layer side.

9. The exterior material for an energy storage device according to claim 1 or 2, wherein the thermal conductivity of the laminate is 0.24 W / (m·K) or more.

10. The exterior material for an energy storage device according to claim 1 or 2, wherein the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate is 38% or more and 75% or less.

11. A method for manufacturing an exterior material for an energy storage device, comprising at least the step of obtaining a laminate in which a base layer, a barrier layer, and a heat-fusible resin layer are laminated in that order from the outside, wherein the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 75 μm or more, and the ratio of the thickness of the aluminum alloy foil to the thickness of the laminate (when the thickness of the laminate is 100%) is 38% or more.

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 the outer material for energy storage devices described in claim 1 or 2.

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