External packaging material for power storage device, manufacturing method for said material, and power storage device

Abstract

An external packaging material for a power storage device, the external packaging material being constituted by a laminate provided with at least a barrier layer and a heat-fusible resin layer in this order from the outside, wherein, in the laminate, when tensile strengths (N / 15 mm) in four directions are measured by the method below, the value of the ratio of the sum of the tensile strengths (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or greater, and the moisture content of the laminate when the laminate has been stored for three days in an environment having a temperature of 65°C and a relative humidity of 90% is 3500 ppm or less. (Measurement of tensile strength) Four types of measurement samples of the laminate are prepared, each having a length of 100 mm in the MD direction, the TD direction, a 45° direction between MD and TD, and a -45° direction between MD and TD, and each having a width, that is orthogonal to the length direction, of 15 mm. Each of the measurement samples is subjected to a tensile test, and is measured for tensile strength at a displacement of 3.3% in the length direction under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and an inter-chuck distance of 30 mm.

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 energy storage 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] For example, exterior materials used in power storage devices such as in-vehicle, ESS, and mobile applications generally tend to require high rigidity. Specifically, exterior materials for power storage devices (exterior materials for batteries) used in lithium-ion batteries are required to be thin and have high formability from the viewpoint of increasing the capacity of batteries. When the rigidity of the exterior material is high, a property that pinholes, cracks and the like are less likely to occur in the barrier layer during forming is exhibited. That is, in order to impart high formability to the exterior material for a power storage device, it is effective to increase the thickness of the barrier layer or the base material layer to enhance the rigidity of the exterior material, so as to suppress the formation of pinholes, cracks and the like in the barrier layer accompanying forming. However, when the thickness of the base material layer or the barrier layer is increased, the total thickness of the exterior material increases, and as a result, the volume of the entire power storage device tends to increase.

[0008] Further, as described above, in the exterior material for a power storage device constituted by a film-shaped laminate, a power storage device in which a power storage device element is housed inside the exterior material for a power storage device can be obtained by thermally fusing the heat-fusible resin layer. Air bubbles may be generated in the heat-sealed portion formed by thermally fusing the heat-fusible resin layer of the exterior material for a power storage device, which may deteriorate the appearance of the exterior material for a power storage device.

[0009] Under such circumstances, the main object is to provide an exterior material for a power storage device that has high rigidity and a good appearance of the heat-sealed portion. The present disclosure also aims to provide a power storage device using the exterior material for a power storage device, and a method for producing the exterior material for a power storage device.

[0010] The inventors of the present disclosure conducted intensive studies to solve the above problems. As a result, in an exterior material for a power storage device constituted by a laminate including at least a barrier layer and a heat-fusible resin layer in this order from the outside, by setting the ratio of the tensile strength to the thickness of the laminate constituting the exterior material for a power storage device to a predetermined value or more, and setting the moisture content contained in the laminate in a high-temperature and high-humidity environment to a predetermined value or less, the inventors found that the exterior material for a power storage device has high rigidity and a good appearance of the heat-sealed portion.

[0011] The present disclosure has been completed through further studies based on these findings. Specifically, the present disclosure provides the inventions according to the following aspects.

[0012] An exterior material for power storage devices, which is constituted of a laminate including at least a barrier layer and a heat-fusible resin layer in this order from the outside, wherein when the tensile strength (N / 15 mm) in four directions of the laminate is measured by the following method, the ratio of the sum of the tensile strength (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or more, and the moisture content of the laminate when the laminate is stored for 3 days in an environment at a temperature of 65°C and a relative humidity of 90% is 3500 ppm or less. (Measurement of Tensile Strength) For the laminate, four types of measurement samples each having a length of 100 mm in the MD direction, the TD direction, the 45° direction between MD and TD, and the -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction, are prepared. A tensile test is performed on the measurement samples, and the tensile strength at a displacement of 3.3% in the length direction is measured under the measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck-to-chuck distance of 30 mm.

[0013] According to the present disclosure, it is possible to provide an exterior material for power storage devices that has high rigidity and provides a good appearance of the heat-sealed portion. Further, according to the present disclosure, it is possible to provide a method for producing the exterior material for power storage devices, and a power storage device using the exterior material for power storage devices.

[0014] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for power storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for power storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for power storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for power storage devices of the present disclosure. This is a schematic diagram for explaining a method of housing a power storage device element in a package formed by the exterior material for power storage devices of the present disclosure. This is a diagram for explaining the MD direction, TD direction, 45° direction, and -45° direction of the exterior material for power storage devices. This is a schematic diagram for explaining the cut-out position of the measurement sample.

[0015] The exterior material for energy storage devices of this disclosure is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-fusible resin layer in that order. The laminate constituting the exterior material for energy storage devices of this disclosure has a ratio of 1.98 or more to the sum of the tensile strengths (N / 15 mm) in four directions to the thickness (μm) of the laminate when the tensile strength (N / 15 mm) in four directions is measured by the following method, and the moisture content of the laminate when stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. (Measurement of tensile strength) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction (0° direction), TD direction (90° direction), 45° direction between MD and TD, and -45° direction between MD and TD (also the 135° direction), and a width of 15 mm perpendicular to the length direction. Tensile tests were performed on the aforementioned sample, and the tensile strength at a longitudinal displacement of 3.3% was measured under the following conditions: 25°C environment, tensile speed of 50 mm / min, and chuck distance of 30 mm.

[0016] The exterior material for energy storage devices of this disclosure, possessing these features, is highly rigid and has a good appearance at the heat-sealed joints.

[0017] 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.

[0018] 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. Specifically, linear lines called rolling marks are formed on the surface of the metal foil, such as aluminum alloy foil, in the rolling direction (RD) of the metal foil contained in the barrier layer 3. 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 the laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and determining the rolling direction (RD) of the metal foil. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined. Similarly, since the MD of the heat-fusible resin layer and the RD of the metal foil coincide, the MD of the heat-fusible resin layer can be determined by observing the surface of the metal foil in the laminate and identifying the rolling direction (RD) of the metal foil. Furthermore, since the TD of the heat-fusible resin layer is perpendicular to the MD of the heat-fusible resin layer, the TD of the heat-fusible resin layer can also be determined.

[0019] If the MD of the casing material for energy storage devices cannot be identified by the rolling marks of the aluminum alloy foil, it can be identified by the following method. One method for confirming the MD of the casing material for energy storage devices is to observe the cross-section of the heat-fusible resin layer of the casing material of the energy storage device with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing each of the cross-sections in the longitudinal direction of the heat-fusible resin layer and the direction perpendicular to the longitudinal cross-section (a total of 10 cross-sections) 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).

[0020] [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 barrier layer 3 and a heat-fusible resin layer 4 in that order, as shown in Figure 1. In the exterior material 10 for energy storage devices, the barrier layer 3 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, the heat-fusible resin layer 4 is on the inside of the barrier layer 3, with the barrier layer 3 as the reference.

[0021] The exterior material 10 for the energy storage device may, for example, have a base layer 1 on the side of the barrier layer 3 opposite to the heat-fusible resin layer 4 (outside), as needed, as shown in Figures 1 to 4. The exterior material 10 for the energy storage device may also have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as needed, for purposes such as improving the adhesion between these layers, as shown in Figures 2 to 4. Furthermore, as shown in Figures 3 and 4, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4, as needed, for purposes such as improving the adhesion between these layers. Additionally, 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 to the heat-fusible resin layer 4), as needed.

[0022] 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 182 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 35 μm or more, about 45 μm or more, about 60 μm or more, about 148 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, the preferred range for the laminate constituting the exterior material 10 for the energy storage device is, for example, approximately 35 to 300 μm, approximately 35 to 250 μm, approximately 35 to 210 μm, approximately 35 to 190 μm, approximately 35 to 182 μm, approximately 35 to 180 μm, approximately 35 to 155 μm, approximately 35 to 120 μm, approximately 45 to 300 μm, approximately 45 to 250 μm, approximately 45 to 210 μm, approximately 45 to 190 μm, approximately 45 to 182 μm, approximately 45 to 180 μm, approximately 45 to 155 μm, approximately 45 to 120 μm, approximately 60 to 300 μm, approximately 60 to 250 μm, approximately 60 to 210 μm, approximately 60 to 190 μm, approximately 60 to 182 μm, approximately 60 to 180 μm, and 60 Examples of suitable thicknesses include approximately ~155 μm, 60~120 μm, 148~300 μm, 148~250 μm, 148~210 μm, 148~190 μm, 148~182 μm, 148~180 μm, 155~300 μm, 155~250 μm, 155~210 μm, 155~190 μm, 155~182 μm, 155~180 μm, 190~300 μm, 190~250 μm, and 190~210 μm. In particular, when making lightweight thin films for energy storage devices, approximately 60~155 μm is preferred, and when improving moldability, approximately 148~182 μm and approximately 155~190 μm are preferred.

[0023] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the optional base layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, heat-fusible resin layer 4, and optional surface coating layer 6 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.

[0024] The laminate constituting the exterior material for the energy storage device of this disclosure has a ratio of 1.98 or more to the sum of the tensile strengths (N / 15 mm) in four directions to the thickness (μm) of the laminate, when the tensile strengths (N / 15 mm) in four directions are measured by the following method. From the viewpoint of more favorably exhibiting the effects of the present invention, the value of the ratio is preferably 2.10 or more, more preferably 2.20 or more, even more preferably 2.30 or more, and also preferably 3.00 or less, more preferably 2.80 or less, even more preferably 2.60 or less. Preferred ranges include 1.98 to 3.00, 1.98 to 2.80, 1.98 to 2.60, 2.10 to 3.00, 2.10 to 2.80, 2.10 to 2.60, 2.20 to 3.00, 2.20 to 2.80, 2.20 to 2.60, 2.30 to 3.00, 2.30 to 2.80, and 2.30 to 2.60. The tensile strength in these four directions is adjusted, for example, by the material, thickness, combination, etc., of each layer constituting the laminate.

[0025] (Measurement of tensile strength in four directions) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction. Tensile tests are performed on the measurement samples, and the tensile strength at a displacement of 3.3% in the length direction is measured under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm.

[0026] More specifically, the exterior materials for energy storage devices are measured using a tensile testing machine in accordance with the provisions of JIS K7127:1999. The tensile test is performed under the following conditions: a 25°C environment, a tensile speed of 50 mm / min, and an initial distance of 30 mm between the chucks. In the tensile test described in this disclosure, the initial distance between the chucks is 30 mm, and this initial distance between the chucks is defined as the distance between the gauge marks. The exterior materials for energy storage devices are prepared as four types of measurement samples, each with a length of 100 mm in the MD direction (0° direction), TD direction (90° direction), the 45° direction between MD and TD, and the -45° direction between MD and TD (which is also the 135° direction), and a width of 15 mm perpendicular to these length directions. Refer to Figure 6 for the MD direction, TD direction, the 45° direction between MD and TD, and the -45° direction between MD and TD of the exterior materials for energy storage devices. Specifically, of the four types of measurement samples, sample 1 is a measurement sample with a length of 100 mm in the MD direction and a width of 15 mm in the TD direction (for MD direction measurement). Sample 2 is a measurement sample with a length of 100 mm in the TD direction and a width of 15 mm in the MD direction (for TD direction measurement). As shown in Figure 6, the MD direction is defined as 0°, and the direction perpendicular to the MD direction is defined as the TD direction. Furthermore, sample 3 is a measurement sample with a length of 100 mm in the direction 45° clockwise from the MD direction (0°), and a width of 15 mm perpendicular to that length direction (for 45° direction measurement). Sample 4 is a measurement sample with a length of 100 mm in the direction 45° counterclockwise from the MD direction (0°), and a width of 15 mm perpendicular to that length direction (for -45° direction measurement). Here, as shown in Figure 7, each sample is cut from the exterior material for the energy storage device to a size of 100 mm in length and 15 mm in width after the exterior material for the energy storage device has been manufactured. At that time, each sample is cut from a range of 300 mm in the TD direction. Next, each of the measurement samples 1 to 4 is subjected to a tensile test in the longitudinal direction of the measurement sample under the measurement conditions described above, and the tensile strength at a displacement of 3.3% is measured, and the sum of the tensile strengths in the four directions is calculated. Furthermore, the value obtained by dividing the sum of the tensile strengths in the four directions by the thickness of the laminate is taken as the ratio of the sum of the strengths in the four directions to the thickness of the laminate.

[0027] The laminate constituting the exterior material for the energy storage device of this disclosure has a moisture content of 3,500 ppm or less when stored for 3 days in an environment of 65°C and 90% relative humidity. From the viewpoint of more favorably exhibiting the effects of the invention of this disclosure, the moisture content is 3,400 ppm or less, more preferably about 3,300 ppm or less, and even more preferably about 3,200 ppm or less, and the lower limit of the moisture content can be, for example, about 200 ppm or more, about 300 ppm or more, etc. A preferred range for the moisture content can be, for example, 200 to 3,500 ppm, 200 to 3,400 ppm, 200 to 3,300 ppm, 200 to 3,200 ppm, 300 to 3,500 ppm, 300 to 3,400 ppm, 300 to 3,300 ppm, and 300 to 3,200 ppm. The moisture content is adjusted, for example, by the thickness of the highly absorbent polyamide film contained in the laminate. The method for measuring the moisture content is as follows.

[0028] <Moisture Content> The moisture content of a laminate constituting the exterior material for energy storage devices will be measured after being stored for three days in an environment of 65°C and 90% relative humidity using the following procedure. To exclude the effect of water ingress from the edges, a 300 mm x 300 mm sample will be stored for 24 hours in an environment of 25°C, 1% relative humidity or less, and a dew point of -20°C or less, and then stored for 72 hours in an environment of 65°C and 90% relative humidity. A 100 mm x 100 mm sample will be cut from the center and used. Moisture content will be measured using a Karl Fischer moisture meter and vaporizer placed in an environment of 25°C, 1% relative humidity or less, and a dew point of -20°C or less, by the moisture vaporization-coulometric titration method. To minimize the influence of the measurement environment, the sample will be placed in a vial that can be sealed off from the outside air and brought into the measurement environment, and placed in the measuring device within 30 minutes after being removed from the vial. The measurement conditions are as follows. Measured component: water, titration cell type: two-component cell, detection electrode type: bipolar platinum electrode, diaphragm material: ceramic, endpoint detection method: AC polarization method using bipolar platinum detection electrode, endpoint determination method: drift stability determination, heating temperature: 180°C, cell purge time: 120 seconds, back purge time: 180 seconds, stability determination value: 0.1 μg / min, endpoint potential: 200 mV. The measurement results are calculated as the ratio of water weight to sample weight (unit: ppm), and the average of three measurements is recorded, rounded to the nearest tenth. Commercially available anode and cathode solutions are used as titration reagents: for example, ChemAqua Anode Solution AGE and ChemAqua Cathode Solution CGE.

[0029] [Each layer forming the exterior material for the energy storage device] [Base layer 1] In this disclosure, the base layer 1 is a layer provided as needed for purposes such as enabling the exterior material for the energy storage device to function as a base material. The base layer 1 is located on the outer layer side of the exterior material for the energy storage device.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0035] 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 mixtures of two or more types.

[0036] 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.

[0037] From the viewpoint of suitably exhibiting the effects of the present invention, it is preferable that the base layer 1 in the exterior material for energy storage devices of the present disclosure includes a polyamide film, and that the thickness of the polyamide film is 20 μm or less. Regarding the lower limit of the thickness of the polyamide film, from the viewpoint of improving the moldability of the exterior material for energy storage devices, for example, 10 μm or more is recommended.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 singly or in combination of two or more types, and it is preferable to use two or more types in combination.

[0044] When the lubricant is present on the surface of the base material layer 1, the amount thereof is not particularly limited, and 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. Examples of the amount of the lubricant present on the surface of the base material layer 1 include about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Preferable ranges of the amount of the lubricant present on the surface of the base material layer 1 include about 3 to 15 mg / m 2 , about 3 to 14 mg / m 2 , about 3 to 10 mg / m 2 , about 4 to 15 mg / m 2 , about 4 to 14 mg / m 2 , about 4 to 10 mg / m 2 , about 5 to 15 mg / m 2 , about 5 to 14 mg / m 2 , about 5 to 10 mg / m 2 .

[0045] The lubricant present on the surface of the base material layer 1 may be a lubricant exuded from the resin constituting the base material layer 1, or may be a lubricant applied to the surface of the base material layer 1.

[0046] 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.

[0047] 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. In addition, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] [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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] [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.

[0063] 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.

[0064] Specific examples of colorants included in the colored layer are the same as those exemplified in the section for [Adhesive Layer 2].

[0065] [Barrier layer 3] In the exterior material for energy storage devices, the barrier layer 3 is a layer that at least prevents moisture from entering.

[0066] Examples of barrier layer 3 include metal foil, vapor-deposited film, and resin layer with barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as barrier layer 3. Multiple layers of barrier layer 3 may be provided. It is preferable that barrier layer 3 includes a layer made of a metal material. Specific examples of metal materials constituting barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0067] In barrier layer 3, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. 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.

[0068] 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.

[0069] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0070] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0071] In the case of metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer that prevents moisture from penetrating, and can be, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Alternatively, the thickness of the barrier layer 3 is preferably about 10 μm or more, even more preferably about 20 μm or more, more preferably about 25 μm or more, and even more preferably about 30 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 3 include approximately 10-85 μm, 10-60 μm, 10-50 μm, 10-40 μm, 10-35 μm, 20-85 μm, 20-60 μm, 20-50 μm, 20-40 μm, 20-35 μm, 25-85 μm, 25-60 μm, 25-50 μm, 25-40 μm, 25-35 μm, 30-85 μm, 30-60 μm, 30-50 μm, 30-40 μm, and 30-35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above ranges are particularly preferred. Furthermore, from the viewpoint of providing high moldability and high rigidity to the exterior material 10 for the energy storage device, the thickness of the barrier layer 3 is preferably about 30 μm or more, preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, even more preferably about 70 μm or less, even more preferably about 60 μm or less, and a preferred range is about 30 to 200 μm and about 30 to 85 μm. The particle sizes are approximately 30-75 μm, 30-70 μm, 30-60 μm, 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 35-60 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 45-60 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 50-60 μm, 55-200 μm, 55-85 μm, 55-75 μm, 55-70 μm, and 55-60 μm.The high formability of the exterior material 10 for the energy storage device facilitates deep drawing, which can contribute to increasing the capacity of the energy storage device. Furthermore, while increasing the capacity of the energy storage device increases its weight, the increased rigidity of the exterior material 10 for the energy storage device contributes to the high sealing performance of the energy storage device. In particular, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred thickness ranges for the stainless steel foil include approximately 10-60 μm, 10-50 μm, 10-40 μm, 10-30 μm, 10-25 μm, 15-60 μm, 15-50 μm, 15-40 μm, 15-30 μm, and 15-25 μm.

[0072] In the exterior material for energy storage devices of this disclosure, the barrier layer 3 more preferably includes a predetermined aluminum alloy foil.

[0073] Specifically, the composition of the specified aluminum alloy foil is 1.20% by mass or more and 1.80% by mass or less of Fe, 0.150% by mass or less of Si, 0.0010% by mass or more and 0.0100% by mass or less of Mg, with the remainder being Al and unavoidable impurities. Furthermore, the physical properties of the aluminum alloy foil are such that the total elongation at fracture in three directions of 0°, 45°, and 90° with respect to the rolling direction is 20.0% or more in all cases, the local elongation in all three directions is 3.0% or more in all cases, the work hardening index n value in all three directions is 0.23 or less in all cases, the Cu orientation density obtained by X-ray diffraction is 50 or more, and when a boundary where the crystal orientation difference between adjacent crystals is 2° or more is defined as a grain boundary, and the region enclosed by the grain boundary is defined as a crystal grain, the average crystal grain size of the crystal grain is 6.00 μm or less, and the value obtained by dividing the maximum crystal grain size of the crystal grain by the average crystal grain size is 2.80 or less. The exterior material for energy storage devices of this disclosure can exhibit the effects of the present invention while also exhibiting excellent moldability by using such a predetermined aluminum alloy foil in the barrier layer 3. The composition and physical properties of the aluminum alloy foil preferably included in the barrier layer 3 will be described in detail below.

[0074] (Composition of aluminum alloy foil) ・Fe: 1.20% by mass or more and 1.80% by mass or less Fe crystallizes on the aluminum substrate as Al-Fe intermetallic compounds during casting. These crystals have different deformability from the aluminum substrate during the rolling process, thus inhibiting the deformation of the aluminum substrate and having the effect of fragmenting and refining the crystal grains. However, if the Fe content is too low, the distribution density of the intermetallic compounds will be low, resulting in a low effect of fine fragmentation and an uneven final crystal grain size distribution. On the other hand, if the Fe content is too high, the size of the Al-Fe intermetallic compounds generated during casting will be very large, reducing the ductility and rollability of the aluminum alloy foil. For this reason, the lower limit of the Fe content is set at 1.20% by mass and the upper limit at 1.80% by mass. For similar reasons, it is more desirable to set the lower limit at 1.30% by mass and the upper limit at 1.70% by mass. Preferred ranges for the Fe content of the aluminum alloy foil include 1.20 to 1.80 mass%, 1.20 to 1.70 mass%, 1.30 to 1.80 mass%, and 1.30 to 1.70 mass%.

[0075] • Si: 0.150 mass% or less. Si crystallizes into coarse intermetallic compounds during casting. To prevent the formation of coarse intermetallic compounds, it is desirable to suppress its content. If the Si content is too high, it may lead to coarser intermetallic compound size and a decrease in density, which may reduce rollability and elongation properties. For this reason, it is desirable to set the upper limit of the Si content to 0.150 mass%. More preferably, the upper limit should be 0.100 mass%. Examples of lower limits include 0.020 mass% and 0.030 mass%. Preferred ranges for the Si content of aluminum alloy foil include 0.020 to 0.150 mass%, 0.020 to 0.100 mass%, 0.030 to 0.150 mass%, and 0.030 to 0.100 mass%.

[0076] ・Mg: 0.0010% by mass or more and 0.0100% by mass or less. If the Mg content is too high, there is a concern that the rollability and elongation properties will decrease. For this reason, it is desirable to set the lower limit of the Mg content to 0.0010% by mass and the upper limit to 0.0100% by mass. More preferably, the lower limit should be 0.0030% by mass and the upper limit to 0.0080% by mass. Preferred ranges for the Mg content of aluminum alloy foil include 0.0010 to 0.0100% by mass, 0.0010 to 0.0080% by mass, 0.0030 to 0.0080% by mass.

[0077] The remainder of the components constituting the aluminum alloy foil consists of Al (aluminum) and unavoidable impurities. These unavoidable impurities are elements that are inevitably mixed in during the manufacturing of the aluminum alloy foil. These unavoidable impurities may be present in a range that does not affect the properties of the aluminum alloy foil of the present invention. Examples of these unavoidable impurities include elements such as chromium (Cr), zinc (Zn), titanium (Ti), vanadium (V), gallium (Ga), nickel (Ni), boron (B), and zirconium (Zr), and one or more of these may be present in amounts of 500 ppm by mass or less. Preferably, the unavoidable impurities among the components constituting the aluminum alloy foil are 0.05% by mass or less individually and 0.15% by mass or less in total.

[0078] (Physical properties of aluminum alloy foil) - The total elongation at break in the 0°, 45°, and 90° directions relative to the rolling direction is 20.0% or more in all directions, and the local elongation in all three directions is 3.0% or more in all directions. In the molding process of exterior materials for energy storage devices, deformation in multiple directions is applied, not just stretching in one direction, but by satisfying the above elongation characteristics, excellent elongation characteristics in all directions can be expected. Furthermore, even when impact is applied, not only high strength but also deformability makes it difficult to break and excellent impact resistance can be expected. For this reason, it is preferable that the total elongation at break in the 0°, 45°, and 90° directions is 20.0% or more in all directions, and that the local elongation in all three directions is 3.0% or more in all directions. Note that "local elongation" is the value obtained by subtracting the total elongation at maximum test force from the total elongation at break.

[0079] From the viewpoint of more favorably exhibiting the effects of the present invention, the total elongation at fracture in the three directions is preferably 23.0% or more, more preferably 25.0% or more, and also preferably 43.0% or less, more preferably 40.0% or less. Preferred ranges include 20.0-43.0%, 20.0-40%, 23.0-43.0%, 23.0-40%, 25.0-43.0%, and 25.0-40%.

[0080] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the local elongation in the three directions is preferably 3.5% or more, more preferably 4.0% or more, and also preferably 20.0% or less, more preferably 16.0% or less. Preferred ranges include 3.0 to 20.0%, 3.0 to 16.0%, 3.5 to 20.0%, 3.5 to 16.0%, 4.0 to 20.0%, and 4.0 to 16.0%.

[0081] (Measurement of elongation in the 0° direction, 45° direction, and 90° direction) For elongation in the 0° direction, 45° direction, and 90° direction (total elongation at fracture), the test specimens shall be as specified in JIS Z 2241:2022 No. 5, taken from 0°, 45°, and 90° directions relative to the rolling direction. Using the aforementioned test specimens, a tensile testing machine shall be used, and measurements shall be taken under the condition of a tensile speed of 5 mm / min. To calculate the elongation rate, two lines shall be marked at 50 mm intervals (gauge length) in the longitudinal center of the test specimen before the test, and the distance between the marks (l) shall be measured by abutting the fracture surfaces after the test. The elongation amount (mm) shall be divided by the gauge length (l0: 50 mm) and calculated using the following formula: ((l - l0) / l0) × 100

[0082] - Work hardening index n-values ​​in the 0°, 45°, and 90° directions relative to the rolling direction: 0.23 or less. When metal is formed, a phenomenon called work hardening occurs as it deforms. The work hardening index n-value is used as an indicator of the degree of this work hardening and is defined in the range of 0 to 1. If the work hardening index n-value is large, the degree of work hardening during deformation is large, making the packaging material brittle and making it impossible to obtain sufficient forming height or form complex shapes. Therefore, it is desirable that the work hardening index n-values ​​in the 0°, 45°, and 90° directions relative to the rolling direction be 0.23 or less.

[0083] (Measurement of work hardening index n value) The n value is measured by a tensile test in accordance with JIS Z2241:2022 and calculated using the method in accordance with JIS Z2253:2022.

[0084] - Average grain size of grains surrounded by grain boundaries with a crystal orientation difference of 2° or more between adjacent crystals: 6.00 μm or less - Grain size ratio expressed as maximum grain size / average grain size: 2.80 or less When metals are plastically deformed, irregularities (surface roughness) occur on the material surface. In particular, in thin materials such as aluminum alloy foil, surface roughness can be seen as thickness non-uniformity, and by suppressing non-uniformity, the localization of stress and deformation can be alleviated, making it possible to prevent a decrease in the forming limit.

[0085] Refining the grain size is effective in suppressing surface roughness, and it is desirable that the average grain size of grains surrounded by grain boundaries with a crystal orientation difference of 2° or more between adjacent crystals is 6.00 μm or less. From the viewpoint of more favorably exhibiting the effects of the present invention, the average grain size of the grains is preferably 5.80 μm or less, more preferably 5.50 μm or less, and also preferably 2.00 μm or more, more preferably 2.50 μm or more. Preferred ranges include 2.00 to 6.00 μm, 2.00 to 5.80 μm, 2.00 to 5.50 μm, 2.50 to 6.00 μm, 2.50 to 5.80 μm, and 2.50 to 5.50 μm.

[0086] Furthermore, in aluminum alloy foil, non-uniformity of grain size also contributes to surface roughness and localization of stress and deformation. Therefore, it is desirable that the grain size ratio, expressed as maximum grain size / average grain size (the value obtained by dividing the maximum grain size of a crystal grain by the average grain size), be 2.80 or less. From the viewpoint of more favorably exhibiting the effects of the present invention, the grain size ratio is preferably 2.70 or less, more preferably 2.60 or less, and also preferably 1.50 or more, more preferably 1.60 or more. Preferred ranges include 1.50 to 2.80, 1.50 to 2.70, 1.50 to 2.60, 1.60 to 2.80, 1.60 to 2.70, and 1.60 to 2.60.

[0087] (Measurement of crystal grain size) The crystal grain size is determined by smoothing the cross-section of the aluminum alloy foil with a cross-section polisher (CP), and performing crystal orientation analysis using SEM (Scanning Electron Microscope) and EBSD (Backscattered Electron Diffraction). In the analysis results, a crystal grain boundary is defined as a difference in crystal orientation of 2° or more between adjacent crystals, and the crystal grain size is calculated by analyzing using the Area method under the following conditions. The analysis software used is OIM Analysis from TSL Solutions. In the Area method, the diameter of the area calculated by taking into account the relative abundance of each crystal grain within the measurement area is assumed to be a circle and is defined as the crystal grain size. The observation magnification is set to 1000x. The field size is 150 μm × 38 μm, and three fields of view are observed to find the average crystal grain size, which is defined as the average crystal grain size. In addition, three fields of view are observed, and the maximum value of the crystal grain size is defined as the maximum crystal grain size. Other conditions for the electron microscope were: acceleration voltage 15 kV, sample tilt angle 70°, and step size 0.5 μm.

[0088] The EBSD detector conditions are as follows: Analysis software: OIM Analysis (Ver. 7.3.1) from TSL Solutions Area: Analysis of 3 fields of view with a field size of 150 μm × 38 μm CI value (Confidence Index): Measurement points with a CI value of 0.1 or less are excluded Minimum Grain Size (points): 2 Anti Grains: 2 (Measurement and calculation conditions for average crystal grain size) Grain Tolerance Angle: 2° Minimum Grain Size (points): 2 Anti Grains: 2 Minimum Confidence Index: 0.1 Multiple rows Required: All turned OFF. Apply partition before calculation: Turned OFF. Include grains at edges of scan in statistics: Turned ON.

[0089] The Cu orientation density and crystal orientation also affect the surface roughness of aluminum alloy foil. Surface roughness occurs frequently in areas close to grain boundaries and is therefore related to deformation and non-uniformity at the grain level. If the variation in crystal orientation is large, non-uniformity occurs in the deformation and rotation of each crystal grain during plastic deformation, leading to the development of surface roughness. For this reason, it is preferable for the crystal orientations to be concentrated. Aluminum alloy foil has a relatively high rolling rate during its manufacturing process, and a rolled texture tends to develop. For this reason, it is desirable to concentrate the crystal orientations in the Cu orientation density and set the orientation density to 50 or higher. From the viewpoint of more favorably exhibiting the effects of the present invention, the Cu orientation density is preferably 55 or higher, more preferably 60 or higher, and also preferably 90 or lower, more preferably 85 or lower, with preferred ranges including 50-90, 50-85, 55-90, 55-85, 60-90, and 60-85.

[0090] (Measurement of crystal orientation (Cu orientation density)) The Cu orientation density was obtained by X-ray diffraction. An incomplete pole figure was obtained, and the crystal orientation function was determined from the incomplete pole figure using crystal orientation function analysis software. For the surface of an aluminum alloy foil sample, the incomplete pole figures of {111}, {200}, and {220} were measured by X-ray diffraction. The three-dimensional orientation distribution function (ODF) was calculated using the measurement results, and the Cu orientation density was calculated. {112} <111> was used as the representative orientation for Cu. As an example, a circular sample with a diameter of 40 mm was taken from the aluminum alloy foil so that the foil surface was the measurement surface. Next, using an X-ray diffractometer, Schulz reflection (α = 20° to 90°, β = 0° to 360°, measurement interval 5.0°) is performed on the measurement surface with a Cu tube voltage of 40kV and tube current of 50mA to obtain incomplete pole figures of (220), (200), and (111). From these incomplete pole figures, the crystal orientation distribution function f(ψ1, φ, ψ2) is determined using crystal orientation distribution function analysis software and a 22nd-order series expansion method. The orientation density of Cu is set to values ​​of ψ1 = 90°, φ = 35°, and ψ2 = 45°.

[0091] (Method for Manufacturing Aluminum Alloy Foil) In order to manufacture aluminum alloy foil having the above composition and physical properties, a molten aluminum alloy satisfying the above composition is prepared, and an aluminum alloy ingot is obtained by a casting method using this molten aluminum alloy. Next, this aluminum alloy ingot is subjected to homogenization treatment and soaking treatment, processed to the desired thickness by hot rolling, cold rolling and foil rolling, and finally annealed to obtain aluminum alloy foil. Specific examples of manufacturing conditions for aluminum alloy foil are shown below.

[0092] Homogenization treatment: Homogenization treatment is performed on the cast ingot at 480°C to 540°C for 7 hours or more. The purpose of homogenization treatment is to eliminate microsegregation in the ingot and adjust the distribution of intermetallic compounds, and it is an important treatment for obtaining a fine and uniform grain structure in aluminum alloy foil after final annealing. If the homogenization treatment temperature is below 480°C, the diffusion and precipitation of solid solution atoms will be insufficient, resulting in a high amount of solid solution. In addition, the growth of intermetallic compounds tends to be insufficient. Intermetallic compounds are effective in promoting grain fragmentation during cold rolling, and if their growth is insufficient, the grain refinement effect due to fragmentation will be reduced. On the other hand, if the homogenization treatment temperature exceeds 540°C, the growth of intermetallic compounds is significant, and their density decreases. In homogenization treatment held in the temperature range of 480 to 540°C, long-term heat treatment is necessary to achieve an appropriate distribution of intermetallic compounds. Therefore, it is preferable to hold the homogenization treatment for 7 hours or more. If the holding time is less than 7 hours, the solid solution elements cannot be sufficiently diffused and precipitated, the distribution of intermetallic compounds becomes non-uniform, and the grain size after final annealing cannot be properly controlled. The homogenization treatment temperature is preferably about 490°C or higher, more preferably about 500°C or higher, and also preferably about 530°C or lower, more preferably about 520°C or lower. Preferred ranges include about 480°C to 540°C, about 480°C to 530°C, about 480°C to 520°C, about 500°C to 540°C, about 500°C to 530°C, and about 500°C to 520°C.

[0093] <Hot Rolling> ・Soaking Treatment: Approximately 400°C to 450°C for 1 hour In the soaking treatment before hot rolling, similar to the homogenization treatment, microsegregation is eliminated and the distribution of intermetallic compounds is adjusted. In addition, reheating is preferable to ensure hot rollability in the next process. However, if the temperature control is insufficient, there is a risk of non-uniformity in the grain size distribution. Therefore, in order to suppress recrystallization during hot rolling and to control the grain structure uniformly, the soaking treatment temperature is set to 400°C to 450°C. If the soaking treatment temperature exceeds 450°C, recrystallization occurs in some areas during hot rolling, driven by the processing strain introduced during hot rolling, resulting in a non-uniform grain structure. This non-uniformity of the structure that occurs during hot rolling also affects the structure of the final product, making it difficult to obtain a fine and uniform grain structure. On the other hand, if the temperature is below 400°C, the temperature during hot rolling will also be low, and there is a concern that cracks will occur on the sides of the aluminum alloy sheet, significantly reducing productivity. Therefore, the soaking temperature should preferably be within the above range.

[0094] • Hot rolling finish temperature: 230°C to 280°C The finish temperature after hot rolling is also important in order to maintain a uniform grain structure during hot rolling. It is necessary to appropriately adjust the finish temperature to suppress recrystallization. If the finish temperature exceeds 280°C, recrystallization will occur in some areas after hot rolling, resulting in a non-uniform structure in which fiber grains and recrystallized grains are mixed. This non-uniform structure will affect the grain structure of the final product and may lead to a decrease in formability. On the other hand, finishing the rolling temperature below 230°C would require extremely low temperatures during hot rolling, which is a concern from the standpoint of rollability. For this reason, the hot rolling finish temperature is preferably within the above range.

[0095] <Cold Rolling> - Final cold rolling rate: 98% or higher - Intermediate annealing: None The grains are refined during the cold rolling process by applying a high rolling rate, so the higher the final cold rolling rate, the finer the grains become. For this reason, a high final cold rolling rate is desirable, and specifically, it is desirable to set the final cold rolling rate to 98% or higher, preferably 98.5°C or higher, and more preferably 99.0°C or higher. If the final cold rolling rate is less than 98%, the grain size after final annealing becomes coarser or non-uniform, making it difficult to achieve the desired strength and ductility. In addition, although intermediate annealing may be performed during cold rolling, it is desirable to omit intermediate annealing from the viewpoint of increasing the final cold rolling rate.

[0096] The thickness of the aluminum alloy foil can be adjusted to the desired thickness by the final cold rolling process. The thickness of the aluminum alloy foil is not particularly limited, and preferred thicknesses are as described below.

[0097] <Final Annealing> - Annealing temperature: 250°C to 350°C for 10 hours or more Final annealing is performed to restore the ductility of the aluminum alloy foil after final cold rolling. For example, the final annealing after foil rolling should be carried out at 250°C to 350°C. If the final annealing temperature is too low, the ductility will be insufficient. On the other hand, if the annealing temperature exceeds 350°C, increased costs and other problems will arise. If the final annealing time is less than 10 hours, the effect of the final annealing will be insufficient. The final annealing temperature is preferably about 260°C, more preferably about 270°C, and also preferably about 340°C or lower, more preferably about 330°C or lower. Preferred ranges include about 250-350°C, about 250-340°C, about 250-330°C, about 260-350°C, about 260-340°C, about 260-330°C, about 270-350°C, about 270-340°C, and about 270-330°C.

[0098] The manufacturing method described above yields an aluminum alloy foil in which the total elongation at fracture in the 0°, 45°, and 90° directions relative to the rolling direction is 20.0% or more, the local elongation in all three directions is 3.0% or more, the work hardening index n value in all three directions is 0.23 or less, the Cu orientation density is 50 or more, the average grain size of grains surrounded by grain boundaries with a crystal orientation difference of 2° or more is 6.00 μm or less, and the grain size ratio expressed as maximum grain size / average grain size is 2.80 or less. The aluminum alloy foil described above is suitable for applications where large deformations are applied by press molding, such as the barrier layer 3 of an exterior material for an energy storage device, and for applications where high elongation or formability is required.

[0099] In barrier layer 3, the aforementioned aluminum alloy foil may be manufactured using recycled aluminum alloy. Recycled aluminum alloy can be obtained by known methods. For example, recycled aluminum alloy can be obtained 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 aluminum alloy refers to aluminum alloy 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 aluminum alloy refers to new aluminum alloy refined from natural metal resources (raw materials) and is not recycled material.

[0100] From the viewpoint of suitably exhibiting the effects of the present invention, the thickness of the aluminum alloy foil contained in the barrier layer 3 is preferably about 25 μm or more, more preferably about 30 μm or more, even more preferably about 35 μm or more, even more preferably about 40 μm or more, and also preferably about 80 μm or less, more preferably about 60 μm or less, even more preferably about 55 μm or less, and even more preferably about 50 μm or less. Preferred ranges include about 25 to 80 μm, about 25 to 60 μm, about 25 to 55 μm, about 30 to 60 μm, about 30 to 55 μm, about 30 to 50 μm, about 35 to 60 μm, about 35 to 55 μm, about 35 to 50 μm, about 40 to 60 μm, about 40 to 55 μm, and about 40 to 50 μm.

[0101] Furthermore, it is preferable that the barrier layer 3 has a corrosion-resistant coating on at least the side facing the heat-fusible resin layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that provides the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance) by performing a corrosion prevention treatment on the surface of the barrier layer, such as a hot water modification treatment like boehmite treatment, a chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or coating agent application. Specifically, the 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 to 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.

[0102] 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.

[0103] 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.

[0104]

[0105]

[0106]

[0107]

[0108] 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.

[0109] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxide (for example, particles with an average crystal grain 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 oxide contained in the corrosion-resistant coating can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0110] 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.

[0111] 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.

[0112] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0113] 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.

[0114] 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:

[0115] 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.

[0116] [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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described later is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0133] [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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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).

[0140] 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).

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0152] 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.

[0153] 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.

[0154] [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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] [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, and at a minimum, a method is given which involves laminating the base layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order.

[0172] 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.

[0173] 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 onto the barrier layer 3 of the laminate A by extrusion (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.

[0174] 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.

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

[0176] 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.

[0177] [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 enclosing an energy storage device element with the enclosure material for energy storage devices of this disclosure.

[0178] 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.

[0179] 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.

[0180] 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 is not 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] <Manufacturing of exterior materials for energy storage devices> [Example 1] 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 15 μm) were bonded together with an adhesive layer (formed with DL two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (ALM-A, thickness 50 μm, manufactured under the conditions described in Table 1, and possessing the composition and physical properties described in Table 1) was prepared as a barrier layer. Both sides of the aluminum alloy foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil consisted of a treatment solution comprising phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 The coating was applied to both sides of the aluminum alloy foil by the roll coating method and then baked to achieve the (dry mass) shown.

[0185] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (DL thickness 3 μm) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0186] Next, maleic anhydride-modified polypropylene forming an adhesive layer (40 μm thick) and polypropylene forming a heat-fusible resin layer (40 μm thick) were co-extruded onto the barrier layer of the 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 energy storage devices consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for energy storage devices are shown in Table 2.

[0187] [Example 2] A laminate was prepared in the same manner as in Example 1, with a base layer, adhesive layer, and barrier layer laminated in that order. Next, maleic anhydride-modified polypropylene forming an adhesive layer (20 μm thick) and polypropylene forming a heat-fusible resin layer (60 μm thick) were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0188] [Example 3] A laminate was prepared in the same manner as in Example 1, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, on the barrier layer of the laminate obtained above, maleic anhydride-modified polypropylene forming an adhesive layer (thickness 30 μm), polypropylene forming a second heat-fusible resin layer (thickness 30 μm), and polypropylene forming a first heat-fusible resin layer (thickness 20 μm) were co-extruded to laminate the adhesive layer and heat-fusible resin layer (second heat-fusible resin layer and first heat-fusible resin layer) on 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0189] [Example 4] An exterior material for an energy storage device was obtained in the same manner as in Example 1, except that a laminate was used in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 25 μm) and an oriented nylon (ONy) film (thickness 12 μm) were bonded together with an adhesive layer (formed with DL two-component curing urethane adhesive, with a thickness of 3 μm after curing). The laminate consisted of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the energy storage device are shown in Table 2.

[0190] [Example 5] A laminate was prepared in the same manner as in Example 4, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (thickness 20 μm), and polypropylene, which forms a heat-fusible resin layer (thickness 60 μm), were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0191] [Example 6] A laminate was prepared in the same manner as in Example 4, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, on the barrier layer of the laminate obtained above, maleic anhydride-modified polypropylene forming an adhesive layer (thickness 30 μm), polypropylene forming a second heat-fusible resin layer (thickness 30 μm), and polypropylene forming a first heat-fusible resin layer (thickness 20 μm) were co-extruded to laminate the adhesive layer and heat-fusible resin layer (second heat-fusible resin layer and first heat-fusible resin layer) on 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0192] [Example 7] An exterior material for an energy storage device was obtained in the same manner as in Example 1, except that a laminate was used in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 6 μm) and an oriented nylon (ONy) film (thickness 20 μm) were bonded together with an adhesive layer (formed with DL two-component curing urethane adhesive, with a thickness of 3 μm after curing). The laminate consisted of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the energy storage device are shown in Table 2.

[0193] [Example 8] A laminate was prepared in the same manner as in Example 7, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (thickness 20 μm), and polypropylene, which forms a heat-fusible resin layer (thickness 60 μm), were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0194] [Example 9] A laminate was prepared in the same manner as in Example 7, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, maleic anhydride-modified polypropylene forming an adhesive layer (30 μm thick), polypropylene forming a second heat-fusible resin layer (30 μm thick), and polypropylene forming a first heat-fusible resin layer (20 μm thick) were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and heat-fusible resin layer (second heat-fusible resin layer and first heat-fusible resin layer) on 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for an energy storage device are shown in Table 2.

[0195] [Example 10] An exterior material for an energy storage device was obtained in the same manner as in Example 1, except that a biaxially oriented polyethylene terephthalate (PET) film (thickness 25 μm) was used as the base layer, and the laminate consisted of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer laminated in this order. The laminate configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the base layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0196] [Example 11] A laminate was prepared in the same manner as in Example 10, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (thickness 20 μm), and polypropylene, which forms a heat-fusible resin layer (thickness 60 μm), were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the base layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0197] [Example 12] A laminate was prepared in the same manner as in Example 10, in which a base layer, adhesive layer, and barrier layer were laminated in that order. Next, maleic anhydride-modified polypropylene forming an adhesive layer (thickness 30 μm), polypropylene forming a second heat-fusible resin layer (thickness 30 μm), and polypropylene forming a first heat-fusible resin layer (thickness 20 μm) were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer and heat-fusible resin layer (second heat-fusible resin layer and first heat-fusible resin layer) on 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 the base layer, adhesive layer, barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the base layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0198] [Example 13] An exterior material for an energy storage device was obtained in the same manner as in Example 1, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0199] [Example 14] An exterior material for an energy storage device was obtained in the same manner as in Example 2, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0200] [Example 15] An exterior material for an energy storage device was obtained in the same manner as in Example 3, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0201] [Example 16] An exterior material for an energy storage device was obtained in the same manner as in Example 4, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a laminate consisting of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the energy storage device are shown in Table 2.

[0202] [Example 17] An exterior material for an energy storage device was obtained in the same manner as in Example 5, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a laminate consisting of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the energy storage device are shown in Table 2.

[0203] [Example 18] An exterior material for an energy storage device was obtained in the same manner as in Example 6, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0204] [Example 19] An exterior material for an energy storage device was obtained in the same manner as in Example 7, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a laminate consisting of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the energy storage device are shown in Table 2.

[0205] [Example 20] An exterior material for an energy storage device was obtained in the same manner as in Example 8, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0206] [Example 21] An exterior material for an energy storage device was obtained in the same manner as in Example 9, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the substrate layer of the exterior material for the energy storage device are shown in Table 2.

[0207] [Example 22] An exterior material for an energy storage device was obtained in the same manner as in Example 10, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a substrate layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the substrate layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0208] [Example 23] An exterior material for an energy storage device was obtained in the same manner as in Example 11, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a laminate consisting of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the base layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0209] [Example 24] An exterior material for an energy storage device was obtained in the same manner as in Example 12, except that an aluminum alloy foil (ALM-B, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer, in which a laminate consisting of a base layer / adhesive layer / barrier layer / adhesive layer / thermofusible resin layer was laminated in this order. The laminate configuration, total thickness (μm), and thickness of the polyamide (i.e., ONy) of the base layer (0 μm) of the exterior material for the energy storage device are shown in Table 2.

[0210] [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 25 μm) were bonded together with an adhesive layer (formed with DL two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (ALM-C, thickness 60 μm, manufactured under the conditions described in Table 1, and possessing the composition and physical properties described in Table 1) was prepared as a barrier layer. Both sides of the aluminum alloy foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil consisted of a treatment solution comprising phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m².2 The coating was applied to both sides of the aluminum alloy foil by the roll coating method and then baked to achieve the (dry mass) shown.

[0211] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (DL thickness 3 μm) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0212] Next, maleic anhydride-modified polypropylene forming an adhesive layer (30 μm thick), polypropylene forming a second heat-fusible resin layer (30 μm thick), and polypropylene forming a first heat-fusible resin layer (20 μm thick) were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer (second heat-fusible resin layer and first heat-fusible resin layer) on the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for energy storage devices consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for energy storage devices are shown in Table 2.

[0213] [Comparative Example 2] 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 DL two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (ALM-C, thickness 60 μm, manufactured under the conditions described in Table 1, and possessing the composition and physical properties described in Table 1) was prepared as a barrier layer. Both sides of the aluminum alloy foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil consisted of a treatment solution comprising phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 The coating was applied to both sides of the aluminum alloy foil by the roll coating method and then baked to achieve the (dry mass) shown.

[0214] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (DL thickness 3 μm) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0215] Next, maleic anhydride-modified polypropylene forming an adhesive layer (40 μm thick) and polypropylene forming a heat-fusible resin layer (40 μm thick) were co-extruded onto the barrier layer of the 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 energy storage devices consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order. The lamination configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for energy storage devices are shown in Table 2.

[0216] [Comparative Example 3] An exterior material for a power storage device was obtained in the same manner as in Example 1, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer was laminated in the following order: base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer are bonded together as the base layer (a laminate formed with DL two-component curing urethane adhesive, with a thickness of 3 μm), and an aluminum alloy foil (ALM-D, 40 μm thick, manufactured under the conditions described in Table 1, and having the composition and physical properties described in Table 1) was used as the barrier layer. The laminate configuration, total thickness (μm), and thickness (μm) of the polyamide (i.e., ONy) of the base layer of the exterior material for the power storage device are shown in Table 2.

[0217]

[0218] In Table 1, "remainder" refers to the value obtained by subtracting the total percentage (mass%) of components other than aluminum (AL) and unavoidable impurities from 100% by mass, where the sum of each component constituting the aluminum alloy foil is 100% by mass. Furthermore, the unavoidable impurities in the aluminum alloy foil are 0.05% by mass or less individually, and 0.15% by mass or less in total. Also, "AL foil" refers to aluminum alloy foil.

[0219] <Physical Properties of Aluminum Alloy Foil> The various physical properties of the aluminum alloy foil used in the examples and comparative examples were measured by the following methods. The results are shown in Table 1.

[0220] (Elongation in the 0° direction, 45° direction, 90° direction) For elongation in the 0° direction, 45° direction, and 90° direction (total elongation at fracture), the test was conducted using test specimens specified in JIS Z 2241:2022 No. 5, from 0°, 45°, and 90° directions relative to the rolling direction. The test was performed using a tensile testing machine (Shimadzu Corporation AGS-X 10kN) with a tensile speed of 5 mm / min. To calculate the elongation, two lines were marked at 50 mm intervals (gauge length) in the longitudinal center of the test specimen before the test. After the test, the fracture surfaces were joined together and the distance between the marks (l) was measured. The elongation (mm) was then divided by the gauge length (l0: 50 mm) using the following formula: ((l - l0) / l0) × 100

[0221] (Work hardening index n value) Measured by tensile testing in accordance with JIS Z2241:2022 and calculated using the method in accordance with JIS Z2253:2022.

[0222] (Grain Size) The grain size was determined by smoothing the cross-section of the aluminum alloy foil with a cross-section polisher (CP), and performing crystal orientation analysis using an SEM (Scanning Electron Microscope, JEOL JSM-IT200LA) and EBSD (Backscattered Electron Diffraction). In the analysis results, a grain boundary was defined as a difference in crystal orientation of 2° or more between adjacent crystals, and the average grain size was calculated by analyzing using the Area method under the following conditions. The analysis software used was OIM Analysis from TSL Solutions. In the Area method, the grain size was defined as the diameter when the area calculated considering the relative abundance of each grain within the measurement area was assumed to be a circle. The observation magnification was set to 1000x, and the field size was 150 μm × 38 μm, with three fields observed and the average value obtained. Other conditions for the electron microscope were an acceleration voltage of 15 kV, a sample tilt angle of 70°, and a step size of 0.5 μm.

[0223] The EBSD detector conditions were as follows: Analysis software: OIM Analysis (Ver. 7.3.1) from TSL Solutions Area: Three fields of view were analyzed with a field size of 150 μm × 38 μm CI value (Confidence Index): Measurement points with a CI value of 0.1 or less were excluded Minimum Grain Size (points): 2 Anti Grains: 2 (Measurement and calculation conditions for average crystal grain size) Grain Tolerance Angle: 2° Minimum Grain Size (points): 2 Anti Grains: 2 Minimum Confidence Index: 0.1 Multiple rows Required: All turned OFF. Apply partition before calculation: Turned OFF. Include grains at edges of scan in statistics: Turned ON.

[0224] (Crystal orientation (Cu orientation density)) The Cu orientation density was obtained by X-ray diffraction. Imperfect pole figures were obtained, and the crystal orientation function was calculated from these imperfect pole figures using crystal orientation function analysis software. Imperfect pole figures of {111}, {200}, and {220} were measured on the surface of an aluminum alloy foil sample by X-ray diffraction. The three-dimensional orientation distribution function (ODF) was calculated using the measurement results, and the Cu orientation density was calculated. {112}<111> was used as the representative orientation for Cu. As an example, a circular sample with a diameter of 40 mm was taken from the aluminum alloy foil so that the foil surface was the measurement surface. Next, using an X-ray diffractometer (SmartLab, manufactured by Rigaku Corporation), Schulz reflection spectroscopy (α = 20° to 90°, β = 0° to 360°, measurement interval 5.0°) was performed on the measurement surface with a Cu tube voltage of 40kV and tube current of 50mA, and incomplete pole figures of (220), (200), and (111) were obtained. From these incomplete pole figures, the crystal orientation distribution function f(ψ1, φ, ψ2) was determined using crystal orientation distribution function analysis software (StandardODF, manufactured by Norm Engineering Co., Ltd.) and a 22nd-order series expansion method. The orientation densities of Cu were set to values ​​of ψ1 = 90°, φ = 35°, and ψ2 = 45°.

[0225] <Tensile Test> (Measurement of Tensile Strength in Four Directions) The laminate constituting the exterior material for energy storage devices was subjected to a tensile test in a 25°C environment according to the following procedure. With the flow direction (MD direction) set to 0°, the tensile strength at a strain of 3.3% was measured in four directions: 0°, 45°, 90°, and 135° clockwise. The ratio of the sum of the tensile strengths in the four directions (N / 15mm) to the thickness (μm) of the laminate was calculated. More specifically, the exterior material for energy storage devices was measured using a tensile testing machine in accordance with the provisions of JIS K7127:1999. The tensile test was performed under the following conditions: 25°C environment, tensile speed of 50 mm / min, and initial distance between chucks of 30 mm. In the tensile test described in this disclosure, the initial distance between chucks was 30 mm, and this initial distance between chucks was defined as the gauge length. The exterior material for the energy storage device was prepared as four types of measurement samples, each with a length of 100 mm in the MD direction (0° direction), the TD direction (90° direction), the 45° direction between MD and TD, and the -45° direction between MD and TD (which is also the 135° direction), and a width of 15 mm perpendicular to these length directions. Refer to Figure 6 for the MD direction, TD direction, the 45° direction between MD and TD, and the -45° direction between MD and TD of the exterior material for the energy storage device. Specifically, of the four types of measurement samples, sample 1 was a measurement sample with a length of 100 mm in the MD direction and a width of 15 mm in the TD direction (for MD direction measurement). Sample 2 was a measurement sample with a length of 100 mm in the TD direction and a width of 15 mm in the MD direction (for TD direction measurement). As shown in Figure 6, the MD direction was defined as 0°, and the direction perpendicular to the MD direction was defined as the TD direction. Furthermore, Sample 3 was a measurement sample (for 45° direction measurement) with a length of 100 mm in the direction 45° clockwise, with the MD direction set to 0°, and a width of 15 mm perpendicular to that length direction. Sample 4 was a measurement sample (for -45° direction measurement) with a length of 100 mm in the direction 45° counterclockwise, with the MD direction set to 0°, and a width of 15 mm perpendicular to that length direction. Here, as shown in Figure 7, each sample was cut from the exterior material for the energy storage device to a size of 100 mm in length and 15 mm in width after the exterior material for the energy storage device was manufactured. At that time, all samples were cut from a range of 300 mm in the TD direction.Next, for each of the measurement samples 1 to 4, a tensile test was performed in the longitudinal direction of the measurement sample under the aforementioned measurement conditions, and the tensile strength at a displacement of 3.3% was measured. The sum of the tensile strengths in the four directions was then calculated. Furthermore, the obtained sum of the tensile strengths in the four directions was divided by the thickness of the laminate, and the result was rounded to three decimal places to obtain the ratio of the sum of the tensile strengths in the four directions to the thickness of the laminate. The results are shown in Table 2.

[0226] <Moisture Content> The moisture content of the laminate constituting the exterior material for energy storage devices was measured after storing it for 3 days in an environment of 65°C and 90% relative humidity using the following procedure. The results are shown in Table 2. For the exterior materials for energy storage devices obtained in each example and comparative example, the moisture content was measured after exposure to an environment of 65°C and 90% relative humidity for 72 hours using the following procedure. To exclude the effect of water intrusion from the edges, the sample to be measured (exterior material for energy storage devices) was 300 mm x 300 mm in size, stored for 24 hours in an environment of 25°C, 1% relative humidity or less, and a dew point of -20°C or less, then stored for 72 hours in an environment of 65°C and 90% relative humidity, and a 100 mm x 100 mm sample was cut from the center and used. Moisture content was measured using a Karl Fischer moisture meter and vaporizer placed in an environment of 25°C, 1% humidity or less, and a dew point of -20°C or less, by the moisture vaporization-coulometric titration method. To minimize the influence of the measurement environment, the sample was placed in a vial that could be sealed off from the outside air and brought into the measurement environment. After removing the sample from the vial, it was placed in the measuring device within 30 minutes. The measurement conditions were as follows: Target component: water, Titration cell type: two-component cell, Detection electrode type: bipolar platinum electrode, Diaphragm material: ceramic, Endpoint detection method: AC polarization method using bipolar platinum detection electrode, Endpoint determination method: Drift stability determination, Heating temperature: 180°C, Cell purge time: 120 seconds, Back purge time: 180 seconds, Stability determination value: 0.1 μg / min, Endpoint potential: 200 mV. The measurement results were calculated as the ratio of water weight to the sample weight (unit: ppm), and the average value of three measurements was recorded, rounded to the nearest tenth. Commercially available anode and cathode solutions (ChemAqua Anode Solution AGE and ChemAqua Cathode Solution CGE) were used as titration reagents.

[0227] <Evaluation of Formability> (Limited Forming Depth) A test specimen measuring 90 mm in the length direction (MD) x 150 mm in the width direction (TD) was taken from the laminate constituting the exterior material for the energy storage device. The length direction (MD) of the laminate corresponds to the rolling direction (RD direction) of the aluminum alloy foil, and the width direction (TD) of the laminate corresponds to the TD of the aluminum alloy foil. The test specimen was subjected to molding in an environment of 25°C using a rectangular molding die in plan view with a diameter of 31.6 mm (MD) x 54.5 mm (TD) (female die, surface has a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimens in JIS B0659-1:2002 Annex 1 (Reference), corner R 2.0 mm, edge R 1.0 mm) and a corresponding molding die (male die, surface has a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2 of the comparative surface roughness standard specimens in JIS B0659-1:2002 Annex 1 (Reference)) The maximum height roughness (nominal value of Rz) is 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimens. Using a corner radius of 2.0 mm and a ridge radius of 1.0 mm, ten test specimens were cold-formed (single-stage pull-in molding) at a pressing pressure (surface pressure) of 0.25 MPa, 23°C, and 50% RH, varying the molding depth in 0.5 mm increments starting from a molding depth of 0.5 mm to form a rectangular housing (a lithium-ion battery housing) in plan view. At this time, the test specimen was placed on the female mold so that the heat-fusible resin layer side was positioned on the male mold side during molding. The clearance between the male and female molds was set to 0.3 mm. After cold-forming, the samples were examined in a dark room using a penlight to check for pinholes or cracks in the aluminum alloy foil by light transmission. The deepest molding depth at which no pinholes or cracks occurred in any of the 10 aluminum alloy foil samples was defined as A mm, and the number of samples at the shallowest molding depth at which pinholes or cracks occurred was defined as B. The value calculated using the following formula was rounded to two decimal places and defined as the limit molding depth for the exterior material of the energy storage device. Limit molding depth = A mm + (0.5 mm / 10 samples) × (10 samples - B samples) The formability based on the limit molding depth was evaluated according to the following criteria. The results are shown in Table 2. (Formability evaluation criteria) A+: Limit molding depth is 8.0 mm or more. A: Limit molding depth is 7.0 mm or more and less than 8.0 mm.B: The limit molding depth is 6.0 mm or more and less than 7.0 mm. C: The limit molding depth is less than 6.0 mm.

[0228] <Appearance Evaluation of Heat-Sealed Parts> The heat-sealable resin layers of the exterior materials for energy storage devices were heat-sealed together under the following conditions: temperature 210°C, surface pressure 1 MPa, and 3 seconds. The surface of the heat-sealed parts was observed visually and with a laser microscope (Keyence VK-9700) (magnification 20x). Specifically, first, each exterior material for energy storage devices was cut to 60 mm (TD direction) x 200 mm (MD direction). Next, the exterior material for energy storage devices was folded in half in the MD direction so that the heat-sealable resin layers faced each other. The heat-sealable resin layers were heat-sealed together under the conditions: seal width 7 mm, temperature 210°C, surface pressure 1.0 MPa, and 3 seconds, with the heat-sealed parts positioned approximately 10 mm inward from the fold in the MD direction. The surface of the heat-sealed exterior material for energy storage devices was inspected visually and with a laser microscope. The appearance of the heat-sealed area was evaluated based on the following criteria (observation area: heat-sealed portion = seal width 7 mm x width direction 60 mm). The results are shown in Table 2. (Appearance evaluation criteria) A+: No bubbles are observed on the surface of the heat-sealed area by visual inspection or under a microscope (20x magnification). A: No bubbles are observed on the surface of the heat-sealed area by visual inspection. Bubbles are observed in an area of ​​less than 50% of the area under a microscope (20x magnification). Bubbles are observed in the seal area under a microscope (20x magnification). B: Bubbles are observed on the surface of the heat-sealed area by visual inspection in an area of ​​less than 50% of the area. C: Bubbles are observed on the surface of the heat-sealed area by visual inspection in an area of ​​50% or more of the area.

[0229]

[0230] The exterior materials for energy storage devices in Examples 1 to 24 are each composed of a laminate comprising, from the outside in this order, at least a barrier layer and a heat-sealable resin layer. When the tensile strength (N / 15 mm) in four directions (N / 15 mm) of the laminate is measured by the method described above, the ratio of the sum of the tensile strengths (N / 15 mm) in four directions to the thickness (μm) of the laminate is 1.98 or higher, and the moisture content of the laminate after being stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. As shown in Table 2, the exterior materials for energy storage devices in Examples 1 to 24 are highly rigid and have a good appearance at the heat-sealed parts.

[0231] As described above, this disclosure provides the invention in the following embodiments. Item 1. An exterior material for an energy storage device, comprising a laminate comprising, from the outside, at least a barrier layer and a heat-fusible resin layer in this order, wherein when the tensile strength (N / 15 mm) in four directions is measured by the following method, the ratio of the sum of the tensile strengths (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or more, and the moisture content of the laminate after being stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. (Measurement of tensile strength) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction. A tensile test is performed on the aforementioned measurement sample, and the tensile strength at a displacement of 3.3% in the longitudinal direction is measured under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. Item 2. The exterior material for an energy storage device according to Item 1, wherein the thickness of the laminate is 148 μm or more and 182 μm or less. Item 3. The exterior material for an energy storage device according to Item 1 or 2, comprising a base layer on the outside of the barrier layer. Item 4. The exterior material for an energy storage device according to Item 3, wherein the base layer comprises at least one of polyamide and polyester. Item 5. The exterior material for an energy storage device according to Item 3 or 4, wherein the base layer comprises a polyamide film, and the thickness of the polyamide film is 20 μm or less. Item 6. The exterior material for an energy storage device according to any one of Items 3 to 5, further comprising an adhesive layer between the base layer and the barrier layer. Item 7. The exterior material for an energy storage device according to any one of Items 1 to 6, wherein the thickness of the barrier layer is 30 μm or more and 60 μm or less. Item 8. An exterior material for an energy storage device according to any one of items 1 to 7, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.Item 9. A method for manufacturing an exterior material for an energy storage device, comprising the step of obtaining a laminate in which at least a barrier layer and a heat-fusible resin layer are laminated in that order from the outside, wherein when the tensile strength (N / 15 mm) in four directions is measured by the following method, the ratio of the sum of the tensile strengths (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or more, and the moisture content of the laminate when stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. (Measurement of tensile strength) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction. A tensile test is performed on the aforementioned measurement sample, and the tensile strength at a displacement of 3.3% in the longitudinal direction is measured under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. Item 10. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer material for energy storage devices as described in any one of items 1 to 8.

[0232] 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 having, from the outside, at least a barrier layer and a heat-fusible resin layer in that order, wherein when the tensile strength (N / 15 mm) in four directions is measured by the following method, the ratio of the sum of the tensile strengths (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or more, and the moisture content of the laminate after being stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. (Measurement of tensile strength) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction. Tensile tests were performed on the aforementioned sample, and the tensile strength at a longitudinal displacement of 3.3% was measured under the following conditions: 25°C environment, tensile speed of 50 mm / min, and chuck distance of 30 mm.

2. The outer material for an energy storage device according to claim 1, wherein the thickness of the laminate is 148 μm or more and 182 μm or less.

3. The exterior material for an energy storage device according to claim 1 or 2, further comprising a base material layer on the outside of the barrier layer.

4. The exterior material for an energy storage device according to claim 3, wherein the base layer comprises at least one of polyamide and polyester.

5. The exterior material for an energy storage device according to claim 3, wherein the base layer includes a polyamide film, and the thickness of the polyamide film is 20 μm or less.

6. The exterior material for an energy storage device according to claim 3, further comprising an adhesive layer between the base material layer and the barrier layer.

7. The exterior material for an energy storage device according to claim 1 or 2, wherein the thickness of the barrier layer is 30 μm or more and 60 μm or less.

8. 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.

9. A method for manufacturing an exterior material for an energy storage device, comprising the step of obtaining a laminate in which at least a barrier layer and a heat-fusible resin layer are laminated in that order from the outside, wherein when the tensile strength (N / 15 mm) in four directions is measured by the following method, the ratio of the sum of the tensile strengths (N / 15 mm) in the four directions to the thickness (μm) of the laminate is 1.98 or more, and the moisture content of the laminate when stored for three days in an environment of 65°C and 90% relative humidity is 3500 ppm or less. (Measurement of tensile strength) For the laminate, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD, and a width of 15 mm perpendicular to the length direction. Tensile tests were performed on the aforementioned sample, and the tensile strength at a longitudinal displacement of 3.3% was measured under the following conditions: 25°C environment, tensile speed of 50 mm / min, and chuck distance of 30 mm.

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

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