Exterior material for power storage device, method for manufacturing same, power storage device, mobile body, and electronic apparatus

Abstract

Provided is an exterior material for a power storage, the exterior material being composed of a laminate that includes in the following order, at least a substrate layer, a barrier layer, and a heat-fusible resin layer, wherein: the substrate layer includes at least one among polyester and polyamide; the substrate layer has a thickness of at least 40 μm; the barrier layer includes an aluminum alloy foil; the aluminum alloy foil has a thickness of at least 55 μm; and the laminate has an average value of slopes of tensile strengths of less than 950 MPa according to the following measurement. (Measurement) For the laminate, four types of test samples are prepared, 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 having a width, orthogonal to the length direction, of 15 mm. A tensile test is performed on the test samples under conditions of 25 °C, a tensile speed of 300 mm / min, and a chuck-to-chuck distance of 30 mm. The tensile strength at a displacement of 0.5% to 2.0% in the length direction is measured, and an average value of slopes of tensile strengths in the four directions is calculated. The slope of each tensile strength is calculated using the following equation. Slope of each tensile strength=[tensile strength at 2.0% displacement (MPa) − tensile strength at 0.5% displacement (MPa)] / (0.02−0.005)

Description

Exterior Material for Energy Storage Device, Method for Manufacturing the Same, Energy Storage Device, Moving Body, and Electronic Device

[0001] The present disclosure relates to an exterior material for an energy storage device, a method for manufacturing the same, an energy storage device, a moving body, and an electronic device.

[0002] Conventionally, various types of energy storage devices have been developed. In all energy storage devices, an exterior material is an essential member for sealing energy storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been widely used as exterior materials for energy storage devices.

[0003] On the other hand, in recent years, with the improvement in performance of automobiles such as electric vehicles and hybrid electric vehicles, and electronic devices such as personal computers, cameras, and mobile phones, various shapes are required for energy storage devices, and thinning and weight reduction are also demanded. However, the conventionally widely used metal exterior materials for energy storage devices have the disadvantages that it is difficult to follow the diversification of shapes and there is also a limit to weight reduction.

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

[0005] In such an exterior material for an energy storage device, generally, a concave portion is formed by cold forming, energy storage device elements such as electrodes and electrolytic solutions are arranged in the space formed by the concave portion, and by heat-sealing the heat-sealable resin layer, an energy storage device in which the energy storage device elements are housed inside the exterior material for an energy storage device can be obtained.

[0006] Japanese Patent Application Laid-Open No. 2008-287971 [[ID=十九]]

[0007] For example, larger energy storage devices used in in-vehicle batteries, stationary batteries, etc. are required to have higher capacities. For this reason, the above-described film-like exterior material for an energy storage device is required to have higher formability from the viewpoint of expanding the space for housing the energy storage device elements.

[0008] In order to meet the requirements for high formability of the exterior material for a power storage device, a method of increasing the thickness of the layers constituting the exterior material for a power storage device (specifically, the aforementioned base material layer, barrier layer, etc.) can be considered.

[0009] The inventors of the present disclosure considered increasing the formability of the exterior material for a power storage device by increasing the thickness of the base material layer and then using an aluminum alloy foil for the barrier layer and increasing the thickness of the aluminum alloy foil. However, contrary to the expectations of the inventors, they obtained the finding that the relationship that the forming depth increases in proportion to the increase in the thickness of the base material layer and the aluminum alloy foil does not hold.

[0010] Under such circumstances, the main object of the present disclosure is to provide an exterior material for a power storage device having excellent formability. Another object of the present disclosure is also to provide a power storage device using the exterior material for a power storage device, a moving body and an electronic device including the power storage device, and a method for manufacturing the exterior material for a power storage device.

[0011] The inventors of the present disclosure intensively studied to solve the above problems. As a result, in an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside, for the base material layer, at least one of polyester and polyamide is used and the thickness of the base material layer is set to 40 μm or more, for the barrier layer, an aluminum alloy foil is used and the thickness of the aluminum alloy foil is set to 55 μm or more, and further by controlling the slope of the predetermined tensile strength of the entire laminate constituting the exterior material for a power storage device, it was found that an exterior material for a power storage device having excellent formability can be obtained.

[0012] The present disclosure was completed by further studies based on such findings. That is, the present disclosure provides the inventions listed below.

[0013] The laminate is composed of a laminate comprising, from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the base layer contains at least one of polyester and polyamide, the thickness of the base layer is 40 μm or more, the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 55 μm or more, and the average value of the slope of each tensile strength measured as follows is less than 950 MPa, and is an exterior material for an energy storage device. (Measurement) 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. Under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, the tensile strength was measured at displacements of 0.5% to 2.0% in the longitudinal direction, and the average value of the slope of the tensile strength in the four directions was calculated. The slope of each tensile strength was calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005)

[0014] This disclosure provides an exterior material for energy storage devices that exhibits excellent moldability. Furthermore, this disclosure provides a method for manufacturing the exterior material for energy storage devices, an energy storage device utilizing the exterior material, a mobile device equipped with the energy storage device, and an electronic device.

[0015] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for energy storage devices of the present disclosure. This is a schematic diagram for explaining a method of housing an energy storage device element in a package formed from the exterior material for energy 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 energy storage devices.

[0016] The exterior material for energy storage devices of this disclosure is composed of a laminate comprising, from the outside in this order, a base layer, a barrier layer, and a heat-fusible resin layer. The base layer contains at least one of polyester and polyamide, and the thickness of the base layer is 40 μm or more. The barrier layer contains aluminum alloy foil, and the thickness of the aluminum alloy foil is 55 μm or more. The laminate constituting the exterior material for energy storage devices of this disclosure has an average value of the slope of each tensile strength measured as follows: less than 950 MPa. By possessing these characteristics, the exterior material for energy storage devices of this disclosure can exhibit excellent moldability. (Measurement) 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. Under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, the tensile strength was measured at displacements of 0.5% to 2.0% in the longitudinal direction, and the average value of the slope of the tensile strength in the four directions was calculated. The slope of each tensile strength was calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005)

[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. For example, when the barrier layer 3 includes metal foil such as aluminum alloy foil or stainless steel foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Also, in the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and 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 exterior material for energy storage devices cannot be identified by the rolling marks of metal foils such as aluminum alloy foil and stainless steel foil, it can be identified by the following method. One method for confirming the MD of the exterior material for energy storage devices is to observe the cross-section of the heat-fusible resin layer of the exterior material for energy storage devices with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing each of the cross-sections (a total of 10 cross-sections) in the longitudinal direction of the heat-fusible resin layer, and each of the cross-sections perpendicular to the longitudinal direction, by changing the angle by 10 degrees from the direction parallel to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, the diameter y is defined as 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. 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 a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order, as shown in Figure 1, for example. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling an energy storage device using the exterior material 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-fussing the peripheral edges of the heat-fusible resin layers 4 of the exterior material 10 facing each other. In the laminate constituting the exterior material 10 for energy storage devices of this disclosure, with respect to the barrier layer 3, the heat-fusible resin layer 4 side is inward of the barrier layer 3, and the base layer 1 side is outward of the barrier layer 3.

[0021] The exterior material 10 for the energy storage device may, for example, have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as needed, for the purpose of improving the adhesion between these layers, as shown in Figures 2 to 4. Also, as shown in Figures 3 and 4, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4, as needed, for the purpose of improving the adhesion between these layers. Furthermore, as shown in Figure 4, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (opposite the heat-fusible resin layer 4 side), as needed.

[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 220 μm or less, about 210 μm or less, about 190 μm or less, or about 180 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 155 μm or more, about 165 μm or more, about 180 μm or more, or about 190 μm or more. Furthermore, the preferred range for the laminate constituting the outer material 10 for the energy storage device is, for example, approximately 155 to 300 μm, approximately 155 to 250 μm, approximately 155 to 220 μm, approximately 155 to 210 μm, approximately 155 to 190 μm, approximately 155 to 180 μm, approximately 165 to 300 μm, approximately 165 to 250 μm, approximately 165 to 220 μm, approximately 165 to 210 μm, and 165 to Examples of thicknesses include approximately 190 μm, 165-180 μm, 180-300 μm, 180-250 μm, 180-220 μm, 180-210 μm, 180-190 μm, 190-300 μm, 190-250 μm, 190-220 μm, and 190-210 μm. In particular, when improving moldability, a thickness of approximately 155-250 μm is preferred.

[0023] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3, the adhesive layer 5 (optionally provided), the heat-fusible resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Specifically, when the exterior material 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even if the exterior material 10 for energy storage devices of this disclosure is a laminate comprising a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0024] The laminates constituting the exterior material for energy storage devices in this disclosure are four types of measurement samples, each with a length of 100 mm in the MD direction, 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 these length directions. Tensile tests are performed on each measurement sample, and under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, the tensile strength at displacements of 0.5% to 2.0% in the length direction is measured, and the average value of the slope of each tensile strength is less than 950 MPa. The reason why the displacement range in the tensile test of the laminates constituting the exterior material for energy storage devices is set to the range of 0.5% to 2.0% in this disclosure is as follows: Among the layers constituting the exterior material for energy storage devices, the barrier layer and base layer, which have high tensile strength, are prone to differences in tensile strength within this displacement range, and furthermore, they have a significant impact on the overall tensile strength of the exterior material for energy storage devices. In contrast, the heat-fusible resin layer, the adhesive layer provided as needed, and the bonding layer have relatively lower tensile strengths compared to the barrier layer and the base material layer, and have little influence on the overall tensile strength of the exterior material for energy storage devices. Therefore, in this disclosure, the average value of the slope of the tensile strength is set to result in an exterior material for energy storage devices with excellent moldability by measuring the tensile strength in the displacement range of 0.5% to 2.0% among the layers constituting the exterior material for energy storage devices, where differences in tensile strength between the barrier layer and the base material layer are likely to occur.

[0025] From the viewpoint of more favorably exhibiting the effects of the present invention, the average value of the gradient of the tensile strength is preferably about 950 MPa or less, more preferably about 850 MPa or less, even more preferably about 800 MPa or less, and also preferably about 500 MPa or more, more preferably about 550 MPa or more, even more preferably about 600 MPa or more. Preferred ranges include about 500 to 950 MPa, about 500 to 850 MPa, about 500 to 800 MPa, about 550 to 950 MPa, about 550 to 850 MPa, about 550 to 800 MPa, about 600 to 950 MPa, about 600 to 850 MPa, and about 600 to 800 MPa. The method for measuring the average value of the gradient of the tensile strength is as follows.

[0026] <Measurement of the average value of the gradient of tensile strength in four directions of the laminate> For the exterior material for energy storage devices, measurements are performed using a tensile testing machine in accordance with the provisions of JIS K7127:1999. The tensile test is performed under the measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and an initial distance between chucks of 30 mm. In the tensile test in this disclosure, the initial distance between chucks is 30 mm, and this initial distance between chucks is defined as the distance between gauge marks. For the exterior material for energy storage devices, four types of measurement samples are prepared, each with a length of 100 mm in the MD direction, 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 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 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). Next, for each of the measurement samples 1 to 4, a tensile test is performed in the longitudinal direction under the aforementioned measurement conditions, and the gradient of tensile strength from a displacement of 0.5% to a displacement of 2.0% (= [tensile strength at 2.0% displacement (MPa) - tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005)) is measured, and the average value of the gradient of tensile strength in the four directions is calculated.

[0027] The exterior material for energy storage devices of the present disclosure comprises a base layer containing at least one of polyester and polyamide, a base layer thickness of 40 μm or more, and a barrier layer containing aluminum alloy foil with a thickness of 55 μm or more. For an exterior material for energy storage devices that tends to have high rigidity due to the inclusion of a thick base layer containing crystalline resins such as polyester and polyamide, and a thick aluminum alloy foil, the following methods can be used to reduce the average value of the slope of the tensile strength to less than 950 MPa. For example, in the manufacturing process of the exterior material for energy storage devices, a heat-fusible resin layer 4 and an adhesive layer 5, if necessary, are laminated to a laminate formed by melt extrusion of the base layer and the barrier layer 3, and it is preferable to rapidly cool the laminate at a temperature (cooling temperature) of 0.45 or less, preferably 0.35 or less, and more preferably 0.15 or less, when the crystallization temperature of the outermost layer of the base layer is taken as 1, thereby suppressing the slow cooling of the base layer 1 and barrier layer 3, which have been heated by heat, such as the heat-fusible resin layer 4 that was melted at a high temperature. Furthermore, when laminating the substrate layer 1 and the barrier layer 3 by a dry lamination method, it is preferable to set the drying temperature to a low temperature, such as 0.55 or less, preferably 0.45 or less, and even more preferably 0.35 or less, when the crystallization temperature of the outermost layer of the substrate layer is set to 1, in order to quickly remove the heat applied to the substrate layer 1 and the barrier layer 3 by the dry lamination method and to suppress the slow cooling of the substrate layer 1 and the barrier layer 3.

[0028] [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.

[0029] The material forming the base layer 1 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.

[0030] In this disclosure, the base layer 1 comprises at least one of polyester and polyamide. In the base layer 1, the polyester and polyamide may constitute separate layers or may be contained within the same layer. Furthermore, the polyester and polyamide may be copolymers of these resins, or modified products of these copolymers. Moreover, they may be mixtures of these resins.

[0031] The base layer 1 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 of the 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. The statement that the base layer 1 contains polyester or polyamide as its main component 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.

[0032] 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.

[0033] 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.

[0034] The base layer 1 can be formed from a resin film containing, for example, at least one of polyester and polyamide. When the base layer 1 is formed from 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, resulting in a base layer 1 formed from 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 resin coating methods include roll coating, gravure coating, and extrusion coating.

[0035] The base layer 1 preferably contains at least one of polyester film and polyamide film, preferably at least one of stretched polyester film and stretched polyamide film, more preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, and stretched nylon film, and even more preferably at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, and biaxially oriented nylon film.

[0036] 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.

[0037] 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. Furthermore, having the polyester resin film as the outermost layer of the base material layer 1 is preferable from the viewpoint of improving the insulation properties of the exterior material for energy storage devices, as it suppresses moisture absorption into the polyamide resin film.

[0038] In a laminate of a polyester resin film and a polyamide resin film, the preferred thickness range for the polyester resin film is approximately 3 to 43 μm, 3 to 28 μm, 3 to 23 μm, 3 to 18 μm, 3 to 11 μm, 3 to 8 μm, 9 to 43 μm, 9 to 28 μm, 9 to 23 μm, 9 to 18 μm, 9 to 11 μm, 18 to 43 μm, and 18 to 28 μm. The thickness is approximately 18 to 23 μm. Preferred ranges for the thickness of the polyamide resin film include approximately 3 to 43 μm, 3 to 28 μm, 3 to 23 μm, 3 to 18 μm, 3 to 11 μm, 3 to 8 μm, 9 to 43 μm, 9 to 28 μm, 9 to 23 μm, 9 to 18 μm, 9 to 11 μm, 18 to 43 μm, 18 to 28 μm, and 18 to 23 μm.

[0039] 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.

[0040] The base layer 1 may further contain other resins different from polyester and polyamide. Examples of other resins include polyolefins, epoxy resins, acrylic resins, fluororesins, polyurethanes, silicon resins, phenolic resins, and modified versions of these resins. The other resins may also be copolymers of these resins or modified versions of copolymers. Furthermore, mixtures of these resins may also be present.

[0041] 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.

[0042] In this disclosure, from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more types, and it is preferable to use two or more types in combination.

[0043] When the lubricant is present on the surface of the base material layer 1, its amount of presence is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Also, as the amount of the lubricant present on the surface of the base material layer 1, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Also, the preferable range of the amount of the lubricant present on the surface of the base material layer 1 is about 3 to 15 mg / m 2 level, about 3 to 14 mg / m 2 level, about 3 to 10 mg / m 2 level, about 4 to 15 mg / m 2 level, about 4 to 14 mg / m 2 level, about 4 to 10 mg / m 2 level, about 5 to 15 mg / m 2 level, about 5 to 14 mg / m 2 level, about 5 to 10 mg / m 2 level.

[0044] The lubricant present on the surface of the base material layer 1 may be one obtained by exuding the lubricant contained in the resin constituting the base material layer 1, or may be one obtained by applying the lubricant to the surface of the base material layer 1.

[0045] Since the base material layer 1 contains a colorant, the exterior material for the power storage device can be colored. As the colorant, known ones such as pigments and dyes can be used. Also, only one type of colorant may be used, or two or more types may be mixed and used.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In this disclosure, the thickness of the base layer 1 is 40 μm or more. From the viewpoint of more favorably exhibiting the effects of the invention of this disclosure, the thickness of the base layer 1 is preferably about 45 μm or more, more preferably about 50 μm or more, even more preferably about 60 μm or more, and also preferably about 100 μm or less, more preferably about 90 μm or less, even more preferably about 80 μm or less. Preferred ranges include about 40 to 100 μm, about 40 to 90 μm, about 40 to 80 μm, about 45 to 100 μm, about 45 to 90 μm, about 45 to 80 μm, about 50 to 100 μm, about 50 to 90 μm, about 50 to 80 μm, about 60 to 100 μm, about 60 to 90 μm, and about 60 to 80 μm.

[0051] From the viewpoint of reducing the average value of the slope of the tensile strength of the laminate constituting the exterior material for the energy storage device of this disclosure to less than 950 MPa, it is effective to control the tensile strength of the base layer. Specifically, for the base layer 1, 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 under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, it is preferable that the average value of each tensile strength (MPa) at a displacement of 5.0% in the length direction (MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD) is 70 MPa or less.

[0052] From the viewpoint of more favorably exhibiting the effects of the present invention, the average value of each tensile strength is more preferably about 55 MPa or less, even more preferably about 40 MPa or less, and also preferably about 20 MPa or more, more preferably about 25 MPa or more, and even more preferably about 30 MPa or more. Preferred ranges include about 20 to 55 MPa, about 20 to 40 MPa, about 25 to 55 MPa, about 25 to 40 MPa, about 30 to 55 MPa, and about 30 to 40 MPa. The method for measuring the average value is as follows.

[0053] <Measurement of the average value of the tensile strength of the base material layer in four directions> (Preparation of measurement sample) For the exterior material for energy storage devices, the base material layer is peeled off from the barrier layer using the following method, and the base material layer is obtained as a measurement sample.

[0054] (Measurement of Tensile Strength) Each of the obtained measurement samples shall be measured using a tensile testing machine in accordance with the provisions of JIS K7127:1999. The tensile test shall be performed under the measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and an initial distance of 30 mm between the chucks. The base layer shall be made into four types of measurement samples, each with 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 these length directions. Specifically, of the four types of measurement samples, sample 1 shall be a measurement sample with a length of 100 mm in the MD direction and a width of 15 mm in the TD direction (for measurement in the MD direction). Sample 2 shall be a measurement sample with a length of 100 mm in the TD direction and a width of 15 mm in the MD direction (for measurement in the TD direction). Similar to the exterior material for energy storage devices 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. Sample 3 is a measurement sample (for 45° direction measurement) with a length of 100 mm in the direction 45° clockwise with the MD direction as 0°, and a width of 15 mm perpendicular to that length direction. Sample 4 is a measurement sample (for -45° direction measurement) with a length of 100 mm in the direction 45° counterclockwise with the MD direction as 0°, and a width of 15 mm perpendicular to that length direction. Next, for each of the measurement samples 1 to 4, a tensile test is performed along the length of the measurement sample under the above measurement conditions, the tensile strength (MPa) at a 5% displacement is measured, and the average value of the tensile strength (MPa) for the four directions of the base layer is calculated.

[0055] [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 layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] [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.

[0066] 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.

[0067] Specific examples of colorants included in the colored layer are the same as those exemplified in the section for [Adhesive Layer 2].

[0068] [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.

[0069] In this disclosure, the barrier layer 3 includes at least an aluminum alloy foil. The aluminum alloy foil included in the barrier layer 3 is preferably one layer, but may be two or more layers (for example, two or three layers).

[0070] 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.

[0071] The aluminum alloy foil used as the barrier layer 3 preferably has a work hardening index n value of 0.23 or less in all three directions: 0°, 45°, and 90° with respect to the rolling direction.

[0072] Furthermore, it is preferable that the aluminum alloy foil used as the barrier layer 3 has a Cu orientation density of 50 or higher, as obtained by X-ray diffraction.

[0073] The aluminum alloy foil used as the barrier layer 3 preferably has a Cu orientation density of 50 or more, obtained by X-ray diffraction, and the n-values ​​of the three-directional work hardening indices (0°, 45°, and 90°) with respect to the rolling direction are all 0.23 or less.

[0074] In this disclosure, the composition of the aluminum alloy foil is preferably 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.

[0075] Furthermore, in this disclosure, it is preferable that the total elongation at break in the three directions of 0°, 45°, and 90° with respect to the rolling direction of the aluminum alloy foil is 20.0% or more in all cases.

[0076] Furthermore, in this disclosure, it is preferable that the local elongation of the aluminum alloy foil in the three directions is 3.0% or more in each of them.

[0077] Furthermore, in this disclosure, when a boundary where the crystal orientation difference between adjacent crystals of the aluminum alloy foil is 2° or more is defined as a grain boundary, and the region enclosed by the grain boundary is defined as a crystal grain, it is preferable that the average crystal grain size of the crystal grain is 6.00 μm or less. Moreover, it is also preferable that 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 preferred composition and physical properties of the aluminum alloy foil included in the barrier layer 3 will be described in detail below in this disclosure.

[0078] (Preferred 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, it is preferable to set the lower limit of the Fe content 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 1.70 mass%, 1.30 to 1.80 mass%, and 1.30 to 1.70 mass%.

[0079] • 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%.

[0080] • 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 0.0080% by mass, 0.0030 to 0.0100% by mass, and 0.0030 to 0.0080% by mass.

[0081] 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.

[0082] (Preferred 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.

[0083] 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 to 43.0%, 20.0 to 40.0%, 23.0 to 43.0%, 23.0 to 40.0%, 25.0 to 43.0%, and 25.0 to 40.0%.

[0084] 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%.

[0085] (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), JIS Z2241:2022 No. 5 test specimens are taken from 0°, 45°, and 90° directions relative to the rolling direction, and measurements are taken using a tensile testing machine at a tensile speed of 5 mm / min. To calculate the elongation rate, two lines are 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) is measured by abutting the fracture surfaces after the test. The elongation amount (mm) is then divided by the gauge length (l0: 50 mm) and calculated using the following formula: ((l - l0) / l0) × 100

[0086] - Work hardening index n-value in the 0°, 45°, and 90° directions relative to the rolling direction: 0.23 or less When forming metal, 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 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 molding height (molding depth) or to form complex shapes. Therefore, it is desirable that the n-value in the 0°, 45°, and 90° directions relative to the rolling direction be 0.23 or less, more preferably 0.22 or less, and also preferably 0.10 or more, more preferably 0.13 or more. Preferred ranges include approximately 0.10 to 0.23, approximately 0.10 to 0.22, approximately 0.13 to 0.23, and approximately 0.13 to 0.22.

[0087] (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.

[0088] - 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.

[0089] 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.

[0090] 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.

[0091] (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.

[0092] 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.

[0093] 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. Therefore, 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. Therefore, it is desirable to concentrate the crystal orientations in the Cu orientation density and make that orientation density 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. Preferred ranges include 50-85, 50-90, 50-85, 55-85, 55-90, 55-85, 60-85, 60-90, 60-85, and so on.

[0094] (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°.

[0095] The most preferred embodiment of the exterior material for an energy storage device of this disclosure is as follows: The barrier layer comprises, from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer in this order, and includes an aluminum alloy foil, the composition of the aluminum alloy foil being 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, the total elongation of the aluminum alloy foil in three directions of 0°, 45°, and 90° with respect to the rolling direction is 20.0% or more in each of the three directions, the local elongation in each of the three directions is 3.0% or more in each of the three directions, the n value in each of the three directions is 0.23 or less, the Cu orientation density obtained by X-ray diffraction is 50 or more, and when a boundary with an orientation difference of 2° or more is defined as a grain boundary, and the region enclosed by the grain boundary is defined as a grain, the average grain size of the grain is 6.00 μm or less. An exterior material for an energy storage device, wherein the value obtained by dividing the maximum grain size of the crystal grain by the average grain size is 2.80 or less.

[0096] (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.

[0097] 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.

[0098] <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, it is desirable to set the soaking treatment temperature to 400°C to 450°C in order to suppress recrystallization during hot rolling and to control the grain structure uniformly. 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 is preferably within the above range. The soaking temperature is preferably about 405°C or higher, more preferably about 410°C or higher, and also preferably about 445°C or lower, more preferably about 440°C or lower. Preferred ranges include about 400-450°C, about 400-445°C, about 400-440°C, about 405-450°C, about 405-445°C, about 405-440°C, about 410-450°C, about 410-445°C, and about 410-440°C.

[0099] • 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.

[0100] <Cold Rolling> ・Final cold rolling ratio: 98% or higher ・Intermediate annealing: None The grain size is refined during the cold rolling process by applying a high rolling load, so the higher the final cold rolling ratio, the finer the grain size becomes. For this reason, a higher final cold rolling ratio is desirable, and specifically, it is desirable to set the final cold rolling ratio to 98% or higher, preferably 98.5% or higher, and more preferably 99.0% or higher. If the final cold rolling ratio is less than 98%, the grain size after final annealing will become 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 ratio.

[0101] 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.

[0102] <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.

[0103] 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.

[0104] Furthermore, in this disclosure, the aluminum alloy foil preferably has the following physical properties and composition, for example, from the viewpoint of improving the formability of the exterior material for energy storage devices.

[0105] (Physical Properties) ・0.2% yield strength in the rolling direction Existing soft foils made of aluminum alloys have low yield strength, and even slight external forces cause wrinkles and bending of the foil, resulting in poor handling during and after molding. Aluminum alloy foils are susceptible to breakage from minor impacts such as drops. By increasing the 0.2% yield strength of the aluminum alloy foil to 70 MPa or higher, handling during molding, shape retention after molding, and resistance to impacts from drops and collisions are improved. Furthermore, the characteristic of being less prone to wrinkle formation when adhesive tape is peeled off from the exterior material for energy storage devices can be more effectively exhibited. The 0.2% yield strength in the rolling direction of the aluminum alloy foil is preferably about 70 MPa or more, more preferably about 80 MPa or more, and even more preferably about 90 MPa or more. The upper limit is, for example, about 120 MPa or less, preferably about 115 MPa or less, and more preferably about 110 MPa or less. Preferred ranges include about 70 to 120 MPa, about 70 to 115 MPa, about 70 to 110 MPa, about 80 to 120 MPa, about 80 to 115 MPa, about 80 to 110 MPa, about 90 to 120 MPa, about 90 to 115 MPa, and about 90 to 110 MPa.

[0106] - Tensile strength in the rolling direction: Existing soft foils made of aluminum alloys have low strength, and even slight external forces cause wrinkles and bending of the foil, resulting in poor handling during and after forming. In addition, aluminum alloy foils are susceptible to breakage from minor impacts such as drops. Increasing the tensile strength of aluminum alloy foils will improve handling during forming, shape retention after forming, and resistance to stress loads such as impacts from drops and collisions.

[0107] The tensile strength of the aluminum alloy foil in the rolling direction is preferably about 100 MPa or more, more preferably about 120 MPa or more, and even more preferably about 130 MPa or more. The upper limit is, for example, about 200 MPa or less, and preferred ranges include about 100 to 200 MPa, about 120 to 200 MPa, and about 130 to 200 MPa.

[0108] • By increasing the elongation in the stretching and rolling direction, the material is expected to have not only high strength but also deformability, making it less prone to breakage and providing excellent impact resistance when subjected to impact. Furthermore, in the molding process of exterior materials for energy storage devices, deformation in multiple directions is added, not just stretching in one direction. By improving the elongation characteristics in each direction, excellent elongation characteristics in all directions can be expected.

[0109] Therefore, the elongation of the aluminum alloy foil in the rolling direction is preferably about 10.0% or more, more preferably about 13.0% or more, and even more preferably about 17.0% or more. The upper limit is, for example, about 40.0% or less, and preferred ranges include about 10.0 to 40.0%, about 13.0 to 40.0%, and about 17.0 to 40.0%. Furthermore, the elongation in the three directions of 0°, 45°, and 90° with respect to the rolling direction is preferably about 10.0% or more, more preferably about 13.0% or more, and even more preferably about 17.0% or more. The upper limit is, for example, about 40% or less, and preferred ranges include about 10.0 to 40.0%, about 13.0 to 40.0%, and about 17.0 to 40.0%.

[0110] When a metal with an average grain size surrounded by grain boundaries with an orientation difference of 2° or more is plastically deformed, surface irregularities (surface roughness) occur. In particular, in thin materials such as aluminum alloy foil, surface roughness can be seen as thickness non-uniformity, and by suppressing this non-uniformity, the localization of stress or deformation can be alleviated, preventing a decrease in the forming limit.

[0111] To suppress surface roughness, grain size refinement is effective, and it is desirable that the average grain size of grains surrounded by grain boundaries with an orientation difference of 2° or more be 5.5 μm or less.

[0112] - Particle size ratio expressed as maximum particle size / average particle size: 3.0 or less. Furthermore, since non-uniformity of particle size in aluminum alloy foil also contributes to surface roughness and localization of stress / deformation, it is desirable that the particle size ratio expressed as maximum particle size / average particle size be 3.0 or less. Note that "particle size ratio expressed as maximum particle size / average particle size" means "the ratio of the maximum particle size to the average particle size".

[0113] 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. Therefore, 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 easily. Therefore, it is preferable to concentrate the crystal orientations in the Cu orientation density and make that orientation density 30 or higher.

[0114] - Number density of intermetallic compounds with an equivalent circle diameter of 1.5 to 2.5 μm: Intermetallic compounds have a different deformability than 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 size of the intermetallic compounds is small or their distribution density is sparse, the effect of fine fragmentation will decrease or become partial. On the other hand, if the size of the intermetallic compounds is too large, it is likely to lead to a decrease in rollability, elongation, and formability, such as pinholes during rolling and voids during forming. Therefore, the number density of intermetallic compounds with an equivalent circle diameter of 1.5 to 2.5 μm is 4000 particles / mm². 2 It is preferable that the above conditions are met.

[0115] - Number density of intermetallic compounds with an equivalent circle diameter of 3.5 μm or more: From the same viewpoint as the number density of intermetallic compounds with an equivalent circle diameter of 1.5 to 2.5 μm, the number density of intermetallic compounds with an equivalent circle diameter of 3.5 μm or more is 500 particles / mm². 2 The following is preferable:

[0116] The measurement methods for each of the above physical properties are as follows: <0.2% proof stress and tensile strength> The 0.2% proof stress and tensile strength are measured by a tensile test (total elongation method) in accordance with JIS Z2241:2022. A JIS No. 5 test specimen is taken as the test specimen, and a universal tensile testing machine is used as the testing machine, and the measurement is performed under the condition of a tensile speed of 5 mm / min.

[0117] <Elongation in the 0°, 45°, and 90° directions relative to the rolling direction> For elongation in the 0°, 45°, and 90° directions relative to the rolling direction, the tests will be conducted using JIS Z2241:2022 No. 5 test specimens taken from 0°, 45°, and 90° directions relative to the rolling direction. The tests will be conducted using a universal tensile testing machine with a tensile speed of 5 mm / min. To calculate the elongation, two lines will be marked at 50 mm intervals (original gauge length) along the longitudinal center of the test specimen before the test. After the test, the fracture surfaces will be joined together to measure the final gauge length (L), and the elongation (mm) will be calculated by dividing it by the distance between the original gauges (Lo: 50 mm) using the following formula: ((L - Lo) / Lo) × 100

[0118] <Grain Grain Size> The 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, grain boundaries are defined as those with an orientation difference of 2° or more, and the average grain size is calculated by analyzing using the Area method under the following conditions.

[0119] The analysis software used is OIM Analysis from TSL Solutions. In the Area method, the diameter of the area calculated by considering the relative abundance of each crystal grain within the measurement region, assuming it to be a circle, is defined as the crystal grain size. The observation magnification is set to 1000x, and the field size is 150 × 38 μm. Three fields of view are observed, and the average value is calculated. Other conditions for the electron microscope are an acceleration voltage of 15 kV, a sample tilt angle of 70°, and a step size of 0.5 μm.

[0120] The conditions for the EBSD detector are as follows: Analysis software: OIM Analysis (Ver. 7.0) 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 were set to OFF. Apply partition before calculation: OFF. Include grains at edges of scan in statistics: ON.

[0121] <Cu Orientation Density> The Cu orientation density is obtained by X-ray diffraction. Imperfect pole figures are obtained, and the orientation function is determined from these imperfect pole figures using crystal orientation function analysis software. Imperfect pole figures of {111}, {200}, and {220} are measured on the surface of an aluminum alloy foil sample by X-ray diffraction. The three-dimensional orientation distribution function (ODF) is calculated using the measurement results, and the Cu orientation density is calculated.

[0122] The representative orientation for Cu is {112}<111>. As an example, a circular sample with a diameter of 40 mm is taken from an aluminum alloy foil so that the foil surface becomes the measurement surface. Next, using an X-ray diffractometer (SmartLab, manufactured by Rigaku Corporation), Schulz reflection diffractometer (α = 20° to 90°, β = 0° to 360°, measurement interval 5.0°) is performed on the measurement surface with a Cu tube voltage of 40 kV and tube current of 50 mA to obtain incomplete pole figures for (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 (StandardODF, manufactured by Norm Engineering Co., Ltd.) and a 22nd-order series expansion method. The azimuthal density for the Cu direction is assumed to be the values ​​ψ1 = 90°, φ = 35°, and ψ2 = 45°.

[0123] <Number Density of Intermetallic Compounds> The number density of intermetallic compounds is determined by mechanically polishing the surface (RD-TD surface) of an aluminum alloy foil and then observing it with a scanning electron microscope (SEM). The density is calculated by analyzing the particles in the images obtained from observations at the following magnification and range using analysis software. Observation magnification: 500x Observation range: Total area of ​​400,000 μm 2 Observation was performed using multiple fields of view as described above. SEM: Commercially available product. Image analysis software: SMILE VIEW TM Lab

[0124] (Composition) The composition of the aluminum alloy foil is preferably Fe: 0.70% by mass or more and 1.50% by mass or less, Mn: 0.160% by mass or less, Cu: 0.250% by mass or less, Si: 0.300% by mass or less, with the remainder being Al and unavoidable impurities. More preferably Fe: 1.00% by mass or more and 1.50% by mass or less, Mn: 0.160% by mass or less, Cu: 0.250% by mass or less, Si: 0.150% by mass or less, with the remainder being Al and unavoidable impurities.

[0125] • Fe: 0.70% by mass or more and 1.50% 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 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 becomes low, the effect of fine fragmentation is reduced, and the final crystal grain size distribution becomes non-uniform. On the other hand, if the Fe content is too high, the size of the Al-Fe intermetallic compounds generated during casting becomes very large, and the ductility and rollability of the aluminum alloy foil decrease. For this reason, it is preferable to set the lower limit of the Fe content to 0.70% by mass and the upper limit to 1.50% by mass. For the same reason, it is more desirable to set the lower limit to 1.00% by mass and the upper limit to 1.40% by mass. Preferred ranges for the Fe content include approximately 0.70 to 1.50 mass%, approximately 0.70 to 1.40 mass%, approximately 1.00 to 1.50 mass%, and approximately 1.00 to 1.40 mass%.

[0126] - Mn: 0.160 mass% or less. The addition of Mn can improve the tensile strength and yield strength of aluminum alloy foil. Furthermore, the addition of Mn has the effect of suppressing recovery and recrystallization during cold rolling and the resulting excessive work softening, which have been reported for Al-Fe alloys. However, if the Mn content exceeds 0.16 mass%, coarse intermetallic compounds of the Al-Fe-Mn(-Si) system tend to form, reducing the ductility and rollability of the aluminum alloy foil. For this reason, it is preferable to set the lower limit of the Mn content to 0.080 mass% and the upper limit to 0.160 mass%. More preferably, the lower limit of the Mn content is 0.100 mass% and the upper limit is 0.140 mass%. Preferred ranges for the Mn content include approximately 0.080 to 0.160 mass%, approximately 0.080 to 0.140 mass%, approximately 0.100 to 0.160 mass%, and approximately 0.100 to 0.140 mass%.

[0127] ・Cu: 0.250 mass% or less Cu is also an additive element that improves the strength of aluminum alloy foil through solid solution strengthening and suppresses recovery and recrystallization during rolling. On the other hand, if the Cu content is excessive, the elongation decreases significantly, cracks occur frequently during rolling, and the rollability decreases. For this reason, it is preferable to set the lower limit of the Cu content to 0.150 mass% and the upper limit to 0.250 mass%. More preferably, the lower limit is 0.180 mass% and the upper limit is 0.230 mass%. Preferred ranges for the Cu content include approximately 0.150 to 0.250 mass%, approximately 0.150 to 0.230 mass%, approximately 0.180 to 0.250 mass%, and approximately 0.180 to 0.230 mass%.

[0128] • Si: 0.300 mass% or less. Si crystallizes into coarse intermetallic compounds during casting. To prevent the formation of coarse intermetallic compounds, it is desirable to limit 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 0.300 mass%. More preferably, the upper limit should be 0.150 mass%, even more preferably 0.080 mass%, and even more preferably 0.060 mass%. Preferred ranges for Si content include approximately 0.010 to 0.300 mass%, 0.010 to 0.150 mass%, 0.010 to 0.080 mass%, 0.010 to 0.060 mass%, 0.020 to 0.300 mass%, 0.020 to 0.150 mass%, 0.020 to 0.080 mass%, 0.020 to 0.060 mass%, 0.040 to 0.300 mass%, 0.040 to 0.150 mass%, 0.040 to 0.080 mass%, and 0.040 to 0.060 mass%.

[0129] The remaining components of the aluminum alloy foil consist of Al 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 amounts that do not affect the properties of the aluminum alloy foil. Examples of these unavoidable impurities include elements such as magnesium (Mg), 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 of each. Preferably, the unavoidable impurities among the components of the aluminum alloy foil are 0.05% by mass or less individually and 0.15% by mass or less in total.

[0130] (Method for manufacturing aluminum alloy foil) 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.

[0131] - Homogenization treatment: Homogenization treatment is applied to 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 crystalline grain structure in the aluminum alloy foil after final annealing.

[0132] If the homogenization temperature is below 480°C, the diffusion / precipitation of solid solution atoms becomes insufficient, resulting in a high solid solution content. Furthermore, the growth of intermetallic compounds tends to be insufficient. Intermetallic compounds are effective in promoting grain fragmentation during cold rolling, and insufficient growth reduces the grain refinement effect due to fragmentation. On the other hand, if the homogenization temperature exceeds 540°C, the growth of intermetallic compounds is significant, leading to a decrease in their density.

[0133] In homogenization treatment held at a temperature range of 480 to 540°C, prolonged 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 / precipitated, the distribution of intermetallic compounds becomes non-uniform, and it becomes impossible to properly control the grain size after final annealing. 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.

[0134] <Hot Rolling> - Soaking Treatment: 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 that non-uniformity will occur 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.

[0135] If the soaking 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 during hot rolling 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 is also low, which may cause cracks to form on the sides of the aluminum alloy sheet, leading to concerns about a significant decrease in productivity. For this reason, the soaking temperature is preferably within the above range. The soaking temperature is preferably about 405°C or higher, more preferably about 410°C or higher, and also preferably about 445°C or lower, more preferably about 440°C or lower. Preferred ranges include about 400-450°C, about 400-445°C, about 400-440°C, about 405-450°C, about 405-445°C, about 405-440°C, about 410-450°C, about 410-445°C, and about 410-440°C.

[0136] • 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.

[0137] <Cold Rolling> - Intermediate annealing: None, or if it is necessary to soften (restore rollability) a material hardened by cold rolling at 300-400°C for 3 hours or more, annealing may be applied during cold rolling. However, if the temperature is below 300°C, there is a risk that recrystallization will not be completed and the grain structure will become non-uniform. Also, if the intermediate annealing temperature is higher than 400°C, the recrystallized grains will coarseen, and the final grain size will also be larger. Even if the processing time is less than 3 hours, there is a risk that recrystallization will be incomplete.

[0138] There are two methods for intermediate annealing: batch annealing, in which coils are placed in a furnace and held for a certain period of time, and continuous annealing line (CAL annealing), which rapidly heats and cools the material. Either method is acceptable when intermediate annealing is required.

[0139] For example, in batch annealing, conditions such as heating at 300-400°C for 3 hours or more can be used, while in CAL annealing, conditions such as heating rate: 100-250°C / second, heating temperature: 500-550°C, holding time: none or holding time: 5 seconds or less, and cooling rate: 20-200°C / second can be used. However, in this embodiment, the presence or absence of intermediate annealing, and the method of intermediate annealing if performed, are not limited to specific ones.

[0140] - Final cold rolling rate: 98% or higher. The grain size is refined during the cold rolling process by a high rolling load. Therefore, the higher the final cold rolling rate, the finer the grain size becomes. For this reason, a higher final cold rolling rate is desirable. Specifically, it is desirable to set the final cold rolling rate to 98%, 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 will become coarser or non-uniform, making it difficult to achieve the desired strength and ductility.

[0141] - The thickness of the aluminum alloy foil can be adjusted to the desired thickness by the final cold rolling process. In this embodiment, the thickness is not particularly limited, but for example, it can be 20 to 100 μm thick.

[0142] <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.

[0143] For example, an aluminum alloy foil having the above composition and physical properties can be suitably manufactured by the above manufacturing method.

[0144] The preferred physical properties and composition of the aluminum alloy foil, as well as its manufacturing method, are as described above. However, in this disclosure, the 0.2% yield strength of the barrier layer 3 must be set to 60 MPa or higher.

[0145] In this disclosure, the 0.2% yield strength of the barrier layer 3 is high rigidity of 60 MPa or more. From the viewpoint of further increasing the rigidity of the exterior material for energy storage devices, the 0.2% yield strength of the barrier layer 3 is preferably 60 MPa or more, more preferably 100 MPa or more, and even more preferably 120 MPa or more. Furthermore, from the viewpoint of improving the moldability of the exterior material for energy storage devices, the upper limit is preferably 200 MPa or less, more preferably 180 MPa or less, and even more preferably 160 MPa or less. Preferred ranges include 60 to 200 MPa, 60 to 180 MPa, 60 to 160 MPa, 100 to 200 MPa, 100 to 180 MPa, 100 to 160 MPa, 120 to 200 MPa, 120 to 180 MPa, and 120 to 160 MPa. The method for measuring the 0.2% yield strength of the barrier layer 3 is as follows.

[0146] <0.2% yield strength of the barrier layer> The 0.2% yield strength of the barrier layer is measured by a tensile test (total elongation method) in accordance with JIS Z2241:2022. A JIS No. 5 test specimen is taken as the test specimen, and the test is performed using a universal tensile testing machine at a tensile speed of 5 mm / min.

[0147] The barrier layer 3 may also include, in addition to the aluminum alloy foil, a barrier-type metal foil (excluding the aluminum alloy foil), a vapor-deposited film, a resin layer, etc. 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. Multiple layers of barrier layer 3 may be provided. If the barrier layer 3 includes a layer composed of a metal material different from the aluminum alloy foil, specific examples of such metal materials include stainless steel, titanium steel, and steel plates. These metal materials can be joined during the rolling of the aluminum alloy foil, or the aluminum alloy foil and stainless steel foil can be bonded together using an adhesive.

[0148] In barrier layer 3, the layers composed of the aforementioned aluminum alloy foil and other metallic materials may each contain recycled aluminum alloy or other metallic materials. Examples of recycled other metallic materials include recycled stainless steel, titanium steel, or steel sheets. 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 materials, or it may be composed of a mixture of recycled and virgin materials. Recycled aluminum alloy and other metallic materials refer to metallic materials that have been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make them reusable. Virgin aluminum alloy and other metallic materials refer to new metallic materials refined from natural metallic resources (raw materials) that are not recycled materials.

[0149] Examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Furthermore, 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.

[0150] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0151] In this disclosure, the thickness of the aluminum alloy foil included in the barrier layer 3 is 55 μm or more. From the viewpoint of more favorably exhibiting the effects of the invention of this disclosure, the thickness of the aluminum alloy foil is preferably about 65 μm or more, more preferably about 75 μm or more, even more preferably about 85 μm or more, and also preferably about 100 μm or less, more preferably about 95 μm or less, even more preferably about 90 μm or less. Preferred ranges include about 55 to 100 μm, about 55 to 95 μm, about 55 to 90 μm, about 65 to 100 μm, about 65 to 95 μm, about 65 to 90 μm, about 75 to 100 μm, about 75 to 95 μm, about 75 to 90 μm, about 85 to 100 μm, about 85 to 95 μm, and about 85 to 90 μm.

[0152] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the thickness of the barrier layer 3 is preferably about 55 μm or more, more preferably about 65 μm or more, even more preferably about 75 μm or more, and also preferably about 120 μm or less, more preferably about 110 μm or less, even more preferably about 100 μm or less. Preferred ranges include about 55 to 120 μm, about 55 to 110 μm, about 55 to 100 μm, about 65 to 120 μm, about 65 to 110 μm, about 65 to 100 μm, about 75 to 120 μm, about 75 to 110 μm, and about 75 to 100 μm.

[0153] Furthermore, it is preferable that the barrier layer 3 has a corrosion-resistant coating on at least the side opposite to the base layer 1 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.

[0154] 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.

[0155] 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.

[0156]

[0157]

[0158]

[0159]

[0160] 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.

[0161] Another example of a corrosion-resistant film is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant film can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0162] 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.

[0163] 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.

[0164] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0165] 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.

[0166] 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:

[0167] 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.

[0168] [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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] [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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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).

[0192] 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).

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0204] 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.

[0205] 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.

[0206] [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.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] [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. One example is a method that includes the step of laminating, from the outside in, at least the barrier layer 3 and the heat-fusible resin layer 4 in that order.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0228] 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.

[0229] [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.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, condensers, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the casing material for energy storage devices disclosed herein can be applied is not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, 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, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. Furthermore, energy storage devices utilizing the casing material for energy storage devices disclosed herein can be suitably used in various devices, automobiles, and the like. In other words, this disclosure can provide mobile devices (specifically, various types of vehicles and means of transport for carrying people and goods, such as automobiles, trucks, buses, bicycles such as electric bicycles and electric-assist bicycles, ships, and unmanned aerial vehicles), electronic devices (specifically, various devices such as mobile products (smartphones, tablets, and personal computers), energy storage systems (ESS), and e-cigarettes), etc., including the energy storage devices of this disclosure.

[0235] 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.

[0236] <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 25 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8079H-O (thickness 80 μm)) 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 made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum alloy foil using the roll coating method and then baking it, so that the dry mass was [dry mass].

[0237] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0238] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (30 μm thick), and random polypropylene, which forms a heat-fusible resin layer (a two-layer structure consisting of a 30 μm thick layer and a 20 μm thick layer), were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order. The laminate configuration is shown in Table 1.

[0239] In Example 1, the average gradient of the tensile strength in the tensile test of the laminate constituting the exterior material for the energy storage device was adjusted by a method in which, in the manufacturing process of the exterior material for the energy storage device, a heat-fusible resin layer 4 and then an adhesive layer 5 were laminated to the laminate, which consists of a base layer 1 and a barrier layer 3, by melt extrusion, and the cooling temperature (cooling temperature) was set to a ratio of 0.7 when Comparative Example 1 was set to a reference value of 1, thereby rapidly cooling the laminate, which was heated by the heat, such as the heat-fusible resin layer 4 that was melted at a high temperature, and the base layer 1 and barrier layer 3 were rapidly cooled. Furthermore, the base layer 1 and barrier layer 3 were laminated by the dry lamination method, and the drying temperature was set to a low temperature of a ratio of 0.8 when Comparative Example 1 was set to a reference value of 1, thereby quickly removing the heat applied to the base layer 1 and barrier layer 3 by the dry lamination method and suppressing the slow cooling of the base layer 1 and barrier layer 3, thereby adjusting the design to reduce the overall rigidity of the laminate.

[0240] [Example 2] As a base layer, a laminate was prepared in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 25 μm) and an oriented nylon (ONy) film (thickness 25 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8079H-O (thickness 80 μm)) 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 made of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 This was carried out by applying the coating to both sides of the aluminum alloy foil using the roll coating method and then baking it, so that the dry mass was [dry mass].

[0241] Next, using a two-component curing urethane adhesive, the substrate layer and the barrier layer were bonded together with an adhesive layer (3 μm thick) by a dry lamination method, and a laminate was fabricated in which the substrate layer / adhesive layer / barrier layer were stacked in that order.

[0242] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 μm thick), were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order. The lamination configuration is shown in Table 1.

[0243] In Example 2, the average gradient of the tensile strength in the tensile test of the laminate constituting the exterior material for the energy storage device was adjusted by rapidly cooling the laminate, which consists of a base layer 1 and a barrier layer 3, with a heat-fusible resin layer 4 and then an adhesive layer 5 laminated to it by melt extrusion during the manufacturing process of the exterior material for the energy storage device. The cooling temperature was set to a ratio of 0.5 compared to Comparative Example 1, which was set to a reference value of 1, thereby suppressing the slow cooling of the base layer 1 and barrier layer 3, which were heated by the heat, such as the heat-fusible resin layer 4 that was melted at a high temperature. Furthermore, when laminating the base layer 1 and the barrier layer 3 by the dry lamination method, the drying temperature was set to a low temperature of 0.6 compared to Comparative Example 1, which was set to a reference value of 1, thereby quickly removing the heat applied to the base layer 1 and barrier layer 3 by the dry lamination method and suppressing the slow cooling of the base layer 1 and barrier layer 3. This was done by designing the laminate to have a reduced overall rigidity.

[0244] [Example 3] The resins for the heat-fusible resin layer and adhesive layer of the exterior material for the energy storage device were the same as in Example 1, and the cooling temperature during melt extrusion and the drying temperature setting for the dry lamination method were the same as in Example 2, thereby obtaining an exterior material for an energy storage device consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in this order.

[0245] [Example 4] In the tensile strength test of the laminate constituting the exterior material for energy storage devices, a method was adopted in which, in the manufacturing process of the exterior material for energy storage devices, a heat-fusible resin layer 4 and an adhesive layer 5 were laminated to the laminate in which the base layer 1 and barrier layer 3 were laminated by melt extrusion, and the temperature during cooling (cooling temperature) was set to a ratio of 0.7 with Comparative Example 1 as the reference value of 1, and the base layer 1 and barrier layer 3, which were heated by the heat such as the heat-fusible resin layer 4 that was melted at a high temperature, were rapidly cooled to suppress the slow cooling of the base layer 1 and barrier layer 3. Furthermore, when laminating the base layer 1 and the barrier layer 3 by dry lamination, the drying temperature was set to a lower temperature, a ratio of 0.6 compared to Comparative Example 1 (where Comparative Example 1 is set to a reference value of 1). This adjustment was made to quickly remove the heat applied to the base layer 1 and the barrier layer 3 by dry lamination, thereby suppressing the slow cooling of the base layer 1 and the barrier layer 3, and thus reducing the overall rigidity of the laminate. In short, an exterior material for an energy storage device was obtained in the same manner as in Example 1, consisting of a laminate in which the base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order.

[0246] [Example 5] In the manufacturing method for the exterior material for energy storage devices of Example 2, an exterior material for energy storage devices was obtained in the same manner as in Example 2, except that an aluminum alloy foil (JIS H4160:1994 A8079H-O (thickness 60 μm)) was used as the barrier layer. The laminate consisted of a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer laminated in this order. In Example 5, due to the effect of having a thinner barrier layer than in Example 2, the design was such that the rigidity of the entire laminate was reduced in addition to the effect of improving the cooling rate, and the average value of the slope of the tensile strength in the tensile test of the laminate constituting the exterior material for energy storage devices was reduced.

[0247] [Comparative Example 1] Except for not actively designing the laminate to reduce the rigidity of the laminate constituting the exterior material for energy storage devices, and manufacturing it under general conditions (the heat-fusible resin layer 4 and further the adhesive layer 5 are laminated by melt extrusion, and the cooling temperature (cooling temperature) is set to a ratio of 0.6 when the crystallization temperature of the outermost layer of the base material is set to a reference value of 1, and when the base material layer 1 and the barrier layer 3 are laminated by a dry lamination method, the drying temperature is set to a ratio of 0.7 when the crystallization temperature of the outermost layer of the base material is set to a reference value of 1), an exterior material for energy storage devices was obtained in the same manner as in Example 2, consisting of a laminate in which a base material layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer is laminated in this order.

[0248]

[0249] In the laminate configurations listed in Table 1, PET represents polyethylene terephthalate film, ONy represents stretched nylon film, AL represents aluminum alloy foil, PPa represents maleic anhydride-modified polypropylene, PP represents random polypropylene, and DL represents the adhesive layer formed by the dry lamination method. The numerical values ​​in the laminate configuration represent the thickness (μm) of each layer, and " / " indicates the boundary between each layer.

[0250] <Measurement of the average value of the gradient of tensile strength in four directions of the laminate> Each exterior material for energy storage devices obtained in the examples and comparative examples was measured using a tensile testing machine (Shimadzu AGX-plus) in accordance with the provisions of JIS K7127:1999. The tensile test was performed under the measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and an initial distance between the chucks of 30 mm. In the tensile tests in this disclosure, the initial distance between the chucks was 30 mm, and this initial distance between the chucks was defined as the distance between the gauge marks. Four types of measurement samples were prepared for each exterior material for energy storage devices, with lengths of 100 mm in the MD direction, 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 these length directions. For the MD direction, TD direction, 45° direction between MD and TD, and -45° direction between MD and TD of the exterior material for energy storage devices, refer to Figure 6. 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 set to 0°, and the direction perpendicular to the MD direction was set to the TD direction. Sample 3 was a measurement sample with a length of 100 mm in the direction 45° clockwise from the MD direction (for 45° direction measurement), and a width of 15 mm perpendicular to that length direction. Sample 4 was a measurement sample (for measurement in the -45° direction) with a length of 100 mm in the direction 45° counterclockwise, with the MD direction set to 0°. Next, each measurement sample was subjected to a tensile test under the above measurement conditions, and the tensile strength was measured from a displacement of 0.5% to a displacement of 2.0%, and the average value of the slope of the tensile strength in the four directions was calculated. The slope of the tensile strength was calculated by measuring the tensile strength (MPa) at a displacement of 2.0% and the tensile strength (MPa) at a displacement of 0.5%, and applying these two tensile strengths (MPa) at displacements to the following formula: (Slope of tensile strength = [Tensile strength (MPa) at 2.0% displacement - Tensile strength (MPa) at 0.5% displacement] / (0.02 - 0.005)).Table 1 shows the average values ​​of the slopes of the tensile strength in each of the four directions mentioned above.

[0251] <Measurement of the average tensile strength of the base material layer in four directions> (Preparation of measurement samples) For each exterior material for energy storage devices obtained in the examples and comparative examples, the base material layer was peeled off from the barrier layer by the following method, and the base material layer (a laminate of PET and ONy) was obtained as a measurement sample. To obtain the measurement sample, a cutter knife was used to cut from the heat-fusible resin layer side of the exterior material for energy storage devices to the barrier layer (cutting the barrier layer as well), and the base material was peeled off by carefully pulling it 180 degrees in the opposite direction, using the cut as a fulcrum.

[0252] (Measurement of Tensile Strength) Each of the obtained measurement samples was measured using a tensile testing machine (Shimadzu AGX-plus) in accordance with the provisions of JIS K7127:1999. The tensile test was performed under the following conditions: a 25°C environment, a tensile speed of 300 mm / min, and an initial distance of 30 mm between the chucks. The base material layers used as measurement samples were divided into four types of measurement samples, each with 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 these length directions. 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 measurement in the MD direction). 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 measurement in the TD direction). Similar to the exterior material for the energy storage device 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. 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 as 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 as 0°, and a width of 15 mm perpendicular to that length direction. Next, for each of the measurement samples 1 to 4, a tensile test was performed along the length of the measurement sample under the above measurement conditions, and the tensile strength (MPa) at a displacement of 5% was measured. The average values ​​of the tensile strength (MPa) for the four directions of the base material layer are shown in Table 1.

[0253] [Moldability Evaluation] <Measurement of Molding Depth> Each exterior material for the energy storage device was cut into a square with a length (MD direction) of 200 mm and a width (TD direction) of 200 mm to prepare a test sample. The MD of the exterior material for the energy storage device corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for the energy storage device corresponds to the TD of the aluminum alloy foil. This sample was subjected to a 25°C environment using a rectangular molding die (female mold, 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 Annex 1 (Reference) of JIS B 0659-1:2002, corner radius 3.0 mm, edge radius 1.0 mm) and a corresponding molding die (male mold, surface of the edge has a maximum height roughness (nominal value of Rz) of 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002, and surface other than the edge has a maximum height roughness (nominal value of Rz) of 1.6 μm, as specified in Table 2 of the comparative surface roughness standard specimens in Annex 1 (Reference) of JIS B 0659-1:2002 The maximum height roughness (nominal value of Rz) is 3.2 μm, as specified in Table 2 of the comparative surface roughness standard specimens. Using corner radius 2.0 mm and edge radius 1.5 mm, cold forming (single-stage pull-in forming) was performed on 10 samples each, with a pressing pressure (surface pressure) of 0.28 MPa and varying the forming depth in 0.5 mm increments starting from 0.5 mm. At this time, the test sample was placed on the female mold so that the heat-fusible resin layer side was positioned on the male mold side, and forming was performed. 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 foil by light transmission. The deepest molding depth at which no pinholes or cracks occurred in any of the 10 aluminum foil samples was defined as A mm. The shallowest molding depth at which pinholes or cracks occurred was defined as B, and the number of samples with pinholes or cracks 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. The results are shown in Table 1. Limit molding depth = A mm + (0.5 mm / 10 samples) × (10 samples - B samples)

[0254] The exterior materials for energy storage devices in Examples 1 to 5 are each composed of a laminate comprising, from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer, in that order. The base layer contains at least one of polyester and polyamide, and the thickness of the base layer is 40 μm or more. The barrier layer contains aluminum alloy foil, and the thickness of the aluminum alloy foil is 55 μm or more. The average value of the gradient of the tensile strength is less than 950 MPa. From the results shown in Table 1, it can be seen that the exterior materials for energy storage devices in Examples 1 to 5 have excellent moldability.

[0255] 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 base layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the base layer contains at least one of polyester and polyamide, the thickness of the base layer is 40 μm or more, the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 55 μm or more, and the average value of the slope of each tensile strength measured as follows is less than 950 MPa. (Measurement) 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 aforementioned sample, and the tensile strength is measured at displacements of 0.5% to 2.0% in the longitudinal direction under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm. The average value of the slope of the tensile strength in the four directions is calculated. The slope of each tensile strength is calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005) Item 2. The exterior material for energy storage devices according to Item 1, wherein the thickness of the aluminum alloy foil is 55 μm or more and 100 μm or less. Item 3. The exterior material for energy storage devices according to Item 1 or 2, wherein the thickness of the base layer is 40 μm or more and 100 μm or less. Item 4. The exterior material for energy storage devices according to any one of Items 1 to 3, further comprising an adhesive layer between the base layer and the barrier layer. Item 5. An exterior material for an energy storage device according to any one of claims 1 to 4, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer. Claim 6. An exterior material for an energy storage device according to any one of claims 1 to 5, wherein the average value of the gradient of each tensile strength is 500 MPa or more and less than 950 MPa. Claim 7. An exterior material for an energy storage device according to any one of claims 1 to 6, wherein the base material layer obtained by peeling off the laminate has an average value of each tensile strength measured as follows: 70 MPa or less.(Measurement) Four types of measurement samples are prepared for the base material layer obtained by peeling off the laminate, with lengths 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 5.0% in the length direction is measured under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the tensile strength in the four directions is calculated. Item 8. The base material layer obtained by peeling off the laminate is an exterior material for an energy storage device according to any one of items 1 to 7, wherein the average value of each tensile strength measured below is 45 MPa or more and 70 MPa or less. (Measurement) Four types of measurement samples are prepared from the substrate layer obtained by peeling off the laminate, with lengths 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 5.0% in the length direction is measured under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the tensile strength in the four directions is calculated. Section 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 base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order from the outside, wherein the base layer comprises at least one selected from the group consisting of polyester and polyamide, the thickness of the base layer is 40 μm or more, the barrier layer comprises aluminum alloy foil, the thickness of the aluminum alloy foil is 55 μm or more, and the average value of the slope of each tensile strength measured as follows is less than 950 MPa. (Measurement) Four types of measurement samples are prepared for the laminate, 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 aforementioned sample, and the tensile strength is measured at displacements of 0.5% to 2.0% in the longitudinal direction under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm. The average value of the slope of the tensile strength in the four directions is calculated. The slope of each tensile strength is calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005) 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. Item 11. A mobile body comprising the energy storage device described in Item 10. Item 12. An electronic device comprising the energy storage device described in Item 10.

[0256] 1. Base layer 2. Adhesive layer 3. Barrier layer 4. Heat-fusible resin layer 5. Adhesive layer 6. Surface coating layer 10. Exterior material for energy storage devices

Claims

1. An exterior material for an energy storage device, comprising a laminate comprising, from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer in this order, wherein the base layer contains at least one of polyester and polyamide, the thickness of the base layer is 40 μm or more, the barrier layer contains aluminum alloy foil, the thickness of the aluminum alloy foil is 55 μm or more, and the average value of the gradient of each tensile strength measured as follows is less than 950 MPa. (Measurement) 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 is measured at displacements from 0.5% to 2.0% in the length direction under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the gradient of the tensile strength in the four directions is calculated. The slope of each tensile strength is calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005) 2. The exterior material for an energy storage device according to claim 1, wherein the thickness of the aluminum alloy foil is 55 μm or more and 100 μm or less.

3. The exterior material for an energy storage device according to claim 1, wherein the thickness of the base material layer is 40 μm or more and 100 μm or less.

4. The exterior material for an energy storage device according to claim 1, further comprising an adhesive layer between the base material layer and the barrier layer.

5. The exterior material for an energy storage device according to claim 1, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.

6. The exterior material for an energy storage device according to claim 1, wherein the average value of the gradient of each tensile strength is 500 MPa or more and less than 950 MPa.

7. The exterior material for an energy storage device according to claim 1, wherein the base material layer obtained by peeling off the laminate has an average value of 70 MPa or less for each tensile strength measured as follows. (Measurement) Four types of measurement samples are prepared for the base material layer obtained by peeling off the laminate, with lengths 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 5.0% in the length direction is measured under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the tensile strength in the four directions is calculated.

8. The exterior material for an energy storage device according to claim 1, wherein the base material layer obtained by peeling off the laminate has an average tensile strength of 45 MPa or more and 70 MPa or less, as measured below. (Measurement) Four types of measurement samples are prepared for the base material layer obtained by peeling off the laminate, with lengths 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 5.0% in the length direction is measured under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the tensile strength in the four directions is calculated.

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 base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order from the outside, wherein the base layer comprises at least one selected from the group consisting of polyester and polyamide, the thickness of the base layer is 40 μm or more, the barrier layer comprises aluminum alloy foil, the thickness of the aluminum alloy foil is 55 μm or more, and the average value of the slope of each tensile strength measured as follows is less than 950 MPa. (Measurement) 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 is measured at displacements from 0.5% to 2.0% in the length direction under measurement conditions of a 25°C environment, a tensile speed of 300 mm / min, and a chuck distance of 30 mm, and the average value of the gradient of the tensile strength in the four directions is calculated. The slope of each tensile strength is calculated using the following formula: Slope of tensile strength = [Tensile strength at 2.0% displacement (MPa) - Tensile strength at 0.5% displacement (MPa)] / (0.02 - 0.005) 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 an energy storage device according to any one of claims 1 to 8.

11. A mobile body comprising the energy storage device described in claim 10.

12. An electronic device comprising the energy storage device described in claim 10.

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