Power storage device, method for manufacturing same, and exterior material for power storage device

Abstract

Provided is an exterior material for a power storage device, which achieves both suppression of wrinkles at a time when an adhesive tape is peeled off and excellent formability.　The exterior material for a power storage device comprises a first exterior material for a power storage device and a second exterior material for the power storage device. The first exterior material for the power storage device and the second exterior material for the power storage device are each composed of a laminated body including at least a barrier layer and a heat-fusible resin layer in the stated order from the outside. The barrier layers include stainless steel foil. When a tensile test is performed on the laminated body constituting the first exterior material for the power storage device under measurement conditions of the environment at 25°C, the tensile speed of 50 mm / min, and the chuck-to-chuck distance of 30 mm, the tensile strength A1 (N / 15 mm) of a measurement sample having dimensions of 15 mm in the TD direction and 100 mm in the MD direction and having been displaced by 10% in the MD direction is measured, and the tensile strength B1 (N / 15 mm) of a measurement sample having dimensions of 15 mm in the MD direction and 100 mm in the TD direction and having been displaced by 10% in the TD direction is measured, the calculated average value of the tensile strength A1 and the tensile strength B1 is 80 N / 15 mm or more. When a tensile test is performed on the laminated body constituting the second exterior material for the power storage device under measurement conditions of the environment at 25°C, the tensile speed of 50 mm / min, and the chuck-to-chuck distance of 30 mm, the tensile strength A2 (N / 15 mm) of a measurement sample having dimensions of 15 mm in the TD direction and 100 mm in the MD direction and having been displaced by 10% in the MD direction is measured, and the tensile strength B2 (N / 15 mm) of a measurement sample having dimensions of 15 mm in the MD direction and 100 mm in the TD direction and having been displaced by 10% in the TD direction is measured, the calculated average value of the tensile strength A2 and the tensile strength B2 is less than 80 N / 15 mm.

Description

Electric storage device, method for manufacturing same, and exterior material for electric storage device

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

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

[0003] On the other hand, in recent years, with the improvement in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., various shapes have been required for electric storage devices, and thinning and weight reduction have been demanded. However, the conventionally frequently used metal exterior materials for electric storage devices have the drawbacks 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 electric 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 / a barrier layer / a heat-sealable resin layer are sequentially laminated has been proposed (for example, see Patent Document 1).

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

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

[0007] In recent years, electric storage devices (such as lithium ion batteries) mounted in mobile products such as smartphones are required to be removable batteries from the viewpoint of reducing the environmental load due to product disposal. When fixing the electric storage device to the housing of the product, the housing and the electric storage device are reinforced and fixed with an adhesive tape. Therefore, when removing the electric storage device from the product, it is necessary to peel the electric storage device from the adhesive tape.

[0008] As described above, in recent years, a film-like laminate has been proposed as an exterior material for a power storage device that can be easily processed into various shapes and can achieve thinning and weight reduction. A power storage device using such a film-like exterior material has a characteristic that the exterior material is soft compared to an exterior material such as a metal can. Therefore, when peeling the power storage device from the adhesive tape, there is a problem that the exterior material is plastically deformed and wrinkles are easily formed.

[0009] Also, for example, when a consumer tries to replace a power storage device such as a mobile product, if the adhesive tape is misapplied and the operation of peeling off the adhesive tape from the power storage device and reapplying it is performed, wrinkles are easily formed in the exterior material. When wrinkles are formed in the exterior material, it may be difficult to fix the power storage device to the product. In addition, if the power storage device is used with wrinkles formed in the exterior material, there is also a possibility that the power storage device may not function properly.

[0010] From the viewpoint of increasing the battery capacity of the power storage device, it is desirable to form a deep recess for accommodating the power storage device element in the exterior material for the power storage device, and the exterior material for the power storage device is required to have excellent formability.

[0011] Under such circumstances, the main object of the present disclosure is to provide a power storage device in which suppression of wrinkles when peeling the adhesive tape and excellent formability are compatible. Another object of the present disclosure is to provide an exterior material for a power storage device for using the power storage device and a manufacturing method of the power storage device.

[0012] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that in an energy storage device in which an energy storage device element is housed in a package formed of an outer material for energy storage devices, the outer material for energy storage devices is composed of a combination of a first outer material for energy storage devices and a second outer material for energy storage devices, and the first and second outer materials for energy storage devices are each composed of a laminate having at least a barrier layer and a heat-fusible resin layer in that order from the outside, the barrier layer of the first outer material for energy storage devices contains stainless steel foil, and the laminates constituting the first and second outer materials for energy storage devices each have a predetermined tensile strength, thereby achieving both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability.

[0013] Furthermore, the inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that in an energy storage device in which an energy storage device element is housed in a package formed of an outer material for energy storage devices, the outer material for energy storage devices is a combination of a first outer material for energy storage devices and a second outer material for energy storage devices, and the first and second outer materials for energy storage devices are each composed of a laminate having at least a barrier layer and a heat-fusible resin layer in that order from the outside, and the barrier layer of the first outer material for energy storage devices contains aluminum alloy foil, the 0.2% yield strength of the aluminum alloy foil is above a predetermined value, and the laminates constituting the first and second outer materials for energy storage devices each have a predetermined tensile strength, thereby achieving both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability.

[0014] Furthermore, the inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that in an energy storage device in which an energy storage device element is housed in a package formed of an outer material for energy storage devices, the outer material for energy storage devices is composed of a combination of a first outer material for energy storage devices and a second outer material for energy storage devices, and the first and second outer materials for energy storage devices are each composed of a laminate having at least a barrier layer and a heat-sealable resin layer in that order from the outside, the barrier layer of the first outer material for energy storage devices contains aluminum alloy foil, the thickness of the aluminum alloy foil is 50 μm or more, and the laminates constituting the first and second outer materials for energy storage devices each have a predetermined tensile strength, thereby achieving both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability.

[0015] This disclosure is the result of further consideration based on these findings. Specifically, this disclosure provides inventions in the following embodiments.

[0016] (First Embodiment) 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and the first energy storage device exterior material and the second energy storage device exterior material are each composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, in that order, and the barrier layer includes stainless steel foil. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

[0017] (Second Embodiment) 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and the first energy storage device exterior material and the second energy storage device exterior material are each composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer in this order, the barrier layer includes an aluminum alloy foil, and the 0.2% yield strength of the aluminum alloy foil is 70 MPa or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

[0018] (Third Embodiment) 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and the first energy storage device exterior material and the second energy storage device exterior material are each composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes an aluminum alloy foil, and the thickness of the aluminum alloy foil is 50 μm or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

[0019] This disclosure provides an energy storage device that achieves both suppression of wrinkles when adhesive tape is peeled off and excellent moldability. Furthermore, this disclosure provides a method for manufacturing the energy storage device and an exterior material for the energy storage device used therein.

[0020] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for the energy storage device (first exterior material for the energy storage device, second exterior material for the energy storage device) of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for the energy storage device (first exterior material for the energy storage device, second exterior material for the energy storage device) of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for the energy storage device (first exterior material for the energy storage device, second exterior material for the energy storage device) of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for the energy storage device (first exterior material for the energy storage device, second exterior material for the energy storage device) of the present disclosure. This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for the energy storage device (first exterior material for the energy storage device, second exterior material for the energy storage device) of the present disclosure. This is a schematic plan view of the energy storage device of the present disclosure. This is a schematic cross-sectional view along line A-A' in Figure 6. This is a schematic diagram for explaining the evaluation method for wrinkle formation. This is a schematic cross-sectional view along line A-A' in Figure 8g. This is a schematic diagram illustrating the method for selecting adhesive tape. This is a schematic cross-sectional view along line A-A' in Figure 10.

[0021] The exterior material for the energy storage device included in the energy storage device of this disclosure provides excellent effects, such as suppressing wrinkles when the adhesive tape is peeled off and achieving excellent moldability, by combining a first exterior material for the energy storage device having a predetermined barrier layer and a laminate constituting the exterior material having a predetermined tensile strength with a second exterior material for the energy storage device having a predetermined tensile strength.

[0022] More specifically, the exterior material for an energy storage device according to a first aspect of the present disclosure comprises a first exterior material for an energy storage device and a second exterior material for an energy storage device, wherein the first exterior material for an energy storage device and the second exterior material for an energy storage device are each composed of a laminate comprising, from the outside in, at least a barrier layer and a heat-sealable resin layer, and the barrier layer includes stainless steel foil. Furthermore, a tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. Furthermore, a tensile test was performed on the laminate constituting the second energy storage device exterior material under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 were calculated to be less than 80 N / 15 mm. The energy storage device exterior material according to the first aspect of this disclosure exhibits the excellent effect of achieving both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability by possessing the above features.

[0023] Furthermore, the exterior material for an energy storage device according to a second aspect of the present disclosure comprises a first exterior material for an energy storage device and a second exterior material for an energy storage device, wherein the first exterior material for an energy storage device and the second exterior material for an energy storage device are each composed of a laminate having, from the outside in at least, a barrier layer and a heat-sealable resin layer, and the barrier layer contains aluminum alloy foil, and the 0.2% yield strength of the aluminum alloy foil is 70 MPa or more. Furthermore, a tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. Furthermore, a tensile test was performed on the laminate constituting the second energy storage device exterior material under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 were calculated to be less than 80 N / 15 mm. The second aspect of the energy storage device exterior material according to this disclosure exhibits the excellent effect of achieving both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability by possessing these features.

[0024] Furthermore, the exterior material for an energy storage device according to a third aspect of the present disclosure comprises a first exterior material for an energy storage device and a second exterior material for an energy storage device, wherein the first exterior material for an energy storage device and the second exterior material for an energy storage device are each composed of a laminate having, from the outside in at least, a barrier layer and a heat-sealable resin layer, and the barrier layer includes an aluminum alloy foil, the thickness of which is 50 μm or more. Furthermore, a tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. Furthermore, a tensile test was performed on the laminate constituting the second energy storage device exterior material under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 were calculated to be less than 80 N / 15 mm. The third aspect of the present disclosure of the energy storage device exterior material, by possessing these features, exhibits the excellent effect of simultaneously suppressing wrinkles when the adhesive tape is peeled off and having excellent moldability.

[0025] The following details the energy storage device and the exterior material for the energy storage device described herein. 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.

[0026] 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.

[0027] 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).

[0028] [Energy Storage Device] [Laminated Structure and Physical Properties of Exterior Material for Energy Storage Device] In the energy storage device 20 of this disclosure, the first exterior material 11 and the second exterior material 12 of the exterior material 10 for the energy storage device are each composed of a laminate having a barrier layer 3 and a heat-fusible resin layer 4 in that order, as shown in Figure 1, for example. In the following description, the first exterior material 11 and the second exterior material 12 for the energy storage device will be collectively referred to as the exterior material 10 for the energy storage device.

[0029] In the first energy storage device exterior material 11 and the second energy storage device exterior material 12, the barrier layer 3 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. As shown in Figures 6 and 7, when assembling an energy storage device using the first energy storage device exterior material 11 and the second energy storage device exterior material 12 and the energy storage device element E, the energy storage device element E is housed in a space formed by heat-fussing the peripheral edges (forming a heat-fusible portion S) with the heat-fusible resin layers of the first energy storage device exterior material 11 and the second energy storage device exterior material 12 facing each other. In the schematic diagrams shown in Figures 6 and 7, the shape of the second energy storage device exterior material 12 is such that a molded portion M (recess) for housing the energy storage device element E is formed from the heat-fusible resin layer side toward the barrier layer side.

[0030] In the energy storage device 20 of this disclosure, the shape of the exterior material 11 for the first energy storage device is preferably flat (no recesses (molded parts) are formed).

[0031] On the other hand, in the energy storage device 20 of this disclosure, the shape of the outer casing material 12 for the second energy storage device is preferably such that a recess (molded portion M) for accommodating the energy storage device element E is formed from the heat-fusible resin layer 4 side toward the barrier layer 3 side. The depth of the recess is not particularly limited and is set appropriately according to the application and size of the energy storage device 20, the thickness of the outer casing material 12 for the second energy storage device, etc. For example, when the thickness of the outer casing material 12 for the second energy storage device is about 70 to 230 μm, from the viewpoint of increasing the energy density of the energy storage device 20, the depth of the recess is preferably 6.0 mm or more, more preferably 7.0 mm or more, more preferably 8.0 mm or more, and the upper limit is 15.0 mm or less.

[0032] In the laminates constituting the first energy storage device exterior material 11 and the second energy storage device exterior material 12, the heat-fusible resin layer 4 side is on the inside relative to the barrier layer 3, and the opposite side is on the outside, with respect to the barrier layer 3.

[0033] The first energy storage device exterior material 11 and the second energy storage device exterior material 12 may each have a base layer 1 on the side of the barrier layer 3 opposite to the heat-fusible resin layer 4, for example, as shown in Figures 2 to 5. Also, as shown in Figures 3 to 5, for example, an adhesive layer 2 may be provided between the base layer 1 and the barrier layer 3, if necessary, for the purpose of improving the adhesion between these layers. Also, as shown in Figures 4 and 5, for example, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4, if necessary, for the purpose of improving the adhesion between these layers. Furthermore, as shown in Figure 5, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (opposite to the heat-fusible resin layer 4), if necessary.

[0034] The thickness of the laminates constituting the first energy storage device exterior material 11 and the second energy storage device exterior material 12 is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, for example, it can be about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the energy storage device exterior material, which is to protect the energy storage device elements, the thickness of the laminates constituting the first energy storage device exterior material 11 and the second energy storage device exterior material 12 can be preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, the preferred range for the laminate constituting the exterior material 10 for the energy storage device is, for example, approximately 35 to 300 μm, approximately 35 to 250 μm, approximately 35 to 210 μm, approximately 35 to 190 μm, approximately 35 to 180 μm, approximately 35 to 155 μm, approximately 35 to 120 μm, approximately 45 to 300 μm, approximately 45 to 250 μm, approximately 45 to 210 μm, approximately 45 to 190 μm, approximately 45 to 180 μm, approximately 45 to 155 μm, approximately 45 to 120 μm, approximately 60 to 300 μm, approximately 60 to 250 μm, and 60 to Examples of suitable thicknesses include approximately 210 μm, 60-190 μm, 60-180 μm, 60-155 μm, 60-120 μm, 155-300 μm, 155-250 μm, 155-210 μm, 155-190 μm, 155-180 μm, 190-300 μm, 190-250 μm, and 190-210 μm. In particular, when creating lightweight thin films for energy storage devices, approximately 60-155 μm is preferred, and when improving moldability, approximately 155-190 μm is preferred.

[0035] In the first energy storage device exterior material 11 and the second energy storage device exterior material 12, the ratio of the total thickness of the optional base layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, heat-fusible resin layer 4, and optional surface coating layer 6 to the thickness (total thickness) of the laminate constituting the energy storage device exterior material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, if the first energy storage device exterior material 11 and the second energy storage device exterior material 12 of this disclosure each include 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 first energy storage device exterior material 11 and the second energy storage device exterior material 12 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even if the first exterior material 11 and the second exterior material 12 for energy storage devices of this disclosure are laminates comprising a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, respectively, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminates constituting the first exterior material 11 and the second exterior material 12 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.Furthermore, even if the first exterior material 11 and the second exterior material 12 for energy storage devices of this disclosure are laminates comprising a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, respectively, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminates constituting the first exterior material 11 and the second exterior material 12 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0036] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, the ratio of the thickness of the barrier layer 3 to the thickness (total thickness) of the laminate constituting the exterior material 10 for the energy storage device is preferably about 15% or more, more preferably about 20% or more, even more preferably about 25% or more, and also preferably about 80% or less, more preferably about 75% or less, even more preferably about 70% or less. Preferred ranges include about 15-80%, about 15-75%, about 15-70%, about 20-80%, about 20-75%, about 20-70%, about 25-80%, about 25-75%, and about 25-70%.

[0037] (First Exterior Material 11 for Energy Storage Device) In the energy storage device 20 of this disclosure, the laminate constituting the first exterior material 11 for energy storage device is subjected to a tensile test under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 are calculated to be 80 N / 15 mm or more. From the viewpoint of more favorably exhibiting the effects of the present invention (effect of suppressing wrinkles when adhesive tape is peeled off), the average value is preferably about 80 N / 15 mm or more, more preferably about 90 N / 15 mm or more, and even more preferably about 100 N / 15 mm or more. As for the upper limit, for example, there are cases where it is about 200 N / 15 mm, about 400 N / 15 mm, about 500 N / 15 mm, and as for the preferred range, there are cases where it is about 80 to 500 N / 15 mm, about 80 to 400 N / 15 mm, about 80 to 200 N / 15 mm, about 90 to 500 N / 15 mm, about 90 to 400 N / 15 mm, about 90 to 200 N / 15 mm, about 100 to 500 N / 15 mm, about 100 to 400 N / 15 mm, and about 100 to 200 N / 15 mm.

[0038] When the barrier layer 3 of the laminate constituting the exterior material 11 for the first energy storage device is formed of aluminum alloy foil, the tensile strength A1 or B1 is preferably about 80 N / 15 mm or more, more preferably about 150 N / 15 mm or more, even more preferably about 220 N / 15 mm or more, and also preferably about 500 N / 15 mm or less, more preferably about 430 N / 15 mm or less, even more preferably about 350 N / 15 mm or less. Preferred ranges include about 80 to 500 N / 15 mm, about 80 to 430 N / 15 mm, about 80 to 350 N / 15 mm, about 150 to 500 N / 15 mm, about 150 to 430 N / 15 mm, about 150 to 350 N / 15 mm, about 220 to 500 N / 15 mm, about 220 to 430 N / 15 mm, and about 220 to 350 N / 15 mm.

[0039] When the barrier layer 3 of the laminate constituting the exterior material 11 for the first energy storage device is made of stainless steel foil, the tensile strength A1 or B1 is preferably about 100 N / 15 mm or more, more preferably about 300 N / 15 mm or more, even more preferably about 500 N / 15 mm or more, and also preferably about 700 N / 15 mm or less, more preferably about 650 N / 15 mm or less, even more preferably about 600 N / 15 mm or less. Preferred ranges include about 100 to 700 N / 15 mm, about 100 to 650 N / 15 mm, about 100 to 600 N / 15 mm, about 300 to 700 N / 15 mm, about 300 to 650 N / 15 mm, about 300 to 600 N / 15 mm, about 500 to 700 N / 15 mm, about 500 to 650 N / 15 mm, and about 500 to 600 N / 15 mm.

[0040] Methods for increasing the average values ​​of the tensile strengths A1 and B1 of the first energy storage device exterior material 11 to 80 N / 15 mm or more include methods for strengthening the molecular orientation of the polymer and methods for improving the crystallinity of the polymer in the resin-formed layers (for example, the base layer 1, adhesive layer 5, and heat-fusible resin layer 4). In particular, the thickness of the barrier layer 3, the ratio of the barrier layer thickness to the thickness of the laminate, the grain size of the barrier layer, and the strain-hardening properties contribute to improving the tensile strengths A1 and B1 of the first energy storage device exterior material 11.

[0041] (Second Exterior Material 12 for Energy Storage Device) Furthermore, in the energy storage device 20 of this disclosure, the laminate constituting the second exterior material 12 for the energy storage device is subjected to a tensile test under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm. From the viewpoint of more favorably exhibiting the effects of the present invention (excellent moldability), the average value is preferably about 70 N / 15 mm or less, more preferably about 60 N / 15 mm or less, and the lower limit can be, for example, about 30 N / 15 mm, about 40 N / 15 mm, about 50 N / 15 mm, and preferred ranges can be about 30 to 80 N / 15 mm, about 30 to 70 N / 15 mm, about 30 to 60 N / 15 mm, about 40 to 80 N / 15 mm, about 40 to 70 N / 15 mm, about 40 to 60 N / 15 mm, about 50 to 80 N / 15 mm, about 50 to 70 N / 15 mm, and about 50 to 60 N / 15 mm.

[0042] When the barrier layer 3 of the laminate constituting the exterior material 12 for the second energy storage device is made of aluminum alloy foil, the tensile strength A2 or B2 is preferably about 75 N / 15 mm or less, more preferably about 70 N / 15 mm or less, and also preferably about 40 N / 15 mm or more, more preferably about 50 N / 15 mm or more, and even more preferably about 60 N / 15 mm or more. Preferred ranges include about 40 to 75 N / 15 mm, about 40 to 70 N / 15 mm, about 50 to 75 N / 15 mm, about 50 to 70 N / 15 mm, about 60 to 75 N / 15 mm, and about 60 to 70 N / 15 mm.

[0043] When the barrier layer 3 of the laminate constituting the exterior material 12 for the second energy storage device is made of stainless steel foil, the tensile strength A2 or B2 is preferably about 75 N / 15 mm or less, more preferably about 70 N / 15 mm or less, and also preferably about 40 N / 15 mm or more, more preferably about 50 N / 15 mm or more, and even more preferably about 60 N / 15 mm or more. Preferred ranges include about 40 to 75 N / 15 mm, about 40 to 70 N / 15 mm, about 50 to 75 N / 15 mm, about 50 to 70 N / 15 mm, about 60 to 75 N / 15 mm, and about 60 to 70 N / 15 mm.

[0044] As a method for setting the average values ​​of the tensile strengths A2 and B2 of the exterior material 12 for the second energy storage device to less than 80 N / 15 mm, for layers formed by resin (for example, the base layer 1, adhesive layer 5, heat-fusible resin layer 4, etc.), methods include strengthening the molecular orientation of the polymer and improving the crystallinity of the polymer. In addition, the thickness of the barrier layer 3, the ratio of the barrier layer thickness to the thickness of the laminate, the decorative particle size of the barrier layer, and the strain hardening properties contribute to the decrease in the tensile strengths A2 and B2 of the exterior material 12 for the second energy storage device.

[0045] [Each Layer Forming the Exterior Material for Energy Storage Devices] The following describes in detail each layer of the laminate constituting the first exterior material 11 and the second exterior material 12 for energy storage devices included in the energy storage device 20 of this disclosure. Descriptions common to the first exterior material 11 and the second exterior material 12 for energy storage devices will be explained as descriptions relating to the exterior material 10 for energy storage devices of this disclosure, and matters specific to the first exterior material 11 or the second exterior material 12 for energy storage devices will be clearly indicated as relating to which exterior material the description pertains to. Furthermore, in the first exterior material 11 for energy storage devices, the description of the barrier layer 3 differs in the first, second, or third embodiment, so the embodiment the description pertains to will be clearly indicated.

[0046] [Base Layer 1] In this disclosure, the base layer 1 is a layer provided as needed for purposes such as enabling the exterior material 10 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 10 for the energy storage device.

[0047] The material forming the base layer 1 is not particularly limited, as long as it has the function of a base material, that is, at least insulating properties. The base layer 1 can be formed using, for example, a resin, and the resin may contain additives described later.

[0048] When the base layer 1 is formed of resin, the base layer 1 can be formed of, for example, a resin film. When the base layer 1 is formed of a resin film, a pre-formed resin film may be used as the base layer 1 when manufacturing the exterior material 10 for the energy storage device of this disclosure by laminating the base layer 1 with a barrier layer 3 or the like. Alternatively, the resin forming the base layer 1 may be formed into a film on the surface of the barrier layer 3 or the like by extrusion molding or coating, and the base layer 1 may be formed of a resin film. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include sequential biaxial stretching, inflation method, and simultaneous biaxial stretching. Examples of methods for coating the resin include roll coating, gravure coating, and extrusion coating.

[0049] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. The resin forming the base layer 1 may also be a copolymer of these resins, or a modified version of a copolymer. Furthermore, it may be a mixture of these resins.

[0050] The base layer 1 preferably contains these resins as its main component, and more preferably contains polyester or polyamide as its main component. Here, "main component" means that among the resin components contained in the base layer 1, the content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the base layer 1 contains polyester or polyamide as its main component, it means that among the resin components contained in the base layer 1, the content of polyester or polyamide is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0051] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0052] 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.

[0053] 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.

[0054] The base layer 1 preferably contains at least one of polyester film, polyamide film, and polyolefin film, preferably at least one of stretched polyester film, stretched polyamide film, and stretched polyolefin film, more preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, and stretched polypropylene film, and even more preferably at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

[0055] 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.

[0056] Specific examples of a laminate of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film is located in the outermost layer of the base layer 1. In a laminate of a polyester resin film and a polyamide resin film, the preferred thickness range of the polyester resin film is approximately 2-33 μm, 2-28 μm, 2-23 μm, 2-18 μm, 2-11 μm, 2-8 μm, 10-33 μm, 10-28 μm, 10-23 μm, 10-18 μm, 10-11 μm, 18-33 μm, and 18-28 μm. The thickness is approximately 18 to 23 μm. Preferred ranges for the thickness of the polyamide resin film include approximately 2 to 33 μm, 2 to 28 μm, 2 to 23 μm, 2 to 18 μm, 2 to 11 μm, 2 to 8 μm, 10 to 33 μm, 10 to 28 μm, 10 to 23 μm, 10 to 18 μm, 10 to 11 μm, 18 to 33 μm, 18 to 28 μm, and 18 to 23 μm.

[0057] 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.

[0058] 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.

[0059] In this disclosure, from the viewpoint of improving the moldability of the exterior material 10 for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0060] 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 degree, about 3 to 14 mg / m 2 degree, about 3 to 10 mg / m 2 degree, about 4 to 15 mg / m 2 degree, about 4 to 14 mg / m 2 degree, about 4 to 10 mg / m 2 degree, about 5 to 15 mg / m 2 degree, about 5 to 14 mg / m 2 degree, about 5 to 10 mg / m 2 degree.

[0061] The lubricant present on the surface of the base material layer 1 may be the one obtained by exuding the lubricant contained in the resin constituting the base material layer 1, or may be the one obtained by applying the lubricant on the surface of the base material layer 1.

[0062] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 μm or more, preferably about 10 μm or more. Also, examples of the thickness of the base layer 1 can be about 100 μm or less, about 90 μm or less, about 70 μm or less, about 50 μm or less, preferably about 35 μm or less, 11 μm or less, or 8 μm or less. Furthermore, preferred thickness ranges for the base layer 1 include approximately 3 to 100 μm, 3 to 90 μm, 3 to 70 μm, 3 to 50 μm, 3 to 35 μm, 3 to 11 μm, 3 to 8 μm, 10 to 100 μm, 10 to 90 μm, 10 to 70 μm, 10 to 50 μm, 10 to 35 μm, and 10 to 11 μm. In particular, when making energy storage devices into lightweight thin films, thicknesses of approximately 3 to 35 μm, 3 to 11 μm, and 3 to 8 μm are preferred, and when improving moldability, thicknesses of approximately 35 to 50 μm are preferred. When the base layer 1 is a laminate of two or more resin films, the thickness of the resin film constituting each layer is not particularly limited, but examples include approximately 2 μm or more, preferably approximately 10 μm or more and approximately 18 μm or more, respectively. Furthermore, the thickness of the resin film constituting each layer can be, for example, about 33 μm or less, preferably about 28 μm or less, about 23 μm or less, about 18 μm or less, 11 μm or less, or 8 μm or less. In addition, preferred ranges for the thickness of the resin film constituting each layer can be about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, or about 18 to 23 μm.

[0063] The base layer 1 contains a coloring agent, which allows the exterior material 10 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.

[0064] 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.

[0065] Among colorants, carbon black is preferred, for example, to give the exterior material 10 for the energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0066] 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.

[0067] The amount of coloring agent in the base layer 1 is not particularly limited as long as the exterior material 10 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.

[0068] [Adhesive layer 2] In the exterior material 10 for energy storage devices of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0069] 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.

[0070] 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.

[0071] 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 the exterior material 10 for the energy storage device with excellent electrolyte resistance, preventing the substrate layer 1 from peeling off even if electrolyte adheres to the sides.

[0072] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. The presence of a colorant in the adhesive layer 2 allows the exterior material 10 for the energy storage device to be colored. 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.

[0073] 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.

[0074] Among colorants, carbon black is preferred for, for example, to give the exterior material 10 for the energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0075] 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.

[0076] The content of the coloring agent in the adhesive layer 2 is not particularly limited as long as the exterior material 10 for the energy storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0077] 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.

[0078] [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 10 for the energy storage device can be colored.

[0079] 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.

[0080] Specific examples of colorants included in the colored layer are the same as those exemplified in the section for [Adhesive Layer 2].

[0081] [Barrier layer 3] In the exterior material 10 for energy storage devices of this disclosure, the barrier layer 3 is a layer that at least prevents moisture from entering.

[0082] (Barrier layer of the first exterior material 11 for the energy storage device) In the first exterior material 11 for the energy storage device of this disclosure, the characteristics of the barrier layer 3 differ in the first, second, and third embodiments, respectively. The barrier layer 3 in each embodiment will be described in detail below, in the order of the first, second, and third embodiments.

[0083] (Barrier layer 3 of the first embodiment) The barrier layer 3 of the first embodiment of the exterior material 11 for the first energy storage device is characterized by including stainless steel foil. The exterior material 11 for the first energy storage device includes such stainless steel foil in the barrier layer 3, and the laminate constituting the exterior material 11 for the first energy storage device has the predetermined tensile strength, so that wrinkles are less likely to form when adhesive tape is peeled off the exterior material 11 for the first energy storage device applied to the energy storage device.

[0084] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Furthermore, from the viewpoint of providing a first exterior material 11 for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0085] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, and among these, SUS304 is particularly preferred.

[0086] In the barrier layer 3 of the first embodiment, the layer made of the aforementioned stainless steel may also contain recycled stainless steel. Recycled stainless steel can be obtained by known methods. The barrier layer 3 may be made of recycled material only, or it may be made of a mixture of recycled material and virgin material. Recycled stainless steel refers to stainless steel that has been recovered, isolated, and refined from various products used in the market or waste generated from the manufacturing process to make it reusable. Virgin stainless steel refers to new stainless steel refined from natural stainless steel resources (raw materials) and is not recycled material.

[0087] From the viewpoint of more favorably exhibiting the effects of the present invention, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 20 μm or more, even more preferably about 40 μm or more, and also preferably about 100 μm or less, more preferably about 80 μm or less, and even more preferably about 60 μm or less. Preferred ranges include about 10 to 100 μm, about 10 to 80 μm, about 10 to 60 μm, about 20 to 100 μm, about 20 to 80 μm, about 20 to 60 μm, about 40 to 100 μm, about 40 to 80 μm, and about 40 to 60 μm. Even when the exterior material for energy storage devices of the present disclosure does not have a base layer 1, the formability of the exterior material for energy storage devices can be improved by including a thick stainless steel foil.

[0088] In the first embodiment, the barrier layer 3 may include stainless steel foil, may include materials other than stainless steel foil, or may consist only of stainless steel foil (however, in this case as well, the corrosion-resistant coating described later may be formed).

[0089] (Barrier layer of the second embodiment) The barrier layer 3 of the second embodiment of the exterior material 11 for the first energy storage device includes an aluminum alloy foil. Furthermore, the 0.2% yield strength of the aluminum alloy foil in the rolling direction is 70 MPa or more. The exterior material 11 for the first energy storage device of the second embodiment includes an aluminum alloy foil with such specific physical properties in the barrier layer 3, and the laminate constituting the exterior material 11 for the first energy storage device of the second embodiment has the predetermined tensile strength, thus exhibiting the characteristic that wrinkles are less likely to form when adhesive tape is peeled off the exterior material 11 for the first energy storage device applied to the energy storage device.

[0090] The aluminum alloy foil included in the barrier layer 3 of the second embodiment will be described in detail below.

[0091] (Physical Properties) ・0.2% yield strength in the rolling direction is 70 MPa or higher Existing soft foils made of aluminum alloys have low yield strength, and wrinkles and bending of the foil occur with even slight external force, resulting in poor handling during and after molding. Aluminum alloy foils are susceptible to breakage from minor impacts such as drops. By making the 0.2% yield strength of the aluminum alloy foil 70 MPa or higher, handling during molding, shape retention after molding, and resistance to impacts such as drops and collisions are improved. Furthermore, the characteristic of being less prone to wrinkle formation when adhesive tape is peeled off the first exterior material 11 for energy storage devices applied to energy storage devices can be more effectively exhibited. The 0.2% yield strength in the rolling direction of the aluminum alloy foil is preferably 70.0 MPa or higher, more preferably 80.0 MPa or higher, and even more preferably 90.0 MPa or higher. The upper limit is, for example, 120.0 MPa or lower, preferably 115.0 MPa or lower, and more preferably 110.0 MPa or lower, with a preferred range being approximately 70 to 120.0 MPa.

[0092] - Tensile strength in the rolling direction. Existing soft foils made of aluminum alloy have low strength, and even slight external forces cause wrinkles and bending of the foil, resulting in poor handling during and after molding. In addition, aluminum alloy foil may break even with minor impacts such as dropping. By increasing the tensile strength of the aluminum alloy foil, handling during molding, shape retention after molding, and resistance to impacts such as dropping and collisions can be further improved. Furthermore, the characteristic of being less prone to wrinkle formation when adhesive tape is peeled off the first exterior material 11 for energy storage devices applied to energy storage devices can be more favorably exhibited.

[0093] The tensile strength of the aluminum alloy foil in the rolling direction is preferably 100.0 MPa or higher, more preferably 120.0 MPa or higher, and even more preferably 130.0 MPa or higher. The upper limit is, for example, 200.0 MPa or lower, and a preferred range is approximately 100.0 to 200.0 MPa.

[0094] - 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, the characteristic of being less prone to wrinkle formation when adhesive tape is peeled off the first exterior material 11 for energy storage devices can be more effectively exhibited. In addition, the molding process of the first exterior material 11 for energy storage devices involves deformation in multiple directions, not just stretching in one direction, and by improving the elongation characteristics in each direction, excellent elongation characteristics in all directions can be expected.

[0095] 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 40.0% 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%.

[0096] 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.

[0097] 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.

[0098] - 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".

[0099] 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.

[0100] - 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.

[0101] - 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:

[0102] 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 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.

[0103] <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, JIS No. 5 test specimens were taken from 0°, 45°, and 90° directions relative to the rolling direction. A universal tensile testing machine was used to measure the elongation of these specimens at a tensile speed of 5 mm / min. To calculate the elongation, two lines were marked at 50 mm intervals (original gauge length) along the longitudinal center of the specimen before the test. After the test, the fracture surfaces were joined together to measure the final gauge length (L), and the elongation (mm) was calculated by dividing it by the distance between the original gauges (Lo: 50 mm) using the following formula: ((L - Lo) / Lo) × 100

[0104] <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.

[0105] 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.

[0106] 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.

[0107] <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.

[0108] 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°.

[0109] <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

[0110] (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, the composition is 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. By satisfying this composition, the characteristic that wrinkles are less likely to form when the adhesive tape is peeled off the first exterior material 11 for the energy storage device applied to the energy storage device can be more preferably exhibited.

[0111] • Fe: 1.50 mass% or less Fe crystallizes into 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 mass% and the upper limit to 1.50 mass%. For the same reason, it is more desirable to set the lower limit to 1.00 mass% and the upper limit to 1.40 mass%.

[0112] - Mn: 0.160 mass% or less. The addition of Mn can improve the tensile strength and yield strength of aluminum alloy foil. In addition, 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, which reduces 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 0.10 mass% and the upper limit is 0.140 mass%.

[0113] Cu: 0.150% by mass or more and 0.250% by 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 too high, 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% by mass and the upper limit to 0.250% by mass. More preferably, the lower limit is 0.180% by mass and the upper limit is 0.230% by mass.

[0114] • 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%, and even more preferably, the upper limit should be 0.050 mass%.

[0115] 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.

[0116] (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.

[0117] - 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.

[0118] 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.

[0119] In homogenization treatment held at a temperature range of 480-540°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.

[0120] <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.

[0121] 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.

[0122] • 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.

[0123] <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.

[0124] 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.

[0125] 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.

[0126] - Final cold rolling ratio: 98% or higher. A high rolling load refines the grains even during the cold rolling process; therefore, a higher final cold rolling ratio results in finer grains. For this reason, a higher final cold rolling ratio is desirable, specifically 98% or higher. Below 98%, the grain size after final annealing becomes coarser or non-uniform, making it difficult to achieve the desired strength and ductility.

[0127] - 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.

[0128] <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.

[0129] For example, an aluminum alloy foil having the above composition and physical properties can be suitably manufactured by the above manufacturing method.

[0130] Aluminum alloy foil may contain recycled aluminum alloy. Recycled aluminum alloy can be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The aluminum alloy may consist solely of recycled material, or it may consist of a mixture of recycled and virgin material. Recycled aluminum alloy refers to aluminum alloy that has been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin aluminum alloy refers to new aluminum alloy refined from natural resources (raw materials) of aluminum alloy, and is not recycled material.

[0131] From the viewpoint of suitably exhibiting the effects of the present invention, the thickness of the aluminum alloy foil included in the barrier layer 3 of the second embodiment is preferably about 30 μm or more, more preferably about 35 μm or more, even more preferably about 40 μm or more, and also preferably about 120 μm or less, more preferably about 100 μm or less, even more preferably about 80 μm or less. Preferred ranges include about 30 to 120 μm, about 30 to 100 μm, about 30 to 80 μm, about 35 to 120 μm, about 35 to 100 μm, about 35 to 80 μm, about 40 to 120 μm, about 40 to 100 μm, and about 40 to 80 μm.

[0132] In a second embodiment, the barrier layer 3 may include the aluminum alloy foil, may include materials other than those described above, or may consist only of the aluminum alloy foil (however, in this case as well, the corrosion-resistant film described later may be formed).

[0133] (Barrier layer of the third embodiment) The barrier layer 3 of the third embodiment of the exterior material 11 for the first energy storage device includes an aluminum alloy foil. Furthermore, the thickness of the aluminum alloy foil is 50 μm or more. The exterior material 11 for the first energy storage device of the third embodiment includes such a thick aluminum alloy foil in the barrier layer 3, and the laminate constituting the exterior material 11 for the first energy storage device has the predetermined tensile strength, thus exhibiting the characteristic that wrinkles are less likely to form when adhesive tape is peeled off the exterior material 11 for the first energy storage device applied to the energy storage device.

[0134] Aluminum alloy foil may contain recycled aluminum alloy. Recycled aluminum alloy can be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The aluminum alloy may consist solely of recycled material, or it may consist of a mixture of recycled and virgin material. Recycled aluminum alloy refers to aluminum alloy that has been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin aluminum alloy refers to new aluminum alloy refined from natural resources (raw materials) of aluminum alloy, and is not recycled material.

[0135] From the viewpoint of improving the formability of the exterior material 11 for the first energy storage device, 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 the 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 11 for the first energy storage device with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material 11 for the first energy storage device 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.

[0136] Furthermore, it is also preferable that the aluminum alloy foil included in the barrier layer 3 of the third embodiment is the aluminum alloy foil with the specific characteristics included in the barrier layer 3 of the second embodiment.

[0137] From the viewpoint of suitably exhibiting the effects of the present invention, the thickness of the aluminum alloy foil included in the barrier layer 3 of the third embodiment may be 50 μm or more, preferably about 60 μm or more, more preferably about 80 μm or more, and also preferably about 150 μm or less, more preferably about 120 μm or less, and even more preferably about 100 μm or less. Preferred ranges include about 50 to 150 μm, about 50 to 120 μm, about 50 to 100 μm, about 60 to 150 μm, about 60 to 120 μm, about 60 to 100 μm, about 80 to 150 μm, about 80 to 120 μm, and about 80 to 100 μm.

[0138] (Other layers of barrier layer 3) As described above, in the first embodiment of the first exterior material 11 for the first energy storage device, the barrier layer 3 includes stainless steel foil, and in the second and third embodiments, the barrier layer 3 includes a predetermined aluminum alloy foil. In each embodiment, the barrier layer 3 may further include other layers as needed.

[0139] When the barrier layer 3 of the exterior material 11 for the first energy storage device includes layers other than the aluminum alloy foil, examples of other layers include metal foil with barrier properties, vapor-deposited films, and resin layers. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. Furthermore, the barrier layer 3 may also be a resin film having at least one of these vapor-deposited films and resin layers. Specifically, examples of metal materials constituting the other layers of the barrier layer 3 include aluminum alloys that do not satisfy the above composition, stainless steel (second and third embodiments), titanium steel, and steel plates. When used as a metal foil, it is preferable to include at least one of aluminum alloy foil that does not satisfy the above composition and stainless steel foil.

[0140] In the barrier layer 3 of the first energy storage device exterior material 11, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 3 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0141] The aluminum alloy foil used in the other layers of the barrier layer 3 of the first energy storage device exterior material 11 is more preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, from the viewpoint of improving the formability of the first energy storage device exterior material 11, and more preferably an aluminum alloy foil containing iron from the viewpoint of further improving formability. In the 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, the first energy storage device exterior material 11 with better formability can be obtained. By having an iron content of 9.0% by mass or less, the first energy storage device exterior material 11 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.

[0142] Furthermore, in the second and third embodiments, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material 11 for a first energy storage device with excellent formability, it is preferable that the stainless steel foil is made of austenitic stainless steel.

[0143] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0144] The thickness of the barrier layer 3 of the first energy storage device exterior material 11 should, in the case of metal foil, be sufficient to function as a barrier layer that at least prevents moisture from penetrating, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Alternatively, the thickness of the barrier layer 3 is preferably about 10 μm or more, even more preferably about 20 μm or more, and even more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 3 include approximately 10 to 85 μm, 10 to 50 μm, 10 to 40 μm, 10 to 35 μm, 20 to 85 μm, 20 to 50 μm, 20 to 40 μm, 20 to 35 μm, 25 to 85 μm, 25 to 50 μm, 25 to 40 μm, and 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above ranges are particularly preferred. Also, from the viewpoint of providing high formability and high rigidity to the exterior material 11 for the first energy storage device, the thickness of the barrier layer 3 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferred ranges are approximately 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 55-200 μm, 55-85 μm, 55-75 μm, and 55-70 μm. The first exterior material 11 for the energy storage device has high moldability, which facilitates deep drawing and can contribute to increasing the capacity of the energy storage device. Furthermore, as the capacity of the energy storage device increases, the weight of the energy storage device increases, but by increasing the rigidity of the first exterior material 11 for the energy storage device, it can contribute to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 3 is composed of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0145] (Barrier layer of the exterior material 12 for the second energy storage device) Examples of the barrier layer 3 of the exterior material 12 for the second energy storage device include metal foil, vapor-deposited film, and resin layer having barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers may also be provided as the barrier layer 3. Multiple layers of the barrier layer 3 may be provided. It is preferable that the barrier layer 3 includes a layer made of a metal material. Specifically, examples of metal materials constituting the barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plate. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0146] In the barrier layer 3 of the second energy storage device exterior material 12, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 3 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and refined from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0147] From the viewpoint of improving the formability of the exterior material 12 for the second energy storage device, 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 the 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 12 for the second energy storage device with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material 12 for the second energy storage device 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.

[0148] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing a second exterior material 12 for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0149] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0150] The thickness of the barrier layer 3 of the second energy storage device exterior material 12 should, in the case of metal foil, be sufficient to function as a barrier layer that at least prevents moisture from entering, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Alternatively, the thickness of the barrier layer 3 is preferably about 10 μm or more, even more preferably about 20 μm or more, and even more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 3 include approximately 10 to 85 μm, 10 to 50 μm, 10 to 40 μm, 10 to 35 μm, 20 to 85 μm, 20 to 50 μm, 20 to 40 μm, 20 to 35 μm, 25 to 85 μm, 25 to 50 μm, 25 to 40 μm, and 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above ranges are particularly preferred. Also, from the viewpoint of providing high formability and high rigidity to the exterior material 12 for the second energy storage device, the thickness of the barrier layer 3 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferred ranges are approximately 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 55-200 μm, 55-85 μm, 55-75 μm, and 55-70 μm. The high moldability of the second energy storage device exterior material 12 facilitates deep drawing, which can contribute to increasing the capacity of the energy storage device. Furthermore, while increasing the capacity of the energy storage device increases its weight, the increased rigidity of the second energy storage device exterior material 12 can contribute to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 3 is composed of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0151] (Corrosion-resistant coating) In the exterior material 10 for energy storage devices of this disclosure, it is preferable that the barrier layer 3 has a corrosion-resistant coating on at least the side facing the heat-fusible resin layer in order to prevent dissolution and corrosion. The barrier layer 3 may have a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing a corrosion prevention treatment on the surface of the barrier layer, such as a hot water modification treatment such as boehmite treatment, 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 layer. Furthermore, among these treatments, hydrothermal modification and anodic oxidation are processes that dissolve the surface of the metal foil with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Additionally, if the barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0152] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of the exterior material 10 for energy storage devices. It also prevents the 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, thus preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0153] 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.

[0154]

[0155]

[0156]

[0157]

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0163] 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.

[0164] 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:

[0165] 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.

[0166] [Heat-fusible resin layer 4] In the exterior material 10 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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 10 for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used.

[0177] 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.

[0178] In this disclosure, from the viewpoint of improving the moldability of the exterior material 10 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.

[0179] 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 10 for the energy storage device, 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.

[0180] 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 10 for the energy storage device, 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 10 for the energy storage device, 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 10 for the energy storage device, 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.

[0181] 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.

[0182] 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.

[0183] [Adhesive layer 5] In the exterior material 10 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.

[0184] 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.

[0185] 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 10 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.

[0186] 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.

[0187] 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.

[0188] Furthermore, from the viewpoint of ensuring durability such as heat resistance and resistance to contents of the exterior material 10 for the energy storage device, and 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.

[0189] 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).

[0190] 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).

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0202] 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.

[0203] 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.

[0204] [Surface coating layer 6] The exterior material 10 for energy storage devices of this disclosure may optionally include a surface coating layer 6 on the base layer 1 (on the side opposite to the barrier layer 3 of the base layer 1) for the purpose of improving at least one of the following: aesthetics, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the exterior material 10 for energy storage devices when the energy storage device is assembled using the exterior material 10 for energy storage devices.

[0205] 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.

[0206] 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.

[0207] 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 made of polyurethane, which provides the exterior material 10 for the energy storage device with excellent electrolyte resistance.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] In this disclosure, from the viewpoint of improving the moldability of the exterior material 10 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.

[0213] 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.

[0214] 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.

[0215] The surface coating layer 6 contains a coloring agent, which allows the exterior material 10 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.

[0216] 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.

[0217] Among colorants, carbon black is preferred, for example, to give the exterior material 10 for the energy storage device a black appearance. Furthermore, from the viewpoint of dissipating heat generated from the energy storage device, mica is preferred.

[0218] 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.

[0219] The amount of coloring agent in the surface coating layer 6 is not particularly limited as long as the exterior material 10 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.

[0220] 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.

[0221] [Method for manufacturing exterior material for energy storage device] The method for manufacturing the exterior material 10 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.

[0222] More specifically, the manufacturing methods for the exterior material 10 for energy storage devices according to the first, second, and third embodiments of the present disclosure are as follows:

[0223] (First Embodiment) The invention comprises a step of obtaining a plurality of laminates in which at least a barrier layer and a heat-fusible resin layer are laminated in that order from the outside, wherein, among the plurality of laminates, the barrier layer includes stainless steel foil, and a tensile test is performed on the laminate under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm, and the tensile strength A1 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction are measured, and the average value of the tensile strength A1 and the tensile strength B1 is calculated to be 80 N / 15 mm or more, and the laminate is used as the first exterior material for an energy storage device. A method for manufacturing an exterior material for an energy storage device, comprising: performing tensile tests on multiple laminates under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm; measuring the tensile strength A2 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and measuring the tensile strength B2 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction; calculating the average value of the tensile strengths A2 and B2, a laminate whose average value is less than 80 N / 15 mm is used as the second exterior material for an energy storage device; and obtaining an exterior material for an energy storage device by combining the first exterior material for an energy storage device and the second exterior material for an energy storage device.

[0224] (Second Embodiment) The invention comprises a step of obtaining a plurality of laminates in which at least a barrier layer and a heat-fusible resin layer are laminated in that order from the outside, wherein the barrier layer of the plurality of laminates contains aluminum alloy foil with a 0.2% yield strength of 70 MPa or more, and the laminate is subjected to a tensile test under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm, and the tensile strength A1 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction are measured, and the average value of the tensile strength A1 and the tensile strength B1 is calculated to be 80 N / 15 mm or more, and the laminate is used as the exterior material for the first energy storage device. A method for manufacturing an exterior material for an energy storage device, comprising: performing tensile tests on multiple laminates under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm; measuring the tensile strength A2 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and measuring the tensile strength B2 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction; calculating the average value of the tensile strengths A2 and B2, a laminate whose average value is less than 80 N / 15 mm is used as the second exterior material for an energy storage device; and obtaining an exterior material for an energy storage device by combining the first exterior material for an energy storage device and the second exterior material for an energy storage device.

[0225] (Third Embodiment) The invention comprises a step of obtaining a plurality of laminates in which at least a barrier layer and a heat-fusible resin layer are laminated in that order from the outside, wherein the barrier layer of the plurality of laminates includes an aluminum alloy foil having a thickness of 50 μm or more, and the laminate is subjected to a tensile test under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm, and the tensile strength A1 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction are measured, and the average value of the tensile strength A1 and the tensile strength B1 is calculated to be 80 N / 15 mm or more, and the laminate is used as the exterior material for the first energy storage device. A method for manufacturing an exterior material for an energy storage device, comprising: performing tensile tests on multiple laminates under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm; measuring the tensile strength A2 (N / 15 mm) when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and measuring the tensile strength B2 (N / 15 mm) when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction; calculating the average value of the tensile strengths A2 and B2, a laminate whose average value is less than 80 N / 15 mm is used as the second exterior material for an energy storage device; and obtaining an exterior material for an energy storage device by combining the first exterior material for an energy storage device and the second exterior material for an energy storage device.

[0226] An example of a method for manufacturing the exterior material 10 for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated body A") is formed by sequentially laminating a base material layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which an adhesive used to form the adhesive layer 2 is applied to the base material 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 material layer 1 is laminated and the adhesive layer 2 is cured.

[0227] 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.

[0228] 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.

[0229] As described above, a laminate is formed comprising, in this order, a surface coating layer 6 provided as needed, a base material layer 1 provided as needed, an adhesive layer 2 provided as needed, a barrier layer 3, an adhesive layer 5 provided as needed, and a heat-fusible resin layer 4. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5, which are provided as needed, the laminate may be subjected to further heat treatment.

[0230] In the exterior material 10 for energy storage devices, each layer constituting the laminate may be subjected to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment as needed to improve processability. 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.

[0231] [Applications of the Outer Packaging Material for Energy Storage Devices] The outer packaging material 10 for energy storage devices of this disclosure is used in packaging for sealing and housing energy storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an energy storage device 20 of this disclosure can be formed by housing an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in packaging formed from the outer packaging material for energy storage devices of this disclosure. In other words, an energy storage device 20 of this disclosure can be formed by wrapping an energy storage device element with the outer packaging material for energy storage devices of this disclosure. As described above, in the energy storage device 20 of this disclosure, the outer packaging material 10 for energy storage devices is used in combination with the first outer packaging material 11 for energy storage devices and the second outer packaging material 12 for energy storage devices.

[0232] 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 create a sealed energy storage device. When housing an 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 heat-sealable resin layers of two energy storage device exterior materials are placed facing each other and overlapped, and the periphery portions of the overlapped energy storage device exterior materials are heat-sealed to form a package. Furthermore, if the innermost and outermost layers of the exterior material for the energy storage device are heat-sealable resin layers, the packaging may be formed by heat-sealing the innermost heat-sealable resin layer and the outermost heat-sealable resin layer.

[0233] 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.

[0234] The cover can be formed, for example, from a resin molded product, a metal molded product, an exterior material for an energy storage device, or a combination thereof. In this disclosure, when the cover is described as a resin molded product, the cover does not include embodiments in which the cover is composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the cover is a metal molded product, the metal terminals can be omitted as the cover also functions as a metal terminal. The cover may be composed of a resin material and a conductive material.

[0235] 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 examples in Figures 6 and 7, it is preferable to provide recesses in the second exterior material 12 for the energy storage device and not in the first exterior material 11 for the energy storage device, but recesses may also be provided in both the first exterior material 11 and the second exterior material 12 for the energy storage device.

[0236] The energy storage device of this disclosure is suitable as an energy storage device such as a battery (including capacitors, capacitors, etc.). The energy storage device of this disclosure may be either a primary battery or a secondary battery, but is preferably used as a secondary battery. The type of secondary battery 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, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are examples of energy storage devices of this disclosure.

[0237] 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.

[0238] <Manufacturing of the first exterior material for energy storage device> [Example 1] A stretched nylon (ONy) film (20 μm thick) was prepared as the base layer. A stainless steel foil (SUS304, 20 μm thick) was prepared as the barrier layer. Both sides of the stainless steel foil were treated with a chemical conversion treatment. The chemical conversion treatment of the stainless steel foil 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 stainless steel foil using the roll coating method and then baking it, so that the dry mass was [dry mass].

[0239] 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.

[0240] Next, by dry lamination, the barrier layer of each laminate obtained above and a heat-sealable resin layer (unstretched polypropylene film, 23 μm thick) were laminated on top of the barrier layer via an adhesive layer (acid-modified polyolefin and epoxy curing agent, 2 μm thick), thereby laminating the adhesive layer / heat-sealable resin layer on top of the barrier layer. Furthermore, a surface coating layer (a resin composition containing acrylic-urethane resin, inorganic filler, and organic filler, 3 μm thick) was formed on the surface of the base layer, and the resulting laminate was aged and heated to obtain a first exterior material for an energy storage device, consisting of a laminate in which the surface coating layer / base layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in this order.

[0241] [Example 2] A stainless steel foil (SUS304, 60 μm thick) was prepared as the barrier layer. Both sides of the stainless steel foil were treated with a chemical conversion treatment. The chemical conversion treatment of the stainless steel foil consisted of a treatment solution made of phenol 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 stainless steel foil using the roll coating method and then baking it, so that the dry mass was [dry mass].

[0242] Next, by dry lamination, a barrier layer and a heat-fusible resin layer (unstretched polypropylene film, 80 μm thick) were laminated on top of the barrier layer via an adhesive layer (acid-modified polyolefin and epoxy curing agent, 2 μm thick). The resulting laminate was aged and heated to obtain a first exterior material for an energy storage device, consisting of a laminate in which the barrier layer, adhesive layer, and heat-fusible resin layer were laminated in this order.

[0243] [Example 3] A stretched nylon (ONy) film (15 μm thick) was prepared as the base layer. An aluminum alloy foil A (40 μm thick) having the composition and physical properties described in Table 1 was prepared as the 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].

[0244] 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.

[0245] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (15 μm thick), and random polypropylene, which forms a heat-fusible resin layer (15 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 a first 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.

[0246] [Example 4] Except for using aluminum alloy foil B (thickness 40 μm) having the composition and physical properties described in Table 1 as the barrier layer, a first exterior material for an energy storage device was obtained in the same manner as in Example 3, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in this order.

[0247] [Example 5] Except for using a stretched nylon (ONy) film (25 μm thick) as the base layer, the same procedure as in Example 4 was used to obtain a first exterior material for an energy storage device, consisting of a laminate in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer are laminated in this order.

[0248] [Example 6] As a base layer, a laminate was prepared in which a biaxially oriented polyethylene terephthalate (PET) film (thickness 12 μm) and an oriented nylon (ONy) film (thickness 25 μm) were bonded together with an adhesive layer (formed with a two-component curing urethane adhesive, with a thickness of 3 μm after curing). In addition, an aluminum alloy foil (JIS H4160:1994 A8079H-O (thickness 60 μm, 0.2% yield strength 39.2 MPa)) 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].

[0249] 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.

[0250] 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 a first 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.

[0251] [Example 7] 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 A8079HH-O (thickness 80 μm, 0.2% yield strength 39.2 MPa)) 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].

[0252] 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.

[0253] 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 a first 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.

[0254] [Comparative Example 1] A stretched nylon (ONy) film (15 μm thick) was prepared as the base layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (35 μm thick, 0.2% yield strength of 53.5 MPa)) was prepared as the 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. 2This 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].

[0255] 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.

[0256] Next, by dry lamination, a barrier layer and a heat-fusible resin layer (unstretched polypropylene film, 30 μm thick) were laminated on top of the barrier layer via an adhesive layer (acid-modified polyolefin and epoxy curing agent, 2 μm thick). The resulting laminate was aged and heated to obtain a first 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.

[0257] [Comparative Example 2] A stretched nylon (ONy) film (15 μm thick) was prepared as the base layer. An aluminum alloy foil (JIS H4160:1994 A8079H-O (40 μm thick, 0.2% yield strength of 39.2 MPa)) was prepared as the 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].

[0258] 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.

[0259] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (15 μm thick), and random polypropylene, which forms a heat-fusible resin layer (15 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 a first 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.

[0260]

[0261] In Table 1, "remainder" refers to the value obtained by subtracting the total percentage (mass%) of components other than aluminum (Al) and unavoidable impurities from 100% by mass, where the sum of each component constituting the aluminum alloy foil is 100% by mass. Furthermore, the unavoidable impurities in the aluminum alloy foil are 0.05% by mass or less individually, and 0.15% by mass or less in total.

[0262] <Combination of the first and second exterior materials for energy storage devices> [Example 1-7] As the second exterior material for energy storage devices to be combined with the first exterior material for energy storage devices in Example 1-7, two types of the first exterior material for energy storage devices obtained in Comparative Example 2 were used.

[0263] [Comparative Examples 1-2] As the second exterior material for an energy storage device, to be combined with the first exterior material for an energy storage device in Comparative Example 1, the first exterior material for an energy storage device obtained in Example 1 was used. Also, as the second exterior material for an energy storage device, to be combined with the first exterior material for an energy storage device in Comparative Example 2, the first exterior material for an energy storage device obtained in Example 2 was used.

[0264] <Measurement of 0.2% yield strength (MPa), tensile strength (MPa), and elongation (%) in the rolling direction of aluminum alloy foil> For aluminum alloy foils A and B, the 0.2% yield strength, tensile strength (MPa), and elongation (%) in the rolling direction were 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 50 mm / min, and an initial distance between the chucks of 30 mm. The initial distance between the chucks was 30 mm, and this initial distance was defined as the gauge length. For the measurement samples of aluminum alloy foils A and B, measurement samples were prepared with a length of 15 mm in the TD direction and a length of 100 mm in the MD direction (rolling direction), respectively. The 0.2% yield strength in the rolling direction of the aluminum alloy foil was determined according to the yield strength (total elongation method) specified in JIS Z 2241:2011. The results are shown in Table 1.

[0265] <Measurement of Tensile Strength> The first 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 following conditions: a 25°C environment, a tensile speed of 50 mm / min, and an initial distance of 30 mm between the chucks. In the tensile test in this disclosure, the initial distance between the chucks was 30 mm, and this initial distance between the chucks was used as the gauge length. Two measurement samples of the exterior material for energy storage devices were prepared: one with a measurement of 15 mm in the TD direction and 100 mm in the MD direction (for MD direction measurement), and another with a measurement of 15 mm in the MD direction and 100 mm in the TD direction (for TD direction measurement). Next, the tensile strength A (N / 15mm) of the measurement sample (for MD direction measurement) when displaced by 10% in the MD direction, and the tensile strength B (N / 15mm) of the measurement sample (for TD direction measurement) when displaced by 10% in the TD direction were each measured three times. The average values ​​of the MD direction measurement and TD direction measurement were taken as tensile strength A and tensile strength B, respectively. Furthermore, the average value of the tensile strengths A and B obtained above was calculated. The results are shown in Table 2.

[0266] <Moldability> For the second exterior material for energy storage devices used in the examples and comparative examples, each exterior material for energy storage devices was cut into a rectangle with a length (MD direction) of 90 mm and a width (TD direction) of 150 mm to prepare a test sample. The MD of the exterior material for energy storage devices corresponds to the rolling direction (RD) of the barrier layer, and the TD of the exterior material for energy storage devices corresponds to the TD of the barrier layer. 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 2.0 mm, edge radius 1.0 mm) and a corresponding molding die (male mold, surface of the edge has a maximum height roughness (nominal value 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 1.0 mm, cold forming (single-stage pull-in forming) was performed on 10 samples each, with a pressing pressure (surface pressure) of 0.25 MPa and a forming depth of 0.5 mm, varying in 0.5 mm increments. 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 with a penlight to check for pinholes and cracks in the barrier layer by light transmission. The deepest molding depth at which no pinholes or cracks occurred in the barrier layer of any of the 10 samples was defined as A mm, and the number of samples at the shallowest molding depth at which pinholes or cracks occurred in the barrier layer 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 moldability was evaluated according to the following evaluation criteria. The results are shown in Table 2. Limit molding depth = A mm + (0.5 mm / 10 samples) × (10 samples - B samples)

[0267] (Evaluation Criteria for Moldability) Comparative Example 2 was used as the "reference," and the limit molding depth was compared and evaluated. A: Limit molding depth is reference - 0.5 mm or more B: Limit molding depth is reference - 1.0 mm or more, and less than reference - 0.5 mm C: Limit molding depth is reference - 1.0 mm or less

[0268] <Evaluation of Wrinkle Formation> (Preparation of Measurement Samples) As shown in Figure 8, a first exterior material 11 for the energy storage device and a second exterior material 12 for the energy storage device were prepared and cut to a size of 90 mm (MD direction) x 75 mm (TD direction) (Figure 8a). Next, a molded part M (recess) was formed in the center of the second exterior material for the energy storage device by cold molding from the heat-fusible resin layer side. Cold molding was performed using a molding die (female mold) with a diameter of 32 mm (MD direction) x 55 mm (TD direction) and a corresponding molding die (male mold with a clearance of 0.3 mm from the female mold) under conditions of a pressing pressure of 0.24 MPa and a molding depth of 3.0 mm (Figure 8a).

[0269] Next, double-sided tape (tesa tape #67215) was attached to the bottom of the molded part M, and then a 3 mm thick copper plate (28 mm x 51 mm, weighing 40 g) was inserted into the molded part M, and the copper plate and tape were pressed together. In this state, the first and second exterior materials for the energy storage device were placed on top of each other so as to close the molded part M (Figures 8a to 8b). At this time, the heat-sealable resin layers of the first and second exterior materials for the energy storage device were aligned so as to overlap, and the peripheral edges were aligned in the MD and TD directions.

[0270] Next, the overlapping portions of the heat-sealable resin layers were heat-sealed in two places along the molding section M in the TD direction (width 7.0 mm, temperature 190°C, 3 seconds, surface pressure 1.0 MPa) (Figure 8c). Furthermore, one heat-sealed portion was also applied along the molding section M in the MD direction (width 7.0 mm, temperature 190°C, 3 seconds, surface pressure 1.0 MPa) (Figure 8c). In Figure 8c, the shaded area S is the heat-sealed portion. Next, two drops (0.5 g) of water were dropped through the unheat-sealed opening E using a dropper (Figure 8c). Then, while evacuating, the opening E was heat-sealed along the molding section M in the MD direction (width 7.0 mm, temperature 190°C, 3 seconds, surface pressure 1.0 MPa) to seal (vacuum seal) the tape, copper plate, and water inside the molding section M (Figure 8d).

[0271] Next, the two heat-sealed locations in the TD direction were cut so that the width of the heat-sealed portion (in the MD direction) was 3.0 mm (at the positions indicated by the dashed lines in Figure 8e). Similarly, the two heat-sealed locations in the MD direction were also cut along the heat-sealed portion so that the width of the heat-sealed portion (in the TD direction) remained 3.0 mm (at the positions indicated by the dashed lines in Figure 8e) (Figures 8e to 8f). Furthermore, double-sided tape was applied to the two heat-sealed locations in the TD direction and attached to the side surface of the molded part M to obtain a measurement sample 13 with the shape shown in Figure 8g. A cross-sectional view along line A-A' is shown in Figure 9.

[0272] (Selection of Adhesive Tape) As shown in Figures 10 and 11, the adhesive tape used for wrinkle formation evaluation was selected using the following procedure. The exterior material 10 for the energy storage device to be evaluated for wrinkle formation was set to a size of 60 mm in width x 60 mm in length. The ends of the double-sided tape (50 mm in width x 60 mm in length) were aligned and attached to an acrylic plate (50 mm in width x 75 mm in length). The release paper of the double-sided tape on the acrylic plate was peeled off and bonded to the heat-sealable resin layer of the exterior material 10 for the energy storage device. An adhesive tape (15 mm in width x 65 mm in length) to be used as the measuring tape was attached to the surface of the base material layer of the exterior material 10 for the energy storage device, and a 2 kg hand roll was passed back and forth twice over the measuring tape to ensure close contact between the exterior material 10 for the energy storage device and the measuring tape. At this point, since the length of the measuring tape was insufficient to perform the tensile test, an extension tape of 130 mm in length was attached to the end of the measuring tape to extend its length. In this state, the samples were left to stand for 2 hours in an environment of atmospheric pressure, 50% relative humidity, and 25°C. Then, the adhesion strength between the base material layer of the energy storage device exterior material and the tape to be measured was measured using a tensile testing machine (Shimadzu AGX-plus 1kN). Tapes with an adhesion strength of 2.5 N / 15 mm were selected as the adhesive tapes to be used for the wrinkle formation evaluation described later. The conditions for the tensile test were: peeling speed: 50 mm / min, peeling angle: 180°, peeling stroke: 50 mm, chuck distance: 100 mm. The maximum strength between strokes was measured with N=3, and the average value was taken as the adhesion strength.

[0273] (Wrinkle Formation Evaluation) In each measurement sample 13 obtained in (Preparation of Measurement Samples) above, the side of the molded part M to which the tape is attached is designated as the front surface, and the opposite side as the back surface. The laminate constituting the back surface is the exterior material for the first energy storage device, and the laminate constituting the front surface is the exterior material for the second energy storage device. A stainless steel plate with a thickness of 2.0 mm was prepared, and double-sided tape (size 50 mm x 60 mm) was attached to the stainless steel plate. Next, the adhesive tape selected in (Selection of Adhesive Tape) above was attached to the double-sided tape with the adhesive side facing upwards. The size of the adhesive tape was set so that the adhesive surface would be in contact with the entire back surface of the measurement sample 13. Next, the back surface of each measurement sample 13 obtained in (Preparation of Measurement Samples) above was attached to the adhesive surface of the adhesive tape, and it was left standing for 24 hours in an environment of atmospheric pressure, relative humidity of 50%, and 25°C. Next, the back of the measurement sample 13 was peeled off the adhesive tape by turning it over, and the wrinkle formation on the back of the measurement sample 13 was visually checked. The results of the evaluation of wrinkle formation according to the following evaluation criteria are shown in Table 2. Note that even after peeling the back of the measurement sample 13 from the adhesive tape, the adhesive tape remained in close contact with the double-sided tape. (Evaluation Criteria) A: No wrinkles are formed on the back of the measurement sample B: There are slight deformations such as localized unevenness, but no wrinkles are formed on the back of the measurement sample C: Wrinkles are formed on the back of the measurement sample

[0274]

[0275] As shown in Table 2, in the exterior materials for energy storage devices of Examples 1-7, by using a first exterior material for energy storage devices that satisfies a predetermined barrier layer and the average value of tensile strengths A and B, and combining it with the first exterior material for energy storage devices, which has excellent moldability as a comparative example, the overall exterior material for energy storage devices achieves both suppression of wrinkles when the adhesive tape is peeled off and excellent moldability.

[0276] As described above, this disclosure provides the invention in the following embodiments. Item 1. 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and the first energy storage device exterior material and the second energy storage device exterior material are each composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer in this order, and the barrier layer includes stainless steel foil. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.Item 2. 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and each of the first and second energy storage device exterior materials is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes an aluminum alloy foil, and the 0.2% yield strength of the aluminum alloy foil is 70 MPa or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.Item 3. 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 of an energy storage device exterior material, wherein the energy storage device exterior material comprises a first energy storage device exterior material and a second energy storage device exterior material, and each of the first and second energy storage device exterior materials is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes an aluminum alloy foil, and the thickness of the aluminum alloy foil is 50 μm or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device. Item 4. The energy storage device according to item 2 or 3, wherein the thickness of the aluminum alloy foil is 50 μm or more and 150 μm or less. Item 5. The energy storage device according to any one of claims 1 to 3, wherein the shape of the exterior material for the second energy storage device is such that recesses for accommodating energy storage device elements are formed from the heat-fusible resin layer side toward the barrier layer side. Claim 6. The energy storage device according to any one of claims 1 to 5, wherein the shape of the exterior material for the first energy storage device is flat.Item 7. The energy storage device according to any one of items 1 to 6, wherein at least one of the first energy storage device exterior material and the second energy storage device exterior material further comprises a base layer on the side of the barrier layer opposite to the heat-fusible resin layer. Item 8. The energy storage device according to item 7, wherein at least one of the first energy storage device exterior material and the second energy storage device exterior material further comprises an adhesive layer between the base layer and the barrier layer. Item 9. The energy storage device according to any one of items 1 to 8, wherein at least one of the first energy storage device exterior material and the second energy storage device exterior material further comprises an adhesive layer between the barrier layer and the heat-fusible resin layer. Item 10. The second energy storage device exterior material for use in manufacturing the energy storage device according to any one of items 1 to 9. Item 11. The first energy storage device exterior material for use in manufacturing the energy storage device according to item 1. Item 12. The first exterior material for an energy storage device, for use in manufacturing the energy storage device described in item 2. Item 13. The first exterior material for an energy storage device, for use in manufacturing the energy storage device described in item 3. Item 14. A method for manufacturing an energy storage device, comprising housing an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the exterior material for an energy storage device described in any one of items 1 to 9.

[0277] 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 device 11. Exterior material for first energy storage device 12. Exterior material for second energy storage device 13. Measurement sample M. Molded part S. Heat-fusible part E. Energy storage device element

Claims

1. An energy storage device comprising an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte, housed in a package formed of an energy storage device outer material, wherein the energy storage device outer material comprises a first energy storage device outer material and a second energy storage device outer material, and each of the first and second energy storage device outer materials is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes stainless steel foil. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

2. 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 of an energy storage device outer material, wherein the energy storage device outer material comprises a first energy storage device outer material and a second energy storage device outer material, and each of the first and second energy storage device outer materials is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes an aluminum alloy foil, and the 0.2% yield strength of the aluminum alloy foil is 70 MPa or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

3. 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 of an energy storage device outer material, wherein the energy storage device outer material comprises a first energy storage device outer material and a second energy storage device outer material, and each of the first and second energy storage device outer materials is composed of a laminate comprising, from the outside, at least a barrier layer and a heat-sealable resin layer, wherein the barrier layer includes an aluminum alloy foil, and the thickness of the aluminum alloy foil is 50 μm or more. A tensile test was performed on the laminate constituting the exterior material for the first energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A1 (N / 15 mm) was measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction was displaced by 10% in the MD direction, and the tensile strength B1 (N / 15 mm) was measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction was displaced by 10% in the TD direction. The average values ​​of the tensile strengths A1 and B1 were calculated to be 80 N / 15 mm or more. A tensile test is performed on the laminate constituting the exterior material for the second energy storage device under measurement conditions of a 25°C environment, a tensile speed of 50 mm / min, and a chuck distance of 30 mm. The tensile strength A2 (N / 15 mm) is measured when a measurement sample with 15 mm in the TD direction and 100 mm in the MD direction is displaced by 10% in the MD direction, and the tensile strength B2 (N / 15 mm) is measured when a measurement sample with 15 mm in the MD direction and 100 mm in the TD direction is displaced by 10% in the TD direction. The average values ​​of the tensile strengths A2 and B2 are calculated to be less than 80 N / 15 mm, which is the energy storage device.

4. The energy storage device according to claim 2 or 3, wherein the thickness of the aluminum alloy foil is 50 μm or more and 150 μm or less.

5. The energy storage device according to any one of claims 1 to 3, wherein the shape of the exterior material for the second energy storage device is such that recesses for housing energy storage device elements are formed from the heat-fusible resin layer side toward the barrier layer side.

6. The energy storage device according to any one of claims 1 to 3, wherein the shape of the exterior material for the first energy storage device is flat.

7. The energy storage device according to any one of claims 1 to 3, wherein at least one of the exterior material for the first energy storage device and the exterior material for the second energy storage device further comprises a base layer on the side of the barrier layer opposite to the heat-fusible resin layer.

8. The energy storage device according to claim 7, wherein at least one of the exterior material for the first energy storage device and the exterior material for the second energy storage device further comprises an adhesive layer between the base material layer and the barrier layer.

9. The energy storage device according to any one of claims 1 to 3, wherein at least one of the exterior material for the first energy storage device and the exterior material for the second energy storage device further comprises an adhesive layer between the barrier layer and the heat-fusible resin layer.

10. The second exterior material for an energy storage device, for use in manufacturing the energy storage device according to any one of claims 1 to 3.

11. The first exterior material for an energy storage device, for use in manufacturing the energy storage device described in claim 1.

12. The first exterior material for an energy storage device, for use in manufacturing the energy storage device described in claim 2.

13. The first exterior material for an energy storage device, for use in manufacturing the energy storage device described in claim 3.

14. A method for manufacturing an energy storage device, comprising housing an energy storage device element having at least a positive electrode, a negative electrode, and an electrolyte in a package formed from an outer material for an energy storage device according to any one of claims 1 to 3.

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