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

Abstract

The present invention provides an outer package material for power storage devices, the outer package material being obtained by shaping a sheet-like multilayer body that comprises, sequentially from the outside, at least a base material layer, a barrier layer and a thermally fusible resin layer. This outer package material for power storage devices is provided with a generally cuboidal space which is formed so as to protrude from the thermally fusible resin layer side toward the base material layer side, and in which a power storage device element is contained on the thermally fusible resin layer side. When viewed in plan, the thickness of the barrier layer in the central part of a generally rectangularly protruded portion is 38 µm or more; when viewed in plan from the base material layer side, the curvature radius of a corner part of the generally rectangularly protruded portion is 2.0 mm or more; in a cross-section in the thickness direction on the line connecting the corner parts, which are opposite to each other, of the generally rectangularly protruded portion, the outer package material for power storage devices is sequentially provided with a first curved part and a second curved part in a portion from the central part to an end; and the thickness D1 of the outer package material for power storage devices in the first curved part, the thickness D2 of the outer package material for power storage devices in the second curved part, and the thickness Dm of the outer package material for power storage devices in a portion that is positioned in between the first curved part and the second curved part satisfy the relational expression D2 > Dm > D1.

Description

[Technical Field]

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

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

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

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

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

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

[0007] By molding the outer casing material for energy storage devices, a roughly rectangular parallelepiped space for housing the energy storage device elements can be formed on the heat-fusible resin layer side. During this molding process, the outer casing material for energy storage devices is stretched considerably, and it is known that when the thickness of the outer casing material for energy storage devices becomes thin (for example, in the case of thin outer casing materials for energy storage devices where the thickness of the barrier layer is less than 40 μm), pinholes and cracks are more likely to occur in the barrier layer.

[0008] On the other hand, in order to impart high mechanical strength to the exterior material for energy storage devices, it is desirable to increase the thickness of the barrier layer. However, after repeated investigations by the inventors of this disclosure, they discovered that when the thickness of the barrier layer is set to 38 μm or more, if the molding depth is increased beyond the limit molding depth (i.e., the maximum molding depth at which damage such as pinholes or cracks does not occur in the barrier layer due to the molding of the exterior material for energy storage devices), the exterior material for energy storage devices tears in the longitudinal direction (direction of the molding depth) at the molded portion formed on the exterior material (specifically, the corner portion of the roughly rectangular protruding part when the exterior material for energy storage devices is viewed from the base layer side in a plan view).

[0009] Here, evaluation by molding beyond the limit molding depth is employed, for example, to evaluate the impact resistance of the exterior material for energy storage devices during thermal expansion after molding. That is, assuming a scenario where the energy storage device is placed in a high-temperature environment and the molded exterior material is further stretched due to thermal expansion, and then subjected to an external impact, the impact resistance of the exterior material for energy storage devices after molding is performed beyond the limit molding depth is used to evaluate the damage that occurs. If molding slightly beyond the limit molding depth results in only pinholes or cracks in the barrier layer, the damage to the exterior material for energy storage devices is small, and it can be evaluated as having excellent impact resistance during thermal expansion. On the other hand, exterior material for energy storage devices that tears vertically at the corners can be evaluated as having insufficient impact resistance, as the damage when the exterior material for energy storage devices is excessively stretched is large. Furthermore, in large-sized energy storage devices for automotive applications and stationary energy storage, heavy battery cells are used and enclosed in energy storage device enclosure materials. These enclosure materials are required to withstand the weight of the heavy battery cells while maintaining high shape retention, and therefore, energy storage device enclosure materials with a barrier layer of 38 μm or more in thickness are used.

[0010] Under these circumstances, the main objective of this disclosure is to provide an exterior material for an energy storage device in which a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer is formed, wherein, despite the exterior material for an energy storage device having a barrier layer with a thickness of 38 μm or more having a substantially rectangular molded portion, the corner portion of the molded portion is preferably suppressed to tear in the vertical direction. [Means for solving the problem]

[0011] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, there is provided an exterior material for a power storage device formed of a sheet-like laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in order from the outside. The exterior material for a power storage device is formed so as to protrude from the heat-sealable resin layer side toward the base material layer side, and includes a substantially rectangular parallelepiped-shaped space in which a power storage device element is accommodated on the heat-sealable resin layer side. When the exterior material for a power storage device is viewed in plan, the thickness of the barrier layer at the center of the portion protruding in a substantially rectangular shape is set to 38 μm or more. When the exterior material for a power storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the portion protruding in a substantially rectangular shape is a predetermined value or more. Further, when the exterior material for a power storage device is viewed in plan from the base material layer side, in the cross section in the thickness direction on the straight line connecting the corner portions facing each other of the portion protruding in a substantially rectangular shape, from the center to the end of the exterior material for a power storage device, there are provided a first curved portion and a second curved portion in order. By designing such that the thickness D1 of the exterior material for a power storage device at the first curved portion, the thickness D2 of the exterior material for a power storage device at the second curved portion, and the thickness Dm of the exterior material for a power storage device at the portion located between the first curved portion and the second curved portion satisfy a predetermined relationship, it has been found that tearing of the corner portion of the molded portion in the longitudinal direction is preferably suppressed.

[0012] Based on such new findings, the present disclosure has been completed through further studies. That is, the present disclosure provides an invention in the following aspects. An exterior material for a power storage device formed of a sheet-like laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in order from the outside, where the exterior material for a power storage device is formed so as to protrude from the heat-sealable resin layer side toward the base material layer side, and includes a substantially rectangular parallelepiped-shaped space in which a power storage device element is accommodated on the heat-sealable resin layer side, when the exterior material for a power storage device is viewed in plan, the thickness of the barrier layer at the center of the portion protruding in a substantially rectangular shape is 38 μm or more, when the exterior material for a power storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the portion protruding in a substantially rectangular shape is 2.0 mm or more. When the exterior material for the power storage device is viewed in plan from the base material layer side, in the cross section in the thickness direction on the straight line connecting the corner portions facing each other of the portions protruding in the substantially rectangular shape, from the center portion to the end portion of the exterior material for the power storage device, in order, a first curved portion and a second curved portion are provided. The thickness D1 of the exterior material for the power storage device in the first curved portion, the thickness D2 of the exterior material for the power storage device in the second curved portion, and the thickness Dm of the exterior material for the power storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship of D2 > Dm > D1. The exterior material for the power storage device.

Effect of the Invention

[0013] According to the present disclosure, there is provided an exterior material for a power storage device in which a sheet-like laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer is formed in order from the outside, and the exterior material for the power storage device includes a barrier layer having a thickness of 38 μm or more. Despite the provision of a substantially rectangular molded portion, it is possible to preferably suppress the longitudinal tearing of the corner portion of the molded portion. Further, according to the present disclosure, it is also possible to provide a method for manufacturing the exterior material for the power storage device and a power storage device using the exterior material for the power storage device.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic view of the exterior material for the power storage device of the present disclosure viewed in plan from the base material layer side. [Figure 2] It is a schematic cross-sectional view taken along line B-B' of FIG. 1. [Figure 3] It is a schematic cross-sectional view showing the laminated structure of the exterior material for the power storage device of the present disclosure. [Figure 4] It is a schematic cross-sectional view showing the laminated structure of the exterior material for the power storage device of the present disclosure. [Figure 5] It is a schematic cross-sectional view showing the laminated structure of the exterior material for the power storage device of the present disclosure. [Figure 6]This is a schematic diagram showing a cross-section of the exterior material for an energy storage device when the exterior material for the energy storage device is cut in the thickness direction along the line A-A' in Figure 1. [Figure 7] This is a schematic diagram showing a cross-section of the barrier layer when the outer material for the energy storage device is cut in the thickness direction along the line A-A' in Figure 1. [Figure 8] This is a schematic diagram illustrating a method for housing an energy storage device element in a package formed from the exterior material for energy storage devices of the present disclosure. [Modes for carrying out the invention]

[0015] The exterior material for an energy storage device of the present disclosure is formed as a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, wherein the exterior material for an energy storage device is formed to protrude from the heat-sealable resin layer side to the base layer side, and has a substantially rectangular parallelepiped space on the heat-sealable resin layer side in which an energy storage device element is housed, and when the exterior material for an energy storage device is viewed in plan view, the thickness of the barrier layer at the center of the substantially rectangular protruding portion is 38 μm or more, and when the exterior material for an energy storage device is viewed in plan view from the base layer side, the corner of the substantially rectangular protruding portion The radius of curvature of the portion is 2.0 mm or more, and when the exterior material for the energy storage device is viewed in plan from the base layer side, in the cross section in the thickness direction along the straight line connecting the opposing corners of the substantially rectangular protruding portion, the exterior material for the energy storage device has, in order from the center to the end, a first curved portion and a second curved portion, and the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located midway between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1. The exterior material for the energy storage device of this disclosure is characterized in that, despite having a substantially rectangular molded portion in an exterior material for an energy storage device having a barrier layer with a thickness of 38 μm or more, the corner portion of the molded portion is preferably suppressed from tearing in the vertical direction. In this specification, "approximately rectangular" means not only a rectangle with right angles at its four corners, but also a rectangle with rounded corners (R), for example. In this specification, "approximately rectangular parallelepiped" means not only a rectangular parallelepiped with right angles at each corner, but also a rectangular parallelepiped with rounded corners (R), for example.

[0016] The exterior materials for energy storage devices described herein will be described in detail below. In this specification, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to". For example, the notation 2~15mm means 2mm or more and 15mm or less.

[0017] 1. Laminated structure of exterior material for energy storage devices The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising, for example, a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order, as shown in Figures 3 to 5. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling an energy storage device using the exterior material 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-fussing the peripheral edges of the heat-fusible resin layers 4 of the exterior material 10 facing each other. In the laminate constituting the exterior material 10 for energy storage devices of this disclosure, with respect to the barrier layer 3, the heat-fusible resin layer 4 side is inward of the barrier layer 3, and the base layer 1 side is outward of the barrier layer 3.

[0018] The exterior material 10 for the energy storage device may, for example, have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as needed, for the purpose of improving the adhesion between these layers, as shown in Figures 3 to 5. Also, as shown in Figures 4 and 5, an adhesive layer 5 may, as needed, have an adhesive layer 5 between the barrier layer 3 and the heat-fusible resin layer 4, 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 the heat-fusible resin layer 4 side), as needed.

[0019] The thickness of the laminate constituting the exterior material 10 for energy storage devices is not particularly limited, but from the viewpoint of cost reduction and improvement of energy density, for example, it can be 300 μm or less, preferably about 250 μm or less, about 200 μm or less, or about 190 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior material for energy storage devices, which is to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 10 for energy storage devices can be preferably about 60 μm or more, about 80 μm or more, about 100 μm or more, about 150 μm or more, or about 180 μm or more. Furthermore, preferred ranges for the laminate constituting the outer casing material 10 for the energy storage device are, for example, approximately 60-300 μm, 60-250 μm, 60-200 μm, 60-190 μm, 80-300 μm, 80-250 μm, 80-200 μm, 80-190 μm, 100-300 μm, 100-250 μm, 100-200 μm, 100-190 μm, 150-300 μm, 150-250 μm, 150-200 μm, 150-190 μm, 180-300 μm, 180-250 μm, 180-200 μm, and 180-190 μm. The thickness of the laminate is the thickness at the center of the roughly rectangular protruding portion when the exterior material 10 for the energy storage device is viewed from above.

[0020] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3, the adhesive layer 5 (optionally provided), the heat-fusible resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. For example, if the exterior material 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even if the exterior material 10 for energy storage devices of this disclosure is a laminate comprising a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0021] 2. Shape of exterior material for energy storage devices As shown in Figures 1 and 2, the exterior material 10 for energy storage devices of this disclosure is molded to protrude from the heat-fusible resin layer 4 side to the base material layer 1 side. Specifically, the exterior material 10 for energy storage devices of this disclosure is molded to protrude from the heat-fusible resin layer 4 side to the base material layer 1 side by molding a sheet-like laminate having the above-described laminated structure. This molding can be performed, for example, by using a straight mold consisting of a substantially rectangular male mold and a female mold having a clearance with the male mold, placing the laminate on the female mold so that the heat-fusible resin layer 4 is positioned on the male mold side, and pressing the laminate with a predetermined pressure (surface pressure). As a result of this molding, when the exterior material 10 for energy storage devices of this disclosure is viewed from the base material layer 1 side, a substantially rectangular protruding portion 10a is formed on the exterior material 10 for energy storage devices. Furthermore, the molding process forms a substantially rectangular parallelepiped space 10b on the heat-fusible resin layer 4 side of the exterior material 10 for energy storage devices, in which the energy storage device elements are housed.

[0022] Alternatively, two of the exterior materials 10 for energy storage devices described herein may be prepared, and the heat-sealable resin layers 4 may be heat-fused together with the heat-sealable resin layers 4 facing each other, thereby housing the energy storage device elements in the combined space of the two spaces 10b. Alternatively, the exterior material 10 for energy storage devices described herein and a sheet-like laminate as described above may be prepared, and the heat-sealable resin layers 4 may be heat-fused together with the heat-sealable resin layers 4 facing each other, thereby housing the energy storage device elements in one space 10b.

[0023] In the exterior material 10 for energy storage devices of this disclosure, when viewed from above, the thickness of the barrier layer 3 at the center of the substantially rectangular protruding portion is 38 μm or more. Furthermore, as shown in Figure 1, when the exterior material 10 for energy storage devices is viewed from above from the base layer 1 side, the radius of curvature (corner R) of the corner portion P of the substantially rectangular protruding portion is 2.0 mm or more.

[0024] From the viewpoint of more favorably exhibiting the effects of the invention disclosed herein, the radius of curvature (corner R) is preferably about 2.0 to 5.0 mm, more preferably about 2.0 to 4.0 mm, and even more preferably about 2.0 to 3.0 mm.

[0025] In the exterior material 10 for energy storage devices of this disclosure, the limit molding depth in the molded portion is not particularly limited, but is preferably 3.0 mm or more, more preferably 5.0 mm or more, even more preferably 6.0 mm or more, even more preferably 8.0 mm or more, and even more preferably 10.0 mm or more, and also preferably 15.0 mm or less, 12.0 mm or less, and other preferred ranges include approximately 3.0 to 15.0 mm, approximately 3.0 to 12.0 mm, approximately 5.0 to 15.0 mm, approximately 5.0 to 12.0 mm, approximately 6.0 to 15.0 mm, approximately 6.0 to 12.0 mm, approximately 8.0 to 15.0 mm, approximately 8.0 to 12.0 mm, approximately 10.0 to 15.0 mm, and approximately 10.0 to 12.0 mm. The limiting molding depth for the exterior material of the energy storage device is determined by increasing the molding depth in 0.5 mm increments, starting from 0.5 mm, and checking for the presence of pinholes and cracks in the barrier layer of 10 test samples at each molding depth. The limiting molding depth is the maximum molding depth at which all 10 test samples are free of pinholes and cracks. Specifically, it is measured by the molding method described in the examples.

[0026] For example, as shown in Figures 1 and 6, when the exterior material 10 for the energy storage device of this disclosure is viewed in plan from the base material layer 1 side, the cross section in the thickness direction along the straight line A-A' connecting the opposing corner portions p of the substantially rectangular protruding portion 10a is such that the energy storage device The exterior material 10 for the wall has a first curved section 12 and a second curved section 14, in order from the center 11 to the end 15.

[0027] One of the features of the exterior material 10 for energy storage devices of this disclosure, as shown in Figure 6, is that the thickness D1 of the exterior material 10 for energy storage devices in the first curved portion 12, the thickness D2 of the exterior material 10 for energy storage devices in the second curved portion 14, and the thickness Dm of the exterior material 10 for energy storage devices in the portion 13 located between the first curved portion 12 and the second curved portion 14 satisfy the relationship D2 > Dm > D1. In this disclosure, the positions of thicknesses D1, Dm, and D2 are the points where the radius of curvature is smallest in each curved portion formed by molding, and usually refer to the central part from the start to the end of the curve.

[0028] As described above, the inventors of this disclosure have found that when the thickness of the barrier layer is set to 38 μm or more, if the molding depth is increased beyond the limit molding depth (i.e., the maximum molding depth at which damage such as pinholes or cracks does not occur in the barrier layer due to the molding of the exterior material for the energy storage device), the exterior material for the energy storage device will tear in the longitudinal direction (direction of the molding depth) at the molded portion formed on the exterior material for the energy storage device (specifically, the corner portion of the roughly rectangular protruding part when the exterior material for the energy storage device is viewed from the base layer side in a plan view).

[0029] In contrast, the exterior material 10 for energy storage devices of this disclosure is designed so that the thicknesses D1, Dm, and D2 of the exterior material 10 for energy storage devices after molding are in the specific relationship described above, thereby effectively suppressing longitudinal tearing when molding is performed beyond the limit molding depth. Specifically, the exterior material 10 for energy storage devices of this disclosure is designed so that the thickness Dm, which is the thinnest of the thicknesses of the exterior material 10 for energy storage devices after molding, is smaller than the thickness D2 but larger than the thickness D1, thereby increasing resistance to forces that cause longitudinal tearing.

[0030] In the exterior material 10 for energy storage devices of this disclosure, one method for satisfying the above relationship between thicknesses D1, Dm, and D2 is to set the thickness of the barrier layer 3 to 38 μm or more and the radius of curvature (corner R) to 2.0 mm or more, and further adjust the molding conditions using a mold. For example, the molding conditions using a mold, such as the molding depth, pressing pressure, and male die lifting speed, can be adjusted to design the thickness to satisfy the above relationship.

[0031] In the exterior material for energy storage devices of the present disclosure, the thickness D1 of the exterior material 10 for energy storage devices in the first curved portion 12 is preferably 80 μm or more, more preferably 90 μm or more, even more preferably 100 μm or more, and also preferably 150 μm or less, more preferably 140 μm or less, even more preferably 130 μm or less, and preferred ranges are approximately 80 to 150 μm, approximately 80 to 140 μm, approximately 80 to 130 μm, approximately 90 to 150 μm, approximately 90 to 140 μm, approximately 90 to 130 μm, approximately 100 to 150 μm, approximately 100 to 140 μm, and approximately 100 to 130 μm.

[0032] In the exterior material for energy storage devices of the present disclosure, the thickness D2 of the exterior material 10 for energy storage devices in the second curved portion 14 is preferably 130 μm or more, more preferably 140 μm or more, even more preferably 150 μm or more, and also preferably 180 μm or less, more preferably 175 μm or less, even more preferably 170 μm or less, and preferred ranges are approximately 130 to 180 μm, approximately 130 to 175 μm, approximately 130 to 170 μm, approximately 140 to 180 μm, approximately 140 to 175 μm, approximately 140 to 170 μm, approximately 150 to 180 μm, approximately 150 to 175 μm, and approximately 150 to 170 μm.

[0033] In the exterior material for energy storage devices of the present disclosure, the thickness Dm of the exterior material 10 for energy storage devices in the portion 13 located between the first curved portion 12 and the second curved portion 14 is preferably 90 μm or more, more preferably 100 μm or more, even more preferably 110 μm or more, and also preferably 150 μm or less, more preferably 140 μm or less, even more preferably 130 μm or less, and preferred ranges are approximately 90 to 150 μm, approximately 90 to 140 μm, approximately 90 to 130 μm, approximately 100 to 150 μm, approximately 100 to 140 μm, approximately 100 to 130 μm, approximately 110 to 150 μm, approximately 110 to 140 μm, and approximately 110 to 130 μm.

[0034] Furthermore, the thickness Dm-thickness D1 is preferably about 11 μm or more, more preferably about 13 μm or more, and also preferably about 55 μm or less, more preferably about 50 μm or less, with preferred ranges being approximately 11-55 μm, 11-50 μm, 13-55 μm, and 13-50 μm.

[0035] Furthermore, from the viewpoint of more favorably demonstrating the effects of the present invention, in the exterior material 10 for energy storage devices of this disclosure, as shown in Figure 7, it is preferable that the thickness Db1 of the barrier layer 3 in the first curved portion 12, the thickness Db2 of the barrier layer 3 in the second curved portion 14, and the thickness Dbm of the barrier layer 3 in the portion 13 located between the first curved portion 12 and the second curved portion 14 satisfy the relationship Db2>Dbm>Db1. In this disclosure, the positions of thicknesses Db1, Dbm, and Db2 correspond to the positions D1, Dm, and D2, respectively, and are the points where the radius of curvature is smallest in each curved portion formed by molding, and usually mean the central part from the start to the end of the curve.

[0036] In the exterior material 10 for energy storage devices of this disclosure, a method for satisfying the relationship between the thicknesses Db1, Dbm, and Db2 is to set the thickness of the barrier layer 3 to 38 μm or more and the radius of curvature (corner R) to 2.0 mm or more, and further adjust the molding conditions by the mold. For example, the molding conditions by the mold, such as the molding depth, pressing pressure, and male die lifting speed, can be adjusted to design the thickness to satisfy the above relationship.

[0037] In the exterior material for energy storage devices of this disclosure, the thickness Db1 of the barrier layer 3 in the first curved portion 12 is preferably 20 μm or more, more preferably 25 μm or more, even more preferably 30 μm or more, and also preferably 55 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, and preferred ranges are approximately 20-55 μm, approximately 20-50 μm, approximately 20-40 μm, approximately 25-55 μm, approximately 25-50 μm, approximately 25-40 μm, approximately 30-55 μm, approximately 30-50 μm, and approximately 30-40 μm.

[0038] In the exterior material for energy storage devices of this disclosure, the thickness Db2 of the barrier layer 3 in the second curved portion 14 is preferably 35 μm or more, more preferably 38 μm or more, even more preferably 40 μm or more, even more preferably 45 μm or more, and also preferably 75 μm or less, more preferably 70 μm or less, even more preferably 65 μm or less, and preferred ranges are approximately 35-75 μm, approximately 35-70 μm, approximately 35-65 μm, approximately 38-75 μm, approximately 38-70 μm, approximately 38-65 μm, approximately 40-75 μm, approximately 40-70 μm, approximately 40-65 μm, approximately 45-75 μm, approximately 45-70 μm, and approximately 45-65 μm.

[0039] In the exterior material for energy storage devices of this disclosure, the thickness Dbm of the barrier layer 3 in the portion 13 located between the first curved portion 12 and the second curved portion 14 is preferably 25 μm or more, more preferably 30 μm or more, even more preferably 35 μm or more, and also preferably 65 μm or less, more preferably 60 μm or less, even more preferably 55 μm or less, and preferred ranges are approximately 25-65 μm, approximately 25-60 μm, approximately 25-55 μm, approximately 30-65 μm, approximately 30-60 μm, approximately 30-55 μm, approximately 35-65 μm, approximately 35-60 μm, and approximately 35-55 μm.

[0040] Furthermore, the thickness Dbm-thickness Db1 is preferably about 2 μm or more, more preferably about 3 μm or more, and also preferably about 25 μm or less, more preferably about 23 μm or less, with preferred ranges being approximately 2-25 μm, 2-23 μm, 3-25 μm, and 3-23 μm.

[0041] 3. Each layer forming the exterior material for the energy storage device [Base material layer 1] In this disclosure, the base material layer 1 is a layer provided for purposes such as enabling it to function as a base material for the exterior material of an energy storage device. The base material layer 1 is located on the outer layer side of the exterior material for the energy storage device.

[0042] 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.

[0043] When the base layer 1 is formed of resin, the base layer 1 may be, for example, a resin film formed from resin, or it may be formed by coating with resin. That is, when the base layer 1 is formed of resin, the base layer 1 can be formed from, for example, a resin film. When the base layer 1 is formed from a resin film, 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, a pre-formed resin film may be used as the base layer 1. Alternatively, the resin forming the base layer 1 may be formed into a film on the surface of a barrier layer 3 or the like by extrusion molding or coating, resulting in a base layer 1 formed from a resin film. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include sequential biaxial stretching, inflation method, and simultaneous biaxial stretching. Examples of methods for coating with resin include roll coating, gravure coating, and extrusion coating.

[0044] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. Furthermore, the resin forming the base layer 1 may be a copolymer of these resins, or a modified version of such copolymer. It may also be a mixture of these resins.

[0045] 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.

[0046] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0047] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene(terephthalate / isophthalate)), polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), and polyethylene(terephthalate / decanedicarboxylate). These polyesters may be used individually or in combination of two or more types.

[0048] Furthermore, specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0049] 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.

[0050] 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.

[0051] 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 be located in the outermost layer of the base layer 1.

[0052] If the base layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in adhesive layer 2 described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and laminated. The anchor coat layer is similar to the adhesive exemplified in adhesive layer 2 described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0053] Furthermore, at least one of the surface and interior of the base layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. Only one type of additive may be used, or two or more types may be mixed and used.

[0054] In this disclosure, from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferable that a lubricant be present on at least one of the surface and interior of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearamide, m-xylylenebishydroxystearamide, 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.

[0055] When the lubricant is present on the surface of the base material layer 1, its amount of presence is not particularly limited. For example, about 3 mg / m 2 , 2 , 2 , 2 , , 2 , , ,

[0056] , 2 , 2 , , 2 , 2 , , 2 ,

[0057] , or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more can be mentioned. Further, as the amount of the lubricant present on the surface of the base material layer 1, for example, about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less can be mentioned. Further, as a preferable range of the amount of the lubricant present on the surface of the base material layer 1, it is about 3 to 15 mg / m 2 level, 3 to 14 mg / m 2 level, 3 to 10 mg / m 2 level, 4 to 15 mg / m 2 level, 4 to 14 mg / m 2 level, 4 to 10 mg / m 2 level, 5 to 15 mg / m 2 level, 5 to 14 mg / m 2 level, 5 to 10 mg / m 2 level can be mentioned.

[0056] The lubricant present on the surface of the base material layer 1 may be one obtained by exuding the lubricant contained in the resin constituting the base material layer 1, or may be one obtained by applying the lubricant to the surface of the base material layer 1.

[0057] 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. Alternatively, the thickness of the base layer 1 can be about 50 μm or less, preferably about 35 μm or less. A preferred range for the thickness of the base layer 1 is about 3 to 50 μm, about 3 to 35 μm, about 10 to 50 μm, or about 10 to 35 μm, with about 3 to 35 μm being particularly preferred when making a lightweight thin film for energy storage devices, and about 35 to 50 μm being preferred when improving moldability. If 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 for example, it can be about 2 μm or more, preferably about 10 μm or more, or about 18 μm or more, respectively. Alternatively, the thickness of the resin film constituting each layer can be about 33 μm or less, preferably about 28 μm or less, about 23 μm or less, or about 18 μm or less. Furthermore, preferred thickness ranges for the resin films constituting each layer include approximately 2-33 μm, 2-28 μm, 2-23 μm, 2-18 μm, 10-33 μm, 10-28 μm, 10-23 μm, 10-18 μm, 18-33 μm, 18-28 μm, and 18-23 μm. Note that the thickness of the base layer 1 is the thickness at the center of the roughly rectangular protruding portion when the exterior material 10 for the energy storage device is viewed in plan.

[0058] [Adhesive layer 2] In the exterior material for energy storage devices of this disclosure, the adhesive layer 2 is a layer provided between the substrate layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0059] 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.

[0060] Specifically, adhesive components included in adhesives include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used individually or in combination of two or more. Among these adhesive components, polyurethane adhesives are particularly preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected appropriately from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components.

[0061] 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. Examples of the second agent are 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). Also, polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are used. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. The adhesive layer 2 is formed from a polyurethane adhesive, which provides excellent electrolyte resistance to the exterior material for energy storage devices, preventing peeling of the substrate layer 1 even if electrolyte adheres to the sides.

[0062] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may include colorants, thermoplastic elastomers, tackifiers, fillers, etc. The inclusion of a colorant in the adhesive layer 2 allows for the coloring of the exterior material for energy storage devices. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0063] The type of pigment is not particularly limited, as long as it does not impair the adhesion of adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0064] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance.

[0065] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0066] The pigment content in the adhesive layer 2 is not particularly limited as long as the exterior material for the energy storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0067] 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. Note that the thickness of the adhesive layer 2 is the thickness at the center of the roughly rectangular protruding portion when the exterior material 10 for the energy storage device is viewed in plan.

[0068] [Colored layer] The colored layer is a layer provided between the base layer 1 and the barrier layer 3 as needed (not shown in the figure). If an adhesive layer 2 is present, the colored layer may be provided between the base layer 1 and the adhesive layer 2, and between the adhesive layer 2 and the barrier layer 3. Alternatively, the colored layer may be provided on the outside of the base layer 1. By providing a colored layer, the exterior material for the energy storage device can be colored.

[0069] 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.

[0070] Specific examples of colorants included in the colored layer are the same as those exemplified in the [Adhesive Layer 2] section.

[0071] [Barrier layer 3] In the exterior material for energy storage devices, the barrier layer 3 is a layer that at least prevents the intrusion of moisture.

[0072] Examples of barrier layer 3 include metal foil, vapor-deposited film, and resin layer with barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as barrier layer 3. Multiple layers of barrier layer 3 may be provided. It is preferable that barrier layer 3 includes a layer made of a metal material. Specific examples of metal materials constituting barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0073] From the viewpoint of improving the formability of the exterior material for energy storage devices, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is more preferably an aluminum alloy foil containing iron. In an iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior material for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material for energy storage devices with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments.

[0074] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0075] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0076] The thickness of the barrier layer 3 is not particularly limited as long as it functions as a barrier layer that at least prevents moisture from penetrating, and is 38 μm or more. The thickness of the barrier layer is preferably about 40 μm or more, more preferably about 45 μm or more, even more preferably about 55 μm or more, even more preferably about 75 μm or more, and also preferably about 150 μm or less, more preferably about 100 μm or less, even more preferably about 85 μm or less, and even more preferably about 65 μm or less, with preferred ranges being approximately 38 to 150 μm, approximately 38 to 100 μm, and 38 to 85 Examples of possible thicknesses include approximately μm, 38-65 μm, 40-150 μm, 40-100 μm, 40-85 μm, 40-65 μm, 45-150 μm, 45-100 μm, 45-85 μm, 45-65 μm, 55-150 μm, 55-100 μm, 55-85 μm, 55-65 μm, 75-150 μm, 75-100 μm, and 75-85 μm. The thickness of the barrier layer 3 is the thickness at the center of the roughly rectangular protruding portion when the exterior material 10 for the energy storage device is viewed from above.

[0077] Furthermore, if the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one. Furthermore, among these treatments, hot water modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. These processes may also be included in the definition of chemical conversion treatment. Furthermore, if barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0078] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of exterior materials for energy storage devices. It also prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolyte and water, particularly the dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil. Furthermore, it improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0079] Various corrosion-resistant coatings are known to be formed by chemical conversion treatments, mainly including corrosion-resistant coatings containing at least one of the following: phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl acetate chromate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphate. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. This coating-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., aluminum alloy foil) using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation. Then, a treatment solution mainly composed of metal phosphate salts such as chromium phosphate, titanium phosphate, zirconium phosphate, and zinc phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphates and mixtures thereof, or a treatment solution consisting of a mixture of these with synthetic resins, etc., is applied to the degreased surface using a well-known coating method such as roll coating, gravure printing, or immersion, and then dried. Various solvents can be used as the treatment solution, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Furthermore, examples of resin components used in this process include polymers such as phenolic resins and acrylic resins, and examples of chromate treatment using an amination phenol polymer having repeating units represented by the following general formulas (1) to (4). In this amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included individually or in any combination of two or more types.The acrylic resin is preferably polyacrylic acid, acrylate methacrylate copolymer, acrylate maleic acid copolymer, acrylate styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, or amine salts. Derivatives of polyacrylic acid, such as ammonium salts, sodium salts, or amine salts of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid means a polymer of acrylic acid. Furthermore, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride, and also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2Examples of 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 2 Examples 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 adding formaldehyde and amine (R 1 R 2 Using NH) to form the functional group (-CH2NR 1 R 2 ) to be introduced into the polymer obtained above. It is manufactured by [method]. The amination phenol polymer is used alone or in a mixture of two or more types.

[0085] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0086] One 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.

[0087] 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.

[0088] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0089] 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 Each serving contains, for example, about 0.5 to 50 mg of chromium equivalent, preferably 1 It is desirable that the product contains approximately 0.0 to 40 mg of phosphorus compounds, for example, approximately 0.5 to 50 mg of phosphorus equivalent, preferably approximately 1.0 to 40 mg of aminophenol polymers, and for example, approximately 1.0 to 200 mg, preferably approximately 5.0 to 150 mg of aminophenol polymers.

[0090] 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. + , C epo4 - (at least one of the above), or, for example, a secondary ion consisting of Cr, P, and O (e.g., CrPO2) + , CrPO4 - Peaks originating from at least one of the following are detected.

[0091] The chemical conversion treatment is carried out by applying a solution containing compounds used to form a corrosion-resistant film to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70-200°C. Alternatively, before applying the chemical conversion treatment to the barrier layer, it may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. This degreasing treatment makes it possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. Furthermore, by using an acid degreasing agent, which is a fluorine-containing compound dissolved in an inorganic acid, it is possible to not only degrease the metal foil but also form a fluoride of the passive metal; in such cases, only the degreasing treatment may be performed.

[0092] [Thermal adhesive resin layer 4] In the exterior material for energy storage devices of this disclosure, the heat-sealable resin layer 4 is the innermost layer and is a layer (sealant layer) that performs the function of sealing the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device.

[0093] The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, are preferred. The presence of a polyolefin backbone in the resin constituting the heat-fusible resin layer 4 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable to detect a peak originating from maleic anhydride. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak derived from maleic anhydride is detected in the vicinity. If the heat-fusible resin layer 4 is composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0094] 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.

[0095] 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.

[0096] Acid-modified polyolefins are polymers obtained by modifying polyolefins through block polymerization or graft polymerization with an acid component. Examples of polyolefins that can be acid-modified include the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or their anhydrides, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0097] 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.

[0098] 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.

[0099] The heat-sealable resin layer 4 may be formed by a single resin or by a blended polymer of two or more resins. Furthermore, the heat-sealable resin layer 4 may be formed as a single layer or as two or more layers made of the same or different resins.

[0100] Furthermore, the heat-fusible resin layer 4 may contain a lubricant or the like as needed. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more types.

[0101] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in base layer 1. The lubricant may be used alone or in combination of two or more types.

[0102] When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount present is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably 10 to 50 mg / m². 2 To a certain extent, more preferably 15-40 mg / m² 2 The degree can be described as follows.

[0103] 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.

[0104] Furthermore, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device elements, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described later is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm. The thickness of the heat-fusible resin layer 4 is the thickness at the center of the substantially rectangular protruding portion when the exterior material 10 for the energy storage device is viewed from above.

[0105] [Adhesive layer 5] In the exterior material for energy storage devices of this disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or corrosion-resistant film) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0106] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. The resin used to form the adhesive layer 5 can be the same as the adhesive exemplified in the adhesive layer 2. Furthermore, from the viewpoint of firmly bonding the adhesive layer 5 to the heat-fusible resin layer 4, the resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, 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 for the exterior material of the energy storage device, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

[0107] When the resin used to form the adhesive layer 5 contains a polyolefin skeleton, it is preferable that the adhesive layer 5 mainly contains a resin containing a polyolefin skeleton, more preferably acid-modified polyolefin, and even more preferably acid-modified polypropylene. 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 mainly contains acid-modified polypropylene, 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.

[0108] 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 determined, for example, by measuring maleic anhydride-modified polyolefin using infrared spectroscopy, at a wavenumber of 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. However, if the degree of acid denaturation is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0109] Furthermore, from the viewpoint of ensuring durability such as heat resistance and resistance to contents of the exterior material for energy storage devices, as well as ensuring moldability while keeping the thickness thin, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. The above-mentioned products are examples of the acid-modified polyolefin.

[0110] 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).

[0111] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups 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).

[0112] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, biuretes, and isocyanurates are also examples.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably around 50 to 2000, more preferably around 100 to 1000, and even more preferably around 200 to 800. In this disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] Furthermore, if the adhesive layer 5 is a cured product of a resin composition containing at least one compound selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups each function as curing agents.

[0122] The adhesive layer 5 may contain a modifier having a carbodiimide group.

[0123] When manufacturing the exterior material 10 for the energy storage device of 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.

[0124] The thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less. Alternatively, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more, or about 0.5 μm or more. The range of the thickness of the adhesive layer 5 is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2, or the cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. 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. Furthermore, when the heat-fusible resin layer 4 and the adhesive layer 5 are formed by co-extrusion molding, the lower limit for the total thickness of the heat-fusible resin layer 4 and the adhesive layer 5 is 35 μm, 55 μm, and 75 μm, and the upper limit is 45 μm, 65 μm, and 85 μm, with preferred numerical ranges being 35-45 μm, 35-65 μm, 35-85 μm, 55-65 μm, 55-85 μm, and 75-85 μm. The thickness of the adhesive layer 5 is the thickness at the center of the portion that protrudes in a roughly rectangular shape when the exterior material 10 for the energy storage device is viewed from above.

[0125] [Surface coating layer 6] The exterior material 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: design, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the exterior material for energy storage devices when the energy storage device is assembled using the exterior material for energy storage devices.

[0126] 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.

[0127] 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.

[0128] 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 include those comprising a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the first agent and an aromatic or aliphatic polyisocyanate as the second agent. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and a polyol compound. Examples of polyurethanes include polyurethanes cured by reacting a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. Furthermore, aliphatic isocyanate compounds refer to isocyanates that have an aliphatic group and no aromatic ring, alicyclic isocyanate compounds refer to isocyanates that have an alicyclic hydrocarbon group, and aromatic isocyanate compounds refer to isocyanates that have an aromatic ring.The surface coating layer 6 is formed of polyurethane, which provides the exterior material for energy storage devices with excellent electrolyte resistance.

[0129] The surface coating layer 6 may contain, as necessary, additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents 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.

[0130] 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.

[0131] 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. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0132] 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.

[0133] 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. The thickness of the surface coating layer 6 is the thickness at the center of the substantially rectangular protruding portion when the exterior material 10 for the energy storage device is viewed in plan.

[0134] 4. Method for manufacturing exterior materials for energy storage devices The method for manufacturing an exterior material for an energy storage device is not particularly limited, as long as a laminate is obtained by stacking the layers of the exterior material for an energy storage device according to this disclosure. Examples of such methods include: preparing a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer; and molding the sheet-like laminate so that it protrudes from the heat-fusible resin layer side to the base layer side, thereby forming a substantially rectangular parallelepiped space on the heat-fusible resin layer side in which an energy storage device element is housed. In other words, the method for manufacturing an exterior material for an energy storage device according to the present disclosure comprises the steps of: preparing a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer; and molding the sheet-like laminate so that it protrudes from the heat-fusible resin layer side to the base layer side, thereby forming a substantially rectangular parallelepiped space on the heat-fusible resin layer side in which an energy storage device element is housed, wherein when the exterior material for the energy storage device is viewed from above, the thickness of the barrier layer at the center of the substantially rectangular protruding portion is 38 μm or more, and when the exterior material for the energy storage device is viewed from above from the base layer side, the substantially rectangular protruding portion The radius of curvature of the corner portion is 2.0 mm or more, and when the exterior material for the energy storage device is viewed in plan view from the base material layer side, in the cross section in the thickness direction along the straight line connecting the opposing corner portions of the substantially rectangular protruding portion, the exterior material for the energy storage device has, in order from the center to the end, a first curved portion and a second curved portion, and the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1.

[0135] An example of a method for manufacturing the exterior material for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated laminate A") is formed by sequentially laminating a base layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form the adhesive layer 2 is applied to the base layer 1 or, if necessary, to the barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured.

[0136] Next, a heat-fusible resin layer 4 is laminated onto the barrier layer 3 of laminate A. When the heat-fusible resin layer 4 is directly laminated onto the barrier layer 3, the heat-fusible resin layer 4 can be laminated onto the barrier layer 3 of laminate A by methods such as thermal lamination or extrusion lamination. 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 the extrusion lamination method is a method in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated by extruding them onto the barrier layer 3 of laminate A (co-extrusion lamination method, tandem lamination method). Furthermore, (2) as a thermal lamination method, for example, a laminate is formed by separately laminating an adhesive layer 5 and a heat-fusible resin layer 4, and this is laminated onto the barrier layer 3 of laminate A, or a laminate is formed by laminating an adhesive layer 5 on the barrier layer 3 of 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 laminate A and a heat-fusible resin layer 4 that has been previously made into a sheet, thereby bonding laminate A and 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 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.

[0137] 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.

[0138] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0139] In exterior materials for energy storage devices, the processability of each layer constituting the laminate may be improved by subjecting it to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as needed. For example, by applying corona treatment to the surface of the substrate layer 1 opposite to the barrier layer 3, the printability of ink on the surface of the substrate layer 1 can be improved.

[0140] The exterior material 10 for energy storage devices according to the present disclosure is obtained by molding the sheet-like laminate obtained above. Specifically, the exterior material 10 for energy storage devices according to the present disclosure is molded so that the sheet-like laminate having the above-described laminate structure protrudes from the heat-fusible resin layer 4 side to the base material layer 1 side. In molding, for example, a straight mold consisting of a substantially rectangular male mold and a female mold having a clearance (usually about 0.5 to 2.0 mm) with the male mold is used, and the laminate is placed on the female mold so that the heat-fusible resin layer side is located on the male mold side, and the laminate is pressed with a predetermined pressure (surface pressure) to form it. As a result of this molding, when the exterior material 10 for energy storage devices is viewed from the base material layer 1 side, a substantially rectangular protruding portion 10a is formed on the exterior material 10 for energy storage devices. Furthermore, as a result of this molding, a substantially rectangular parallelepiped space 10b is formed on the heat-fusible resin layer 4 side of the exterior material 10 for energy storage devices, in which an energy storage device element is housed.

[0141] 5. Applications of exterior materials for energy storage devices The exterior material for energy storage devices of this disclosure is used in packaging for sealing and housing energy storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an energy storage device can be formed by housing energy storage device elements, which include at least a positive electrode, a negative electrode, and an electrolyte, in packaging formed from the exterior material for energy storage devices of this disclosure.

[0142] Specifically, an energy storage device is provided by covering an energy storage device element, which comprises at least a positive electrode, a negative electrode, and an electrolyte, with the energy storage device exterior material of this disclosure, such that a flange portion (an area where heat-sealable resin layers come into contact) is formed around the periphery of the energy storage device element, with the metal terminals connected to the positive electrode and negative electrode respectively protruding outward, and then heat-sealing the heat-sealable resin layers of the flange portion to seal it. When housing the energy storage device element in a package formed from the energy storage device exterior material of this disclosure, the package is formed such that the heat-sealable resin portion of the energy storage device exterior material of this disclosure faces inward (the surface in contact with the energy storage device element). The packaging can be formed by overlapping the heat-sealable resin layers of two energy storage device casing materials facing each other and heat-sealing the periphery of the overlapped casing materials. Alternatively, as shown in the example in Figure 8, one energy storage device casing material can be folded and overlapped, and the periphery can be heat-sealed to form a packaging. When folding and overlapping, as shown in the example in Figure 8, the edges other than the folded edge can be heat-sealed to form a three-sided seal to form the packaging, or it can be folded so that a flange portion is formed and sealed on all four sides. Alternatively, the energy storage device casing material can be wrapped around the energy storage device element, the heat-sealable resin layers can be sealed together to form a heat-sealed portion, and a lid or the like can be placed to close the openings at both ends. Furthermore, recesses for housing energy storage device elements may be formed in the exterior material for the energy storage device by deep drawing or stretch molding. As shown in the example in Figure 8, recesses may be provided in one exterior material for the energy storage device while not being provided in the other, or recesses may be provided in the other exterior material for the energy storage device as well.

[0143] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The types of secondary batteries to which the casing material for energy storage devices disclosed herein can be applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, pseudo-solid-state batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. [Examples]

[0144] 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.

[0145] <Manufacturing of exterior materials for energy storage devices> (Layer stacking of each layer) Examples 1, 4 and Comparative Examples 1, 4 As the base layer, stretched polyethylene terephthalate (PET) film (12 μm thick) and stretched nylon (ONy) film (25 μm thick) were prepared. Using a two-component urethane adhesive (polyol compound and aromatic isocyanate compound), the PET film and ONy film were bonded via the adhesive layer (DL: formed by dry lamination) so that the thickness of the adhesive layer after curing was 3 μm. In addition, aluminum foil (JIS H4160:1994 A8079H-O (80 μm thick)) was prepared as the barrier layer. After laminating the aluminum foil and the base layer (ONy film side) by dry lamination so that the thickness of the adhesive layer after curing was 3 μm, an aging treatment was performed to create a laminate of base layer / adhesive layer / barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil consisted of a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 (Dry mass) This was done by applying the coating to both sides of the aluminum foil using the roll-coating method and then baking it.

[0146] Next, maleic anhydride-modified polypropylene as an adhesive layer and random polypropylene as a heat-fusible resin layer were melt-extruded onto the barrier layer of each laminate obtained above, thereby laminating an adhesive layer (30 μm thick) and a heat-fusible resin layer (30 μm thick) on the barrier layer, and an exterior material for energy storage devices (total thickness 183 μm) was obtained in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in that order.

[0147] Examples 2, 5 and Comparative Examples 2, 5 Except for using aluminum foil (JIS H4160:1994 A8079H-O (thickness 60 μm)) as the barrier layer and setting the thickness of the adhesive layer and the heat-sealable resin layer to 40 μm each, an exterior material for an energy storage device (total thickness 183 μm) was obtained in the same manner as in Examples 1 and 4 and Comparative Examples 1 and 4, in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in that order.

[0148] Examples 3, 6 and Comparative Examples 3, 6 Except for using a stretched nylon (ONy) film with a thickness of 15 μm, using aluminum foil (JIS H4160:1994 A8079H-O (thickness 40 μm)) as the barrier layer, and setting the thickness of the adhesive layer and the heat-sealable resin layer to 40 μm each, an exterior material for an energy storage device (total thickness 153 μm) was obtained in the same manner as in Examples 1 and 4 and Comparative Examples 1 and 4, in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in that order.

[0149] Comparative Example 7 A stretched nylon (ONy) film (20 μm thick) was prepared as the base layer. Aluminum foil (JIS H4160:1994 A8021H-O (30 μm thick)) was prepared as the barrier layer. The aluminum foil and base layer were laminated by dry lamination so that the thickness of the adhesive layer after curing was 3 μm, and then an aging treatment was performed to create a laminate of base layer / adhesive layer / barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil 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 (Dry mass) This was done by applying the coating to both sides of the aluminum foil using the roll-coating method and then baking it.

[0150] Next, maleic anhydride-modified polypropylene as an adhesive layer and random polypropylene as a heat-fusible resin layer were melt-extruded onto the barrier layer of each laminate obtained above, thereby laminating an adhesive layer (thickness 14 μm) and a heat-fusible resin layer (thickness 10 μm) on the barrier layer, and an exterior material for energy storage devices (total thickness 77 μm) was obtained in which a base layer / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in that order.

[0151] <Molding> The sheet-like exterior materials for each energy storage device obtained as described above were cut into rectangles measuring 200 mm in length (MD) x 360 mm in width (TD). The MD of the exterior material for the energy storage device corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for the energy storage device corresponds to the TD of the aluminum alloy foil. Next, in an environment of 25℃, a rectangular molding die with a bore diameter of 90mm (MD) × 250mm (TD) (female mold, the 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. The corner radii are the radii of curvature listed in Table 1, and the ridge radius is 1.0 mm) and a molding die with a clearance of 0.3 mm (male mold, the surface of the ridges 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 surface other than the ridges is as specified in Annex 1 (Reference) of JIS B 0659-1:2002. Cold forming was performed using a standard surface roughness sample for comparison, with a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2. The corner radius was the radius of curvature listed in Table 1, and the edge radius was 1.0 mm. The mold clamping pressure was the pressure listed in Table 1. The forming depth was 6.0 mm for Examples 1, 2, 4, and 5 and Comparative Examples 1, 2, 4, and 5 (total thickness 183 μm), and 4.0 mm for Examples 3 and 6 and Comparative Examples 3, 6, and 7.

[0152] After molding, each exterior material for the energy storage device was examined in a dark room using a penlight to check for pinholes or cracks in the corners of the aluminum foil. The results showed that no pinholes or cracks were present in the aluminum foil of any of the exterior materials for the energy storage devices.

[0153] <Measurement of the thickness of the exterior material for energy storage devices after molding> For each of the molded exterior materials for energy storage devices after the above (molding) procedure, as shown in Figures 1 and 6, when viewed from the base material side, the exterior material 10 for the energy storage device was divided into two by cutting in the thickness direction along a straight line connecting the opposing corners p of the substantially rectangular protruding portion 10a using a microtome (Daiwa Koki Kogyo Co., Ltd.: REM-710 retratome). The resulting cross-sections were observed with a laser microscope (Keyence Co., Ltd.: VKX-100) to measure the thickness D1 of the exterior material for the energy storage device at the first curved portion, the thickness D2 of the exterior material for the energy storage device at the second curved portion, and the thickness Dm of the exterior material for the energy storage device at the portion located midway between the first and second curved portions. Furthermore, the thickness Db1 of the barrier layer at the first curved portion, the thickness Db2 of the barrier layer at the second curved portion, and the thickness Dbm of the barrier layer at the portion located midway between the first and second curved portions were also measured. The results are shown in Table 1.

[0154] <Evaluation of molding beyond the limit molding depth> In the aforementioned (molding) process, the molding depth was set to 11.0 mm for Examples 1 and 4 and Comparative Examples 1 and 4 (total thickness 183 μm, barrier layer thickness 80 μm), to 10.0 mm for Examples 2 and 5 and Comparative Example 2 and 5 (total thickness 183 μm, barrier layer thickness 60 μm), to 8.0 mm for Examples 3 and 6 and Comparative Example 3 and 5 (total thickness 153 μm, barrier layer thickness 40 μm), and to 7.0 mm for Comparative Example 7 (total thickness 77 μm, barrier layer thickness 30 μm). Cold forming was performed in the same manner as described above. These molding depths were set to evaluate the impact resistance when the exterior material for the energy storage device undergoes thermal expansion after molding, and each exceeds the limit molding depth by only 0.5 mm. The limit molding depth is determined by increasing the molding depth in 0.5 mm increments, starting from 0.5 mm, and checking for the presence of pinholes and cracks in the barrier layer of 10 test samples at each molding depth. The limit molding depth is the maximum molding depth at which all 10 test samples are free of pinholes and cracks.

[0155] As mentioned above, evaluation by molding beyond the limit molding depth is used, for example, to evaluate the impact resistance of the exterior material for energy storage devices during thermal expansion after molding. That is, assuming a scenario where the energy storage device is placed in a high-temperature environment and the molded exterior material is further stretched by thermal expansion, and then subjected to an external impact, the impact resistance of the exterior material for energy storage devices after molding is performed beyond the limit molding depth is used to evaluate the damage that occurs. If the damage to the barrier layer is only slight when molding is performed slightly beyond the limit molding depth, such as pinholes or cracks, the damage to the exterior material for energy storage devices is small, and it is evaluated as having excellent impact resistance during thermal expansion. On the other hand, if the corner of the exterior material for energy storage devices tears vertically, it is evaluated as having insufficient impact resistance because the exterior material for energy storage devices is significantly damaged. Table 1 shows whether the damage was a pinhole or a vertical tear.

[0156] After molding, each exterior material for the energy storage device was viewed from the base layer side, and the corners of the molded parts were observed to check for any vertical cracks (in the direction of the molding depth) at the corners. Furthermore, each exterior material for the energy storage device after molding was examined in a dark room using a penlight to check for pinholes or cracks in the corners of the aluminum foil by light transmission.

[0157] The pinholes formed at the corners of the barrier layer were observed at the locations of corner p (a total of 4 locations) in the schematic diagrams of Figures 1 and 6. Furthermore, when the corner p of the exterior material for the energy storage device is described as cracking in the vertical direction (direction of molding depth) from the first curved section 12 to the second curved section 14 in the schematic diagrams of Figures 1 and 6, the degree of damage to the exterior material for the energy storage device is significantly greater compared to the pinholes formed at the corner p of the barrier layer.

[0158] [Table 1]

[0159] As described above, this disclosure provides inventions in the following embodiments. Item 1. An exterior material for an energy storage device, formed by creating a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, The exterior material for the energy storage device is molded to protrude from the heat-sealable resin layer side towards the base material layer side, and has a substantially rectangular parallelepiped space on the heat-sealable resin layer side in which the energy storage device element is housed. When the exterior material for the energy storage device is viewed in plan view, the thickness of the barrier layer at the center of the substantially rectangular protruding portion is 38 μm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the substantially rectangular protruding part is 2.0 mm or more. When the exterior material for the energy storage device is viewed in plan view from the base material layer side, in the cross-section in the thickness direction along a straight line connecting the opposing corners of the substantially rectangular protruding portion, the exterior material for the energy storage device is provided with, in order from the center to the end, a first curved portion and a second curved portion. An exterior material for an energy storage device, wherein the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1. Item 2. The exterior material for an energy storage device according to Item 1, wherein the thickness Db1 of the barrier layer in the first curved portion, the thickness Db2 of the barrier layer in the second curved portion, and the thickness Dbm of the barrier layer in the portion located between the first curved portion and the second curved portion satisfy the relationship Db2 > Dbm > Db1. Item 3. The exterior material for an energy storage device according to item 1 or 2, wherein the barrier layer is made of aluminum alloy foil. Item 4. The exterior material for an energy storage device according to Item 3, wherein the thickness of the aluminum alloy foil is 60 μm or more. Item 5. An exterior material for an energy storage device according to any one of items 1 to 4, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer. Item 6. The exterior material for an energy storage device according to any one of items 1 to 5, wherein, when the exterior material for the energy storage device is viewed in plan, the thickness of the laminate at the center of the substantially rectangular protruding portion is 100 μm or more. Item 7. A step of preparing a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, The process involves forming the sheet-like laminate so that it protrudes from the heat-sealable resin layer side to the base material layer side, thereby forming a substantially rectangular parallelepiped space on the heat-sealable resin layer side in which the energy storage device element is housed, It is equipped with, When the exterior material for the energy storage device is viewed in plan view, the thickness of the barrier layer at the center of the roughly rectangular protruding portion is 38 μm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the substantially rectangular protruding part is 2.0 mm or more. When the exterior material for the energy storage device is viewed in plan view from the base material layer side, in the cross-section in the thickness direction along a straight line connecting the opposing corners of the substantially rectangular protruding portion, the exterior material for the energy storage device is provided with, in order from the center to the end, a first curved portion and a second curved portion. A method for manufacturing an exterior material for an energy storage device, wherein the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1. Item 8. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer casing material for an energy storage device as described in any one of items 1 to 6. [Explanation of symbols]

[0160] 1 Base material layer 2 Adhesive layer 3. Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices 10a A roughly rectangular protruding portion 10b A roughly rectangular space 11. The central part of the exterior material for energy storage devices when viewed from above. 12. First curved section 13. The section located midway between the first and second curved sections. 14. Second Curve Section 15 End

Claims

1. An exterior material for an energy storage device, formed by creating a sheet-like laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, The exterior material for the energy storage device is molded to protrude from the heat-sealable resin layer side to the base material layer side, and has a substantially rectangular parallelepiped space on the heat-sealable resin layer side in which the energy storage device element is housed. When the exterior material for the energy storage device is viewed in plan view, the thickness of the barrier layer at the center of the substantially rectangular protruding portion is 38 μm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the substantially rectangular protruding part is 2.0 mm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, in the cross-section in the thickness direction along a straight line connecting the opposing corners of the substantially rectangular protruding portion, the exterior material for the energy storage device is provided with, in order from the center to the end, a first curved portion and a second curved portion. An exterior material for an energy storage device, wherein the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1.

2. The exterior material for an energy storage device according to claim 1, wherein the thickness Db1 of the barrier layer in the first curved portion, the thickness Db2 of the barrier layer in the second curved portion, and the thickness Dbm of the barrier layer in the portion located between the first curved portion and the second curved portion satisfy the relationship Db2 > Dbm > Db1.

3. The exterior material for an energy storage device according to claim 1 or 2, wherein the barrier layer is made of aluminum alloy foil.

4. The exterior material for an energy storage device according to claim 3, wherein the thickness of the aluminum alloy foil is 60 μm or more.

5. The exterior material for an energy storage device according to claim 1 or 2, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.

6. The exterior material for an energy storage device according to claim 1 or 2, wherein, when the exterior material for the energy storage device is viewed in plan, the thickness of the laminate at the center of the substantially rectangular protruding portion is 100 μm or more.

7. The process involves preparing a sheet-like laminate comprising, in order from the outside in, at least a base layer, a barrier layer, and a heat-sealable resin layer, The process involves forming the sheet-like laminate so that it protrudes from the heat-sealable resin layer side to the base material layer side, thereby forming a substantially rectangular parallelepiped space on the heat-sealable resin layer side in which the energy storage device element is housed, It is equipped with, When the exterior material for the energy storage device is viewed in plan view, the thickness of the barrier layer at the center of the roughly rectangular protruding portion is 38 μm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, the radius of curvature of the corner portion of the substantially rectangular protruding part is 2.0 mm or more. When the exterior material for the energy storage device is viewed in plan from the base material layer side, in the cross-section in the thickness direction along a straight line connecting the opposing corners of the substantially rectangular protruding portion, the exterior material for the energy storage device is provided with, in order from the center to the end, a first curved portion and a second curved portion. A method for manufacturing an exterior material for an energy storage device, wherein the thickness D1 of the exterior material for the energy storage device in the first curved portion, the thickness D2 of the exterior material for the energy storage device in the second curved portion, and the thickness Dm of the exterior material for the energy storage device in the portion located between the first curved portion and the second curved portion satisfy the relationship D2 > Dm > D1.

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

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