JP7347455B2 - Exterior material for power storage device, power storage device, and manufacturing method thereof - Google Patents

Description

The present disclosure relates to an exterior material for a power storage device, a power storage device, and a manufacturing method thereof.

Conventionally, various types of power storage devices have been developed, and in all power storage devices, an exterior material has become an essential member for sealing power storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been frequently used as exterior materials for power storage devices.

On the other hand, in recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like have become more sophisticated, power storage devices are required to have a variety of shapes, as well as to be thinner and lighter. However, metal exterior materials for power storage devices, which have been widely used in the past, have the disadvantage that it is difficult to keep up with the diversification of shapes, and there is also a limit to the reduction in weight.

Therefore, in recent years, film-like materials in which a base material layer, a barrier layer, and a heat-fusible resin layer are sequentially laminated have been developed as exterior materials for power storage devices that can be easily processed into various shapes and can be made thinner and lighter. A laminate has been proposed (see, for example, Patent Document 1).

In such an exterior material for a power storage device, a recess is generally formed by cold forming using a mold, and power storage device elements such as electrodes and electrolyte are placed in the space formed by the recess. By heat-sealing the heat-fusible resin layer, a power storage device in which power storage device elements are housed inside the power storage device exterior material is obtained.

JP2008-287971A

In recent years, large-sized power storage devices with large aspect ratios are sometimes required. For example, with energy storage devices used in electric vehicles, hybrid electric vehicles, etc., by laying energy storage devices (without stacking them) on height-restricted areas of the vehicle floor, more energy storage devices can be installed in the vehicle. The power storage devices installed in such vehicles will be large in size and have a large aspect ratio.

On the other hand, as described above, in the exterior material for an electricity storage device made of a film-like laminate, the concave portion is formed by cold forming using a mold. Therefore, it is necessary to form a concave portion having a large size and a large aspect ratio (for example, a long side of 200 mm or more and an aspect ratio of 2.5 or more) in an exterior material used for a large-sized power storage device with a large aspect ratio.

However, the inventors of the present disclosure have investigated and found that when attempting to form a recess with a large size and aspect ratio in an exterior material for an energy storage device made of a film-like laminate, the periphery of the exterior material for an energy storage device It has been found that when the portions (particularly the long side portions) are curled (curved) by molding and the electricity storage device element is sealed in the recessed portion, the thermal fusion of the heat-fusible resin layer is inhibited.

Under such circumstances, the main objective of the present disclosure is to provide an exterior material for a power storage device in which curling due to molding is suppressed.

The inventors of the present disclosure have conducted extensive studies to solve the above problems. As a result, an exterior material for an electricity storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is formed, The exterior material for a power storage device is formed so as to protrude from the heat-fusible resin layer side to the base material layer side, and has a rectangular parallelepiped-shaped recess in which the power storage device element is housed on the heat-fusible resin layer side. When the exterior material for power storage device is observed from the base layer side, the center of the recess is on the straight line connecting the shortest distance between the center of the recess and the short side of the exterior material for power storage device. A first short side curved surface portion and a second short side curved surface portion are provided in order from the short side of the exterior material for an electricity storage device, and when the exterior material for an energy storage device is observed from the base material layer side, On a straight line connecting the center of the concave portion and the long side of the exterior material for power storage device at the shortest distance, from the center of the concave portion to the long side of the exterior material for power storage device, a first long side curved surface portion and a second and long side curved surface portions in order, the radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion, and the first long side curved surface portion The exterior material for a power storage device, in which the radius of curvature R _B ¹ is 3.8 mm or more, effectively suppresses curling due to molding, and when sealing the power storage device element in the recess, the heat of the heat-fusible resin layer is reduced. It has been found that fusion is less likely to be inhibited.

The present disclosure has been completed through further studies based on these findings. That is, the present disclosure provides inventions of the following aspects.
An exterior material for an electricity storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is molded,
The exterior material for the power storage device is formed to protrude from the heat-fusible resin layer side to the base material layer side, and has a rectangular parallelepiped shape in which the power storage device element is housed on the heat-fusible resin layer side. Equipped with a recess,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
An exterior material for an electricity storage device ^{, wherein a radius of curvature R B1} _of the first long side curved surface portion is 3.8 mm or more.

According to the present disclosure, it is possible to provide an exterior material for a power storage device in which curling due to molding is suppressed. Further, according to the present disclosure, it is also possible to provide a method for manufacturing an exterior material for a power storage device, a power storage device, and a method for manufacturing the same.

FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure of an exterior material for a power storage device according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure of an exterior material for a power storage device according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure of an exterior material for a power storage device according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure of an exterior material for a power storage device according to the present disclosure. FIG. 1 is a schematic plan view of an exterior material for a power storage device according to the present disclosure. 6 is a schematic cross-sectional view taken along line A-A' in FIG. 5 (the laminated structure is omitted). FIG. 6 is a schematic cross-sectional view taken along line B-B' in FIG. 5 (the laminated structure is omitted). FIG. FIG. 2 is a schematic diagram for explaining a method for evaluating curling due to molding of an exterior material for a power storage device. FIG. 2 is a schematic diagram for explaining a method for evaluating curling due to molding of an exterior material for a power storage device.

The exterior material for a power storage device of the present disclosure is for a power storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is molded. The exterior material for a power storage device is formed so as to protrude from the heat-fusible resin layer side to the base material layer side, and the power storage device element is housed on the heat-fusible resin layer side. When the exterior material for power storage device is observed from the base material layer side, the shape is on a straight line connecting the center of the recess and the shortest side of the exterior material for power storage device at the shortest distance. A first short side curved surface portion and a second short side curved surface portion are sequentially provided from the center of the recess to the short side of the power storage device exterior material, and the power storage device exterior material is connected to the base material layer. When observed from the side, on a straight line connecting the center of the concave portion and the long side of the exterior material for power storage device at the shortest distance, a first long side extends from the center of the concave portion to the long side of the exterior material for power storage device. a curved surface portion and a second long side curved surface portion in order, the radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion; The first long side curved surface portion has a radius of curvature R _B ¹ of 3.8 mm or more. The exterior material for a power storage device according to the present disclosure has this configuration, thereby suppressing curling due to molding.

Hereinafter, the exterior material for a power storage device of the present disclosure will be described in detail. In this specification, the numerical range indicated by "~" means "more than" or "less than". For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less.

The present disclosure is an exterior material for a power storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is molded. Below, the shape, size, etc. of the exterior material for a power storage device of the present disclosure will be explained first, and then the laminated structure of the laminate that constitutes the exterior material for a power storage device of the present disclosure, and each layer that constitutes the laminate. The details, the manufacturing method of the exterior material for the electricity storage device, etc. will be sequentially explained.

1. Shape and size of exterior material for power storage device The exterior material 10 for power storage device of the present disclosure protrudes from the heat-fusible resin layer 4 side to the base material layer 1 side, as shown in the schematic diagrams of FIGS. 5 to 7. It is formed in such a manner (so that the power storage device element is accommodated), and is provided with a rectangular parallelepiped-shaped recess 100 in which the power storage device element is accommodated on the heat-fusible resin layer 4 side. The recess 100 is formed by molding. That is, the exterior material 10 for a power storage device of the present disclosure includes a film-like laminate including at least a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order. A rectangular parallelepiped-shaped recess 100 in which an electricity storage device element is accommodated is formed on the heat-fusible resin layer 4 side.

When observed from the base layer 1 side, the exterior material 10 for an energy storage device of the present disclosure is located on a straight line connecting the center P of the recess 100 and the short side 13A of the exterior material 10 for an energy storage device at the shortest distance (i.e., on a long line). A first short side curved surface portion 11A and a second short side curved surface portion 12A are provided in this order from the center P of the recess 100 to the short side 13A of the power storage device exterior material 10 (on a straight line parallel to the side 13B). (See Figures 5 and 6). In addition, in the exterior material 10 for a power storage device according to the present disclosure, the recess 100 forms a rectangular parallelepiped space and is substantially axisymmetric (in the long side direction) with respect to the center P of the recess 100. The disclosed exterior material 10 for a power storage device includes a pair of first short side curved surfaces 11A and a pair of second short side curved surfaces 12A with respect to the center P of the recess 100 (see FIG. 6). reference). The center P of the recess 100 is the point where a straight line connecting the midpoints of the short sides 13A facing each other and a straight line joining the midpoints of the long sides 13B facing each other intersect.

When observed from the base layer 1 side, the exterior material 10 for an energy storage device of the present disclosure is located on a straight line connecting the center P of the recess 100 and the long side 13B of the exterior material 10 for an energy storage device at the shortest distance (i.e., a short distance). A first long side curved surface portion 11B and a second long side curved surface portion 12B are provided in this order from the center P of the recess 100 to the long side 13B of the exterior material 10 for an electricity storage device. (See Figures 5 and 7). In addition, in the exterior material 10 for a power storage device according to the present disclosure, the recess 100 forms a rectangular parallelepiped space and is substantially axisymmetric (in the direction of the short side) with respect to the center P of the recess 100. The disclosed exterior material 10 for a power storage device includes a pair of second long side curved surfaces 11B and a pair of second long side curved surfaces 12B with respect to the center P of the recess 100 (see FIG. 7). reference).

Moreover, in the exterior material 10 for a power storage device of the present disclosure, when observed from the base material layer 1 side, the area between the pair of first short side curved surfaces 11A and the pair of first long side curved surfaces The area between 11B and 11B becomes the top surface portion 100A (plane portion) of the recess. Further, the area between the first short side curved surface portion 11A and the second short side curved surface portion 12A becomes the side surface portion 100B of the recess. The region between the first long side curved surface portion 11B and the second long side curved surface portion 12B also becomes the side surface portion 100B of the recessed portion 100. Since the recess 100 has a rectangular parallelepiped shape, there are four side surfaces 100B. The first short side curved surface portion 11A and the first long side curved surface portion 11B are curved surface portions that form a boundary between the top surface portion and the side surface portion B of the recessed portion, respectively.

Furthermore, a region between the second short side curved surface portion 12A and the short side 13A of the exterior material 10 for an electricity storage device, and a region between the second long side curved surface portion 12B and the long side 13B of the exterior material 10 for an energy storage device. The region in between becomes the peripheral edge portion 100C (flange portion) of the recessed portion 100. The second short-side curved surface portion 12A and the second long-side curved surface portion 12B are curved surface portions that form a boundary between the flange portion and the side surface portion B of the recess, respectively. As mentioned above, when the peripheral edge (particularly the long side) of the exterior material for the power storage device is curled (curved) by molding and the power storage device element is sealed in the recess, the heat fusion of the heat-fusible resin layer is caused. inhibited. In the exterior material for a power storage device of the present disclosure, the mechanism by which curling due to molding is suppressed can be considered as follows. In other words, if the curvature of the curved surface of the concave portion formed by molding the exterior material for a power storage device is small, the stress that pulls the exterior material for a power storage device during molding will increase, and the force that will cause the base material layer to shrink after molding will also increase. It becomes larger and a large molding curl occurs. On the other hand, when the curvature of the curved surface portion of the recess is large, the stress that pulls the exterior material for the power storage device during molding becomes small, so the force that causes the base material layer to shrink after molding becomes small, and the molding curl becomes small. In the exterior material 10 for a power storage device of the present disclosure, the radius of curvature of the long side curved surface portion is larger than the curvature of the short side curved surface portion and is equal to or greater than a predetermined value, so that the long side side longer than the short side is formed. The curl is small, and it is thought that this suppresses the molding curl on the short side.

In the power storage device exterior material 10 of the present disclosure, the radius of curvature R _B ¹ of the first long side curved surface portion 11B is larger than the radius of curvature R _A ¹ of the first short side curved surface portion 11A. Furthermore, the radius of curvature R _B ¹ of the first long side curved surface portion 11B is 3.8 mm or more. The exterior material 10 for a power storage device of the present disclosure satisfies such a specific curvature radius relationship, thereby suppressing curling due to molding. As described above, in the exterior material 10 for a power storage device of the present disclosure, the recess 100 forms a rectangular parallelepiped space, and is substantially axisymmetric (long side direction, short side direction) with respect to the center P of the recess 100. ), so the first short side curved surface portion 11A, the second short side curved surface portion 12A, the first long side curved surface portion 11B, and the second long side curved surface portion 12B, which are present in pairs, are respectively, They will have substantially the same radius of curvature.

The radius of curvature R _B ¹ of the first long side curved surface portion 11B only needs to be larger than the radius of curvature R _{A 1 of the first short side curved surface portion 11A, and the ratio of the radius of curvature R B} ¹ _to ^the radius of curvature R _A ¹ (radius of curvature R _B ¹ /radius of curvature R _A ¹ ) is, for example, about 1.1 or more, and particularly preferably about 2.5 or more from the viewpoint of more effectively suppressing molding curl. The upper limit of the ratio is, for example, about 3.0 or less, and the preferable range of the ratio is about 1.1 to 3.0, and about 2.5 to 3.0.

The radius of curvature R _B ¹ of the first long side curved surface portion 11B may be 3.8 mm or more, but from the viewpoint of more effectively suppressing molding curl, it is preferably about 4.0 mm or more, more preferably about 4.0 mm or more. Examples include about 4.1 mm or more, more preferably about 4.5 mm or more, still more preferably about 8.0 mm or more, particularly preferably about 10.0 mm or more. Further, the upper limit of the radius of curvature R _B ¹ is, for example, 12.0 mm or less, and the preferable range of the radius of curvature R _B ¹ is about 3.8 to 12.0 mm, about 4.0 to 12.0 mm, Examples include about 4.1 to 12.0 mm, about 4.5 to 12.0 mm, about 8.0 to 12.0 mm, and about 10.0 to 12.0 mm.

Further, from the viewpoint of more effectively suppressing molding curl, the radius of curvature R _A ¹ of the first short side curved surface portion is preferably about 3.0 mm or more, more preferably about 3.4 mm or more, and even more preferably about 3.0 mm or more. .6 mm or more, particularly preferably about 3.8 mm or more. Further, the upper limit of the radius of curvature R _A ¹ of the first short side curved surface portion is, for example, about 4.5 mm or less, and the preferable range of the radius of curvature R _A ¹ is about 3.0 to 4.5 mm, 3. Examples include about .4 to 4.5 mm, about 3.6 to 4.5 mm, and about 3.8 to 4.5 mm.

From the viewpoint of more effectively suppressing molding curl, the radius of curvature R _B ² of the second long side curved surface portion 12B is preferably larger than the radius of curvature R _A ² of the second short side curved surface portion 12A. The ratio of the radius of curvature R _B ² to the radius of curvature R _A ² (radius of curvature R _B ² /radius of curvature R _A ² ) is, for example, about 1.2 or more, and from the viewpoint of more effectively suppressing molding curl, Particularly preferred is about 1.6 or more. The upper limit of the ratio is, for example, about 2.0 or less, and the preferable range of the ratio is about 1.1 to 2.0, and about 1.6 to 2.0.

In addition, from the viewpoint of more effectively suppressing molding curl, the radius of curvature R _B2 of the second long side curved surface portion is preferably about 2.6 mm or more, more preferably ^about 3.0 mm or more, and even more preferably about 3 mm. .3 mm or more, particularly preferably about 3.7 mm or more. Further, the upper limit of the radius of curvature R _B ² of the second long side curved surface portion is, for example, about 4.5 mm or less, and the preferable range of the radius of curvature R _B ² is about 2.6 to 4.5 mm, 3. Examples include about .0 to 4.5 mm, about 3.3 to 4.5 mm, about 3.7 to 4.5 mm, and about 3.7 to 4.5 mm.

Further, from the viewpoint of more effectively suppressing molding curl, the radius of curvature R _A ² of the second short side curved surface portion is preferably about 2.1 mm or more. Further, the upper limit of the radius of curvature R _A ² of the second short side curved surface portion is preferably about 3.0 mm or less, more preferably about 2.5 mm or less, and the preferable range of the radius of curvature R _A ² is as follows: Examples include about 2.1 to 3.0 mm and about 2.1 to 2.5 mm.

In the exterior material for a power storage device of the present disclosure, when observed from the base layer 1 side, the length of the long side of the recess 100 may be about 200 mm or more, or about 220 mm or more, It may be about 230 mm or more, about 240 mm or more, or about 250 mm or more. The upper limit of the length of the long side of the recess 100 is, for example, 500 mm or less, and the preferable range is about 200 to 500 mm, about 220 to 500 mm, about 230 to 500 mm, about 240 to 500 mm, and about 250 to 500 mm. Can be mentioned. Further, the aspect ratio (long side/short side) of the long side and short side of the recess 100 may be about 2.5 or more, about 2.8 or more, or about 3.0. or more, or about 3.2 or more. The upper limit of the aspect ratio is, for example, about 4.0 or less, and the preferable ranges are about 2.5 to 4.0, about 2.8 to 4.0, about 3.0 to 4.0, and about 3. An example is about .2 to 4.0. As mentioned above, conventionally, when attempting to form a recess with a large size and aspect ratio, the peripheral edge (particularly the long side) of the exterior material for a power storage device curls (curves) due to molding, causing the power storage device element to form a recess. When sealing, the heat fusion of the heat-fusible resin layer is inhibited. On the other hand, in the exterior material 10 for a power storage device according to the present disclosure, even if the recess 100 having such a large size and aspect ratio is formed, molding curl can be suitably suppressed.

Further, in the exterior material 10 for a power storage device of the present disclosure, when observed from the base layer 1 side, the length of the long side 13B may be approximately 300 mm or more, or approximately 320 mm or more. , may be about 330 mm or more, about 340 mm or more, or about 350 mm or more. The upper limit of the length of the long side of the power storage device exterior material 10 is, for example, 500 mm or less. Further, the aspect ratio between the long side and the short side (long side/short side) of the exterior material 10 for power storage device may be about 1.3 or more, about 1.4 or more, It may be about 1.5 or more, or about 1.6 or more. The upper limit of the aspect ratio is, for example, about 2.5 or less, and preferable ranges include about 1.3 to 2.5, about 1.4 to 2.5, about 1.5 to 2.5, and about 1. An example is about .6 to 2.5.

In addition, in the peripheral edge 100C of the recess 100, although the width of the peripheral edge 100C (width of the flange part) is not particularly limited, from the viewpoint of suitably suppressing molding curl, the short side 13A of the exterior material 10 for power storage device The shortest distance between the second short side curved surface portion 12A is preferably about 5 to 30 mm, and the shortest distance between the long side 13B of the power storage device exterior material 10 and the second long side curved surface portion 12B is preferably 10 to 40 mm. That's about it.

In the power storage device exterior material 10 of the present disclosure, the method for forming the recess 100 to have each of the curvature radii described above includes the size, aspect ratio, laminated structure of the power storage device exterior material, the shape and size of the mold, etc. , a method of adjusting the surface roughness, etc. as appropriate, and further adjusting the pressing pressure of the mold when forming the recess 100, etc. can be mentioned. For example, by adjusting the pressing pressure of the mold to be low, each of the radii of curvature described above can be suitably adjusted, and molding curl can be effectively suppressed.

Further, the depth D (see FIGS. 6 and 7) of the recess 100 of the exterior material 10 for a power storage device according to the present disclosure is adjusted as appropriate depending on the size of the power storage device, and is, for example, about 4 to 10 mm. It will be done.

2. Laminated structure of exterior material for power storage device The exterior material 10 for power storage device of the present disclosure is a laminate including a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order, for example, as shown in FIG. It consists of In the exterior material 10 for a power storage device, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling a power storage device using the power storage device exterior material 10 and the power storage device element, heat-seal the peripheral edges with the heat-sealable resin layers 4 of the power storage device exterior material 10 facing each other. A power storage device element is accommodated in the space formed by. In the laminate forming the exterior material 10 for a power storage device according to the present disclosure, with the barrier layer 3 as a reference, the heat-fusible resin layer 4 side is on the inner side than the barrier layer 3, and the base material layer 1 side is on the inner side than the barrier layer 3. It is outside.

For example, as shown in FIGS. 2 to 4, the exterior material 10 for a power storage device includes a layer between the base material layer 1 and the barrier layer 3, as necessary, for the purpose of increasing the adhesion between these layers. It may also have an adhesive layer 2. Further, as shown in FIGS. 3 and 4, for example, an adhesive layer 5 may be formed between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of increasing the adhesiveness between these layers. It may have. Further, as shown in FIG. 4, a surface coating layer 6 or the like may be provided on the outside of the base material layer 1 (on the side opposite to the heat-fusible resin layer 4 side), if necessary.

The thickness of the laminate that constitutes the exterior material 10 for power storage devices is not particularly limited, but the upper limit is preferably about 180 μm or less, about 155 μm or less, about 120 μm or less from the viewpoint of cost reduction, energy density improvement, etc. The lower limit is preferably about 35 μm or more, about 45 μm or more, and about 60 μm or more, from the viewpoint of maintaining the function of the exterior material for the power storage device to protect the power storage device element, and the preferable range is For example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm. , particularly preferably about 60 to 155 μm.

In the exterior material 10 for a power storage device, the base material layer 1, the adhesive layer 2 provided as necessary, the barrier layer 3, and the The ratio of the total thickness of the adhesive layer 5 provided, the heat-fusible resin layer 4, and the surface coating layer 6 provided as necessary is preferably 90% or more, more preferably 95% or more, More preferably, it is 98% or more. As a specific example, when the exterior material 10 for a power storage device of the present 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 exterior material for a power storage device The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the material 10 is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. Further, even when the exterior material 10 for an energy storage device of the present disclosure is a laminate including a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the exterior material for an energy storage device The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting 10 is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. I can do it.

3. Each layer of exterior material for power storage device [base material layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exhibiting a function as a base material of an exterior material for a power storage device. Base material layer 1 is located on the outer layer side of the exterior material for a power storage device.

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

When the base material layer 1 is formed of resin, the base material layer 1 may be, for example, a resin film formed of resin, or may be formed by applying resin. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include uniaxially stretched film and biaxially stretched film, with biaxially stretched film being preferred. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating.

Examples of the resin forming the base layer 1 include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. Further, the resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Furthermore, a mixture of these resins may be used.

Among these, preferred examples of the resin forming the base layer 1 include polyester and polyamide.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester, and the like. Examples of the copolyester include copolyesters containing ethylene terephthalate as a main repeating unit. Specifically, copolymer polyester polymerized with ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/adipate), etc. Examples include sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), and polyethylene (terephthalate/decanedicarboxylate). These polyesters may be used alone or in combination of two or more.

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; terephthalic acid and/or isophthalic acid; Hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides, polyamide MXD6 (polymethacrylic acid), etc. containing structural units derived from nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid), etc. Aromatic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); and lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate. Polyamides such as copolymerized polyamides, polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of copolymerized polyamides and polyesters or polyalkylene ether glycols; and copolymers of these are exemplified. These polyamides may be used alone or in combination of two or more.

The base layer 1 preferably contains at least one of a polyester film, a polyamide film, and a polyolefin film, and preferably contains at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, More preferably, at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film is included, and the film preferably includes a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, and a biaxially stretched nylon film. , a biaxially oriented polypropylene film.

The base material layer 1 may be a single layer or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a resin film may be coextruded to form two or more layers. It may also be a laminate of resin films. Further, a laminate of two or more resin films formed by coextruding resins may be used as the base layer 1 without being stretched, or may be uniaxially or biaxially stretched as the base layer 1.

In the base material layer 1, specific examples of a laminate of two or more resin films include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more layers of stretched nylon films, and a laminate of two or more layers of stretched polyester films are preferred. For example, when the base material layer 1 is a laminate of two resin films, it may be a laminate of a polyester resin film and a polyester resin film, a laminate of a polyamide resin film and a polyamide resin film, or a laminate of a polyester resin film and a polyamide resin film. A laminate is preferred, and a laminate of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film is more preferred. In addition, since polyester resin is difficult 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, the polyester resin film is the same as the base layer 1. Preferably, it is located in the outermost layer.

When the base material layer 1 is a laminate of two or more layers of resin films, the two or more layers of resin films may be laminated via an adhesive. Preferred adhesives include those similar to the adhesives exemplified in adhesive layer 2 described below. The method for laminating two or more layers of resin films is not particularly limited, and any known method can be used, such as a dry lamination method, a sandwich lamination method, an extrusion lamination method, a thermal lamination method, etc., and preferably a dry lamination method. One example is the lamination method. When laminating by dry lamination, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on a resin film and laminated thereon. Examples of the anchor coat layer include the same adhesive as the adhesive layer 2 described below. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

Further, even if additives such as lubricants, flame retardants, anti-blocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents are present on at least one of the surface and inside of the base layer 1, good. Only one type of additive may be used, or a mixture of two or more types may be used.

In the present disclosure, it is preferable that a lubricant be present on the surface of the base material layer 1 from the viewpoint of improving the moldability of the exterior material for a power storage device. The lubricant is not particularly limited, but preferably includes an amide lubricant. 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, aromatic bisamides, and the like. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. 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 stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Furthermore, specific examples of methylolamide include methylolstearamide and the like. Specific examples of saturated fatty acid bisamides include methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, and hexamethylene bis stearic acid amide. Examples include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleyl sebacic acid amide. Examples include. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearamide, m-xylylene bishydroxystearamide, and N,N'-distearylisophthalic acid amide. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the base layer 1, its amount is not particularly limited, but is preferably about 3 mg/m ² or more, more preferably about 4 to 15 mg/m ² , and even more preferably 5 to 14 mg. / ^m2 .

The lubricant present on the surface of the base layer 1 may be one obtained by exuding a lubricant contained in the resin constituting the base layer 1, or a lubricant coated on the surface of the base layer 1. It's okay.

The thickness of the base material layer 1 is not particularly limited as long as it functions as a base material, but may be, for example, about 3 to 50 μm, preferably about 10 to 35 μm. When the base layer 1 is a laminate of two or more layers of resin films, the thickness of the resin films constituting each layer is preferably about 2 to 25 μm.

[Adhesive layer 2]
In the exterior material for a power storage device according to the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as necessary for the purpose of increasing the adhesiveness between the two.

The adhesive layer 2 is formed of an adhesive capable of bonding the base material layer 1 and the barrier layer 3 together. The adhesive used to form the adhesive layer 2 is not limited, but may be any one of a chemical reaction type, a solvent volatilization type, a heat melt type, a heat pressure type, and the like. Further, it may be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. Furthermore, the adhesive layer 2 may be a single layer or a multilayer.

Specifically, the adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether; polyurethane; epoxy resin; Phenol resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; Examples include polyimide; polycarbonate; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, polyurethane adhesives are preferred. Further, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives that use polyols such as polyester polyols, polyether polyols, and acrylic polyols as a main ingredient and aromatic or aliphatic polyisocyanates as a curing agent. Further, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the end of the repeating unit. Examples of the curing agent include aliphatic, alicyclic, aromatic, and araliphatic 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), naphthalene diisocyanate (NDI), and the like. Also included are polyfunctional isocyanate modified products of one or more of these diisocyanates. It is also possible to use multimers (for example trimers) as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. Since the adhesive layer 2 is formed of a polyurethane adhesive, the exterior material for the power storage device has excellent electrolyte resistance, and peeling of the base material layer 1 is suppressed even if the electrolyte adheres to the side surface. .

Further, the adhesive layer 2 may contain other components such as colorants, thermoplastic elastomers, tackifiers, fillers, etc., as long as they do not impede adhesiveness. Since the adhesive layer 2 contains the coloring agent, the exterior material for the electricity storage device can be colored. As the colorant, known colorants such as pigments and dyes can be used. Moreover, only one type of coloring agent may be used, or two or more types of coloring agents may be used in combination.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigothioindigo pigments, perinone-perylene pigments, isoindolenine pigments, and benzimidazolone pigments. Examples of the pigment include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and in addition, mica (mica) fine powder, fish scale foil, and the like.

Among the colorants, carbon black is preferable, for example, in order to make the exterior of the power storage device exterior black.

The average particle diameter of the pigment is not particularly limited, and may be, for example, about 0.05 to 5 μm, preferably about 0.08 to 2 μm. Note that the average particle diameter of the pigment is the median diameter measured by a laser diffraction/scattering particle diameter distribution measuring device.

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

The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base material layer 1 and the barrier layer 3, but the lower limit is, for example, about 1 μm or more, about 2 μm or more, and the upper limit is about 10 μm or less. , about 5 μm or less, and preferred ranges include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[Colored layer]
The colored layer is a layer provided as necessary between the base material layer 1 and the barrier layer 3 (not shown). When having the adhesive layer 2, a colored layer may be provided between the base material layer 1 and the adhesive layer 2 and between the adhesive layer 2 and the barrier layer 3. Further, a colored layer may be provided on the outside of the base layer 1. By providing a colored layer, the exterior material for an electricity storage device can be colored.

The colored layer can be formed, for example, by applying ink containing a coloring agent to the surface of the base layer 1 or the surface of the barrier layer 3. As the colorant, known colorants such as pigments and dyes can be used. Moreover, only one type of coloring agent may be used, or two or more types of coloring agents may be used in combination.

As specific examples of the coloring agent contained in the colored layer, the same ones as those exemplified in the column of [Adhesive layer 2] are exemplified.

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

Examples of the barrier layer 3 include a metal foil, a vapor deposited film, and a resin layer having barrier properties. Examples of the vapor-deposited film include a metal vapor-deposited film, an inorganic oxide vapor-deposited film, a carbon-containing inorganic oxide vapor-deposited film, etc., and resin layers include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), and tetrafluoroethylene. Examples include fluorine-containing resins such as polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, and polymers containing fluoroalkyl units as a main component, and ethylene vinyl alcohol copolymers. Further, examples of the barrier layer 3 include a resin film provided with at least one of these vapor-deposited films and a resin layer. A plurality of barrier layers 3 may be provided. It is preferable that the barrier layer 3 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 3 include aluminum alloy, stainless steel, titanium steel, steel plate, etc. When used as metal foil, it includes at least one of aluminum alloy foil and stainless steel foil. It is preferable.

From the perspective of improving the formability of the exterior material for power storage devices, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, annealed aluminum alloy, and from the perspective of further improving the formability. Therefore, an aluminum alloy foil containing iron is preferable. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain an exterior material for a power storage device that has better formability. By having an iron content of 9.0% by mass or less, it is possible to obtain an exterior material for a power storage device that has more excellent flexibility. Examples of the soft aluminum alloy foil include an aluminum alloy having a composition specified by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. One example is foil. Further, silicon, magnesium, copper, manganese, etc. may be added as necessary. Further, softening can be performed by annealing treatment or the like.

Examples of the stainless steel foil include austenitic, ferritic, austenite-ferritic, martensitic, and precipitation hardening stainless steel foils. Furthermore, from the viewpoint of providing an exterior material for a power storage device with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

In the case of metal foil, the thickness of the barrier layer 3 may be about 9 to 200 μm, as long as it can at least function as a barrier layer to prevent moisture from entering. For example, the upper limit of the thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, particularly preferably about 35 μm or less, and the lower limit is preferably about The thickness may be 10 μm or more, more preferably about 20 μm or more, and even more preferably about 25 μm or more, and the preferable range of the thickness is about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, and about 20 to 35 μm. Examples include about 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above range is particularly preferable. In particular, when the barrier layer 3 is made of stainless steel foil, the upper limit of the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, and even more preferably about 40 μm or less. More preferably, it is about 30 μm or less, particularly preferably about 25 μm or less, and the lower limit is preferably about 10 μm or more, more preferably about 15 μm or more, and the preferred thickness range is about 10 to 60 μm, about 10 μm or more. Examples include about 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

Moreover, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite to the base material layer is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant film refers to, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent to the surface of the barrier layer. A thin film that provides corrosion resistance to the barrier layer. As the treatment for forming a corrosion-resistant film, one type of treatment may be performed or a combination of two or more types may be performed. Furthermore, it is possible to have not only one layer but also multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodization treatment are treatments in which the surface of the metal foil is dissolved with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of chemical conversion treatment. Further, when the barrier layer 3 includes a corrosion-resistant film, the barrier layer 3 includes the corrosion-resistant film.

Corrosion-resistant coatings are used to prevent delamination between the barrier layer (for example, aluminum alloy foil) and the base material layer during the molding of exterior materials for power storage devices, and to prevent delamination by hydrogen fluoride generated by the reaction between electrolyte and moisture. , prevents the dissolution and corrosion of the barrier layer surface, especially when the barrier layer is an aluminum alloy foil, and prevents the aluminum oxide present on the barrier layer surface from dissolving and corroding, and the adhesion (wettability) of the barrier layer surface. It shows the effect of preventing delamination between the base material layer and the barrier layer during heat sealing and the delamination between the base material layer and the barrier layer during molding.

Various types of corrosion-resistant coatings are known that are formed by chemical conversion treatment, and mainly include at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples include corrosion-resistant coatings containing. Examples of chemical conversion treatments using phosphates and chromates include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment. Examples of the compound include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromic acid acetylacetate, chromium chloride, potassium chromium sulfate, and the like. Further, examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment, and coating type chromate treatment is preferred. In this coating-type chromate treatment, at least the inner layer side of the barrier layer (for example, aluminum alloy foil) is first coated using a well-known method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, etc. Degrease treatment is performed using a treatment method, and then metal phosphates such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, and Zn (zinc) phosphate are applied to the degreased surface. Treatment liquids whose main components are salts and mixtures of these metal salts, treatment liquids whose main components are nonmetallic phosphoric acid salts and mixtures of these nonmetallic salts, or combinations of these with synthetic resins, etc. This is a process in which a treatment liquid consisting of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method, or a dipping method, and then dried. Various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used as the treatment liquid, and water is preferable. In addition, the resin component used at this time includes polymers such as phenolic resins and acrylic resins, and aminated phenol polymers having repeating units represented by the following general formulas (1) to (4) are used. Examples include chromate treatment. In addition, in the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. Good too. The acrylic resin must be polyacrylic acid, acrylic acid methacrylate copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salt, ammonium salt, or amine salt. is preferred. Particularly preferred are polyacrylic acid derivatives such as ammonium salts, sodium salts, or amine salts of polyacrylic acid. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. Further, the acrylic resin is also preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, such as ammonium salt, sodium salt, Or it is also preferable that it is an amine salt. Only one type of acrylic resin may be used, or a mixture of two or more types may be used.

In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Further, R ¹ and R ² are each the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to ( ⁴ ), ^the alkyl group represented by Examples include straight chain or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl group. Furthermore, examples of the hydroxyalkyl group represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, Straight chain or branched chain with 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group Examples include alkyl groups. In the general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably about 500 to 1,000,000, and preferably about 1,000 to 20,000, for example. More preferred. Aminated phenol polymers can be produced, for example, by polycondensing a phenol compound or a 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 to the polymer. and amine (R ¹ R ² NH) to introduce a functional group (-CH ₂ NR ¹ R ² ) into the polymer obtained above. Aminated phenol polymers may be used alone or in combination of two or more.

Another example of a corrosion-resistant film is a film formed by a coating-type corrosion-preventing treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. Examples include thin films that are The coating agent may further contain phosphoric acid or a phosphate salt, a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol includes rare earth element oxide fine particles (for example, particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant film can be used alone or in combination of two or more. As the liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, with water being preferred. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex consisting of a polymer containing polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is graft-polymerized onto an acrylic main skeleton, polyallylamine or its derivatives. , aminated phenol, etc. are preferred. The anionic polymer is preferably poly(meth)acrylic acid or a salt thereof, or a copolymer containing (meth)acrylic acid or a salt thereof as a main component. Further, it is preferable that the crosslinking agent is at least one selected from the group consisting of a compound having a functional group such as an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. Moreover, it is preferable that the phosphoric acid or phosphate is a condensed phosphoric acid or a condensed phosphate.

An example of a corrosion-resistant film is to coat fine particles of barium sulfate or metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide in phosphoric acid on the surface of the barrier layer. Examples include those formed by performing baking treatment at temperatures above .degree.

The corrosion-resistant film may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated, if necessary. Examples of the cationic polymer and anionic polymer include those mentioned above.

Note that the composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment ^is not particularly limited. is, for example, about 0.5 to 50 mg in terms of chromium, preferably 1
．． about 0 to 40 mg, the phosphorus compound in terms of phosphorus, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, and the aminated phenol polymer, for example, about 1.0 to 200 mg, preferably 5.0 to 150 mg. It is desirable that it be contained in a certain proportion.

The thickness of the corrosion-resistant film is not particularly limited, but from the viewpoint of the cohesive force of the film and the adhesion with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm. More preferably, it is about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation using a transmission electron microscope, or by a combination of observation using a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. Analysis of the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry reveals that, for example, secondary ions consisting of Ce, P, and O (e.g., Ce ₂ PO ₄ ⁺ , C
Peaks originating from at least one type of ions such as ePO ₄ ^-, etc.) and secondary ions consisting of Cr, P, and O (for example, at least one type of ions such as CrPO ₂ ⁺ and CrPO ₄ ^- ) are detected.

Chemical conversion treatment involves applying a solution containing a compound used to form a corrosion-resistant film to the surface of the barrier layer using a bar coating method, roll coating method, gravure coating method, dipping method, etc., and then changing the temperature of the barrier layer. This is done by heating to a temperature of about 70 to 200°C. Furthermore, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be previously subjected to a degreasing treatment using an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this manner, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. In addition, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for degreasing treatment, it is possible to not only degrease the metal foil but also form passive metal fluoride. In such cases, only degreasing treatment may be performed.

[Thermofusible resin layer 4]
In the exterior material for a power storage device of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and has a function of thermally fusing the heat-fusible resin layers to each other and sealing the power storage device element during assembly of the power storage device. This is a layer (sealant layer) that exhibits the following properties.

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it can be heat-fusible, but resins containing a polyolefin skeleton such as polyolefin and acid-modified polyolefin are preferred. The fact that the resin constituting the heat-fusible resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride be detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers around 1760 cm ^-1 and around 1780 cm ^-1 wave numbers. When the heat-fusible resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specifically, the polyolefins include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; ethylene-α olefin copolymers; homopolypropylene, block copolymers of polypropylene (for example, polyethylene and Examples include polypropylene such as block copolymers of ethylene), random copolymers of polypropylene (eg, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; terpolymers of ethylene-butene-propylene, and the like. Among these, polypropylene is preferred. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

Moreover, a cyclic polyolefin may be sufficient as a polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. It will be done. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as crosslinked polyolefins can also be used. Further, examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or their anhydrides.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. Acid-modified cyclic polyolefin is a polymer obtained by copolymerizing some of the monomers constituting the cyclic polyolefin in place of the acid component, or by block polymerizing or graft polymerizing the acid component to the cyclic polyolefin. be. The cyclic polyolefin to be acid-modified is the same as described above. Further, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

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.

The heat-fusible resin layer 4 may be formed from one type of resin alone, or may be formed from a blended polymer that is a combination of two or more types of resin. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, but may be formed of two or more layers of the same or different resins.

Further, the heat-fusible resin layer 4 may contain a lubricant or the like, if necessary. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for a power storage device can be improved. The lubricant is not particularly limited, and any known lubricant can be used. The lubricants may be used alone or in combination of two or more.

The lubricant is not particularly limited, but preferably includes an amide lubricant. Specific examples of the lubricant include those exemplified for the base layer 1. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the heat-fusible resin layer 4, its amount is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for power storage devices, it is preferably about 10 to 50 mg/m ² More preferably, it is about 15 to 40 mg/m ² .

The lubricant present on the surface of the heat-fusible resin layer 4 may be one obtained by exuding a lubricant contained in the resin constituting the heat-fusible resin layer 4, or The surface may be coated with a lubricant.

Further, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers exhibit the function of thermally fusing each other and sealing the electricity storage device element, but is preferably about 100 μm or less, for example. The thickness is about 85 μm or less, more preferably about 15 to 85 μm. Note that, for example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-fusible resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm, for example. When the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 is preferably about 20 μm or more, more preferably 35 to 85 μm. The degree is mentioned.

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

The adhesive layer 5 is formed of a resin that can bond the barrier layer 3 and the heat-fusible resin layer 4 together. As the resin used for forming the adhesive layer 5, for example, the same adhesive as the adhesive exemplified for the adhesive layer 2 can be used. In addition, from the viewpoint of firmly adhering the adhesive layer 5 and the heat-fusible resin layer 4, it is preferable that the resin used for forming the adhesive layer 5 contains a polyolefin skeleton. Examples include the polyolefin and acid-modified polyolefin exemplified in the resin layer 4. On the other hand, from the viewpoint of firmly adhering the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains 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. Maleic acid is most preferred. In addition, from the viewpoint of heat resistance of the exterior material for a power storage device, the olefin component is preferably a polypropylene resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analytical method is not particularly limited. Furthermore, the fact that the resin constituting the adhesive layer 5 contains an acid-modified polyolefin means that, for example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, there is no anhydride at a wave number of around 1760 cm ^-1 and around a wave number of 1780 cm ^-1 . A peak derived from maleic acid is detected. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Furthermore, from the viewpoint of ensuring durability such as heat resistance and content resistance of the exterior material for power storage devices, and ensuring moldability while reducing thickness, the adhesive layer 5 is made of a resin composition containing acid-modified polyolefin and a curing agent. A cured product is more preferable. Preferred examples of the acid-modified polyolefin include those mentioned above.

Further, the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. A cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of an isocyanate group-containing compound and an epoxy group-containing compound is particularly preferable. Further, 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. Preferred examples of the polyester include 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. Note that if unreacted substances of a curing agent such as a compound having an isocyanate group, a compound having an oxazoline group, or an epoxy resin remain in the adhesive layer 5, the presence of the unreacted substances can be detected by, for example, infrared spectroscopy, Confirmation can be performed by a method selected from Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

Further, from the viewpoint of further increasing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is made of at least one selected from the group consisting of oxygen atoms, heterocycles, C=N bonds, and C-O-C bonds. It is preferable that it is a cured product of a resin composition containing one type of curing agent. Examples of the curing agent having a heterocycle include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. Further, examples of the curing agent having a C=N bond include a curing agent having an oxazoline group, a curing agent having an isocyanate group, and the like. Further, examples of the curing agent having a C--O--C bond include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be achieved by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF). -SIMS), X-ray photoelectron spectroscopy (XPS), and other methods.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the barrier layer 3 and the adhesive layer 5, polyfunctional isocyanate compounds are preferably used. 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), and these can be polymerized or nurated. Examples include polymers, mixtures thereof, and copolymers with other polymers. Further examples include adduct bodies, bullet bodies, isocyanurate bodies, and the like.

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 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. It is more preferable that it is within this range. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain, and those having an acrylic main chain. Furthermore, commercially available products include, for example, the Epocross series manufactured by Nippon Shokubai Co., Ltd.

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 preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. It is more preferable that the Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin that can form a crosslinked structure by the epoxy groups present in the molecule, and any known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2,000, more preferably about 100 to 1,000, and still more preferably about 200 to 800. In the first disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include trimethylolpropane glycidyl ether derivatives, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. can be mentioned. One type of epoxy resin may be used alone, or two or more types may be used in combination.

The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. is more preferable. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

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 two-part curable polyurethane.

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. More preferred. Thereby, it is possible to effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere where a component that induces corrosion of the barrier layer, such as an electrolytic solution, is present.

In addition, when the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin. , the acid-modified polyolefin functions as a main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

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

The upper limit of 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, and about 5 μm or less, and the lower limit is preferably about 0.1 μm or more. , about 0.5 μm or more, and the range of the thickness 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, 0. Examples include about .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, and about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2 or a cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Further, when using the resin exemplified for the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. In addition, when the adhesive layer 5 is a cured product of the adhesive exemplified in the adhesive layer 2 or a resin composition containing an acid-modified polyolefin and a curing agent, for example, the resin composition is applied and cured by heating etc. By doing so, the adhesive layer 5 can be formed. Further, when using the resin exemplified for the heat-fusible resin layer 4, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example.

[Surface coating layer 6]
The exterior material for a power storage device of the present disclosure is provided on the base material layer 1 (base material layer 1 A surface coating layer 6 may be provided on the opposite side of the barrier layer 3). The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for a power storage device when the power storage device is assembled using the exterior material for a power storage device.

The surface coating layer 6 can be formed of a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-liquid curing type or a two-liquid curing type, but preferably a two-liquid curing type. Examples of the two-part curable resin include two-part curable polyurethane, two-part curable polyester, and two-part curable epoxy resin. Among these, two-component curing polyurethane is preferred.

Examples of the two-component curable polyurethane include polyurethane containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use polyols such as polyester polyols, polyether polyols, and acrylic polyols as main ingredients and aromatic or aliphatic polyisocyanates as curing agents. Further, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the end of the repeating unit. Examples of the curing agent include aliphatic, alicyclic, aromatic, and araliphatic 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), naphthalene diisocyanate (NDI), and the like. Also included are polyfunctional isocyanate modified products of one or more of these diisocyanates. It is also possible to use multimers (for example trimers) as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. In addition, an aliphatic isocyanate-based compound refers to an isocyanate that has an aliphatic group and does not have an aromatic ring, and an alicyclic isocyanate-based compound refers to an isocyanate that has an alicyclic hydrocarbon group. refers to isocyanate having an aromatic ring. Since the surface coating layer 6 is formed of polyurethane, excellent electrolyte resistance is imparted to the exterior material for the electricity storage device.

The surface coating layer 6 may contain the above-mentioned lubricant or anti-oxidant on at least one of the surface and inside of the surface coating layer 6, depending on the functionality to be provided to the surface coating layer 6 and its surface. It may contain additives such as blocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents. Examples of the additive include fine particles having an average particle diameter of about 0.5 nm to 5 μm. The average particle diameter of the additive is the median diameter measured by a laser diffraction/scattering particle size distribution measuring device.

The additive may be either inorganic or organic. Further, the shape of the additive is not particularly limited, and examples include spherical, fibrous, plate-like, amorphous, and scaly shapes.

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, Examples include crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone 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. Further, the additive may be subjected to various surface treatments such as insulation treatment and high dispersion treatment.

The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin that forms the surface coating layer 6. When adding additives to the surface coating layer 6, a resin mixed with the additives may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned function as the surface coating layer 6, and may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

4. Method for manufacturing an exterior material for an energy storage device The method for manufacturing an exterior material for an energy storage device according to the present disclosure is not particularly limited as long as a laminate in which each layer of the exterior material for an energy storage device of the present invention is laminated can be obtained. An example of a method includes a step of forming a recess so as to satisfy the relationship of the radius of curvature. That is, the method for manufacturing the exterior material 10 for a power storage device according to the present disclosure is as follows. The details of each layer of the laminate that constitutes the exterior material for a power storage device, the radius of curvature, etc. are as described above.

a step of preparing a film-like laminate comprising at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order;
The laminate is molded to protrude from the heat-fusible resin layer side to the base material layer side, and a rectangular parallelepiped-shaped recess in which the electricity storage device element is accommodated is formed on the heat-fusible resin layer side. Forming step (specifically, using a female mold placed on the base layer side of the laminate and a male mold placed on the heat-fusible resin layer side, the heat-fusible resin forming a rectangular parallelepiped-shaped recess in which an electricity storage device element is accommodated on the heat-fusible resin layer side by molding the laminate so as to protrude from the layer side toward the base material layer side;
It is equipped with
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
A method for manufacturing an exterior material for a power storage device, wherein the first long side curved surface portion has a radius of curvature R _B ¹ of 3.8 mm or more.

As described above, in the power storage device exterior material 10 of the present disclosure, the method for forming the recess 100 to have each of the curvature radii described above includes the size, aspect ratio, laminated structure, and mold of the power storage device exterior material. An example of a method is to appropriately adjust the shape, size, surface roughness, etc. of the recess 100, and further adjust the pressing pressure of the mold when forming the recess 100. That is, in the method for manufacturing the exterior material 10 for a power storage device according to the present disclosure, by appropriately adjusting these, the recesses 100 having the respective curvature radii described above can be formed. For example, in the step of forming the concave portion, by adjusting the pressing pressure of the mold to be low, each of the radii of curvature described above can be suitably adjusted, and molding curl can be effectively suppressed. Furthermore, the radius of curvature can also be adjusted by adjusting the surface roughness of the mold, causing the exterior material for the power storage device to slide appropriately during molding, and drawing it into the mold.

Further, an example of a method for manufacturing a film-like laminate that constitutes the exterior material for a power storage device of the present disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminate A") in which a base material layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order is formed. Specifically, the formation of the laminate A is performed by applying the adhesive used for forming the adhesive layer 2 on the base layer 1 or on the barrier layer 3 whose surface has been subjected to a chemical conversion treatment as necessary, using a gravure coating method, It can be carried out by a dry lamination method in which the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after coating and drying by a coating method such as a roll coating method.

Next, a heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A by a method such as a thermal lamination method or an extrusion lamination method. do it. In addition, when providing the adhesive layer 5 between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) the adhesive layer 5 and the heat-fusible resin layer are provided on the barrier layer 3 of the laminate A. 4 (coextrusion lamination method, tandem lamination method), (2) Separately, a laminate is formed by laminating the adhesive layer 5 and the heat-fusible resin layer 4, and this is laminate A. A method of laminating the adhesive layer 5 on the barrier layer 3 of the laminate A by a thermal laminating method, or forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and then laminating this with the heat-fusible resin layer 4 by a thermal laminating method. Lamination method (3) While pouring the molten adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 formed into a sheet in advance, the adhesive layer 5 is laminated. (4) solution coating the barrier layer 3 of the laminate A with an adhesive to form the adhesive layer 5; For example, the adhesive layer 5 may be laminated by a drying method or a baking method, and a heat-fusible resin layer 4 previously formed in a sheet shape may be laminated on the adhesive layer 5.

When providing the surface coating layer 6, the surface coating layer 6 is laminated on the surface of the base material layer 1 on the side opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above resin for forming the surface coating layer 6 onto the surface of the base material layer 1. Note that the order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 on the opposite side to the surface coating layer 6.

As described above, surface coating layer 6 provided as necessary/base material layer 1/adhesive layer 2 provided as necessary/barrier layer 3/adhesive layer 5 provided as necessary/thermal fusion A laminate including the adhesive resin layers 4 in this order is formed, but in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, it may be further subjected to heat treatment.

In the exterior material for a power storage device, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blasting treatment, oxidation treatment, or ozone treatment to improve processing suitability, if necessary. . For example, by subjecting the surface of the base layer 1 opposite to the barrier layer 3 to a corona treatment, the printability of the ink on the surface of the base layer 1 can be improved.

5. Application of exterior packaging material for power storage devices The exterior packaging material for power storage devices of the present disclosure is used for a package for sealing and accommodating power storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte can be housed in a package formed of the exterior material for a power storage device according to the present disclosure to form a power storage device.

Specifically, an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is provided with the exterior material for an electricity storage device of the present disclosure, with metal terminals connected to each of the positive electrode and the negative electrode protruding outward. , Covering the electricity storage device element so that a flange portion (an area where the heat-fusible resin layers contact each other) is formed around the periphery of the power storage device element, and sealing the heat-fusible resin layers of the flange portion by heat-sealing each other. provides an electricity storage device using an exterior material for an electricity storage device. Note that when a power storage device element is housed in a package formed of the power storage device exterior material of the present disclosure, the heat-fusible resin portion of the power storage device exterior material of the present disclosure is placed on the inside (the surface in contact with the power storage device element). ) to form a package.

The exterior material for power storage devices of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Further, the exterior material for a power storage device of the present disclosure may be used for either a primary battery or a secondary battery, but preferably for a secondary battery. The types of secondary batteries to which the exterior material for power storage devices of the present disclosure is applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, and nickel-metal hydride batteries. Examples include cadmium storage batteries, nickel/iron storage batteries, nickel/zinc storage batteries, silver oxide/zinc storage batteries, metal air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable for application of the exterior material for power storage devices of the present disclosure.

The present disclosure will be explained in detail by showing Examples and Comparative Examples below. However, the present disclosure is not limited to the examples.

<Manufacture of exterior materials for power storage devices>
Examples 1 to 5 and comparative example 1
As a base material layer, a polyethylene terephthalate film (thickness 12 μm) and a biaxially stretched nylon film (thickness 15 μm) are used as an adhesive layer (cured A laminated film having a thickness of 3 μm) was prepared. Next, on the biaxially stretched nylon film of the base material layer, a barrier layer composed of an aluminum alloy foil (thickness: 40 μm) with a corrosion-resistant film formed on both sides was laminated by a dry lamination method. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) is applied to one side of an aluminum alloy foil with a corrosion-resistant film formed on both sides, and an adhesive layer is formed on the aluminum alloy foil. (thickness 3 μm after curing) was formed. Next, after laminating the adhesive layer on the aluminum alloy foil and the biaxially stretched nylon film, an aging treatment was performed to produce a laminate of base material layer/adhesive layer/barrier layer.

Next, by coextruding maleic anhydride-modified polypropylene (40 μm thick) as an adhesive layer and polypropylene (40 μm thick) as a heat-fusible resin layer on the barrier layer side of the obtained laminate, An adhesive layer/thermal adhesive resin layer was laminated on the barrier layer. Next, by aging and heating the obtained laminate, polyethylene terephthalate film (12 μm)/adhesive layer (3 μm)/biaxially stretched nylon film (15 μm)/adhesive layer (3 μm)/barrier layer ( A film-like laminate (total thickness: 153 μm) was obtained in which layers (40 μm)/adhesive layer (40 μm)/thermofusible resin layer (40 μm) were laminated in this order.

Next, each of the obtained laminates was cut into strips of 360 mm (TD: Transverse Direction) x 200 mm (MD: Machine Direction). Note that the MD of the laminate corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the laminate corresponds to the TD of the aluminum alloy foil. Next, a strip was placed between a molding die (female mold) having a diameter of 270 mm (TD) x 80 mm (MD) and a corresponding mold (male mold) (the female mold side was placed on the base material layer). ), using four cylinders (with a cylinder diameter of 80 mm), and setting the pressure of each cylinder to the value shown in Table 1, increasing it by 0.10 MPa, and cold forming at a forming depth of 5 mm. Molding was performed (Examples 1 to 5 and Comparative Example 1 were cold molded under the same conditions except for the pressing pressure of the cylinder), and a recess 100 was formed at the position of the molded part M in the schematic diagram of FIG. An exterior material for a power storage device (the exterior material has dimensions of TD 357 mm and MD 198 mm, an aspect ratio of approximately 1.8, and a concave portion of a size corresponding to the mold) was obtained.

The clearance between the female mold and the male mold was 0.5 mm. The surface of the female mold has a maximum height roughness (nominal value of Rz) of 0.8 μm as specified in Table 2 of JIS B 0659-1:2002 Annex 1 (Reference) Comparative Surface Roughness Standard Piece. . The corner R of the female mold is 2.0 mm, and the ridge R is 2.5 mm. The surface of the male mold has a maximum height roughness (nominal value of Rz) of 3.2 μm as specified in Table 2 of JIS B 0659-1:2002 Annex 1 (Reference) Comparative Surface Roughness Standard Piece. . The corner R of the male mold is 2.0 mm, and the ridge R is 2.0 mm. The corner R and ridge R of the male mold have a maximum height roughness (nominal value of Rz) of 1 as specified in Table 2 of JIS B 0659-1:2002 Annex 1 (Reference) Comparison Surface Roughness Standard Piece. .6 μm.

<Measurement of the radius of curvature of each curved surface part of the exterior material for power storage devices>
The radius of curvature R B ¹ of the first long-side curved surface portion 11B, the radius of curvature R _B ² of the second long-side curved surface portion 12B, and the radius of curvature of the first short-side curved surface portion 11A of the exterior material for a power storage _device after molding obtained above. The radius of curvature R _A ¹ and the radius of curvature R _A ² of the second short side curved surface portion 12A are, respectively, as shown in FIG. I followed the surface. The radius of curvature was measured using a contour length measuring machine (contour length measuring machine PGI-1240 manufactured by Taylor Hobson Division of Ametek Co., Ltd.), and the measuring needle used had a shape of 60° and a tip radius of 2 μm. The results are shown in Table 1.

<Evaluation of molded curl>
The exterior materials for a power storage device after the molding obtained above were placed on a horizontal surface 20 as shown in FIG. 9, respectively. Next, the height (maximum height t (mm)) at the position N where the distance in the vertical direction y from the horizontal surface 20 to the exterior material for the energy storage device is the maximum was measured (the maximum height t is the exterior material for the energy storage device). This is the height at the position where the forming curl is the largest among the four sides of the material). For each of the 10 test samples, the average value of the maximum height t measured with a Digimatic Height Gauge (manufactured by Mitutoyo Co., Ltd., HD-30AX) was defined as the molded curl (mm). The results are shown in Table 1.

<Evaluation of defects during heat fusion>
The occurrence of defects when the heat-fusible resin layers of the exterior material for a power storage device after the molding obtained above were heat-fused to each other was evaluated as follows. As a heat sealing device, a heat seal tester TP-701-B manufactured by Tester Sangyo Co., Ltd. was prepared, and two Teflon-coated metal heat seal bars with a width of 7 mm and a length of 300 mm were used. Two pairs of exterior materials for power storage devices after molding were each used as samples. In the sample, the heat-fusible resins were arranged so as to face each other. At this time, the TD direction (long side direction) and MD direction (short side direction) of the exterior material for a power storage device were made to match. Next, the heat-fusible resin layers are sandwiched between heat-seal bars in the MD direction (short side direction) at the peripheral edge (flange) of the concave portion of the sample. Fusion was carried out (thermal fusion conditions were 190° C., 3 seconds, surface pressure 1.0 MPa). When heat-sealing, hold both ends of the sample in the TD (long side direction) with left and right hands, and sandwich the MD direction (short side direction) with a heat seal bar to heat the heat-sealable resin layers together. It was fused. The evaluation criteria are as follows. The results are shown in Table 1.
A+: Curl is very small, and there is no problem at all in heat fusing work.
A: Curl is small and there are almost no problems in heat fusing work.
B: The curls are somewhat large, but heat-sealing can be done by pressing the curls with your hands.
C: Warpage remains in the heat-sealed portion even when the curled portion is pressed by hand, making heat-sealing work difficult.

Note that each radius of curvature of the curved surface portion of the recess shown in Table 1 is a value obtained by rounding off the second decimal point of the measured value. Furthermore, the molding curl (mm) is a value obtained by rounding off the measured value to the first decimal point. The air cylinder holding pressure is a set value.

As described above, the present disclosure provides inventions of the following aspects.
Item 1. An exterior material for an electricity storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is molded,
The exterior material for the power storage device is formed to protrude from the heat-fusible resin layer side to the base material layer side, and has a rectangular parallelepiped shape in which the power storage device element is housed on the heat-fusible resin layer side. Equipped with a recess,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
An exterior material for an electricity storage device ^{, wherein a radius of curvature R B1} _of the first long side curved surface portion is 3.8 mm or more.
Item 2. Item 2. The exterior material for an electricity storage device according to Item 1, wherein the first short side curved surface portion has a radius of curvature R _A ¹ of 3.0 mm or more.
Item 3. Item 3. The exterior material for an electricity storage device according to Item 1 or 2, wherein the second long side curved surface portion has a radius of curvature R _B ² of 2.6 mm or more.
Item 4. Item 4. The exterior material for an electricity storage device according to any one of Items 1 to 3, wherein the radius of curvature R _A ² of the second short side curved surface portion is 2.1 mm or more.
Item 5. Item 5. The exterior material for a power storage device according to any one of Items 1 to 4, wherein the length of the long side of the recess is 200 mm or more when the exterior material for a power storage device is observed from the base layer side. Item 6. Item 5. The exterior material for a power storage device according to any one of Items 1 to 5, wherein the laminate has a thickness of 180 μm or less.
Section 7. a step of preparing a film-like laminate comprising at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order;
The laminate is molded to protrude from the heat-fusible resin layer side to the base material layer side, and a rectangular parallelepiped-shaped recess in which the electricity storage device element is accommodated is formed on the heat-fusible resin layer side. a step of forming;
It is equipped with
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
A method for manufacturing an exterior material for a power storage device, wherein the first long side curved surface portion has a radius of curvature R _B ¹ of 3.8 mm or more.
Section 8. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of an exterior material for an electricity storage device,
The exterior material for the power storage device has a rectangular shape in plan view, in which a film-like laminate including at least a base layer, a barrier layer, and a heat-fusible resin layer in this order is molded;
The exterior material for the power storage device is formed in a rectangular parallelepiped shape so as to protrude from the heat-fusible resin layer side to the base material layer side, and the power storage device element is housed on the heat-fusible resin layer side. It is equipped with a recessed part,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
A power storage device in which a radius of curvature R _B ¹ of the first long side curved surface portion is larger than a radius of curvature R _A ¹ of the first short side curved surface portion.
Item 9. An electricity storage device comprising the step of accommodating an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in a package formed using the exterior material for an electricity storage device according to any one of Items 1 to 6. manufacturing method.

1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for power storage device 11A First short side curved portion 11B First long side curved portion 12A Second short side Curved surface portion 12B Second long side curved surface portion 13A Short side 13B of exterior material for power storage device Long side 100 of exterior material for power storage device Recessed portion 100A Top surface portion 100B of recess Side surface portion 100C of recess Peripheral portion 110 of recess Short side 120 of recess Long side M of the recess Molded part P Center R _A ¹ Radius of curvature of the first short side curved surface R _A ² Radius of curvature of the second short side curved surface R _B ¹ Radius of curvature of the first long side curved surface R _B ² Second Radius of curvature of long side curved surface

Claims (8)

An exterior material for an electricity storage device having a rectangular shape in plan view, in which a film-like laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order is molded,
The base layer includes at least one of a polyester film and a polyamide film,
The exterior material for the power storage device is formed to protrude from the heat-fusible resin layer side to the base material layer side, and has a rectangular parallelepiped shape in which the power storage device element is housed on the heat-fusible resin layer side. Equipped with a recess,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
The radius of curvature R _B ² of the second long side curved surface portion is larger than the radius of curvature R _A ² of the second short side curved surface portion,
The radius of curvature R _B1 of the first long side curved surface portion is 8.0 mm or more ^,
An exterior material for an electricity storage device, wherein the first short side curved surface portion has a radius of curvature R _A ¹ of 3.4 mm or more. The exterior material for an electricity storage device according to claim 1, wherein the second long side curved surface portion has a radius of curvature R _B ² of 2.6 mm or more. The exterior material for an electricity storage device according to claim 1 or 2, wherein the second short side curved surface portion has a radius of curvature R _A ² of 2.1 mm or more. The exterior material for a power storage device according to any one of claims 1 to 3, wherein the length of a long side of the recess is 200 mm or more when the exterior material for a power storage device is observed from the base layer side. . The exterior material for a power storage device according to any one of claims 1 to 4, wherein the thickness of the laminate is 180 μm or less. a step of preparing a film-like laminate comprising at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order;
The laminate is molded to protrude from the heat-fusible resin layer side to the base material layer side, and a rectangular parallelepiped-shaped recess in which the electricity storage device element is accommodated is formed on the heat-fusible resin layer side. a step of forming;
It is equipped with
The base layer includes at least one of a polyester film and a polyamide film,
When the exterior material for an energy storage device is observed from the base layer side, on the straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the exterior material for an energy storage device is connected from the center of the recess to the exterior material for an energy storage device. A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
The radius of curvature R _B ² of the second long side curved surface portion is larger than the radius of curvature R _A ² of the second short side curved surface portion,
The radius of curvature R _B1 of the first long side curved surface portion is 8.0 mm or more ^,
A method for manufacturing an exterior material for a power storage device, wherein a radius of curvature R _A ¹ of the first short side curved surface portion is 3.4 mm or more. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of an exterior material for an electricity storage device ,
The exterior material for the power storage device has a rectangular shape in plan view, in which a film-like laminate including at least a base layer, a barrier layer, and a heat-fusible resin layer in this order is molded;
The base layer includes at least one of a polyester film and a polyamide film,
The exterior material for the power storage device is formed in a rectangular parallelepiped shape so as to protrude from the heat-fusible resin layer side to the base material layer side, and the power storage device element is housed on the heat-fusible resin layer side. It is equipped with a recessed part,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the short side of the exterior material for an energy storage device at the shortest distance, the line from the center of the recess to the exterior material for the energy storage device is A first short side curved surface portion and a second short side curved surface portion are provided in order along the short side of the exterior material,
When the exterior material for an energy storage device is observed from the base layer side, on a straight line connecting the center of the recess and the long side of the exterior material for an energy storage device at the shortest distance, the distance from the center of the recess to the exterior material for the energy storage device is A first long side curved surface portion and a second long side curved surface portion are provided in order along the long side of the exterior material,
The radius of curvature R _B ¹ of the first long side curved surface portion is larger than the radius of curvature R _A ¹ of the first short side curved surface portion,
The radius of curvature R _B ² of the second long side curved surface portion is larger than the radius of curvature R _A ² of the second short side curved surface portion,
The radius of curvature R _B1 of the first long side curved surface portion is 8.0 mm or more ^,
A power storage device, wherein the first short side curved surface portion has a radius of curvature R _A ¹ of 3.4 mm or more. A power storage device comprising the step of accommodating a power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in a package formed using the exterior material for a power storage device according to any one of claims 1 to 5. Method of manufacturing the device.