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

Abstract

A storage device, an electrode body, and an exterior body that seals the electrode body, wherein the exterior body has an exterior film that wraps the electrode body, and a lid body that seals the electrode body together with the exterior film, the exterior film is composed of a laminate including at least a barrier layer and a heat-sealable resin layer, the barrier layer is in a direction perpendicular to the rolling direction of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body, and for a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer, when the grain boundary is defined as 5°, the area average angular difference of GOS (grain orientation spread) obtained by performing crystal analysis by the EBSD method is 2.50° or less, a storage device.

Description

Technical Field

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

Background Art

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

[0003] On the other hand, in recent years, with the improvement in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., various shapes are required for power storage devices, and thinning and weight reduction are also demanded. However, the conventionally frequently used metal exterior film has the drawbacks that it is difficult to follow the diversification of shapes and there is also a limit to weight reduction.

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

[0005] Further, Patent Document 2 discloses an example of a power storage device. This power storage device includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body and a lid body that is joined to the exterior film. This power storage device is manufactured, for example, by accommodating an electrode body inside a cylindrically configured exterior film and closing the opening of the cylindrically shaped exterior film with a lid body. The side surface of the lid body and the exterior film are joined, for example, by heat sealing.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An exterior body including an exterior film that wraps an electrode body and a lid body joined to the exterior film (exterior material for a power storage device) is useful, for example, as an exterior body for a large power storage device.

[0008] Such an exterior body has a sealed portion (joint portion) between the exterior film (exterior material for a power storage device) and the lid body. When the inventors of the present disclosure studied, a new problem was found that cracks occurred in the sealed portion of the exterior film when the power storage device was repeatedly exposed to temperature changes between high and low temperatures.

[0009] Under such circumstances, the main object of the present disclosure is to provide a power storage device in which cracking in the sealed portion of the exterior film with the lid body is suppressed when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, using an exterior body including an exterior film (exterior material for a power storage device) that wraps an electrode body and a lid body.

[0010] Another object of the present disclosure is to provide an exterior material for a power storage device in which cracking in the sealed portion of the exterior material for a power storage device with the lid body is suppressed when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, using an exterior body including an exterior material for a power storage device that wraps an electrode body and a lid body.

Means for Solving the Problems

[0011] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, in a power storage device including an electrode body and an exterior body that seals the electrode body, the exterior body has an exterior film that wraps the electrode body and a lid body that seals the electrode body together with the exterior film. The exterior film is composed of at least a laminate including a barrier layer and a heat-sealable resin layer. At a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body, the area average angular difference of GOS (Grain Orientation Spread) when the grain boundaries of the barrier layer are defined as 5° obtained by performing crystal analysis by the EBSD method on a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer is 2.50° or less. It has been found that when the power storage device is repeatedly exposed to temperature changes at high and low temperatures, cracking is suppressed at the sealing portion between the exterior film and the lid body.

[0012] Based on these findings, the present disclosure has been completed through further studies. That is, the present disclosure provides an invention in the following aspects. A power storage device, including an electrode body, and an exterior body that seals the electrode body, wherein the exterior body has an exterior film that wraps the electrode body, and a lid body that seals the electrode body together with the exterior film, the exterior film is composed of at least a laminate including a barrier layer and a heat-sealable resin layer, the barrier layer is in a direction perpendicular to the rolling direction of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body, and for a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer, the area average angular difference of GOS (Grain Orientation Spread) when the grain boundaries are defined as 5° obtained by performing crystal analysis by the EBSD method is 2.50° or less. A power storage device.

[0013] Furthermore, the inventors of the present disclosure have intensively studied to solve the above problems. As a result, at least in the exterior material for a power storage device composed of a laminate including a barrier layer and a heat-sealable resin layer, the heat-sealable resin layer of the exterior material for a power storage device and a polypropylene plate are heat-sealed under the condition that the thickness of the heat-sealable resin layer is 20% or more and 80% or less. At the position where they are heat-sealed, for the cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer, when the grain boundary is defined as 5°, the area average angular difference of GOS (Grain Orientation Spread) obtained by performing crystal analysis by the EBSD method is 2.50° or less. Thus, it has been found that when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, cracking is suppressed at the sealing portion with the lid of the exterior material for the power storage device.

[0014] Based on these findings, the present disclosure has been completed through further studies. That is, the present disclosure also provides inventions in the following aspects. An exterior material for a power storage device, which is composed of at least a laminate including a barrier layer and a heat-sealable resin layer, wherein the barrier layer has an area average angular difference of GOS (Grain Orientation Spread) of 2.50° or less, which is obtained by performing crystal analysis by the EBSD method on the cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer at the position where the heat-sealable resin layer of the exterior material for the power storage device and a polypropylene plate are heat-sealed under the condition that the thickness of the heat-sealable resin layer is 20% or more and 80% or less. An exterior material for a power storage device.

Effect of the Invention

[0015] According to the present disclosure, in a power storage device using an exterior body including an exterior film wrapping an electrode body and a lid body, when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, cracking is suppressed from occurring at the sealing portion of the exterior film with the lid body (more specifically, cracking occurs in the barrier layer). A power storage device can be provided. Further, according to the present disclosure, a method for manufacturing the power storage device can also be provided.

[0016] Further, according to the present disclosure, in a power storage device using an exterior body including an exterior material for a power storage device wrapping an electrode body and a lid body, when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, cracking is suppressed from occurring at the sealing portion of the exterior material for a power storage device with the lid body (more specifically, cracking occurs in the barrier layer). An exterior material for a power storage device can also be provided. Further, according to the present disclosure, a method for manufacturing the exterior material for a power storage device, and a power storage device using the exterior material for a power storage device can also be provided.

Brief Description of the Drawings

[0017]

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Embodiments for Carrying Out the Invention

[0018] In the power storage device of the present disclosure, the exterior film includes an electrode body and an exterior body that seals the electrode body. The exterior body has an exterior film that wraps the electrode body and a lid body that seals the electrode body together with the exterior film (exterior material for the power storage device). The exterior film is composed of a laminate including at least a barrier layer and a heat-sealable resin layer. The barrier layer is in a direction perpendicular to the rolling direction of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body, and for a cross-section obtained by cutting the barrier layer in a direction perpendicular to the surface of the barrier layer (that is, a direction perpendicular to the surface of the barrier layer), the area average angular difference of GOS (grain orientation dispersion) defined with the grain boundary being 5° is 2.50° or less as obtained by performing crystal analysis by the EBSD method. By having such a configuration, the power storage device of the present disclosure suppresses the occurrence of cracks in the sealing portion between the exterior film and the lid body.

[0019] In addition, the exterior material for a power storage device of the present disclosure is composed of a laminate including at least a barrier layer and a heat-sealable resin layer. The barrier layer is formed at a position where the heat-sealable resin layer of the exterior material for a power storage device and a polypropylene plate are heat-sealed under the condition that the thickness of the heat-sealable resin layer is 20% or more and 80% or less. In a direction perpendicular to the rolling direction of the barrier layer, for a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer, the area average angular difference of GOS (grain orientation spread) when the grain boundary is defined as 5° is 2.50° or less, which is obtained by performing crystal analysis by the EBSD method. According to the exterior material for a power storage device of the present disclosure, by having such a configuration, the occurrence of cracks in the sealing portion with the lid of the exterior material for a power storage device is suppressed.

[0020] Hereinafter, the power storage device and the exterior film of the present disclosure (hereinafter also referred to as the exterior material for a power storage device) will be described in detail. In the present disclosure, the numerical range indicated by "~" means "or more" and "or less". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range of other step-by-step descriptions. In addition, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value described separately may be combined to form a numerical range, respectively. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0021] In the case of the exterior film and the exterior material for the power storage device, for the barrier layer 52 and the barrier layer 3 described later, generally, the MD (Machine Direction) and TD (Transverse Direction) in the manufacturing process can be distinguished respectively. For example, when the barrier layer 52 and the barrier layer 3 are each composed of a metal foil such as an aluminum alloy foil or a stainless steel foil, linear streaks called so-called rolling marks are formed on the surface of the metal foil in the rolling direction (RD: Rolling Direction) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be grasped by observing the surface of the metal foil. Further, in the manufacturing process of the laminate, generally, since the MD of the laminate coincides with the RD of the metal foil, the MD of the laminate can be specified by observing the surface of the metal foil of the laminate and specifying the rolling direction (RD) of the metal foil. Also, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be specified.

[0022] Also, when the MD of the exterior film cannot be specified by the rolling marks of a metal foil such as an aluminum alloy foil or a stainless steel foil, it can be specified by the following method. As a method for confirming the MD of the exterior film, there is a method of observing a cross-section of the heat-sealing resin layer of the exterior film with an electron microscope and confirming a sea-island structure. In this method, the direction parallel to the cross-section where the average of the diameters of the island shapes in the direction perpendicular to the thickness direction of the heat-sealing resin layer is the largest can be determined as the MD. Specifically, the cross-section in the length direction of the heat-sealing resin layer and the cross-sections at angles changed by 10 degrees each from the direction parallel to the cross-section in the length direction are observed with electron microscope photographs to confirm the sea-island structure up to the cross-section perpendicular to the cross-section in the length direction (a total of 10 cross-sections). Next, in each cross-section, the shape of each individual island is observed. Regarding the shape of each individual island, the straight-line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealing resin layer and the rightmost end in the said perpendicular direction is defined as the diameter y. In each cross-section, the average of the top 20 diameters y in descending order of the diameter y of the island shape is calculated. The direction parallel to the cross-section where the average of the diameter y of the island shape is the largest is determined as the MD.

[0023] <1-1. Configuration of Energy Storage Device> FIG. 1 is a perspective view schematically showing an energy storage device 10. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1. FIG. 3 is a schematic view showing an example of a lid body 60. FIG. 4 is a cross-sectional view showing an example of a laminated structure of an exterior film 50 included in the energy storage device 10 of FIG. 1. In FIGS. 1 to 3, the arrow z direction (z1 direction and z2 direction) indicates the thickness direction of the energy storage device 10, the arrow x direction (x1 direction and x2 direction) indicates the width direction of the energy storage device 10, and the arrow y direction (y1 direction and y2 direction) indicates the depth direction of the energy storage device 10. The directions indicated by each of the arrows x, y, and z are common in each of the subsequent figures.

[0024] The energy storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes, for example, electrodes (a positive electrode and a negative electrode) constituting an energy storage member such as a lithium-ion battery, a capacitor, an all-solid-state battery, a semi-solid-state battery, a quasi-solid-state battery, a polymer battery, an all-resin battery, a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator and the like. In the present disclosure, the shape of the electrode body 20 is, for example, a substantially rectangular parallelepiped. Note that the "substantially rectangular parallelepiped" includes, in addition to a perfect rectangular parallelepiped, a three-dimensional body that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0025] The power storage device 10 in FIGS. 1 and 2 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for power input and output in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from the edge of the exterior body 40, for example. Note that the electrode terminal 30 only needs to be capable of power input and output of the electrode body 20, and for example, it does not necessarily have to protrude from the exterior body 40. When the lid body 60 described later is made of, for example, a conductive material, the lid body 60 may also serve as the function of the electrode terminal 30. In this case, the lid body 60 having the function as the electrode terminal may or may not protrude from the exterior body 40.

[0026] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, or the like. For example, when the electrode body 20 is a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum or the like, and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, or the like. Note that the outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator. The outer shape of the electrode body 20 is, for example, a rectangular parallelepiped.

[0027] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a lid body 60. The exterior film 50 wraps the electrode body 20. In FIGS. 1 and 2, the exterior film 50 is wound around the electrode body 20. The lid body 60 is disposed on the side of the electrode body 20 in the y direction. In another example, the electrode body 20 may be accommodated inside the cylindrical exterior film 50 configured such that openings are formed at both ends in the y direction, and the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the lid body 60 may be accommodated inside the cylindrical exterior film 50 configured such that an opening is formed, and the opening may be closed by the lid body 60.

[0028] The outer package 40 has a pair of main surfaces and a pair of side surfaces formed by the outer film 50. In FIGS. 1 and 2, the pair of main surfaces are substantially the same size. Also, the pair of side surfaces are substantially the same size. Each of the pair of main surfaces has a larger area than the pair of side surfaces. The pair of lid bodies 60 are respectively arranged on the sides of the electrode body 20 so as to close the pair of openings. In the present disclosure, the main surface and the side surface are surfaces configured excluding the lid body 60 among the surfaces of the outer package 40.

[0029] For example, there is a method of forming a housing portion (depression) for housing the electrode body 20 in the outer film 50 through cold forming. However, it is not always easy to form a deep housing portion by such a method. If an attempt is made to deeply form the housing portion (depression) (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks are likely to occur in the outer film 50, increasing the possibility of deterioration of battery performance. On the other hand, since the outer package 40 seals the electrode body 20 by winding the outer film 50 around the electrode body 20, the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In order to reduce the dead space between the electrode body 20 and the outer film 50 in order to improve the volume energy density of the power storage device 10, a state in which the outer film 50 is wound so as to contact the outer surface of the electrode body 20 is preferable. Also, in a all-solid-state battery, from the viewpoint that it is necessary to uniformly apply a high pressure from the outside of the battery in order to exhibit battery performance, it is necessary to eliminate the space between the electrode body 20 and the outer film 50, so a state in which the outer film 50 is wound so as to contact the outer surface of the electrode body 20 is preferable. When winding the outer film 50 around the electrode body 20, only one outer film 50 may be wound, or a plurality of outer films 50 may be wound. Also, in addition to the mode in which the surfaces of the outer film 50 facing each other are heat-sealed, a mode in which the outer surface and the inner surface of the outer film 50 are heat-sealed is also preferable.

[0030] As shown in FIG. 4, the exterior film 50 is a laminate (laminated film) having at least a barrier layer 52 and a heat-sealable resin layer 53. Details of each layer included in the exterior film 50 will be described later.

[0031] The lid 60 may have any shape such as, for example, a cylinder, a prism, a cuboid, or a cube, and is composed of, for example, a resin material. Here, "composed of a resin material" means that when the total amount of the materials constituting the lid 60 is 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. That is, the material constituting the lid 60 may contain a material other than the resin material in addition to the resin material.

[0032] Specific examples of the resin include resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, and thermoplastic resins such as modified products of these resins. The resin material may be a mixture of these resins, a copolymer, or a modified product of a copolymer. Among these, the resin material is preferably a heat-sealable resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the lid 60 may be formed by any molding method.

[0033] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include copolyesters having ethylene terephthalate as the main repeating unit. Specifically, copolyester polyethylenes obtained by polymerizing ethylene terephthalate with ethylene isophthalate (hereinafter abbreviated following the name polyethylene(terephthalate / isophthalate)), polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), polyethylene(terephthalate / decanedicarboxylate), etc. are included. Among these, the resin material is preferably polybutylene terephthalate from the viewpoint of enhancing heat resistance and pressure resistance.

[0034] Examples of the polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; ethylene-α olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α olefin copolymers; and terpolymers of ethylene-butene-propylene. The polyolefin resin in the case of being a copolymer may be a block copolymer or a random copolymer. Among these, the resin material is preferably polypropylene because of its excellent heat fusion property and electrolyte resistance.

[0035] The resin as the resin material may contain a filler as required. Specific examples of the filler include glass beads, graphite, glass fiber, and carbon fiber. By the resin as the resin material containing the filler, the deformation resistance of the lid body 60 against temperature changes can be improved.

[0036] The melt mass flow rate (measurement temperature 230°C) of the resin material contained in the material constituting the lid body 60 is preferably in the range of 1 g / 10 min to 100 g / 10 min, preferably in the range of 1 g / 10 min to 80 g / 10 min, preferably in the range of 1 g / 10 min to 60 g / 10 min, preferably in the range of 5 g / 10 min to 100 g / 10 min, preferably in the range of 5 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0037] The lid body 60 may be configured to include a conductive material. "Configured to include a conductive material" means that when the total amount of the material constituting the lid body 60 is 100% by mass, the content of the conductive material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. That is, the material constituting the lid body 60 can contain, in addition to the conductive material, a material other than the conductive material.

[0038] The conductive material constituting the lid body 60 is, for example, a metal material. The metal material constituting the lid body 60 is, for example, aluminum, an aluminum alloy, nickel, copper, or a copper alloy. For example, when the electrode body 20 is a lithium-ion battery, the lid body 60 connected to the positive electrode is preferably constituted by aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably constituted by nickel, copper, or a copper alloy. The material constituting the lid body 60 connected to the negative electrode may be nickel-plated copper. The material constituting the lid body 60 may include a recycled material of the metal material. When the lid body 60 is constituted to include a conductive material, since the lid body 60 also serves as the electrode terminal 30, the power storage device 10 can also omit the electrode terminal 30.

[0039] The lid body 60 may be configured such that at least a part of the lid main body 61 is covered by the covering body 62. In the lid body 60 of FIG. 3, the periphery of the lid main body 61 (the periphery of the thick portion) is covered by the covering body 62. The lid body 60 may be joined to the heat-sealable resin layer 53 of the exterior film 50 via the covering body 62. The covering body 62 is preferably constituted to include a resin material. The lid body 60 has the lid main body 61 and the covering body 62 that joins the lid main body 61 and the exterior film 50, and the covering body 62 can be configured to include a resin (resin material). The definition of "constituted to include a resin material" for the covering body 62 is the same as that for the lid body 60.

[0040] When the lid body 60 is constituted to include a conductive material, the lid main body 61 is constituted by the conductive material, and at least a part of the lid main body 61 may be covered by the covering body 62.

[0041] When the lid body 60 is made of a conductive material, the lid body 60 may be joined to the exterior film 50 via an adhesive film instead of the coating. The adhesive film can be arbitrarily selected as long as it can bond the exterior film 50 and the lid body 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant base material layer, and a heat-sealable resin layer in this order. The specifications of the heat-sealable resin layer of the adhesive film can be applied to the specifications of the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same kind of material or different kinds of materials, and are appropriately selected according to the material constituting the heat-sealable resin layer 53 of the exterior film 50 and the material constituting the lid body 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that is adhered to the lid body 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer on the side of the adhesive film that is adhered to the exterior film 50 is preferably made of the same kind of material as the material constituting the heat-sealable resin layer 53 of the exterior film 50.

[0042] The heat-resistant base material layer may be a film made of a heat-resistant resin. For example, unstretched or stretched films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, and polypropylene can be used. Note that polyethylene terephthalate is inexpensive and has high strength, and is particularly preferred.

[0043] The adhesive film preferably has adhesiveness. When forming the second sealing portion 80 described later with the adhesive film disposed between the outer packaging film 50 and the lid body 60, the position of the adhesive film with respect to the lid body 60 and the outer packaging film 50 is less likely to shift. By incorporating an adhesion-imparting resin into the heat-sealable resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the adhesion-imparting resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene, or a copolymer of amorphous propylene and other α-olefins. The content of the adhesion-imparting resin with respect to the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less.

[0044] The lid body 60 includes a first main surface located on the inner side (electrode body 20 side) of the power storage device, a second main surface located on the outer side of the power storage device, and four side surfaces heat-sealed to the heat-sealable resin layer 53 of the outer packaging film 50. The first main surface faces the electrode body 20. The second main surface is the surface on the opposite side of the first main surface.

[0045] When the lid body 60 is a cylinder, a prism, a cuboid, a cube, or the like, even when the power storage devices 10 are stacked, the lid body 60 preferably has a certain thickness in the thickness direction (y direction) so that the exterior body 40 is prevented from deforming. From another perspective, when the lid body 60 is a cylinder, a prism, a cuboid, a cube, or the like, the lid body 60 preferably has a certain thickness in the thickness direction (y direction) so that the lid joint of the lid body 60 and the exterior film 50 can be preferably joined when forming the second sealing portion 80. The minimum value of the thickness of the lid body 60 in the thickness direction (y direction) (the distance in the y direction between the first main surface and the second main surface) is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid body 60 in the y direction is, for example, 20 mm, preferably 15.0 mm, more preferably 10.0 mm, even more preferably 8.0 mm, and even more preferably 7.0 mm. The maximum value of the thickness of the lid body 60 in the y direction may be 10 mm or more. The preferable range of the thickness of the material constituting the lid body 60 is 1.0 mm to 20.0 mm, 1.0 mm to 15.0 mm, 1.0 mm to 10.0 mm, 1.0 mm to 8.0 mm, 1.0 mm to 7.0 mm, 3.0 mm to 20.0 mm, 3.0 mm to 15.0 mm, 3.0 mm to 10.0 mm, 3.0 mm to 8.0 mm, 3.0 mm to 7.0 mm, 4.0 mm to 20.0 mm, 4.0 mm to 15.0 mm, 4.0 mm to 10.0 mm, 4.0 mm to 8.0 mm, 4.0 mm to 7.0 mm. In the present disclosure, when the lid body 60 is described as a cylinder, a prism, a cuboid, a cube, or the like, an aspect in which the lid body 60 is composed only of a film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. Note that the thickness of the lid body 60 may vary depending on the part of the lid body 60. When the thickness of the lid body 60 varies depending on the part, the thickness of the lid body 60 is the thickness of the thickest part.

[0046] In FIGS. 1 and 2, a through hole into which the electrode terminal 30 is inserted is formed in the lid body 60. The through hole penetrates the first main surface and the second main surface of the lid body. With the electrode body 20 housed, the electrode terminal 30 protrudes outside the exterior body 40 through the through hole formed in the lid body 60. The slight gap between the through hole in the lid body 60 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the position where the electrode terminal 30 protrudes outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude outside through a hole formed in any one of the six surfaces of the exterior body 40. In this case, the slight gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. The electrode terminal 30 may protrude from between the lid body 60 and the exterior film 50, or may protrude from the first sealing portion 70 described later. In the power storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies, but the lid body 60 and the electrode terminal 30 may be integrally formed. Note that when the electrode terminal 30 does not protrude from the edge of the exterior body 40, the through hole may not be formed in the lid body 60.

[0047] In FIGS. 1 and 2, with the exterior film 50 wound around the periphery of the electrode body 20, the first sealing portion 70 is formed by heat-sealing the mutually facing surfaces (heat-sealable resin layers 53) of the exterior film 50.

[0048] The first sealing portion 70 is formed by heat-sealing the heat-sealable resin layers of the exterior film 50. The first sealing portion 70 extends in the longitudinal direction of the exterior body 40. In the exterior body 40, the position where the first sealing portion 70 is formed can be arbitrarily selected. As shown in FIG. 1, the base of the first sealing portion 70 is preferably located on the edge of the boundary between the main surface and the side surface of the exterior body 40. The base of the first sealing portion 70 may be located on any surface of the exterior body 40. In FIG. 1, in plan view, the first sealing portion 70 protrudes outside the electrode body 20. The first sealing portion 70 may be folded, for example, toward the side surface of the exterior body 40, or may be folded toward the main surface.

[0049] The second sealing portion 80 is formed by joining the heat-sealing resin layer 53 of the outer film 50 and the lid joint portion of the lid body 60 (the portion where the heat-sealing resin layer 53 of the outer film 50 and the lid body 60 are in contact) by, for example, heat sealing. The outer film 50 and the lid body 60 can be joined by any method such as welding.

[0050] <1-2. Physical properties of the power storage device> In the power storage device of the present disclosure, the barrier layer 52 of the outer film 50 is in a direction perpendicular to the rolling direction of the barrier layer 52 at the position where the heat-sealing resin layer 53 of the outer film 50 is heat-sealed to the lid body 60. For a cross-section obtained by cutting the barrier layer 52 in a direction perpendicular to the surface of the barrier layer 52 (that is, in a direction perpendicular to the surface of the barrier layer), the area average angular difference of GOS (grain orientation spread) defined with the grain boundary being 5° is 2.50° or less as obtained by performing crystal analysis by the EBSD method.

[0051] From the viewpoint of more preferably exerting the effects of the invention of the present disclosure, the area average angular difference of the GOS (grain orientation spread) is preferably about 2.50° or less, more preferably about 2.00° or less, still more preferably about 1.50° or less, and also, for example, about 0° or more, about 0.20° or more, etc. Preferred ranges include about 0 to 2.50°, about 0 to 2.00°, about 0 to 1.50°, about 0.20 to 2.50°, about 0.20 to 2.00°, about 0.20 to 1.50°, etc.

[0052] The area average angular difference of the GOS (grain orientation spread) of the barrier layer 52 is a value measured by the following method.

[0053] <Measurement of the area average angular difference of the GOS (grain orientation spread) of the barrier layer> For a power storage device, obtain the barrier layer at the position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid (sealing portion (second sealing portion)), perform crystal analysis by the EBSD method, and measure the area-average angular difference of GOS (grain orientation spread) when the grain boundaries of the barrier layer are defined as 5°. The specific measurement method is as follows.

[0054] For the cross-section perpendicular to the rolling direction of each barrier layer, perform crystal analysis by the EBSD method, and measure the area-average angular difference of GOS (grain orientation spread) when the grain boundaries of the barrier layer are defined as 5°. The details of the measurement conditions are as follows. The area-average angular difference of GOS (grain orientation spread) is obtained by connecting a plurality of images acquired by crystal analysis by the EBSD method to form a measurement region of about 5000 μm 2 This is the area-average angular difference of GOS (grain orientation spread) of the crystals included in the above measurement region (the entire thickness direction of the barrier layer is taken as the measurement region).

[0055] (Measuring device) Use a device equipped with an EBSD detector on a Schottky field emission scanning electron microscope.

[0056] (Pretreatment) As a pretreatment, the barrier layer is cut in a direction perpendicular to the rolling direction (RD) to obtain a cross-section. The rolling direction of the barrier layer is the direction in which linear rolling marks extend when the glossy surface of the barrier layer is observed with a metallurgical microscope. As a specific procedure, first, the barrier layer to be used as a sample is cut out to 5 mm (in a direction perpendicular to the rolling direction) × 10 mm (in the rolling direction) with a trimming razor, and then embedded in resin. Next, using a trimming razor, the barrier layer is cut together with the resin in a direction perpendicular to the rolling direction of the barrier layer and in a direction perpendicular to the surface of the barrier layer to expose the cross-section of the barrier layer. Next, the obtained cross-section is trimmed using a microtome. In this trimming, in order to reduce mechanical distortion of the cross-sectional shape, the microtome is advanced by about 1 mm in a direction perpendicular to the cross-section together with the embedded resin. Next, using an ion milling device, a broad argon beam is irradiated in a direction perpendicular to the cross-section under the conditions of a jump-out width of 50 μm, a voltage of 6 kV, and 4 hours to produce a measurement cross-section. This is an operation of precisely exposing the cross-section of the barrier layer so that mechanical damage to the crystal structure generated in the previous process is minimized. In the present disclosure, since the "perpendicular direction" when cutting the aluminum alloy foil is confirmed under a stereomicroscope, an error of about 10° may be included. That is, the direction perpendicular to the rolling direction allows a range of 80 to 100° with respect to the rolling direction, and the direction perpendicular to the surface allows a range of 80 to 100° with respect to the surface.

[0057] (SEM conditions) The conditions of the scanning electron microscope (SEM) used for the EBSD method are as follows. Observation magnification: 2000 times (the standard observation magnification at the time of photography shall be Polaroid 545) Accelerating voltage: 15 kV Working distance: 15 mm Sample tilt angle: 70°

[0058] (EBSD conditions) The conditions for crystal analysis by the EBSD method are as follows. Step size: 150 nm Analysis conditions: The following analysis is performed using the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. Connect multiple images, and the measurement area is about 5000 μm 2 The above shall be the case. Regarding the upper limit of the measurement area, for example, it shall be about 30000 μm 2 The following shall be the case. At this time, the measurement area shall be from the center in the thickness direction of the barrier layer to both end sides, and the parts where resin adheres to the cross-section and the parts where the acid-resistant film exists shall be excluded from the measurement area. The CI value shall be 0.1 or more, the grain boundary condition shall be 5° or more, and the minimum grain size shall be 3 steps or more. After connecting the images, check the pole figure. When the center of the pole figure is shifted by 10° or more, rotate the crystal data so that the symmetry is adjusted. The pole figure for reference at that time is measured from the sample surface by XRD. When obtaining the pole figure from the surface by EBSD, in order to remove the influence of the mechanical crystal structure of the sample surface, after performing mechanical polishing, plane milling, electrolytic polishing, etc. on the sample surface, perform a wide-range measurement. Then, rotate the pole figure obtained from the surface direction by 90° so that it is the same as the one obtained from the same orientation as the pole figure obtained from the cross-section of the target sample. Refer to this pole figure. Exclude the data with a CI value (Confidence Index: CI value) defined by the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. that is 0.1 or less and perform the analysis. Thereby, it is possible to exclude the resin used for the pretreatment existing on the front and back of the sample, the grain boundaries existing in the cross-section, and the data based on the amorphous.

[0059] The area average angular difference of the GOS (crystal grain orientation dispersion) of the barrier layer 52 can be adjusted by the material constituting the barrier layer 52, the thickness of the barrier layer 52, the material of the lid 60, the sealing conditions (temperature, pressure, time) when heat-sealing the outer film 50 and the lid 60 to form the second sealing portion 80, etc.

[0060] For example, by increasing the Young's modulus of the barrier layer 52 (i.e., increasing the Young's modulus of the outer packaging film 50), the area average angular difference of the GOS (grain orientation dispersion) of the barrier layer 52 can be reduced. The preferred Young's modulus of the barrier layer 52 will be described later. For example, increasing the thickness of the barrier layer 52, using a high-strength metal, etc. are effective.

[0061] Also, for example, when the barrier layer 52 is formed of an aluminum alloy foil, if it has an aluminum alloy composition in the 8000 series of JIS standards, the strength can be increased by adding a small amount of Si to the aluminum ingot. Also, if it has an aluminum alloy composition in the 5000 series of JIS standards, the strength of the soft foil can be increased by solid-solution strengthening by dissolving Mg in aluminum.

[0062] Refining the crystal grains of the metal forming the barrier layer 52 is also effective for increasing the above ratio (R1 / R2). For example, in the case of aluminum alloy compositions in the 8000 series and 5000 series of JIS standards, it crystallizes as an Al-Fe-based intermetallic compound during casting, and this becomes the nucleus and the crystal grains are refined. Also, when adopting cross-roll rolling (a method of rolling with rolls having different peripheral speeds), the rolled material undergoes shear deformation throughout the plate thickness in addition to normal rolling deformation. As a result, crystal rotation is promoted and the change from subgrain boundaries to large-angle grain boundaries is promoted, generating fine crystal grains. This method is effective even in cold working, but the effect is greater in warm working. Furthermore, increasing the number of rolling passes in the hot rolling of aluminum alloy foil and increasing the final cold rolling ratio are also effective. The higher the final cold rolling ratio from after intermediate annealing to the final thickness (for example, 80% or more), the greater the amount of strain accumulated in the aluminum alloy foil and the finer the recrystallized grains after final annealing.

[0063] Regarding the rolling conditions of the aluminum foil, conditions such as the rolling ratio, heating temperature, and heating time are adjusted. For example, a process of homogenizing an aluminum metal or aluminum alloy ingot at about 500 to 600 °C for about 1 to 2 hours, a hot rolling process, a cold rolling process, an intermediate annealing process of holding at about 300 to 450 °C for about 1 to 10 hours, a cold rolling process in which the rolling ratio from after the intermediate annealing to the final rolling is carried out at 80% or more, more preferably 90% or more, and a final annealing process of holding at about 250 to 400 °C for about 30 to 100 hours are included, but the conditions for refining the crystal grains are not limited to this.

[0064] Furthermore, it is also effective to make the linear expansion coefficient of the barrier layer 52 close to the linear expansion coefficient of the material used for the lid body 60 (lid main body 61 or covering body 62).

[0065] <1-3. Method for manufacturing a power storage device> The power storage device of the present disclosure can be manufactured by assembling the electrode body 20, the electrode terminal 30, the exterior film 50, and the lid body 60 of the present disclosure. For these assemblies, for example, known methods can be adopted. Specific examples of the power storage device of the present disclosure are shown below.

[0066] A pair of lid bodies 60 to which the electrode terminals 30 are joined are arranged with respect to the electrode body 20, and the electrode terminals 30 and the electrode body 20 are electrically connected. Note that the lid body 60 may be joined to the electrode terminals 30 electrically connected to the electrode body 20.

[0067] Next, the electrode body 20 and the lid body 60 are wrapped with the exterior film 50. While restricting the movement of the electrode body 20 and the lid body 60 by the restricting means, the exterior film 50 is wound around the electrode body 20 and the lid body 60 in a state where tension is applied to the exterior film 50. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force in a direction opposite to the direction in which the exterior film 50 is pulled to the electrode body 20 and the lid body 60. Note that the restricting means may include a roller that travels on the exterior film 50 in a state where the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50.

[0068] Next, a step of sealing the electrode body 20 with the exterior body 40 is performed. Specifically, a step of forming the first sealing portion 70 by heat-sealing the heat-sealing resin layers 53 of the exterior film 50 facing each other, and a step of forming the second sealing portion 80 by heat-sealing the heat-sealing resin layer 53 of the exterior film 50 and the side surface of the lid body 60 are performed. The order of these steps is not particularly limited. For example, the first sealing portion 70 is formed after the second sealing portion 80 is formed. The first sealing portion 70 and the second sealing portion 80 can be formed by heat-sealing the heat-sealing resin layer 53 using a heat-sealing bar or the like.

[0069] <2-1. Laminated Structure and Physical Properties of Exterior Film> The exterior film (exterior material for a power storage device) 50 of the present disclosure is composed of a laminate including a barrier layer 52 and a heat-sealable resin layer 53, as shown in FIG. 4, for example. In the exterior film 50, the barrier layer 52 is on the outermost layer side, and the heat-sealable resin layer 53 is on the innermost layer. When assembling a power storage device using the exterior film 50 and power storage device elements (such as the electrode body 20 and the electrode terminal 30), the electrode body 20 is accommodated in a space formed by heat-sealing the ends of the heat-sealable resin layers 53 of the exterior film 50 in a state where they face each other, together with the lid body 60. In the laminate constituting the exterior film 50 of the present disclosure, with the barrier layer 52 as a reference, the side of the heat-sealable resin layer 53 is the inner side with respect to the barrier layer 52, and the opposite side is the outer side.

[0070] The exterior film 50 may have a base material layer 51 outside the barrier layer 52, as needed, as shown in FIG. 4, for example. Further, the exterior film 50 may have an adhesive layer 54 between the base material layer 51 and the barrier layer 52, as needed, for the purpose of enhancing the adhesiveness between these layers, as shown in FIG. 4, for example. Further, an adhesive layer 55 may be provided between the barrier layer 52 and the heat-sealable resin layer 53, as needed, for the purpose of enhancing the adhesiveness between these layers, as shown in FIG. 4, for example. Further, a surface coating layer (not shown) or the like may be provided outside the base material layer 51 (the side opposite to the heat-sealable resin layer 53 side), as needed, as shown in FIG. 4.

[0071] The thickness of the laminate constituting the exterior film 50 is not particularly limited. However, from the viewpoints of cost reduction, improvement of energy density, etc., for example, it may be about 250 μm or less, preferably about 190 μm or less, about 180 μm or less, about 155 μm or less, about 120 μm or less. Also, from the viewpoint of maintaining the function of the exterior film of protecting the electrode body 20, the thickness of the laminate constituting the exterior film 50 is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more. Further, regarding the preferable range of the laminate constituting the exterior film 50, for example, about 35 to 250 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 250 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 250 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm can be mentioned. Particularly, when making the power storage device lightweight and thin-film-like, about 60 to 155 μm is preferable, and when improving the followability when winding the exterior film around the electrode body, about 155 to 190 μm is preferable.

[0072] In the outer packaging film 50, the ratio of the total thickness of the base material layer 51 provided as necessary, the adhesive layer 54 provided as necessary, the barrier layer 52, the adhesive layer 55 provided as necessary, the heat-sealable resin layer 53, and the surface coating layer provided as necessary to the thickness (total thickness) of the laminate constituting the outer packaging film 50 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the outer packaging film 50 of the present disclosure includes the base material layer 51, the adhesive layer 54, the barrier layer 52, the adhesive layer 55, and the heat-sealable resin layer 53, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the outer packaging film 50 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, even when the outer packaging film 50 of the present disclosure is a laminate including the base material layer 51, the adhesive layer 54, the barrier layer 52, and the heat-sealable resin layer 53, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the outer packaging film 50 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0073] From the viewpoint of more suitably exhibiting the effects of the invention of the present disclosure, the Young's modulus of the outer packaging film 50 is preferably 6000 MPa or more, more preferably 8000 MPa or more, and even more preferably 10000 MPa or more. Also, it is preferably 40000 MPa or less, more preferably 35000 MPa or less, and even more preferably 30000 MPa or less. Preferred ranges include about 6000 to 40000 MPa, about 6000 to 35000 MPa, about 6000 to 30000 MPa, about 8000 to 40000 MPa, about 8000 to 35000 MPa, about 8000 to 30000 MPa, about 10000 to 40000 MPa, about 10000 to 35000 MPa, and about 10000 to 30000 MPa. In the present disclosure, the Young's modulus of the outer packaging film is a value measured by the following method.

[0074] <Measurement of Young's Modulus of Outer Packaging Film> In accordance with the provisions of JIS K6251:2017, the S-S curve in the TD direction of the exterior film was obtained under the following measurement conditions, and the Young's modulus (MPa) was calculated from the maximum value of the slope of the S-S curve. (Measurement conditions) Use a tensile testing machine. Shape of test piece: dumbbell No. 7 Width of test piece: 2 mm Length of test piece: 35 mm Thickness of test piece: Measure with a thickness gauge Distance between gauge marks: 20 mm Tensile speed: 50 mm / min Test environment: 23 ± 5°C, 50 ± 30% RH Number of measurements: Average value of 3 times

[0075] As a method for increasing the Young's modulus of the exterior film 50, for example, it is effective to increase the Young's modulus of the barrier layer 52 as described above.

[0076] <2-2. Each layer constituting the exterior film> [Base material layer 51] In the present disclosure, the base material layer 51 is a layer provided as needed for the purpose of, for example, exerting the function of the base material of the exterior film. The base material layer 51 is located on the outer layer side of the exterior film.

[0077] The material for forming the base material layer 51 is not particularly limited as long as it has the function of the base material, that is, at least has insulation properties. The base material layer 51 can be formed using, for example, a resin, and the resin may contain additives described later.

[0078] When the base material layer 51 is formed of a resin, the base material layer 51 can be formed of, for example, a resin film. When the base material layer 51 is formed of a resin film, when manufacturing the exterior film 50 of the present disclosure by laminating the base material layer 51 with a barrier layer 52 or the like, a pre-formed resin film may be used as the base material layer 51. Further, the resin forming the base material layer 51 may be formed into a film on the surface of the barrier layer 52 or the like by extrusion molding, coating, or the like, and used as the base material layer 51 formed of a resin film. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferred. Examples of the stretching method for forming the biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of the method for applying the resin include a roll coating method, a gravure coating method, and an extrusion coating method.

[0079] Examples of the resin forming the base material layer 51 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 51 may be a copolymer of these resins or a modified product of the copolymer. Furthermore, a mixture of these resins may be used.

[0080] The base material layer 51 preferably contains these resins as the main components, and more preferably contains polyester or polyamide as the main components. Here, the main component means a resin component having a content of, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and still more preferably 99% by mass or more among the resin components contained in the base material layer 51. For example, when the base material layer 51 contains polyester or polyamide as the main components, it means that the content of polyester or polyamide among the resin components contained in the base material layer 51 is, respectively, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and still more preferably 99% by mass or more.

[0081] Among these, the resins for forming the base material layer 51 preferably include polyester and polyamide.

[0082] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include copolyesters mainly composed of ethylene terephthalate as a repeating unit. Specifically, examples include copolyester polyethylenes (hereinafter abbreviated following polyethylenes (terephthalate / isophthalate)) polymerized with ethylene isophthalate with ethylene terephthalate as a main repeating unit, polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), and the like. These polyesters may be used alone or in combination of two or more.

[0083] Examples of the polyamide include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid, polyamides containing aromatics such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (poly-bis(4-aminocyclohexyl)methane adipamide); furthermore, polyamides copolymerized with a lactam component or an isocyanate component such as 4,4'-diphenylmethane-diisocyanate, polyester amide copolymers and polyether ester amide copolymers which are copolymers of a copolyamide and a polyester or a polyalkylene ether glycol; and polyamides such as these copolymers. These polyamides may be used alone or in combination of two or more.

[0084] The base material layer 51 preferably contains at least one of a polyester film, a polyamide film, and a polyolefin film, preferably contains at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, and more preferably contains at least one of a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, a biaxially stretched nylon film, and a biaxially stretched polypropylene film.

[0085] The base material layer 51 may be a single layer or may be composed of two or more layers. When the base material layer 51 is composed of two or more layers, the base material layer 51 may be a laminate obtained by laminating resin films with an adhesive or the like, or may be a laminate of resin films formed by co-extruding resins into two or more layers. Further, the laminate of resin films formed by co-extruding resins into two or more layers may be used as the base material layer 51 without stretching, or may be used as the base material layer 51 after uniaxial stretching or biaxial stretching.

[0086] In the base material layer 51, specific examples of the 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, a laminate of two or more polyester films, etc. Preferably, a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base material layer 51 is a laminate of two resin films, 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 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. Also, since the polyester resin is less likely to change color when, for example, the electrolytic solution adheres to the surface, when the base material layer 51 is a laminate of two or more resin films, it is preferable that the polyester resin film is located in the outermost layer of the base material layer 51. In the laminate of a polyester resin film and a polyamide resin film, the preferable range of the thickness of the polyester resin film is about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, about 18 to 23 μm, and the preferable range of the thickness of the polyamide resin film is about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, about 18 to 23 μm.

[0087] When the base material layer 51 is a laminate of two or more resin films, the two or more resin films may be laminated via an adhesive. Preferred adhesives include the same ones as those exemplified for the adhesive layer 54 described below. Note that the method for laminating two or more resin films is not particularly limited, and known methods can be adopted. For example, dry lamination method, sandwich lamination method, extrusion lamination method, thermal lamination method, etc. can be mentioned, and preferably the dry lamination method can be mentioned. When laminating by the dry lamination method, 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. Further, an anchor coat layer may be formed on and laminated to the resin film. The anchor coat layer includes the same ones as those exemplified for the adhesive layer 54 described below. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0088] In addition, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, etc. may be present on at least one of the surface and inside of the base material layer 51. Only one type of additive may be used, or two or more types may be mixed and used.

[0089] In the present disclosure, from the viewpoint of enhancing the followability of the exterior film, it is preferable that a lubricant is present on at least one of the surface and the interior of the base material layer 51. The lubricant is not particularly limited, but preferably an amide-based lubricant. Specific examples of the amide-based lubricant include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the 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 the unsaturated fatty acid amides include oleic acid amide, erucic acid amide, and the like. Specific examples of the 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. Further, specific examples of the methylol amides include methylol stearic acid amide, and the like. Specific examples of the saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic 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 the unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, and the like. Specific examples of the fatty acid ester amides include stearamide ethyl stearate, and the like. Further, specific examples of the aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, and the like.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0090] When a lubricant is present on the surface of the base material layer 51, its amount of presence is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Also, as the amount of the lubricant present on the surface of the base material layer 51, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Further, the preferable range of the amount of the lubricant present on the surface of the base material layer 51 is about 3 to 15 mg / m 2 level, about 3 to 14 mg / m 2 level, about 3 to 10 mg / m 2 level, about 4 to 15 mg / m 2 level, about 4 to 14 mg / m 2 level, about 4 to 10 mg / m 2 level, about 5 to 15 mg / m 2 level, about 5 to 14 mg / m 2 level, about 5 to 10 mg / m 2 level and the like can be mentioned.

[0091] The lubricant present on the surface of the base material layer 51 may be one obtained by exuding the lubricant contained in the resin constituting the base material layer 51, or may be one obtained by applying a lubricant to the surface of the base material layer 51.

[0092] The thickness of the base material layer 51 is not particularly limited as long as it exhibits the functions of a base material. For example, it is about 3 μm or more, preferably about 10 μm or more. Also, examples of the thickness of the base material layer 51 include about 50 μm or less, preferably about 35 μm or less, about 11 μm or less, and about 8 μm or less. Further, preferable ranges of the thickness of the base material layer 51 include about 3 to 50 μm, about 3 to 35 μm, about 3 to 11 μm, about 3 to 8 μm, about 10 to 50 μm, and about 10 to 35 μm. Particularly when making the power storage device lightweight and thin-film, about 3 to 35 μm, about 3 to 11 μm, and about 3 to 8 μm are preferable, and when improving followability, about 35 to 50 μm is preferable. When the base material layer 51 is a laminate of two or more resin films, the thickness of the resin film constituting each layer is not particularly limited. For example, each is about 2 μm or more, preferably about 10 μm or more, and about 18 μm or more. Also, examples of the thickness of the resin film constituting each layer include about 33 μm or less, preferably about 28 μm or less, about 23 μm or less, about 18 μm or less, about 11 μm or less, and about 8 μm or less. Further, preferable ranges of the thickness of the resin film constituting each layer include about 2 to 33 μm, about 2 to 28 μm, about 2 to 23 μm, about 2 to 18 μm, about 2 to 11 μm, about 2 to 8 μm, about 10 to 33 μm, about 10 to 28 μm, about 10 to 23 μm, about 10 to 18 μm, about 10 to 11 μm, about 18 to 33 μm, about 18 to 28 μm, and about 18 to 23 μm.

[0093] [Adhesive layer 54] In the exterior film of the present disclosure, the adhesive layer 54 is a layer provided between the base material layer 51 and the barrier layer 52 as needed for the purpose of enhancing the adhesiveness therebetween.

[0094] Next, the adhesive layer 54 is formed of an adhesive capable of adhering the base material layer 51 and the barrier layer 52. The adhesive used for forming the adhesive layer 54 is not limited, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot press type, etc. 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. Also, the adhesive layer 54 may be a single layer or multiple layers.

[0095] Specific examples of the adhesive component contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin-based resins such as polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; 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, a polyurethane adhesive is preferably mentioned. Also, the resins serving as these adhesive components can increase the adhesive strength by using an appropriate curing agent in combination. The curing agent is appropriately selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., according to the functional groups of the adhesive components.

[0096] Examples of the polyurethane adhesive include a polyurethane adhesive comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curable polyurethane adhesive is used, in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as the first agent, and an aromatic or aliphatic polyisocyanate is used as the second agent. Further, examples of the polyurethane adhesive include a polyurethane adhesive comprising a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and an isocyanate compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive comprising a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and a polyol compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive cured by reacting a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound with moisture in the air or the like. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group not only at the terminal of the repeating unit but also in the side chain. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of the isocyanate compound 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. Further, examples thereof include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Further, a multimer (for example, a trimer) can also be used as the polyisocyanate compound. Examples of such multimers include adducts, biurets, and nurates. Since the adhesive layer 54 is formed of a polyurethane adhesive, excellent electrolyte resistance is imparted to the exterior film, and peeling of the base material layer 51 is suppressed even when the electrolyte adheres to the side surface.

[0097] Further, the adhesive layer 54 allows the addition of other components as long as the adhesiveness is not inhibited, and may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, etc. Since the adhesive layer 54 contains a colorant, the exterior film can be colored. As the colorant, known ones such as pigments and dyes can be used. Also, only one type of colorant may be used, or two or more types may be mixed and used.

[0098] The type of the pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 54. Examples of the organic pigment include pigments such as azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, benzimidazolone-based, etc. Examples of the inorganic pigment include pigments such as carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, iron-based, etc. In addition, fine powders of mica (muscovite), fish scale foil, etc. are included.

[0099] Among the colorants, for example, in order to make the appearance of the exterior film black, carbon black is preferable. Also, from the viewpoint of dissipating heat generated from the power storage device, it is preferable to use mica.

[0100] The average particle diameter of the pigment is not particularly limited, and for example, it is about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle diameter of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution measuring device.

[0101] The content of the pigment in the adhesive layer 54 is not particularly limited as long as the exterior film is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0102] The thickness of the adhesive layer 54 is not particularly limited as long as the base material layer 51 and the barrier layer 52 can be adhered. For example, it is about 1 μm or more, about 2 μm or more. Also, the thickness of the adhesive layer 54 is, for example, about 10 μm or less, about 5 μm or less. Regarding the preferable range of the thickness of the adhesive layer 54, examples include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0103] [Coloring layer] The coloring layer is a layer provided between the base material layer 51 and the barrier layer 52 as needed (omitted in the illustration). When having the adhesive layer 54, the coloring layer may be provided between the base material layer 51 and the adhesive layer 54, and between the adhesive layer 54 and the barrier layer 52. Also, the coloring layer may be provided outside the base material layer 51. By providing the coloring layer, the exterior film can be colored.

[0104] The coloring layer can be formed, for example, by applying ink containing a colorant to the surface of the base material layer 51 or the surface of the barrier layer 52. As the colorant, known ones such as pigments and dyes can be used. Also, only one type of colorant may be used, or two or more types may be mixed and used.

[0105] Specific examples of the colorant contained in the coloring layer are the same as those exemplified in the column of [adhesive layer 54].

[0106] [Barrier layer 52] In the exterior film, the barrier layer 52 is a layer that at least suppresses the intrusion of moisture.

[0107] Examples of the barrier layer 52 include a metal foil having barrier properties, a vapor deposition film, and a resin layer. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, and a carbon-containing inorganic oxide vapor deposition film. Examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, and polymers mainly composed of fluoroalkyl units, and ethylene vinyl alcohol copolymers. Further, examples of the barrier layer 52 include a resin film provided with at least one of these vapor deposition films and resin layers. A plurality of barrier layers 52 may be provided. The barrier layer 52 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum, aluminum alloy, titanium, titanium alloy, steel (including stainless steel), copper, copper alloy, nickel, nickel alloy, magnesium, magnesium alloy, niobium, and iron. Among these, aluminum alloy, stainless steel, titanium steel, and steel sheets are preferable. When used as a metal foil, it preferably includes at least one of an aluminum alloy foil and a stainless steel foil.

[0108] In the barrier layer 52, the layer made of the above-described metal material may contain a recycled material of the metal material. Examples of the recycled material of the metal material include recycled materials of aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can be obtained by known methods respectively. The recycled material of aluminum alloy can be obtained, for example, by the production method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed only of recycled materials or may be composed of a mixed material of recycled materials and virgin materials. The recycled material of the metal material refers to a metal material that has been recovered, isolated, refined, etc. from various products used in the market, waste from the manufacturing process, etc. and made reusable. The virgin material of the metal material refers to a new metal material refined from natural resources (raw materials) of the metal and not a recycled material.

[0109] From the viewpoint of improving the followability when winding the exterior film around the electrode body, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the followability, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the content of iron is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the content of iron is 0.1% by mass or more, an exterior film having more excellent followability can be obtained. When the content of iron is 9.0% by mass or less, an exterior film having more excellent flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having a composition defined by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Also, silicon, magnesium, copper, manganese, etc. may be added as necessary. The softening can be performed by annealing or the like.

[0110] From the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil composed of, for example, a work-hardened aluminum alloy or the like. As the hard aluminum alloy foil, for example, aluminum alloy foils having compositions defined by JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14 can be mentioned. From the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil is preferably an aluminum alloy foil containing magnesium. In the aluminum alloy foil containing magnesium (100% by mass), the content of magnesium is preferably 0.2 to 5.6% by mass, and more preferably 0.2 to 3.0% by mass. As the aluminum alloy foil containing magnesium, for example, aluminum alloy foils having compositions defined by JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JISH4000:2017 A5052P-O can be mentioned. Further, from the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil may preferably be an aluminum alloy foil containing manganese. In the aluminum alloy foil containing manganese (100% by mass), the content of manganese is preferably 0.3 to 1.5% by mass, and more preferably 1.0 to 1.5% by mass. As the aluminum alloy foil containing manganese, for example, aluminum alloy foils having compositions defined by JIS H4000:2017 A3003P-O, JIS H4000:2017 A3103P-O, JISH4000:2017 A3004P-O, and JISH4000:2017 A3104P-O can be mentioned.

[0111] In addition, examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Further, from the viewpoint of providing an outer film with excellent followability, the stainless steel foil is preferably composed of austenitic stainless steel.

[0112] Specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

[0113] In the case of a metal foil, the thickness of the barrier layer 52 only needs to function as a barrier layer that at least suppresses the ingress of moisture, and for example, it can be about 9 to 200 μm. The thickness of the barrier layer 52 is preferably about 200 μm or less, more preferably about 150 μm or less, still more preferably about 120 μm or less, even more preferably about 100 μm or less, and particularly preferably about 90 μm or less. Also, the thickness of the barrier layer 52 is preferably about 10 μm or more, more preferably about 20 μm or more, and even more preferably about 25 μm or more. Also, the preferable range of the thickness of the barrier layer 52 includes about 9 to 200 μm, about 9 to 150 μm, about 9 to 120 μm, about 9 to 100 μm, about 9 to 90 μm, about 10 to 200 μm, about 10 to 150 μm, about 10 to 120 μm, about 10 to 100 μm, about 10 to 90 μm, about 20 to 200 μm, about 20 to 150 μm, about 20 to 120 μm, about 20 to 100 μm, about 20 to 90 μm, about 25 to 200 μm, about 25 to 150 μm, about 25 to 120 μm, about 25 to 100 μm, about 25 to 90 μm. When the barrier layer 52 is made of an aluminum alloy foil, from the viewpoint of imparting high followability and high rigidity to the outer film 50, the thickness of the barrier layer 52 is preferably about 40 μm or more, more preferably about 60 μm or more, still more preferably about 70 μm or more, even more preferably about 80 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, still more preferably about 120 μm or less, even more preferably about 100 μm or less, and even more preferably about 90 μm or less. The preferable range includes about 40 to 200 μm, about 40 to 150 μm, about 40 to 120 μm, about 40 to 100 μm, about 40 to 90 μm, about 60 to 200 μm, about 60 to 150 μm, about 60 to 120 μm, about 60 to 100 μm, about 60 to 90 μm, about 70 to 200 μm, about 70 to 150 μm, about 70 to 120 μm, about 70 to 100 μm, about 70 to 90 μm, about 80 to 200 μm, about 80 to 150 μm, about 80 to 120 μm, about 80 to 100 μm, about 80 to 90 μm. By the outer film 50 having high followability, it can contribute to increasing the capacity of the power storage device.In addition, when the storage device has a higher capacity, the weight of the storage device increases. However, by increasing the rigidity of the outer film 50, it is possible to contribute to the high sealing performance of the storage device. In particular, when the barrier layer 52 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 80 μm or less, more preferably about 70 μm or less, still more preferably about 65 μm or less, still more preferably about 60 μm or less, and particularly preferably about 50 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Also, the preferable range of the thickness of the stainless steel foil includes about 10 to 80 μm, about 10 to 70 μm, about 10 to 65 μm, about 10 to 60 μm, about 10 to 50 μm, about 15 to 80 μm, about 15 to 70 μm, about 15 to 65 μm, about 15 to 60 μm, and about 15 to 50 μm.

[0114] In addition, when the barrier layer 52 is a metal foil, it is preferable to provide a corrosion-resistant film on at least the surface opposite to the base material layer in order to prevent dissolution and corrosion. The barrier layer 52 may be provided with corrosion-resistant films on both sides. Here, the corrosion-resistant film refers to, for example, a hot water conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, or a corrosion prevention treatment of applying a coating agent to the surface of the barrier layer to provide the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant film means a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), etc. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be combined. Also, it can be made into multiple layers instead of just one layer. Furthermore, among these treatments, the hot water conversion treatment and the anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of the chemical conversion treatment. Also, when the barrier layer 52 is provided with a corrosion-resistant film, the barrier layer 52 including the corrosion-resistant film is used.

[0115] The corrosion-resistant film prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base material layer during the molding of the exterior film, and prevents dissolution and corrosion of the surface of the barrier layer due to hydrogen fluoride generated by the reaction of the electrolyte and moisture. In particular, when the barrier layer is an aluminum alloy foil, it prevents dissolution and corrosion of the aluminum oxide present on the surface of the barrier layer, and improves the adhesiveness (wettability) of the surface of the barrier layer, showing the effect of preventing delamination between the base material layer and the barrier layer during heat sealing and preventing delamination between the base material layer and the barrier layer during molding.

[0116] As the corrosion-resistant film formed by chemical conversion treatment, various ones are known, and mainly include corrosion-resistant films containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, chromate treatment, etc. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, dichromic acid chromium, acetylacetate chromium, chromium chloride, potassium sulfate chromium, etc. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, etc. Examples of chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating-type chromate treatment, etc., and coating-type chromate treatment is preferred. This coating-type chromate treatment first degreases at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) by well-known treatment methods such as alkali immersion method, electrolytic cleaning method, acid cleaning method, electrolytic acid cleaning method, acid activation method, etc., and then, on the degreased surface, a treatment liquid mainly composed of metal phosphates such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, zinc (Zn) phosphate, etc. and mixtures of these metal salts, or a treatment liquid mainly composed of non-metal phosphates and mixtures of these non-metal salts, or a treatment liquid composed of a mixture of these and synthetic resin, etc. is applied by well-known coating methods such as roll coating method, gravure printing method, immersion method, etc. and dried. For the treatment liquid, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, etc. can be used, and water is preferred. Examples of the resin component used at this time include polymers such as phenolic resins and acrylic resins, and chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4) can be mentioned. 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 types.The acrylic resin is preferably a derivative such as polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or their sodium salts, ammonium salts, amine salts, etc. Particularly preferred are derivatives of polyacrylic acid such as ammonium salts, sodium salts, or amine salts of polyacrylic acid. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Also, the acrylic resin is preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride, and preferably an ammonium salt, sodium salt, or amine salt of the copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride. The acrylic resin may be used alone or in combination of two or more.

[0117]

Chemical formula

[0118]

Chemical formula

[0119]

Chemical formula

[0120]

Chemical formula

[0121] In 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. Also, R 1 and R 2 each independently represent the same or different hydroxy groups, alkyl groups, or hydroxyalkyl groups. In general formulas (1) to (4), X, R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, and 4-hydroxybutyl group. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. 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, more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating units represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 ). The aminated phenol polymer is used alone or in a mixture of two or more.

[0122] As another example of the corrosion-resistant film, there is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxides sols, anionic polymers, and cationic polymers is applied. The coating agent may further contain phosphoric acid or a phosphate and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of a rare earth element oxide (for example, particles having an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of the rare earth element oxide include cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, etc., and cerium oxide is preferred from the viewpoint of further improving the adhesion. The rare earth element oxide contained in the corrosion-resistant film can be used alone or in combination of two or more. As the liquid dispersion medium of 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, and water is preferred. Examples of the cationic polymer include polyethyleneimine, an ion polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin obtained by graft polymerizing a primary amine onto an acrylic main skeleton, polyallylamine or its derivative, and aminated phenol. Further, as the anionic polymer, poly(meth)acrylic acid or its salt, or a copolymer mainly composed of (meth)acrylic acid or its salt is preferred. Further, it is preferred that the crosslinking agent is at least one selected from the group consisting of a compound having any one of functional groups of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group and a silane coupling agent. Further, it is preferred that the phosphoric acid or the phosphate is a condensed phosphoric acid or a condensed phosphate.

[0123] As an example of the corrosion-resistant film, there is one formed by applying, to the surface of a barrier layer, a material in which fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide and barium sulfate are dispersed in phosphoric acid and performing a baking treatment at 150°C or higher.

[0124] The corrosion-resistant film may, if necessary, have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of the cationic polymer and the anionic polymer include those described above.

[0125] In addition, the analysis of the composition of the corrosion-resistant film can be performed, for example, using time-of-flight secondary ion mass spectrometry.

[0126] The amount of the corrosion-resistant film formed on the surface of the barrier layer 52 in the chemical conversion treatment is not particularly limited. For example, in the case of performing a coating-type chromate treatment, per 1 m 2 of the surface of the barrier layer 52, it is desirable that the chromic acid compound is contained in an amount of, for example, about 0.5 to 50 mg in terms of chromium, preferably about 1.0 to 40 mg; the phosphorus compound is contained in an amount of, for example, about 0.5 to 50 mg in terms of phosphorus, preferably about 1.0 to 40 mg; and the aminated phenol polymer is contained in an amount of, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

[0127] The thickness of the corrosion-resistant film is not particularly limited. From the viewpoints of the cohesion of the film and the adhesion to the barrier layer or the heat-sealable resin layer, it is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation with a transmission electron microscope, or a combination of observation with a transmission electron microscope and energy-dispersive X-ray spectroscopy or electron energy loss spectroscopy. By analyzing the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry, for example, peaks derived from secondary ions composed of Ce, P, and O (for example, at least one of Ce2PO4 + and CePO4 - etc.) and secondary ions composed of, for example, Cr, P, and O (for example, at least one of CrPO2 + and CrPO4 - etc.) are detected.

[0128] The chemical conversion treatment is carried out by applying a solution containing a compound used for forming a corrosion-resistant film onto the surface of the barrier layer by means such as the bar coating method, roll coating method, gravure coating method, dipping method, etc., and then heating the barrier layer so that its temperature becomes about 70 to 200 °C. Further, before applying the chemical conversion treatment to the barrier layer, the barrier layer may be preliminarily subjected to a degreasing treatment by means such as the alkali dipping method, electrolytic cleaning method, acid cleaning method, electrolytic acid cleaning method, etc. By carrying out such a degreasing treatment, it becomes possible to carry out the chemical conversion treatment on the surface of the barrier layer more efficiently. Also, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for the degreasing treatment, it is possible to form not only a degreasing effect on the metal foil but also a fluoride of a passive metal. In such a case, only the degreasing treatment may be carried out.

[0129] [Heat-sealable resin layer 53] In the exterior film of the present disclosure, the heat-sealable resin layer 53 corresponds to the innermost layer and is a layer (sealant layer) that exhibits a function of heat-sealing during the assembly of the power storage device to seal the electrode body 20.

[0130] The resin constituting the heat-sealable resin layer 53 is not particularly limited as long as it is heat-sealable, but resins containing a polyolefin backbone such as polyolefin and acid-modified polyolefin are preferred. Whether the resin constituting the heat-sealable resin layer 53 contains a polyolefin backbone can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, etc. Also, when the resin constituting the heat-sealable resin layer 53 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, peaks derived from maleic anhydride are detected in the vicinity of a wave number of 1760 cm -1 and in the vicinity of a wave number of 1780 cm -1 When the heat-sealable resin layer 53 is a layer composed of maleic anhydride-modified polyolefin, peaks derived from maleic anhydride are 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.

[0131] The heat-sealing resin layer 53 preferably contains a resin containing a polyolefin backbone as a main component, more preferably contains a polyolefin as a main component, and even more preferably contains polypropylene as a main component. Here, the main component means that among the resin components contained in the heat-sealing resin layer 53, the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component. For example, when the heat-sealing resin layer 53 contains polypropylene as a main component, it means that among the resin components contained in the heat-sealing resin layer 53, the content rate of polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0132] Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), and random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and terpolymers of ethylene-butene-propylene. Among these, polypropylene is preferred. The polyolefin resin in the case of being a copolymer may be a block copolymer or a random copolymer. These polyolefin-based resins may be used alone or in combination of two or more.

[0133] In addition, the polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. 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.

[0134] In addition, the polyolefin may be an acid-modified polyolefin. The acid-modified polyolefin is a polymer obtained by block polymerization or graft polymerization of a polyolefin with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefin, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above-mentioned polyolefin, or a polymer such as a crosslinked polyolefin can also be used. 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.

[0135] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing them with an acid component, or by block polymerization or graft polymerization of an acid component with respect to the cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Also, the acid component used for acid modification is the same as the acid component used for the modification of the above-mentioned polyolefin.

[0136] 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.

[0137] The heat-sealable resin layer 53 may be formed of a single resin alone, or may be formed of a blend polymer combining two or more resins. Further, the heat-sealable resin layer 53 may be formed of only one layer, but may also be formed of two or more layers with the same or different resins.

[0138] When manufacturing the exterior film 50 of the present disclosure by laminating the heat-sealable resin layer 53 with the barrier layer 52, the adhesive layer 55, etc., a pre-formed resin film may be used as the heat-sealable resin layer 53. Further, the heat-sealable resin forming the heat-sealable resin layer 53 may be formed into a film on the surface of the barrier layer 52, the adhesive layer 55, etc. by extrusion molding, coating, etc., to form the heat-sealable resin layer 53 formed of a resin film.

[0139] Also, the heat-sealable resin layer 53 may contain a lubricant or the like as necessary. When the heat-sealable resin layer 53 contains a lubricant, the followability when winding the exterior film around the electrode body can be enhanced. The lubricant is not particularly limited, and known lubricants can be used.

[0140] The lubricant is not particularly limited, but preferably includes amide-based lubricants. Specific examples of the lubricant include those exemplified in the base material layer 51. The lubricant may be used alone or in combination of two or more, and it is preferable to use a combination of two or more.

[0141] In the present disclosure, from the viewpoint of enhancing the followability when the exterior film is wound around the electrode body, it is preferable that a lubricant is present on at least one of the surface and the inside of the heat-sealable resin layer 53. The lubricant is not particularly limited, but preferably an amide-based lubricant. Specific examples of the amide-based lubricant include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of the unsaturated fatty acid amide include oleic acid amide, erucic acid amide, and the like. Specific examples of the substituted amide 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. Specific examples of the methylol amide include methylol stearic acid amide, and the like. Specific examples of the saturated fatty acid bisamide include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic 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 the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, and the like. Specific examples of the fatty acid ester amide include stearamide ethyl stearate, and the like. Specific examples of the aromatic bisamide include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, and the like.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0142] When the lubricant is present on the surface of the heat-sealable resin layer 53, its amount of presence is not particularly limited. However, from the viewpoint of enhancing the followability of the outer packaging film, it is preferably about 1 mg / m 2 or more, more preferably about 3 mg / m 2 or more, still more preferably about 5 mg / m 2 or more, still more preferably about 10 mg / m 2 or more, still more preferably about 15 mg / m 2 or more, and preferably about 50 mg / m 2 or less, more preferably about 40 mg / m 2 or less. The preferable range is about 1 to 50 mg / m 2 level, about 1 to 40 mg / m 2 level, about 3 to 50 mg / m 2 level, about 3 to 40 mg / m 2 level, about 5 to 50 mg / m 2 level, about 5 to 40 mg / m 2 level, about 10 to 50 mg / m 2 level, about 10 to 40 mg / m 2 level, about 15 to 50 mg / m 2 level, about 15 to 40 mg / m 2 level, etc.

[0143] When a lubricant is present inside the heat-sealing resin layer 53, its amount of presence is not particularly limited. However, from the perspective of enhancing the followability of the exterior film, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, still more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. When two or more types of lubricants are present inside the heat-sealing resin layer 53, the above-mentioned lubricant amount is the total lubricant amount. Also, when two or more types of lubricants are present inside the heat-sealing resin layer 53, the amount of presence of the first type of lubricant is not particularly limited. However, from the perspective of enhancing the followability of the exterior film, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, still more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. The amount of presence of the second type of lubricant is not particularly limited. However, from the perspective of enhancing the followability of the exterior film, it is preferably about 50 ppm or more, more preferably about 100 ppm or more, still more preferably about 200 ppm or more, and is preferably about 1500 ppm or less, more preferably about 1000 ppm or less. Preferred ranges include about 50 to 1500 ppm, about 50 to 1000 ppm, about 100 to 1500 ppm, about 100 to 1000 ppm, about 200 to 1500 ppm, and about 200 to 1000 ppm.

[0144] The lubricant present on the surface of the heat-sealing resin layer 53 may be one obtained by exuding the lubricant contained in the resin constituting the heat-sealing resin layer 53, or may be one obtained by applying a lubricant to the surface of the heat-sealing resin layer 53.

[0145] In addition, the thickness of the heat-sealing resin layer 53 is not particularly limited as long as the heat-sealing resin layers can exhibit the function of heat-sealing to seal the electrode body. For example, it is about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 55 described later is 10 μm or more, the thickness of the heat-sealing resin layer 53 is preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer 55 described later is less than 10 μm or when the adhesive layer 55 is not provided, the thickness of the heat-sealing resin layer 53 is preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0146] [Adhesive layer 55] In the exterior film of the present disclosure, the adhesive layer 55 is a layer provided between the barrier layer 52 (or the corrosion-resistant film) and the heat-sealing resin layer 53 as needed to firmly bond them.

[0147] The adhesive layer 55 is formed of a resin capable of bonding the barrier layer 52 and the heat-sealing resin layer 53. As the resin used for forming the adhesive layer 55, for example, the same adhesives as those exemplified in the adhesive layer 54 can be used.

[0148] In addition, from the viewpoint of firmly bonding the adhesive layer 55 and the heat-sealing resin layer 53, the resin used for forming the adhesive layer 55 preferably contains a polyolefin backbone, and examples thereof include the polyolefins, acid-modified polyolefins, cyclic polyolefins, and acid-modified cyclic polyolefins exemplified in the above-mentioned heat-sealing resin layer 53. On the other hand, from the viewpoint of firmly bonding the barrier layer 52 and the adhesive layer 55, the adhesive layer 55 preferably contains an acid-modified polyolefin. Examples of the acid-modifying component include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, anhydrides thereof, acrylic acid, methacrylic acid, etc. Among them, maleic anhydride is most preferred in terms of ease of modification and versatility. Further, from the viewpoint of the heat resistance of the exterior film, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 55 most preferably contains maleic anhydride-modified polypropylene.

[0149] When the resin used for forming the adhesive layer 55 contains a polyolefin backbone, the adhesive layer 55 preferably contains, as a main component, a resin containing a polyolefin backbone, more preferably contains, as a main component, an acid-modified polyolefin, and even more preferably contains, as a main component, an acid-modified polypropylene. Here, the main component means that among the resin components contained in the adhesive layer 55, the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component. For example, when the adhesive layer 55 contains an acid-modified polypropylene as a main component, it means that among the resin components contained in the adhesive layer 55, the content rate of the acid-modified polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0150] Whether the resin constituting the adhesive layer 55 contains a polyolefin backbone can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, etc., and the analysis method is not particularly limited. Also, whether the resin constituting the adhesive layer 55 contains an acid-modified polyolefin, for example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, peaks derived from maleic anhydride are detected at around a wave number of 1760 cm -1 and around a wave number of 1780 cm -1 . However, when the degree of acid modification is low, the peak may become small and not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

[0151] Furthermore, from the viewpoints of durability such as heat resistance and resistance to contents of the exterior film, and ensuring followability while reducing the thickness, it is more preferable that the adhesive layer 55 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Examples of the acid-modified polyolefin preferably include those described above.

[0152] Also, the adhesive layer 55 is preferably 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, and particularly preferably 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 and a compound having an epoxy group. Further, the adhesive layer 55 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. Examples of the polyester preferably include an ester resin produced by the reaction of an epoxy group and a maleic anhydride group, and an amide ester resin produced by the reaction of an oxazoline group and a maleic anhydride group. When unreacted products of curing agents such as a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin remain in the adhesive layer 55, the presence of the unreacted products can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

[0153] Further, from the viewpoint of further enhancing the adhesion between the barrier layer 52 and the adhesive layer 55, the adhesive layer 55 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocyclic ring, a C=N bond, and a C-O-C bond. Examples of the curing agent having a heterocyclic ring include a curing agent having an oxazoline group and a curing agent having an epoxy group. Examples of the curing agent having a C=N bond include a curing agent having an oxazoline group and a curing agent having an isocyanate group. Examples of the curing agent having a C-O-C bond include a curing agent having an oxazoline group and a curing agent having an epoxy group. Whether the adhesive layer 55 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0154] The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively enhancing the adhesion between the barrier layer 52 and the adhesive layer 55, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), those obtained by polymerizing or nurating these, mixtures thereof, and copolymers with other polymers. Further, adducts, biurets, isocyanurates, etc. are included.

[0155] The content of the compound having an isocyanate group in the adhesive layer 55 is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 55. Thereby, the adhesion between the barrier layer 52 and the adhesive layer 55 can be effectively enhanced.

[0156] The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain, those having an acrylic main chain, and the like. Commercially available products include, for example, the Epocros series manufactured by Nippon Shokubai Co., Ltd.

[0157] The proportion of the compound having an oxazoline group in the adhesive layer 55 is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 55. Thereby, the adhesiveness between the barrier layer 52 and the adhesive layer 55 can be effectively enhanced.

[0158] Examples of the compound having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the epoxy groups present in the molecule, and known epoxy resins can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and even more preferably about 200 to 800. In the present disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) measured under the condition of using polystyrene as a standard sample.

[0159] Specific examples of the epoxy resin include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, and the like. The epoxy resin may be used alone or in combination of two or more.

[0160] In the adhesive layer 55, the proportion of the epoxy resin is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 55. Thereby, the adhesion between the barrier layer 52 and the adhesive layer 55 can be effectively enhanced.

[0161] The polyurethane is not particularly limited, and known polyurethanes can be used. The adhesive layer 55 may be, for example, a cured product of a two-component curable polyurethane.

[0162] In the adhesive layer 55, the proportion of the polyurethane is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 55. Thereby, in an atmosphere where there are components that induce corrosion of the barrier layer such as an electrolytic solution, the adhesion between the barrier layer 52 and the adhesive layer 55 can be effectively enhanced.

[0163] When the adhesive layer 55 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 component, 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.

[0164] The adhesive layer 55 may contain a modifier having a carbodiimide group.

[0165] From the perspective of more preferably exerting the effects of the present disclosure, the adhesive layer 55 is preferably formed of a resin composition containing acid-modified polypropylene and an elastomer, and further containing at least one of block polypropylene and homopolypropylene. The resin composition may further contain random polypropylene, polyethylene, etc. Note that from the perspective of enhancing the adhesion and heat resistance with the barrier layer 52, the homopolypropylene is preferably acid-modified (that is, acid-modified homopolypropylene).

[0166] From the perspective of more preferably exerting the effects of the present disclosure, in the resin composition forming the adhesive layer 55, the content of acid-modified polypropylene is preferably about 5% by mass or more, more preferably about 10% by mass or more, still more preferably about 15% by mass or more, and is preferably about 90% by mass or less, more preferably about 80% by mass or less, still more preferably about 70% by mass or less. Preferred ranges include about 5 to 90% by mass, about 5 to 80% by mass, about 5 to 70% by mass, about 10 to 90% by mass, about 10 to 80% by mass, about 10 to 70% by mass, about 15 to 90% by mass, about 15 to 80% by mass, about 15 to 70% by mass, etc.

[0167] From the perspective of more preferably exerting the effects of the present disclosure, in the resin composition forming the adhesive layer 55, the content of the elastomer is preferably about 25% by mass or more, more preferably about 30% by mass or more, still more preferably about 35% by mass or more, and is preferably about 60% by mass or less, more preferably about 55% by mass or less, still more preferably about 50% by mass or less. Preferred ranges include about 25 to 60% by mass, about 25 to 55% by mass, about 25 to 50% by mass, about 30 to 60% by mass, about 30 to 55% by mass, about 30 to 50% by mass, about 35 to 60% by mass, about 35 to 55% by mass, about 35 to 50% by mass, etc.

[0168] From the viewpoint of more preferably exerting the effects of the present disclosure, the elastomer contained in the resin composition forming the adhesive layer 55 is preferably a binary copolymer or a ternary copolymer. Further, the elastomer is preferably a propylene-based elastomer. Examples of the propylene-based elastomer include a binary copolymer, a ternary copolymer, etc. Examples of the binary copolymer include a propylene-ethylene copolymer elastomer, a propylene-butene copolymer elastomer, and examples of the ternary copolymer include a propylene-ethylene-butene copolymer elastomer, an ethylene-propylene-diene copolymer elastomer, etc. Among the elastomers, as the binary copolymer, a propylene-ethylene copolymer elastomer, and as the ternary copolymer, a propylene-ethylene-butene copolymer elastomer are preferable.

[0169] From the viewpoint of more preferably exerting the effects of the present disclosure, in the resin composition forming the adhesive layer 55, the content of block polypropylene is preferably about 30% by mass or more, more preferably about 35% by mass or more, still more preferably about 40% by mass or more, and is preferably about 95% by mass or less, more preferably about 90% by mass or less, still more preferably about 85% by mass or less. Preferable ranges include about 30 to 95% by mass, about 30 to 90% by mass, about 30 to 85% by mass, about 35 to 95% by mass, about 35 to 90% by mass, about 35 to 85% by mass, about 40 to 95% by mass, about 40 to 90% by mass, about 40 to 85% by mass, etc.

[0170] From the perspective of more preferably exerting the effects of the present disclosure, in the resin composition for forming the adhesive layer 55, the content of homopolypropylene is preferably about 20% by mass or more, more preferably about 25% by mass or more, still more preferably about 30% by mass or more, and is preferably about 80% by mass or less, more preferably about 75% by mass or less, still more preferably about 70% by mass or less. Preferred ranges include about 20 to 80% by mass, about 20 to 75% by mass, about 20 to 70% by mass, about 25 to 80% by mass, about 25 to 75% by mass, about 25 to 70% by mass, about 30 to 80% by mass, about 30 to 75% by mass, about 30 to 70% by mass, etc.

[0171] From the perspective of more preferably exerting the effects of the present disclosure, in the resin composition for forming the adhesive layer 55, the content of random polypropylene is preferably about 0% by mass or more, more preferably about 1% by mass or more, still more preferably about 2% by mass or more, and is preferably about 30% by mass or less, more preferably about 25% by mass or less, still more preferably about 20% by mass or less. Preferred ranges include about 0 to 30% by mass, about 0 to 25% by mass, about 0 to 20% by mass, about 1 to 30% by mass, about 1 to 25% by mass, about 1 to 20% by mass, about 2 to 30% by mass, about 2 to 25% by mass, about 2 to 20% by mass, etc.

[0172] From the perspective of more preferably exerting the effects of the present disclosure, in the resin composition for forming the adhesive layer 55, the content of polyethylene is, for example, about 0% by mass or more, preferably about 1% by mass or more, more preferably about 2% by mass or more, still more preferably about 3% by mass or more, and is preferably about 30% by mass or less, more preferably about 25% by mass or less, still more preferably about 20% by mass or less. Preferred ranges include about 0 to 30% by mass, about 0 to 25% by mass, about 0 to 20% by mass, about 1 to 30% by mass, about 1 to 25% by mass, about 1 to 20% by mass, about 2 to 30% by mass, about 2 to 25% by mass, about 2 to 20% by mass, about 3 to 30% by mass, about 3 to 25% by mass, about 3 to 20% by mass, etc.

[0173] From the perspective of more preferably exerting the effects of the present disclosure, specific compositions of the resin composition include, for example, the content of acid-modified polypropylene is about 5% by mass or more (more preferably about 10% by mass or more, still more preferably about 15% by mass or more), and preferably about 90% by mass or less, more preferably about 80% by mass or less, still more preferably about 70% by mass or less. Preferred ranges include about 5 to 90% by mass, about 5 to 80% by mass, about 5 to 70% by mass, about 10 to 90% by mass, about 10 to 80% by mass, about 10 to 70% by mass, about 15 to 90% by mass, about 15 to 80% by mass, about 15 to 70% by mass, etc.; the content of the elastomer is about 25% by mass or more (more preferably about 30% by mass or more, still more preferably about 35% by mass or more), and preferably about 60% by mass or less, more preferably about 55% by mass or less, still more preferably about 50% by mass or less. Preferred ranges include about 25 to 60% by mass, about 25 to 55% by mass, about 25 to 50% by mass, about 30 to 60% by mass, about 30 to 55% by mass, about 30 to 50% by mass, about 35 to 60% by mass, about 35 to 55% by mass, about 35 to 50% by mass, etc.; the content of block polypropylene is about 30% by mass or more (more preferably about 35% by mass or more, still more preferably about 40% by mass or more), and preferably about 95% by mass or less, more preferably about 90% by mass or less, still more preferably about 85% by mass or less.Preferred ranges are about 30 to 95% by mass, about 30 to 90% by mass, about 30 to 85% by mass, about 35 to 95% by mass, about 35 to 90% by mass, about 35 to 85% by mass, about 40 to 95% by mass, about 40 to 90% by mass, about 40 to 85% by mass, etc. The content of homopolypropylene is about 20% by mass or more (more preferably about 25% by mass or more, still more preferably about 30% by mass or more), and preferably about 80% by mass or less, more preferably about 75% by mass or less, still more preferably about 70% by mass or less. Preferred ranges are about 20 to 80% by mass, about 20 to 75% by mass, about 20 to 70% by mass, about 25 to 80% by mass, about 25 to 75% by mass, about 25 to 70% by mass, about 30 to 80% by mass, about 30 to 75% by mass, about 30 to 70% by mass, etc. The content of random polypropylene is about 0% by mass or more (more preferably about 1% by mass or more, still more preferably about 2% by mass or more), and preferably about 30% by mass or less, more preferably about 25% by mass or less, still more preferably about 20% by mass or less. Preferred ranges are about 0 to 30% by mass, about 0 to 25% by mass, about 0 to 20% by mass, about 1 to 30% by mass, about 1 to 25% by mass, about 1 to 20% by mass, about 2 to 30% by mass, about 2 to 25% by mass, about 2 to 20% by mass, etc. The content of polyethylene is, for example, about 0% by mass or more (preferably about 1% by mass or more, more preferably about 2% by mass or more, still more preferably about 3% by mass or more), and preferably about 30% by mass or less, more preferably about 25% by mass or less, still more preferably about 20% by mass or less. Preferred ranges are about 0 to 30% by mass, about 0 to 25% by mass, about 0 to 20% by mass, about 1 to 30% by mass, about 1 to 25% by mass, about 1 to 20% by mass, about 2 to 30% by mass, about 2 to 25% by mass, about 2 to 20% by mass, about 3 to 30% by mass, about 3 to 25% by mass, about 3 to 20% by mass, etc. The resin composition is preferably formed of a resin composition containing acid-modified polypropylene and an elastomer, and further containing at least one of block polypropylene and homopolypropylene (excluding additives such as lubricants described later).

[0174] When manufacturing the exterior film 50 of the present disclosure by laminating the adhesive layer 55 with the barrier layer 52, the heat-sealable resin layer 53, etc., a resin film formed in advance may be used as the adhesive layer 55. Further, the heat-sealable resin forming the adhesive layer 55 may be formed into a film on the surface of the barrier layer 52, the heat-sealable resin layer 53, etc. by extrusion molding, coating, etc., to form the adhesive layer 55 formed by the resin film.

[0175] The thickness of the adhesive layer 55 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, about 5 μm or less. Further, the thickness of the adhesive layer 55 is preferably about 0.1 μm or more, about 0.5 μm or more. Further, as the range of the thickness of the adhesive layer 55, preferably, it is about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified by the adhesive layer 54 or the cured product of an acid-modified polyolefin and a curing agent, preferably it is about 1 to 10 μm, more preferably about 1 to 5 μm. Further, in the case of using the resin exemplified by the heat-sealable resin layer 53, preferably it is about 2 to 50 μm, more preferably about 10 to 40 μm. In the case where the adhesive layer 55 is the adhesive exemplified by the adhesive layer 54 or the cured product of a resin composition containing an acid-modified polyolefin and a curing agent, for example, the adhesive layer 55 can be formed by applying the resin composition and curing it by heating or the like. Further, in the case of using the resin exemplified by the heat-sealable resin layer 53, for example, it can be formed by extrusion molding of the heat-sealable resin layer 53 and the adhesive layer 55.

[0176] [Surface coating layer] The exterior film of the present disclosure may be provided with a surface coating layer, as needed, on the barrier layer 52, and / or, as needed, on the substrate layer 51 (on the side opposite to the barrier layer 52 of the substrate layer 51), etc., for the purpose of improving at least one of design, electrolytic solution resistance, scratch resistance, followability, etc. The surface coating layer is a layer located on the outermost layer side of the exterior film when an electrical storage device is assembled using the exterior film.

[0177] Examples of the surface coating layer include resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. Further, copolymers of these resins, modified products of copolymers, or mixtures of these resins may also be used. The resin is preferably a curable resin. That is, the surface coating layer is preferably composed of a cured product of a resin composition containing a curable resin.

[0178] When the resin forming the surface coating layer is a curable resin, the resin may be either a one-component curable type or a two-component curable type, but preferably a two-component curable type. Examples of the two-component curable type resin include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0179] Examples of two-component curable polyurethanes include polyurethanes containing a first component containing a polyol compound and a second component containing an isocyanate compound. Preferably, polyurethanes are those in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as the first component and an aromatic or aliphatic polyisocyanate is used as the second component. Examples of polyurethanes also include polyurethanes containing a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and an isocyanate compound. Examples of polyurethanes also include polyurethanes containing a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and a polyol compound. Examples of polyurethanes also include polyurethanes cured by reacting a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound with moisture in the air or the like. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group not only at the terminal of the repeating unit but also in the side chain. Examples of the second component include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of the 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 derived from one or more of these diisocyanates. In addition, a multimer (for example, a trimer) can also be used as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. Note that an aliphatic isocyanate compound refers to an isocyanate having an aliphatic group and no aromatic ring, an alicyclic isocyanate compound refers to an isocyanate having an alicyclic hydrocarbon group, and an aromatic isocyanate compound refers to an isocyanate having an aromatic ring.The surface coating layer is formed of polyurethane, thereby imparting excellent electrolyte resistance to the exterior film.

[0180] The surface coating layer may contain additives such as lubricants, flame retardants, anti-blocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents, as necessary, depending on the functionality to be provided on the surface and inside of the surface coating layer and its surface. Examples of the additives include fine particles having an average particle diameter of about 0.5 nm to 5 μm. The average particle diameter of the additives is the median diameter measured by a laser diffraction / scattering particle size distribution measuring device.

[0181] The additives may be either inorganic or organic. Also, the shape of the additives is not particularly limited, and examples include spherical, fibrous, plate-like, amorphous, and scaly shapes.

[0182] Specific examples of the 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, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, etc. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferably mentioned from the viewpoints of dispersion stability and cost. Also, mica is preferably mentioned from the viewpoint of heat dissipation from the power storage device. Further, various surface treatments such as insulation treatment and high dispersibility treatment may be performed on the surface of the additives.

[0183] The method for forming the surface coating layer is not particularly limited. For example, a method of applying a resin for forming the surface coating layer can be mentioned. When an additive is blended in the surface coating layer, a resin mixed with the additive may be applied.

[0184] In the present disclosure, from the viewpoint of improving the followability when the exterior film is wound around the electrode body, it is preferable that a lubricant is present on at least one of the surface and the interior of the surface coating layer. The lubricant is not particularly limited, but preferably an amide-based lubricant. Specific examples of the amide-based lubricant include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the 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 the unsaturated fatty acid amides include oleic acid amide, erucic acid amide, and the like. Specific examples of the 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. Further, specific examples of the methylol amides include methylol stearic acid amide, and the like. Specific examples of the saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic 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 the unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, and the like. Specific examples of the fatty acid ester amides include stearoamide ethyl stearate, and the like. Further, specific examples of the aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, and the like.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0185] When the lubricant is present on the surface of the surface coating layer, the amount thereof is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Also, as the amount of the lubricant present on the surface of the surface coating layer, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Also, the preferable range of the amount of the lubricant present on the surface of the surface coating layer is about 3 to 15 mg / m 2 level, about 3 to 14 mg / m 2 level, about 3 to 10 mg / m 2 level, about 4 to 15 mg / m 2 level, about 4 to 14 mg / m 2 level, about 4 to 10 mg / m 2 level, about 5 to 15 mg / m 2 level, about 5 to 14 mg / m 2 level, about 5 to 10 mg / m 2 level.

[0186] The lubricant present on the surface of the surface coating layer may be one obtained by exuding the lubricant contained in the resin constituting the surface coating layer, or may be one obtained by applying the lubricant to the surface of the surface coating layer.

[0187] The thickness of the surface coating layer is not particularly limited as long as the above functions as the surface coating layer are exhibited. For example, it is about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0188] <2-3. Method for manufacturing exterior film> The method for manufacturing the exterior film is not particularly limited as long as a laminate in which each layer included in the exterior film of the present disclosure is laminated can be obtained. For example, a method including a step of laminating at least the barrier layer 52 and the heat-sealable resin layer 53 can be mentioned.

[0189] As an example of the method for manufacturing the exterior film of the present disclosure, it is as follows. First, a laminate (hereinafter, may also be referred to as "laminate A") in which a base material layer 51, an adhesive layer 54, and a barrier layer 52 are laminated in this order is formed. Specifically, the formation of laminate A is carried out by applying, by a coating method such as a gravure coating method or a roll coating method, an adhesive used for forming the adhesive layer 54 onto the base material layer 51 or, if necessary, the barrier layer 52 whose surface has been chemical conversion-treated, drying it, and then laminating the barrier layer 52 or the base material layer 51 to cure the adhesive layer 54 by a dry lamination method.

[0190] Next, a heat-sealable resin layer 53 is laminated on the barrier layer 52 of the laminate A. When the heat-sealable resin layer 53 is directly laminated on the barrier layer 52, it may be laminated on the barrier layer 52 of the laminate A by a method such as a thermal lamination method or an extrusion lamination method. When an adhesive layer 55 is provided between the barrier layer 52 and the heat-sealable resin layer 53, the adhesive layer 55 and the heat-sealable resin layer 53 can be laminated, for example, by (1) an extrusion lamination method, (2) a thermal lamination method, (3) a sandwich lamination method, (4) a dry lamination method, etc. (1) As the extrusion lamination method, for example, there is a method of laminating by extruding the adhesive layer 55 and the heat-sealable resin layer 53 on the barrier layer 52 of the laminate A (co-extrusion lamination method, tandem lamination method), etc. Also, (2) As the thermal lamination method, for example, a method of separately forming a laminate in which the adhesive layer 55 and the heat-sealable resin layer 53 are laminated and laminating this on the barrier layer 52 of the laminate A, or forming a laminate in which the adhesive layer 55 is laminated on the barrier layer 52 of the laminate A and laminating this with the heat-sealable resin layer 53, etc. are mentioned. Also, (3) As the sandwich lamination method, for example, a method of laminating the laminate A and the heat-sealable resin layer 53 via the adhesive layer 55 while pouring the melted adhesive layer 55 between the barrier layer 52 of the laminate A and the heat-sealable resin layer 53 previously formed in a sheet shape, etc. are mentioned. Also, (4) As the dry lamination method, for example, a method of solution coating and drying an adhesive for forming the adhesive layer 55 on the barrier layer 52 of the laminate A, or further baking, etc. for lamination, and laminating the heat-sealable resin layer 53 previously formed in a sheet shape on this adhesive layer 55, etc. are mentioned.

[0191] When providing a surface coating layer, the surface coating layer is laminated on the surface of the base material layer 51 opposite to the barrier layer 52. The surface coating layer can be formed, for example, by applying the above-mentioned resin for forming the surface coating layer to the surface of the base material layer 51. Note that the order of the step of laminating the barrier layer 52 on the surface of the base material layer 51 and the step of laminating the surface coating layer on the surface of the base material layer 51 is not particularly limited. For example, after forming the surface coating layer on the surface of the base material layer 51, the barrier layer 52 may be formed on the surface of the base material layer 51 opposite to the surface coating layer.

[0192] As described above, a laminate including a surface coating layer provided as necessary / a base material layer 51 provided as necessary / an adhesive layer 54 provided as necessary / a barrier layer 52 / an adhesive layer 55 provided as necessary / a heat-fusible resin layer 53 is formed in this order. However, in order to strengthen the adhesiveness of the adhesive layer 54 and the adhesive layer 55 provided as necessary, it may be further subjected to a heat treatment.

[0193] In the exterior film, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, ozone treatment, etc. as necessary to improve the processability. For example, by performing corona treatment on the surface of the base material layer 51 opposite to the barrier layer 52, the printability of ink on the surface of the base material layer 51 can be improved.

[0194] <3-1. Laminated Structure and Physical Properties of Exterior Material for Power Storage Device> The exterior material 50 for a power storage device of the present disclosure corresponds to the above-described exterior film 50, and is common for each layer. That is, in the laminate constituting the exterior material 50 for a power storage device of the present disclosure, the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, the heat-fusible resin layer 4, and the surface coating layer 6 respectively correspond to the base material layer 51, the adhesive layer 54, the barrier layer 52, the adhesive layer 55, the heat-fusible resin layer 53, and the surface coating layer of the laminate constituting the above-described exterior film 50.

[0195] The exterior material 50 for a power storage device of the present disclosure is also composed of a laminate including a barrier layer 3 and a heat-sealable resin layer 4, for example, as shown in FIG. 5. In the exterior material 50 for a power storage device, the barrier layer 3 is on the outermost layer side, and the heat-sealable resin layer 4 is on the innermost layer. For example, as shown in FIGS. 10 and 11, when assembling a power storage device using the exterior material 50 for a power storage device and power storage device elements (such as the electrode body 20 and the electrode terminal 30), the electrode body 20 is accommodated in a space formed by heat-sealing the ends of the heat-sealable resin layers 4 of the exterior material 50 for a power storage device in a state where they face each other together with the lid body 60. In the laminate constituting the exterior material 50 for a power storage device of the present disclosure, with the barrier layer 3 as a reference, the side of the heat-sealable resin layer 4 is the inner side with respect to the barrier layer 3, and the opposite side is the outer side.

[0196] The exterior material 50 for a power storage device may have a base material layer 1 outside the barrier layer 3, for example, as shown in FIGS. 5 to 8. Further, the exterior material 50 for a power storage device may have an adhesive layer 2 between the base material layer 1 and the barrier layer 3, for example, as shown in FIGS. 6 to 8, for the purpose of enhancing the adhesiveness between these layers. Further, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-sealable resin layer 4, for example, as shown in FIGS. 7 and 8, for the purpose of enhancing the adhesiveness between these layers. Further, a surface coating layer 6 or the like may be provided outside the base material layer 1 (the side opposite to the heat-sealable resin layer 4), for example, as shown in FIG. 8.

[0197] The thickness of the laminate constituting the exterior material 50 for the power storage device is not particularly limited. However, from the viewpoints of cost reduction, improvement of energy density, etc., for example, it is about 250 μm or less, preferably about 190 μm or less, about 180 μm or less, about 155 μm or less, about 120 μm or less. Also, from the viewpoint of maintaining the function of the exterior material for the power storage device of protecting the electrode body 20, the thickness of the laminate constituting the exterior material 50 for the power storage device is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more. Further, regarding the preferable range of the laminate constituting the exterior material 50 for the power storage device, for example, about 35 to 250 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 250 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 250 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm can be mentioned. Particularly, when making the power storage device lightweight and thin-film, about 60 to 155 μm is preferable, and when improving followability, about 155 to 190 μm is preferable.

[0198] In the exterior material 50 for a power storage device, the ratio of the total thickness of the base material layer 1 provided as necessary, the adhesive layer 2 provided as necessary, the barrier layer 3, the adhesive layer 5 provided as necessary, the heat-fusible resin layer 4, and the surface coating layer 6 provided as necessary to the thickness (total thickness) of the laminate constituting the exterior material 50 for a power storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the exterior material 50 for a power storage device of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 50 for a power storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, even when the exterior material 50 for a power storage device of the present disclosure is a laminate including the base material layer 1, the adhesive layer 2, the barrier layer 3, and the heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the exterior material 50 for a power storage device can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0199] From the viewpoint of more suitably exhibiting the effects of the invention of the present disclosure, the Young's modulus of the exterior material 50 for a power storage device is preferably 6000 MPa or more, more preferably 8000 MPa or more, and even more preferably 10000 MPa or more. Also, it is preferably 40000 MPa or less, more preferably 35000 MPa or less, and even more preferably 30000 MPa or less. Preferred ranges include about 6000 to 40000 MPa, about 6000 to 35000 MPa, about 6000 to 30000 MPa, about 8000 to 40000 MPa, about 8000 to 35000 MPa, about 8000 to 30000 MPa, about 10000 to 40000 MPa, about 10000 to 35000 MPa, and about 10000 to 30000 MPa. In the present disclosure, the Young's modulus of the exterior material for a power storage device is a value measured by the following method.

[0200] <Measurement of Young's Modulus of Exterior Material for Power Storage Device> In accordance with the provisions of JIS K6251:2017, the S-S curve in the TD direction of the adhesive film was obtained under the following measurement conditions, and the Young's modulus (MPa) was calculated from the maximum value of the slope of the S-S curve. (Measurement conditions) Use a tensile testing machine. Shape of test piece: dumbbell No. 7 Width of test piece: 2 mm Length of test piece: 35 mm Thickness of test piece: Measure with a thickness gauge Distance between gauge marks: 20 mm Tensile speed: 50 mm / min Test environment: 23 ± 5°C, 50 ± 30% RH Number of measurements: Average value of 3 times

[0201] As a method for increasing the Young's modulus of the exterior material 50 for a power storage device, as described for the exterior film 50, it is effective to increase the Young's modulus of the barrier layer 3.

[0202] <3-2. Each layer constituting the exterior material for a power storage device> As described above, in the laminate constituting the exterior material 50 for a power storage device of the present disclosure, the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, the heat-sealable resin layer 4, and the surface coating layer 6 respectively correspond to the base material layer 51, the adhesive layer 54, the barrier layer 52, the adhesive layer 55, the heat-sealable resin layer 53, and the surface coating layer of the laminate constituting the exterior film 50 described above. Therefore, the descriptions of the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, the heat-sealable resin layer 4, and the surface coating layer 6 are common to the descriptions of the base material layer 51, the adhesive layer 54, the barrier layer 52, the adhesive layer 55, the heat-sealable resin layer 53, and the surface coating layer of the laminate constituting the exterior film 50 described above, and duplicate descriptions are omitted.

[0203] In the exterior material for a power storage device of the present disclosure, in the barrier layer 3 of the exterior material 50 for a power storage device, the heat-sealable resin layer of the exterior material for a power storage device and a polypropylene plate are heat-sealed under the condition that the thickness of the heat-sealable resin layer is 20% or more and 80% or less. At a position where heat-sealing is performed, in a direction perpendicular to the rolling direction of the barrier layer, for a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer, the area average angular difference of GOS (grain orientation spread) when the grain boundary is defined as 5° is 2.50° or less, which is a characteristic. The polypropylene plate is assumed to be a lid that constitutes the exterior body. The condition that the thickness of the heat-sealable resin layer is 20% or more and 80% or less is adjusted, for example, by setting the temperature during heat-sealing to about 160 to 240°C, the surface pressure to about 0.2 to 1.5 MPa, and the heat-sealing time to about 1 to 12 seconds.

[0204] From the viewpoint of more suitably exhibiting the effects of the invention of the present disclosure, the area average angular difference of the GOS (grain orientation spread) is preferably about 2.50° or less, more preferably about 2.00° or less, still more preferably about 1.50° or less. Also, for example, it is about 0° or more, about 0.20° or more, etc. Preferred ranges include about 0 to 2.50°, about 0 to 2.00°, about 0 to 1.50°, about 0.20 to 2.50°, about 0.20 to 2.00°, about 0.20 to 1.50°, etc.

[0205] The area average angular difference of the GOS (grain orientation spread) of the barrier layer 3 is a value measured by the following method. When obtaining the exterior material for a power storage device from a power storage device (for example, obtaining the exterior material for a power storage device from a power storage device mounted on a used automobile) and measuring the area average angular difference of the GOS (grain orientation spread) of the barrier layer 3, a sample is obtained from a portion where the heat-sealable resin layer of the exterior material for a power storage device is not heat-sealed, and the following measurement is performed.

[0206] <Measurement of the area average angular difference of the GOS (grain orientation spread) of the barrier layer> Regarding a power storage device, a barrier layer at a position where a heat-sealing resin layer of an exterior material for the power storage device and a polypropylene plate (assuming a lid) are heat-sealed under the condition that the thickness of the heat-sealing resin layer is 20% or more and 80% or less is obtained. This heat-sealing condition is set such that the ratio of "(the thickness of the heat-sealing resin layer at the position where the heat-sealing resin layer is heat-sealed to the lid) / (the thickness of the heat-sealing resin layer at the position where the heat-sealing resin layer is not heat-sealed to the lid)" is 20 to 80%. Specifically, the exterior material for the power storage device is cut into a rectangular shape with a size of MD 360 mm × TD 160 mm. On the other hand, as a lid of the exterior body, a polypropylene lid (polypropylene plate) in the shape of a rectangular parallelepiped (length 100 mm × width 30 mm × thickness 5 mm) is prepared. Further, as a simulated electrode body, an aluminum block in the shape of a rectangular parallelepiped (length 140 mm × width 98 mm × thickness 28 mm) is prepared. Next, as shown in the schematic diagram of FIG. 1, lids are arranged on both sides in the length direction of the electrode body, and this is wrapped with the exterior material for the power storage device. The position where the heat-sealing resin layers of the exterior material for the power storage device face each other (the first sealing portion 70) and the position where the heat-sealing resin layer of the exterior material for the power storage device contacts the lid (the second sealing portion 80) are heat-sealed using a heat-sealing bar respectively to obtain a simulated power storage device. Note that the simulated power storage device is not provided with electrode terminals as shown in FIG. 1. The sealing width at the position where the heat-sealing resin layers of the exterior material for the power storage device face each other (the first sealing portion 70) is 10 mm. Also, the sealing width at the position where the heat-sealing resin layer of the exterior material for the power storage device contacts the lid (the second sealing portion 80) is the thickness of the lid (10 mm). Further, the heat-sealing conditions (temperature, surface pressure, time) of the second sealing portion 80 are respectively set under the condition that the thickness of the heat-sealing resin layer is 20% or more and 80% or less. Next, regarding the barrier layer of the obtained simulated power storage device, a barrier layer at the position where the heat-sealing resin layer of the exterior material for the power storage device is heat-sealed to the polypropylene plate (polypropylene lid) (the sealing portion (the second sealing portion)) is obtained, and crystal analysis by the EBSD method is performed to measure the area average angular difference of GOS (grain orientation spread) when the grain boundary of the barrier layer is defined as 5°. The specific measurement method is as follows.

[0207] For the cross-section perpendicular to the rolling direction of each barrier layer, crystal analysis is performed by the EBSD method, and the area average angular difference of GOS (grain orientation spread) is measured when the grain boundaries of the barrier layer are defined as 5°. The details of the measurement conditions are as follows. The area average angular difference of GOS (grain orientation spread) is obtained by connecting a plurality of images acquired by crystal analysis using the EBSD method, and is about 5000 μm 2 It is the area average angular difference of GOS (grain orientation spread) of the crystals included in the measurement region (the entire thickness direction of the barrier layer is defined as the measurement region) of the above measurement.

[0208] (Measuring device) Use a device equipped with an EBSD detector on a Schottky field emission scanning electron microscope.

[0209] (Pretreatment) As a pretreatment, the barrier layer is cut perpendicular to the rolling direction (RD) to obtain a cross-section. The rolling direction of the barrier layer is the direction in which linear rolling marks extend when the glossy surface of the barrier layer is observed with a metallurgical microscope. As a specific procedure, first, the barrier layer to be used as a sample is cut out to 5 mm (perpendicular to the rolling direction) × 10 mm (rolling direction) with a trimming razor, and then embedded in resin. Next, using a trimming razor, the barrier layer is cut together with the resin in a direction perpendicular to the rolling direction of the barrier layer and perpendicular to the surface of the barrier layer to expose the cross-section of the barrier layer. Next, the obtained cross-section is trimmed using a microtome. In this trimming, in order to reduce mechanical distortion of the cross-sectional shape, the microtome is advanced by about 1 mm in a direction perpendicular to the cross-section together with the embedded resin. Next, using an ion milling device, a broad argon beam is irradiated in a direction perpendicular to the cross-section under the conditions of a jump-out width of 50 μm, a voltage of 6 kV, and 4 hours to prepare a measurement cross-section. This is an operation to precisely expose the cross-section of the barrier layer so that mechanical damage to the crystal structure generated in the previous process is minimized. In the present disclosure, since the "perpendicular direction" when cutting the aluminum alloy foil is confirmed under a stereomicroscope, it may include an error of about 10°. That is, the direction perpendicular to the rolling direction allows a range of 80 to 100° with respect to the rolling direction, and the direction perpendicular to the surface allows a range of 80 to 100° with respect to the surface.

[0210] (SEM conditions) The conditions of the scanning electron microscope (SEM) used for the EBSD method are as follows. Observation magnification: 2000 times (the standard observation magnification at the time of photography is Polaroid545) Acceleration voltage: 15 kV Working distance: 15 mm Sample tilt angle: 70°

[0211] (EBSD conditions) The conditions for crystal analysis by the EBSD method are as follows. Step size: 150 nm Analysis conditions: The following analysis is carried out using the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. Connect multiple images, and the measurement area is about 5000 μm 2 The above shall be the case. Regarding the upper limit of the measurement area, for example, it shall be about 30000 μm 2 The following shall be the case. At this time, the measurement area shall be from the center in the thickness direction of the barrier layer to both ends, and the parts where resin adheres to the cross-section and the parts where the acid-resistant film exists shall be excluded from the measurement area. The CI value shall be 0.1 or more, the grain boundary condition shall be 5° or more, and the minimum grain size shall be 3 steps or more. After connecting the images, check the pole figure. If the center of the pole figure is deviated by 10° or more, rotate the crystal data so that the symmetry is adjusted. The reference pole figure at that time is measured from the sample surface by XRD. When obtaining the pole figure from the surface by EBSD, in order to remove the influence of the mechanical crystal structure of the sample surface, after performing mechanical polishing, plane milling, electrolytic polishing, etc. on the sample surface, perform a wide-range measurement. Then, the pole figure obtained from the surface direction is rotated by 90° so that it is the same as that obtained from the same orientation as the pole figure obtained from the cross-section of the target sample. Refer to this pole figure. Perform the analysis by excluding the data with a Confidence Index (CI value) of 0.1 or less defined by the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. Thereby, it is possible to exclude the resin used for the pretreatment existing on the front and back of the sample, the grain boundaries existing in the cross-section, and the data based on amorphous.

[0212] The area average angular difference of the GOS (crystal grain orientation dispersion) of the barrier layer 3 can be adjusted according to the material constituting the barrier layer 3, the thickness of the barrier layer 3, etc.

[0213] For example, by increasing the Young's modulus of the barrier layer 3 (i.e., increasing the Young's modulus of the exterior material 50 for the power storage device), the area average angular difference of the GOS (grain orientation spread) of the barrier layer 3 can be reduced. The preferable Young's modulus of the barrier layer 3 will be described later. For example, increasing the thickness of the barrier layer 3, using a high-strength metal, etc. are effective.

[0214] Also, for example, when the barrier layer 3 is formed of an aluminum alloy foil, if it has an aluminum alloy composition in the 8000 series of JIS standards, the strength can be increased by adding a small amount of Si to the aluminum ingot. Also, if it has an aluminum alloy composition in the 5000 series of JIS standards, the strength of the soft foil can be increased by solid-solution strengthening by dissolving Mg in aluminum.

[0215] Refining the crystal grains of the metal forming the barrier layer 3 is also effective for increasing the above ratio (R1 / R2). For example, in the case of aluminum alloy compositions in the 8000 series and 5000 series of JIS standards, it crystallizes as an Al-Fe-based intermetallic compound during casting, and this becomes the nucleus and the crystal grains are refined. Also, when adopting cross-roll rolling (a method of rolling with rolls having different peripheral speeds), the rolled material undergoes shear deformation throughout the plate thickness in addition to normal rolling deformation. As a result, crystal rotation is promoted and the change from sub-grain boundaries to large-angle grain boundaries is promoted, generating fine crystal grains. This method is effective even in cold working, but the effect is greater in warm working. Furthermore, increasing the number of rolling passes in the hot rolling of the aluminum alloy foil and increasing the final cold rolling ratio are also effective. The higher the final cold rolling ratio from after the intermediate annealing to the final thickness (e.g., 80% or more), the greater the amount of strain accumulated in the aluminum alloy foil and the finer the recrystallized grains after the final annealing.

[0216] Regarding the rolling conditions of the aluminum foil, conditions such as the rolling ratio, heating temperature, and heating time are adjusted. For example, a process of homogenizing an aluminum metal or aluminum alloy ingot at about 500 to 600 °C for about 1 to 2 hours, a hot rolling process, a cold rolling process, an intermediate annealing process of holding at about 300 to 450 °C for about 1 to 10 hours, a cold rolling process in which the rolling ratio from after the intermediate annealing to the final rolling is carried out at 80% or more, more preferably 90% or more, and a final annealing process of holding at about 250 to 400 °C for about 30 to 100 hours are included, but the conditions for refining the crystal grains are not limited to this.

[0217] <3-3. Manufacturing Method of Exterior Material for Power Storage Device> As described above, since the exterior material 50 for a power storage device of the present disclosure corresponds to the exterior film 50, the manufacturing method thereof is also common, and thus the description is omitted.

[0218] <3-4. Use of Exterior Material for Power Storage Device> The exterior material for a power storage device of the present disclosure is used for a package for sealing and housing 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 by the exterior material for a power storage device of the present disclosure to obtain a power storage device. In other words, a power storage device can be obtained by wrapping the power storage device element with the exterior material for a power storage device of the present disclosure.

[0219] For example, a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte is coated with the exterior material for a power storage device of the present disclosure in a state where metal terminals connected to each of the positive electrode and the negative electrode protrude outward, so that a flange portion (a region where heat-sealable resin layers contact each other) can be formed on the periphery of the power storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed and sealed, thereby providing a power storage device using the exterior material for a power storage device. When the power storage device element is accommodated in a package formed by the exterior material for a power storage device of the present disclosure, the heat-sealable resin portion of the exterior material for a power storage device of the present disclosure is made to be the inner side (the surface in contact with the power storage device element) to form the package. The heat-sealable resin layers of two exterior materials for a power storage device may be opposed and overlapped, and the peripheral portion of the overlapped exterior materials for a power storage device may be heat-sealed to form a package. Also, as in the example shown in FIG. 9, one exterior material for a power storage device may be folded back and overlapped, and the peripheral portion may be heat-sealed to form a package. When folding back and overlapping, as in the example shown in FIG. 9, the sides other than the folded-back side may be heat-sealed to form a package by a three-side seal, or may be folded back so that a flange portion can be formed and four-side sealed. When the innermost layer and the outermost layer of the exterior material for a power storage device are heat-sealable resin layers, the package may be formed by heat-sealing the heat-sealable resin layer of the innermost layer and the heat-sealable resin layer of the outermost layer. Also, in addition to the mode in which the surfaces of the exterior material for a power storage device facing each other are heat-sealed, the mode in which the outer surface and the inner surface of the exterior material for a power storage device are heat-sealed is also preferable.

[0220] Further, a recess for accommodating the power storage device element may be formed in the exterior material for a power storage device by deep drawing or protrusion forming. As in the example shown in FIG. 9, one of the exterior materials for a power storage device may be provided with a recess and the other exterior material for a power storage device may not be provided with a recess, or the other exterior material for a power storage device may also be provided with a recess.

[0221] In a power storage device using an exterior body including an exterior material for a power storage device that wraps an electrode body and a lid body, when the power storage device is repeatedly exposed to temperature changes between high and low temperatures, cracking is suppressed from occurring in the sealing portion between the exterior material for the power storage device and the lid body. Therefore, the power storage device element may be sealed by the lid body in addition to the exterior material for the power storage device. That is, the exterior material for the power storage device and the lid body constitute an exterior body (exterior body for the power storage device) that seals the power storage device element. For example, the power storage device element may be housed inside an exterior material for the power storage device configured in a cylindrical shape, and the opening may be closed by the lid body. In another example, the power storage device element in a state connected to the lid body may be housed inside an exterior material for the power storage device configured in a cylindrical shape so that an opening is formed, and the opening may be closed by the lid body. The lid body and the exterior material for the power storage device are preferably joined by any means. From the viewpoint of reducing the dead space between the power storage device element and the exterior material for the power storage device in order to improve the volume energy density of the power storage device, the exterior material for the power storage device is preferably wound around the power storage device element and the lid body. When winding the exterior material for the power storage device around the power storage device element and the lid body, only one exterior material for the power storage device may be wound, or a plurality of exterior materials for the power storage device may be wound.

[0222] As described above, the lid body can be formed of, for example, a resin molded product, a metal molded product, an exterior material for a power storage device, and combinations thereof. In the present disclosure, when the lid body is described as a resin molded product, an aspect in which the lid body is constituted only by a film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. When the lid body is a metal molded product, since the lid body also functions as a metal terminal, the metal terminal can be omitted. The lid body may be configured to include a resin material and a conductive material.

[0223] The following specifically describes the case where the power storage device includes an electrode body and an exterior body that seals the electrode body, and the exterior body has an exterior material for the power storage device that wraps the electrode body and a lid that seals the electrode body together with the exterior material for the power storage device.

[0224] Similar to FIG. 1, FIG. 10 is a perspective view schematically showing the power storage device 10. FIG. 11 is a cross-sectional view taken along the line A-A of FIG. 1. In FIGS. 10 to 12, the arrow z direction (z1 direction and z2 direction) indicates the thickness direction of the power storage device 10, the arrow x direction (x1 direction and x2 direction) indicates the width direction of the power storage device 10, and the arrow y direction (y1 direction and y2 direction) indicates the depth direction of the power storage device 10. The directions indicated by each of the arrows x, y, and z are common in the subsequent figures.

[0225] As described above, the power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes, for example, electrodes (positive electrode and negative electrode) constituting a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid-state battery, a quasi-solid-state battery, a polymer battery, an all-resin battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator and the like. In the present disclosure, the shape of the electrode body 20 is, for example, a substantially rectangular parallelepiped. Note that the "substantially rectangular parallelepiped" includes, in addition to a perfect rectangular parallelepiped, a solid that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0226] Similar to FIGS. 1 and 2, the power storage device 10 in FIGS. 10 and 11 includes two electrode terminals 30. The electrode terminal 30 is a metal terminal used for power input and output in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward, for example, from the edge of the exterior body 40. Note that the electrode terminal 30 only needs to be capable of power input and output of the electrode body 20, and for example, it does not necessarily have to protrude from the exterior body 40. When the lid body 60 described later is made of, for example, a conductive material, the lid body 60 may also serve as the function of the electrode terminal 30. In this case, the lid body 60 having the function as an electrode terminal may or may not protrude from the exterior body 40.

[0227] As described above, the metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, or the like. For example, when the electrode body 20 is a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum or the like, and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, or the like. Note that the outermost layer of the electrode body 20 does not necessarily have to be an electrode, and for example, it may be a protective tape or a separator. The outer shape of the electrode body 20 is, for example, a rectangular parallelepiped.

[0228] As described above, the exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior material 50 for a power storage device and a lid body 60. The exterior material 50 for a power storage device wraps the electrode body 20. Similar to FIGS. 1 and 2, in FIGS. 10 and 11, the exterior material 50 for a power storage device is wound around the electrode body 20. The lid body 60 is disposed on the side of the electrode body 20 in the y direction. In another example, the electrode body 20 may be accommodated inside the exterior material 50 for a power storage device configured in a cylindrical shape such that openings are formed at both ends in the y direction, and the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the lid body 60 may be accommodated inside the exterior material 50 for a power storage device configured in a cylindrical shape such that an opening is formed, and the opening may be closed by the lid body 60.

[0229] As described above, the exterior body 40 has a pair of main surfaces and a pair of side surfaces formed by the exterior material 50 for the power storage device. Similar to FIGS. 1 and 2, in FIGS. 10 and 11, the pair of main surfaces are substantially the same size. Also, the pair of side surfaces are substantially the same size. Each of the pair of main surfaces has a larger area than the pair of side surfaces. The pair of lid bodies 60 are respectively arranged on the sides of the electrode body 20 so as to close the pair of openings. In the present disclosure, the main surface and the side surface are surfaces configured excluding the lid body 60 among the surfaces of the exterior body 40.

[0230] As described above, for example, there is a method of forming a housing portion (depression) for housing the electrode body 20 in the exterior material 50 for the power storage device through cold forming. However, it is not always easy to form a deep housing portion by such a method. If an attempt is made to deeply form the housing portion (depression) (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks are likely to occur in the exterior material 50 for the power storage device, leading to a decrease in battery performance. On the other hand, since the exterior body 40 seals the electrode body 20 by winding the exterior material 50 for the power storage device around the electrode body 20, the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In order to reduce the dead space between the electrode body 20 and the exterior material 50 for the power storage device to improve the volume energy density of the power storage device 10, a state where the exterior material 50 for the power storage device is wound so as to contact the outer surface of the electrode body 20 is preferable. Also, in all-solid-state batteries, from the viewpoint that it is necessary to uniformly apply a high pressure from the outside of the battery to exhibit battery performance, it is necessary to eliminate the space between the electrode body 20 and the exterior material 50 for the power storage device, so a state where the exterior material 50 for the power storage device is wound so as to contact the outer surface of the electrode body 20 is preferable.

[0231] The exterior material 50 for the power storage device is a laminate (laminate film) having at least a barrier layer 3 and a heat-sealable resin layer 4. Details of each layer included in the exterior material 50 for the power storage device are as described above.

[0232] As described above, the lid body 60 may have any shape such as a cylinder, a prism, a cuboid, or a cube, and is, for example, composed of a resin material. Here, "composed of a resin material" means that when the total amount of the material constituting the lid body 60 is 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. That is, the material constituting the lid body 60 can contain materials other than the resin material in addition to the resin material.

[0233] In the lid body 60, specific examples of the resin are as described above.

[0234] Also, as described above, the resin as the resin material may contain a filler as necessary. Specific examples of the filler are as described above.

[0235] As described above, the melt mass flow rate (measurement temperature: 230°C) of the resin material contained in the material constituting the lid body 60 is preferably in the range of 1 g / 10 min to 100 g / 10 min, preferably in the range of 1 g / 10 min to 80 g / 10 min, preferably in the range of 1 g / 10 min to 60 g / 10 min, preferably in the range of 5 g / 10 min to 100 g / 10 min, preferably in the range of 5 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0236] As described above, the lid body 60 may be composed of a conductive material. "Composed of a conductive material" means that when the total amount of the material constituting the lid body 60 is 100% by mass, the content of the conductive material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. That is, the material constituting the lid body 60 can contain materials other than the conductive material in addition to the conductive material.

[0237] As described above, the conductive material constituting the lid body 60 is, for example, a metal material. The metal material constituting the lid body 60 is, for example, aluminum, an aluminum alloy, nickel, copper, or a copper alloy. For example, when the electrode body 20 is a lithium-ion battery, the lid body 60 connected to the positive electrode is preferably composed of aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably composed of nickel, copper, or a copper alloy. The material constituting the lid body 60 connected to the negative electrode may be nickel-plated copper. The material constituting the lid body 60 may include a recycled material of the metal material. When the lid body 60 is composed of a conductive material, since the lid body 60 also functions as the electrode terminal 30, the power storage device 10 can also omit the electrode terminal 30.

[0238] As described above, the lid body 60 may have a configuration in which at least a part of the lid main body 61 is covered by the covering body 62. In the lid body 60 of FIG. 12, the periphery of the lid main body 61 (the periphery of the thick portion) is covered by the covering body 62. The lid body 60 may be joined to the heat-sealable resin layer 4 of the exterior material 50 for the power storage device via the covering body 62. The covering body 62 is preferably composed of a resin material. The lid body 60 has the lid main body 61 and the covering body 62 that joins the lid main body 61 and the exterior material 50 for the power storage device, and the covering body 62 can be configured to include a resin (resin material). The definition of "composed of a resin material" regarding the covering body 62 is the same as that of the lid body 60.

[0239] As described above, when the lid body 60 is composed of a conductive material, the lid main body 61 is composed of a conductive material, and at least a part of the lid main body 61 may be covered by the covering body 62.

[0240] As described above, when the lid body 60 is configured to include a conductive material, the lid body 60 may be joined to the exterior material 50 for the power storage device via an adhesive film instead of the coating. The adhesive film can be arbitrarily selected as long as it can adhere the exterior material 50 for the power storage device and the lid body 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant base material layer, and a heat-sealable resin layer in this order. The specifications regarding the heat-sealable resin layer of the adhesive film can be applied to the specifications regarding the heat-sealable resin layer 4. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same kind of materials or different kinds of materials, and are appropriately selected according to the materials constituting the heat-sealable resin layer 4 of the exterior material 50 for the power storage device and the materials constituting the lid body 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that is adhered to the lid body 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer on the side of the adhesive film that is adhered to the exterior material 50 for the power storage device preferably uses the same kind of material as the material constituting the heat-sealable resin layer 4 of the exterior material 50 for the power storage device.

[0241] As described above, the heat-resistant base material layer may be a film made of a heat-resistant resin. For example, unstretched or stretched films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, and polypropylene can be used. Note that polyethylene terephthalate is inexpensive and has high strength, and is particularly preferable.

[0242] As described above, the adhesive film preferably has adhesiveness. When the second sealing portion 80 described later is formed in a state where the adhesive film is disposed between the exterior material 50 for the power storage device and the lid body 60, the position of the adhesive film with respect to the lid body 60 and the exterior material 50 for the power storage device is less likely to shift. By including an adhesion-imparting resin in the heat-fusible resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the adhesion-imparting resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene, or a copolymer of amorphous propylene and another α-olefin. The content of the adhesion-imparting resin with respect to the base material constituting the heat-fusible resin is preferably 10 to 20% by weight or less.

[0243] As described above, the lid body 60 includes a first main surface located on the inner side (electrode body 20 side) of the power storage device, a second main surface located on the outer side of the power storage device, and four side surfaces that are heat-fused to the heat-fusible resin layer 4 of the exterior material 50 for the power storage device. The first main surface faces the electrode body 20. The second main surface is the surface on the opposite side of the first main surface.

[0244] As described above, when the lid body 60 is a cylinder, a prism, a cuboid, a cube, or the like, even when the power storage devices 10 are stacked, the lid body 60 preferably has a certain thickness in the thickness direction (y direction) so that the exterior body 40 is suppressed from deforming. From another perspective, when the lid body 60 is a cylinder, a prism, a cuboid, a cube, or the like, the lid body 60 preferably has a certain thickness in the thickness direction (y direction) so that the lid joint portion of the lid body 60 and the exterior film 50 can be preferably joined when forming the second sealing portion 80. The minimum value of the thickness of the lid body 60 in the thickness direction (y direction) (the distance in the y direction between the first main surface and the second main surface) is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid body 60 in the y direction is, for example, 20 mm, preferably 15.0 mm, more preferably 10.0 mm, even more preferably 8.0 mm, and even more preferably 7.0 mm. The maximum value of the thickness of the lid body 60 in the y direction may be 10 mm or more. The preferred range of the thickness of the material constituting the lid body 60 is 1.0 mm to 20.0 mm, 1.0 mm to 15.0 mm, 1.0 mm to 10.0 mm, 1.0 mm to 8.0 mm, 1.0 mm to 7.0 mm, 3.0 mm to 20.0 mm, 3.0 mm to 15.0 mm, 3.0 mm to 10.0 mm, 3.0 mm to 8.0 mm, 3.0 mm to 7.0 mm, 4.0 mm to 20.0 mm, 4.0 mm to 15.0 mm, 4.0 mm to 10.0 mm, 4.0 mm to 8.0 mm, 4.0 mm to 7.0 mm. In the present disclosure, when the lid body 60 is described as a cylinder, a prism, a cuboid, a cube, or the like, an aspect in which the lid body 60 is composed of only a film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. Note that the thickness of the lid body 60 may vary depending on the part of the lid body 60. When the thickness of the lid body 60 varies depending on the part, the thickness of the lid body 60 is the thickness of the thickest part.

[0245] Similar to FIGS. 1 and 2, in FIGS. 10 and 11, a through-hole into which the electrode terminal 30 is inserted is formed in the lid body 60. The through-hole penetrates the first main surface and the second main surface of the lid body. In a state where the electrode body 20 is housed, the electrode terminal 30 protrudes outside the exterior body 40 through the through-hole formed in the lid body 60. A slight gap between the through-hole of the lid body 60 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the position where the electrode terminal 30 protrudes outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude outside through a hole formed in any one of the six surfaces of the exterior body 40. In this case, a slight gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. The electrode terminal 30 may protrude from between the lid body 60 and the exterior material 50 for the power storage device, or may protrude from the first sealing portion 70 described later. In the power storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies, but the lid body 60 and the electrode terminal 30 may be integrally formed. In addition, when the electrode terminal 30 does not protrude from the edge of the exterior body 40, the through-hole may not be formed in the lid body 60.

[0246] Similar to FIGS. 1 and 2, in FIGS. 10 and 11, with the exterior material 50 for the power storage device wound around the electrode body 20, the surfaces (heat-sealable resin layers 4) of the exterior material 50 for the power storage device facing each other are heat-sealed to form the first sealing portion 70.

[0247] As described above, the first sealing portion 70 is formed by heat-sealing the heat-fusible resin layers of the exterior material 50 for the power storage device together. The first sealing portion 70 extends in the longitudinal direction of the exterior body 40. In the exterior body 40, the position where the first sealing portion 70 is formed can be arbitrarily selected. Similar to FIG. 1, as shown in FIG. 10, the base of the first sealing portion 70 is preferably located on the edge of the boundary between the main surface and the side surface of the exterior body 40. The base of the first sealing portion 70 may be located on any surface of the exterior body 40. Similar to FIG. 1, in FIG. 10, the first sealing portion 70 protrudes outward beyond the electrode body 20 in plan view. The first sealing portion 70 may be folded, for example, toward the side surface of the exterior body 40 or toward the main surface.

[0248] As described above, the heat-fusible resin layer 4 of the exterior material 50 for the power storage device and the lid joint portion of the lid body 60 (the portion where the heat-fusible resin layer 4 of the exterior material 50 for the power storage device and the lid body 60 are in contact) are joined by, for example, heat-sealing, whereby the second sealing portion 80 is formed. The exterior material 50 for the power storage device and the lid body 60 can be joined by any method such as welding.

[0249] The exterior material for the power storage device of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Further, the exterior material for the power storage device of the present disclosure can be used for either primary batteries or secondary batteries, but is preferably used for secondary batteries. The type of secondary battery to which the exterior material for the power storage device of the present disclosure is applied is not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, semi-solid-state batteries, quasi-solid-state batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are mentioned as suitable application targets for the exterior material for the power storage device of the present disclosure.

Example

[0250] Examples and comparative examples are shown below to explain the present disclosure in detail. However, the present disclosure is not limited to the examples.

[0251] <Method for manufacturing exterior film> Comparative Example 1A As the base material layer, a laminate in which a biaxially stretched polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 15 μm) are adhered with an adhesive layer (formed of a two-component curable urethane adhesive, thickness after curing is 3 μm) was prepared. Also, as the barrier layer, an aluminum foil (JIS H4160:1994 A8079H-O (thickness 40 μm)) was prepared. Chemical conversion treatment was performed on both sides of the aluminum foil. The chemical conversion treatment of the aluminum foil was carried out by applying a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum foil by a roll coating method so that the coating amount of chromium was 10 mg / m 2 (dry mass), and baking.

[0252] Next, using a two-component curable urethane adhesive, the base material layer and the barrier layer were adhered with an adhesive layer (thickness 3 μm) by a dry lamination method to produce a laminate in which the base material layer / adhesive layer / barrier layer were laminated in this order.

[0253] Next, maleic anhydride-modified polypropylene for forming an adhesive layer (thickness 40 μm) and random polypropylene for forming a heat-sealable resin layer (thickness 40 μm) were co-extruded on the barrier layer of each laminate obtained above, so that an adhesive layer / heat-sealable resin layer was laminated on the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior film composed of a laminate in which the base material layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in this order.

[0254] Comparative Example 2A An exterior film was obtained which consisted of a laminate in which a base material layer / an adhesive layer / a barrier layer / an adhesive layer / a heat-sealable resin layer were laminated in this order, in the same manner as Comparative Example 1A except that aluminum foil (JIS H4160:1994 A8079H-O (thickness 60 μm)) was used as the barrier layer.

[0255] Example 1A An exterior film was obtained which consisted of a laminate in which a base material layer / an adhesive layer / a barrier layer / an adhesive layer / a heat-sealable resin layer were laminated in this order, in the same manner as Comparative Example 1A except that aluminum foil (JIS H4160:1994 A8079H-O (thickness 80 μm)) was used as the barrier layer.

[0256] Example 2A An exterior film was obtained which consisted of a laminate in which a base material layer / an adhesive layer / a barrier layer / an adhesive layer / a heat-sealable resin layer were laminated in this order, in the same manner as Comparative Example 1A except that stainless steel foil (JIS G4303 SUS304 (thickness 60 μm)) was used as the barrier layer.

[0257] Example 3A The same exterior film as in Comparative Example 1A was used. In the thermal shock test described later, the material of the lid of the exterior body used for the simulated power storage device was different from that of Comparative Example 1A.

[0258] Example 4A The same exterior film as in Comparative Example 1A was used. In the thermal shock test described later, the material of the lid of the exterior body used for the simulated power storage device was different from that of Comparative Example 1A and Example 3A.

[0259] <Measurement of the area average angular difference of GOS (grain orientation spread) of the barrier layer> A simulated power storage device was manufactured in the same manner as the simulated power storage device manufactured in the <thermal shock test> described below. Next, for the simulated power storage device, a barrier layer at the position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body (sealing portion (second sealing portion)) was obtained, and crystal analysis by the EBSD method was performed to measure the area average angular difference of GOS (grain orientation spread) when the grain boundary of the barrier layer was defined as 5°. The specific measurement method is as follows.

[0260] For the cross-section perpendicular to the rolling direction of each barrier layer, crystal analysis by the EBSD method was performed to measure the area average angular difference of GOS (grain orientation spread) when the grain boundary of the barrier layer was defined as 5°. The details of the measurement conditions are as follows. The measurement results are shown in Table 1A. The area average angular difference of GOS (grain orientation spread) is obtained by connecting a plurality of images acquired by crystal analysis by the EBSD method, and about 5000 μm 2 is the area average angular difference of GOS (grain orientation spread) of the crystals included in the measurement region (the entire thickness direction of the barrier layer is taken as the measurement region) as described above.

[0261] (Measuring device) A device equipped with an EBSD detector (manufactured by TSL Solutions Co., Ltd.) was used for the Schottky field emission scanning electron microscope.

[0262] (Pretreatment) As a pretreatment, the barrier layer is cut in a direction perpendicular to the rolling direction (RD) to obtain a cross-section. The rolling direction of the barrier layer is the direction in which linear rolling marks extend when the glossy surface of the barrier layer is observed with a metallurgical microscope. As a specific procedure, first, the barrier layer to be used as a sample is cut out to 5 mm (in a direction perpendicular to the rolling direction) × 10 mm (in the rolling direction) with a trimming razor, and then embedded in resin. Next, using a trimming razor, the barrier layer is cut together with the resin in a direction perpendicular to the rolling direction of the barrier layer and vertically from the surface of the barrier layer to expose the cross-section of the barrier layer. Next, the obtained cross-section is trimmed using a microtome (ultramicrotome manufactured by Leica Microsystems). In this trimming, in order to reduce the mechanical distortion of the cross-sectional shape, the microtome was advanced about 1 mm in a direction perpendicular to the cross-section together with the embedded resin. Next, using an ion milling device (manufactured by Hitachi High-Technologies Corporation), a broad argon beam was irradiated in a direction perpendicular to the cross-section under the conditions of a protrusion width of 50 μm, a voltage of 6 kV, and 4 hours to prepare a measurement cross-section. This is an operation to precisely expose the cross-section of the barrier layer so that the mechanical destruction of the crystal structure generated in the previous process is minimized. In the present disclosure, since the "perpendicular direction" when cutting the aluminum alloy foil is confirmed under a stereomicroscope, it may include an error of about 10°. That is, the direction perpendicular to the rolling direction allows a range of 80 to 100° with respect to the rolling direction, and the direction perpendicular to the surface allows a range of 80 to 100° with respect to the surface.

[0263] (SEM conditions) The conditions of the scanning electron microscope (SEM) used for the EBSD method are as follows. Observation magnification: 2000 times (the standard observation magnification at the time of shooting is Polaroid545) Acceleration voltage: 15 kV Working distance: 15 mm Sample tilt angle: 70°

[0264] (EBSD conditions) The conditions for crystal analysis by the EBSD method are as follows. Step size: 150 nm Analysis conditions: The following analysis was performed using the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. Multiple images were concatenated, and the measurement area was approximately 5000 μm. 2 The above was done. At this time, the measurement area was from the center to both ends in the thickness direction of the barrier layer, and the parts where resin adhered to the cross-section and the parts where the acid-resistant film existed were excluded from the measurement area. The CI value was 0.1 or more, the grain boundary condition was 5° or more, and the minimum grain size was 3 steps or more. After concatenating the images, the pole figure was confirmed. If the center of the pole figure is shifted by 10° or more, the crystal data is rotated so that the symmetry is adjusted. The pole figure for reference at that time is measured from the sample surface by XRD. When obtaining the pole figure from the surface by EBSD, in order to remove the influence of the mechanical crystal structure of the sample surface, after performing mechanical polishing, surface milling, electrolytic polishing, etc. on the sample surface, a wide-area measurement is performed. Then, the pole figure obtained from the surface direction is rotated by 90° so that it is the same as that obtained from the same orientation as the pole figure obtained from the cross-section of the target sample. This pole figure is used as a reference. The analysis was performed by excluding the data with a confidence index (Confidence Index: CI value) CI value of 0.1 or less defined by the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. As a result, it is possible to exclude the resin used for the pretreatment existing on the front and back of the sample, the grain boundaries existing in the cross-section, and the data based on amorphous.

[0265] <Measurement of Young's modulus of the exterior film> The Young's modulus of the exterior film was measured by the following method. The results are shown in Table 1A. In accordance with the provisions of JIS K6251:2017, the S-S curve in the TD direction of the exterior film was obtained under the following measurement conditions, and the Young's modulus (MPa) was calculated from the maximum value of the slope of the S-S curve. (Measurement conditions) A tensile testing machine (Shimadzu Autograph AG-X Plus) was used. Shape of test piece: dumbbell No. 7 Width of test piece: 2 mm Length of test piece: 35 mm Thickness of test piece: Measured with a thickness gauge Distance between gauge marks: 20 mm Tensile speed: 50 mm / min Test environment: 23 ± 5°C, 50 ± 30% RH Number of measurements: Average value of 3 times

[0266] <Thermal shock test> The exterior films produced in each example and comparative example were each cut into a rectangular shape with a size of MD 360 mm × TD 160 mm. On the other hand, as the lid of the exterior body, in Comparative Examples 1A - 2A and Example 1A - 2A, a lid made of polypropylene in the shape of a rectangular parallelepiped (length 100 mm × width 30 mm × thickness 5 mm) was prepared. In Example 3A, a lid (length 100 mm × width 30 mm × thickness 5 mm) in which the periphery (around the thickness part) of an aluminum lid body in the shape of a rectangular parallelepiped (length 98 mm × width 28 mm × thickness 5 mm) was covered with a coating made of polypropylene (PP) was prepared. In Example 4A, a lid (length 100 mm × width 30 mm × thickness 5 mm) in which the periphery (around the thickness part) of an aluminum lid body in the shape of a rectangular parallelepiped (length 98 mm × width 28 mm × thickness 5 mm) was covered with a coating made of maleic anhydride-modified polypropylene (PPa) was prepared. Furthermore, as a simulated electrode body, a block made of aluminum in the shape of a rectangular parallelepiped (length 140 mm × width 98 mm × thickness 28 mm) was prepared.

[0267] Next, as shown in the schematic diagram of FIG. 1, lid bodies were arranged on both sides in the length direction of the electrode body, and these were wrapped with an exterior film. The position where the heat-fusible resin layers of the exterior film faced each other (first sealing portion 70) and the position where the heat-fusible resin layer of the exterior film contacted the lid body (second sealing portion 80) were heat-sealed using a heat-sealing bar respectively, to obtain a simulated power storage device. Note that the simulated power storage device was not provided with electrode terminals as shown in FIG. 1. The seal width at the position where the heat-fusible resin layers of the exterior film faced each other (first sealing portion 70) was set to 10 mm. Also, the seal width at the position where the heat-fusible resin layer of the exterior film contacted the lid body (second sealing portion 80) was set to the thickness of the lid body (5 mm). Regarding the heat-sealing conditions (temperature, surface pressure, time) of the second sealing portion 80, Comparative Example 1A was 180°C, 0.60 MPa, 3 seconds, Comparative Examples 2A and Example 1A-3A were 180°C, 1.20 MPa, 5 seconds, and Example 4A was 180°C, 0.60 MPa, 7 seconds respectively. In each case, the conditions were set so that the ratio of “(the thickness of the heat-fusible resin layer at the position where the heat-fusible resin layer was heat-fused to the lid body) / (the thickness of the heat-fusible resin layer at the position where the heat-fusible resin layer was not heat-fused to the lid body)” was 10 to 90%. Note that the condition where the thickness of the heat-fusible resin layer was 20% or more and 80% or less could be adjusted, for example, by setting the temperature during heat fusion to about 160 to 240°C, the surface pressure to about 0.2 to 1.5 MPa, and the heat-fusion time to about 1 to 12 seconds.

[0268] Regarding each of the obtained simulated power storage devices, standing still in a -30°C environment for 30 minutes and then standing still in an 80°C environment for 30 minutes was defined as one cycle, and this was repeated 800 times to conduct a thermal shock test. It was evaluated whether cracking was suppressed from occurring in the sealing portion (surface layer of the exterior film) between the exterior film and the lid body when the power storage device was repeatedly exposed to temperature changes between high and low temperatures. The results are shown in Table 1A.

[0269] In the thermal shock test results shown in Table 1A, cracks occurred in the sealing portion of the power storage device of Comparative Examples 1A-2A with the lid of the outer film. On the other hand, in the power storage device of Example 1A, although fine cracks occurred in the sealing portion with the lid of the outer film, it could be evaluated that the occurrence of cracks in the sealing portion with the lid of the outer film was suppressed. In the power storage devices of Examples 2A-4A, no cracks occurred in the sealing portion with the lid of the outer film, respectively, and it could be evaluated that the occurrence of cracks in the sealing portion with the lid of the outer film was particularly well suppressed. Fine cracks refer to cracks to such an extent that no voids are observed in the barrier layer when the sealing portion is observed by SEM, whereas the cracks observed in Comparative Examples 1A-2A were cracks to such an extent that voids were observed in the barrier layer when the sealing portion was observed by SEM. The conditions for SEM observation were observation magnification: 1000 times, acceleration voltage: 5 kV, and working distance: 10 mm.

[0270]

Table 1A

[0271] In Table 1A, PET is a polyethylene terephthalate film, DL is an adhesive layer formed by the dry lamination method, ONy is a stretched nylon film, AL is an aluminum alloy foil, SUS is a stainless steel foil, PPa is a maleic anhydride-modified polypropylene layer, and PP is a polypropylene layer. Also, the Young's modulus and the area average angular difference of GOS (grain orientation dispersion) are values calculated by rounding up the measured values that are one digit smaller than the numerical values described in Table 1A, respectively.

[0272] <Manufacture of Outer Material for Power Storage Device> Comparative Example 1B As the base material layer, a laminate was prepared in which a biaxially stretched polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 15 μm) were adhered with an adhesive layer (formed of a two-component curable urethane adhesive, with a thickness of 3 μm after curing). Also, as the barrier layer, an aluminum foil (JIS H4160:1994 A8079H-O (thickness 60 μm)) was prepared. Chemical conversion treatment was performed on both sides of the aluminum foil. The chemical conversion treatment of the aluminum foil was carried out by applying a treatment liquid composed of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum foil by a roll coating method so that the coating amount of chromium was 10 mg / m 2 (dry mass), and then baking.

[0273] Next, using a two-component curable urethane adhesive, the base material layer and the barrier layer were adhered with an adhesive layer (thickness 3 μm) by a dry lamination method to produce a laminate in which the base material layer / adhesive layer / barrier layer were laminated in this order.

[0274] Next, maleic anhydride-modified polypropylene for forming an adhesive layer (thickness 40 μm) and random polypropylene for forming a heat-sealable resin layer (thickness 40 μm) were co-extruded on the barrier layer of each laminate obtained above, so that the adhesive layer / heat-sealable resin layer was laminated on the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for a power storage device composed of a laminate in which the base material layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in this order.

[0275] Example 1B An exterior material for a power storage device composed of a laminate in which the base material layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer were laminated in this order was obtained in the same manner as in Comparative Example 1B, except that an aluminum foil (JIS H4160:1994 A8079H-O (thickness 80 μm)) was used as the barrier layer.

[0276] Example 2B A power storage device exterior material comprising a laminate in which a base material layer / adhesive layer / barrier layer / adhesive layer / heat-sealable resin layer are laminated in this order was obtained in the same manner as in Comparative Example 1B, except that a stainless steel foil (JIS G4303 SUS304 (thickness: 60 μm)) was used as the barrier layer.

[0277] <Measurement of the area average angular difference of GOS (grain orientation spread) of the barrier layer> A simulated power storage device was manufactured in the same manner as the simulated power storage device manufactured in the <thermal shock test> described below. Next, for the simulated power storage device, a barrier layer at the position (sealing portion (second sealing portion)) where the heat-sealable resin layer of the power storage device exterior material is heat-sealed to a polypropylene plate (lid made of polypropylene) was obtained, and crystal analysis by the EBSD method was performed to measure the area average angular difference of GOS (grain orientation spread) when the grain boundaries of the barrier layer were defined as 5°. The specific measurement method is as follows.

[0278] For the cross-section perpendicular to the rolling direction of each barrier layer, crystal analysis by the EBSD method was performed to measure the area average angular difference of GOS (grain orientation spread) when the grain boundaries of the barrier layer were defined as 5°. Details of the measurement conditions are as follows. The measurement results are shown in Table 1B. The area average angular difference of GOS (grain orientation spread) is the area average angular difference of GOS (grain orientation spread) of the crystals included in the measurement region (the entire thickness direction of the barrier layer is defined as the measurement region) obtained by connecting a plurality of images obtained by crystal analysis by the EBSD method, about 5000 μm 2 It is the area average angular difference of GOS (grain orientation spread) of the crystals included in the measurement region described above.

[0279] (Measuring device) An apparatus in which an EBSD detector (manufactured by TSL Solutions Co., Ltd.) was mounted on a Schottky field emission scanning electron microscope was used.

[0280] (Pretreatment) As a pretreatment, the barrier layer is cut in a direction perpendicular to the rolling direction (RD) to obtain a cross-section. The rolling direction of the barrier layer is the direction in which linear rolling marks extend when the glossy surface of the barrier layer is observed with a metallurgical microscope. As a specific procedure, first, the barrier layer to be used as a sample is cut out to 5 mm (in a direction perpendicular to the rolling direction) × 10 mm (in the rolling direction) with a trimming razor, and then embedded in resin. Next, using a trimming razor, the barrier layer is cut together with the resin in a direction perpendicular to the rolling direction of the barrier layer and vertically from the surface of the barrier layer to expose the cross-section of the barrier layer. Next, the obtained cross-section is trimmed using a microtome (ultramicrotome manufactured by Leica Microsystems). In this trimming, in order to reduce mechanical distortion of the cross-sectional shape, the microtome was advanced by about 1 mm in a direction perpendicular to the cross-section together with the embedded resin. Next, using an ion milling device (manufactured by Hitachi High-Technologies Corporation), a broad argon beam was irradiated in a direction perpendicular to the cross-section under the conditions of a jump-out width of 50 μm, a voltage of 6 kV, and 4 hours to prepare a measurement cross-section. This is an operation to precisely expose the cross-section of the barrier layer so that mechanical damage to the crystal structure generated in the previous process is minimized. In the present disclosure, the "perpendicular direction" when cutting the aluminum alloy foil is confirmed under a stereomicroscope, and thus may include an error of about 10°. That is, the direction perpendicular to the rolling direction allows a range of 80 to 100° with respect to the rolling direction, and the direction perpendicular to the surface allows a range of 80 to 100° with respect to the surface.

[0281] (SEM conditions) The conditions of the scanning electron microscope (SEM) used for the EBSD method are as follows. Observation magnification: 2000 times (the standard observation magnification at the time of photography is Polaroid 545) Acceleration voltage: 15 kV Working distance: 15 mm Sample tilt angle: 70°

[0282] (EBSD conditions) The conditions for crystal analysis by the EBSD method are as follows. Step size: 150 nm Analysis conditions: The following analysis was performed using the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. Multiple images were connected, and the measurement area was approximately 5000 μm. 2 The above was done. At this time, the measurement area was from the center to both ends in the thickness direction of the barrier layer, and the parts where resin adhered to the cross-section and the parts where the acid-resistant film existed were excluded from the measurement area. The CI value was set to 0.1 or more, the grain boundary condition was set to 5° or more, and the minimum grain size was set to 3 steps or more. After connecting the images, the pole figure was checked. If the center of the pole figure is shifted by 10° or more, the crystal data is rotated so that the symmetry is adjusted. The pole figure used as a reference at that time is measured from the sample surface by XRD. When obtaining the pole figure from the surface by EBSD, in order to remove the influence of the mechanical crystal structure of the sample surface, after performing mechanical polishing, plane milling, electrolytic polishing, etc. of the sample surface, wide-area measurement is performed. After that, the pole figure obtained from the surface direction is rotated by 90° so that it is the same as the one obtained from the same orientation as the pole figure obtained from the cross-section of the target sample. This pole figure is used as a reference. Analysis was performed by excluding data with a CI value (Confidence Index: CI value) of 0.1 or less defined by the crystal orientation analysis software OIM (Ver. 7.3) manufactured by TSL Solutions Co., Ltd. As a result, it is possible to exclude data based on the resin used for the pretreatment present on the front and back of the sample, the grain boundaries present in the cross-section, and the amorphous.

[0283] <Measurement of Young's modulus of the exterior material for power storage devices> The Young's modulus of the exterior material for power storage devices was measured by the following method. The results are shown in Table 1B. In accordance with the provisions of JIS K6251:2017, the S-S curve in the TD direction of the adhesive film was obtained under the following measurement conditions, and the Young's modulus (MPa) was calculated from the maximum value of the slope of the S-S curve. (Measurement conditions) A tensile testing machine (Shimadzu Autograph AG-X Plus) was used. Shape of test piece: dumbbell No. 7 Width of test piece: 2 mm Length of test piece: 35 mm Thickness of test piece: measured with a thickness gauge Distance between gauge marks: 20 mm Tensile speed: 50 mm / min Test environment: 23 ± 5°C, 50 ± 30% RH Number of measurements: average value of 3 times

[0284] <Thermal shock test> The exterior materials for power storage devices manufactured in each example and comparative example were each cut into a rectangular shape with a size of MD 360 mm × TD 160 mm. On the other hand, as the lid of the exterior body, a lid (polypropylene plate) made of polypropylene in the shape of a rectangular parallelepiped (length 100 mm × width 30 mm × thickness 5 mm) was prepared. Further, as a simulated electrode body, an aluminum block in the shape of a rectangular parallelepiped (length 140 mm × width 98 mm × thickness 28 mm) was prepared.

[0285] Next, as shown in the schematic diagram of FIG. 1, lids were arranged on both sides in the length direction of the electrode body, and this was wrapped with the exterior material for power storage devices. The position where the heat-fusible resin layers of the exterior material for power storage devices face each other (the first sealing portion 70) and the position where the heat-fusible resin layer of the exterior material for power storage devices contacts the lid (the second sealing portion 80) were each heat-sealed using a heat-sealing bar to obtain a simulated power storage device. Note that the simulated power storage device is not provided with electrode terminals as shown in FIG. 1. The seal width at the position where the heat-fusible resin layers of the exterior material for power storage devices face each other (the first sealing portion 70) was set to 10 mm. Also, the seal width at the position where the heat-fusible resin layer of the exterior material for power storage devices contacts the lid (the second sealing portion 80) was set to the thickness of the lid (5 mm). Further, the heat-sealing conditions (temperature, surface pressure, time) of the second sealing portion 80 were set to 180°C, 1.20 MPa, and 5 seconds, respectively. These heat-sealing conditions were set such that the ratio of "(the thickness of the heat-fusible resin layer at the position where the heat-fusible resin layer is heat-fused to the lid) / (the thickness of the heat-fusible resin layer at the position where the heat-fusible resin layer is not heat-fused to the lid)" is 20 to 80%.

[0286] For each of the obtained simulated power storage devices, one cycle consisted of allowing the device to stand still in an environment of -30°C for 30 minutes and then in an environment of 80°C for 30 minutes. This cycle was repeated 800 times to conduct a thermal shock test, and it was evaluated whether cracks were suppressed from occurring in the sealing part (the surface layer of the exterior material for the power storage device) between the exterior material for the power storage device and the lid when the power storage device was repeatedly exposed to temperature changes between high and low temperatures. The results are shown in Table 1B.

[0287] In the thermal shock test results shown in Table 1B, cracks occurred in the sealing part between the exterior material for the power storage device and the lid of the power storage device of Comparative Example 1B. On the other hand, in the power storage device of Example 1B, although fine cracks occurred in the sealing part between the exterior material for the power storage device and the lid, it could be evaluated that the occurrence of cracks in the sealing part between the exterior material for the power storage device and the lid was suppressed. In the power storage device of Example 2B, no cracks occurred in the sealing part between the exterior material for the power storage device and the lid, and it could be evaluated that the occurrence of cracks in the sealing part between the exterior material for the power storage device and the lid was particularly well suppressed. Fine cracks refer to cracks to such an extent that no voids are observed in the barrier layer when the sealing part is observed by SEM, whereas the cracks observed in Comparative Example 1B were cracks to such an extent that voids were observed in the barrier layer when the sealing part was observed by SEM. The conditions for SEM observation were: observation magnification: 1000 times, acceleration voltage: 5 kV, working distance: 10 mm.

[0288]

Table 1B

[0289] In Table 1B, PET is a polyethylene terephthalate film, DL is an adhesive layer formed by a dry lamination method, ONy is a stretched nylon film, AL is an aluminum alloy foil, SUS is a stainless steel foil, PPa is a maleic anhydride-modified polypropylene layer, and PP is a polypropylene layer. Also, the Young's modulus and the area average angular difference of GOS (grain orientation spread) are values calculated by rounding up the measured values that are one digit smaller than the numerical values described in Table 1B, respectively.

[0290] As described above, the present disclosure provides an invention in the following aspects. Item 1A. A power storage device, an electrode body, and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body, and a lid body that seals the electrode body together with the exterior film. The exterior film is composed of a laminate including at least a barrier layer and a heat-sealable resin layer. The barrier layer is in a direction perpendicular to the rolling direction of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body. For a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer, the area average angular difference of GOS (grain orientation spread) defined with a grain boundary of 5° is 2.50° or less, obtained by performing crystal analysis by the EBSD method. Power storage device. Item 2A. The power storage device according to Item 1A, wherein the barrier layer is formed of stainless steel, a steel plate, or an aluminum alloy. Item 3A. The lid body has a lid main body and a covering body that joins the lid main body and the exterior film. The power storage device according to Item 1A or 2A, wherein the covering body contains a resin. Item 4A. The power storage device according to any one of Items 1A to 3A, further including an adhesive layer between the barrier layer and the heat-sealable resin layer. Item 5A. The power storage device according to any one of Items 1A to 4A, further comprising a base material layer on the side opposite to the heat-sealable resin layer of the barrier layer. Item 6A. The power storage device according to Item 5A, further comprising an adhesive layer between the base material layer and the barrier layer. Item 7A. The power storage device according to any one of Items 1A to 6A, wherein the exterior film has a Young's modulus of 6000 MPa or more. Item 8A. A method for manufacturing a power storage device, wherein the power storage device comprises an electrode body and an exterior body for sealing the electrode body, wherein the exterior body comprises an exterior film that wraps the electrode body and a lid body that seals the electrode body together with the exterior film, wherein the exterior film is composed of at least a laminate including a barrier layer and a heat-sealable resin layer, wherein the barrier layer, at the position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid body, is in a direction perpendicular to the rolling direction of the barrier layer, and for a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer, when the grain boundary is defined as 5°, the area average angular difference of GOS (grain orientation spread) obtained by performing crystal analysis by the EBSD method is 2.50° or less, and includes a step of sealing the electrode body with the exterior body. A method for manufacturing a power storage device.

[0291] Also, as described above, the present disclosure provides an invention in the following aspects. Item 1B. An exterior material for a power storage device composed of at least a laminate including a barrier layer and a heat-sealable resin layer, The barrier layer is formed by thermally fusing the heat-sealable resin layer of the exterior material for the power storage device and a polypropylene plate at a position where the thickness of the heat-sealable resin layer is 20% or more and 80% or less. For a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer, the area average angular difference of GOS (grain orientation spread) when the grain boundary is defined as 5° is 2.50° or less, which is obtained by performing crystal analysis by the EBSD method. Exterior material for a power storage device. Item 2B. The exterior material for a power storage device according to Item 1B, wherein the barrier layer is formed of stainless steel, a steel plate, or an aluminum alloy. Item 3B. The exterior material for a power storage device according to Item 1B or 2B, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. Item 4B. The exterior material for a power storage device according to any one of Items 1B to 3B, further comprising a base material layer on the side opposite to the heat-sealable resin layer side of the barrier layer. Item 5B. The exterior material for a power storage device according to Item 4B, further comprising an adhesive layer between the base material layer and the barrier layer. Item 6B. The exterior material for a power storage device according to any one of Items 1B to 5B, wherein the power storage device exterior material has a Young's modulus of 6000 MPa or more. Item 7B. A method for manufacturing an exterior material for a power storage device, comprising at least a step of obtaining a laminate in which a barrier layer and a heat-sealable resin layer are laminated, The barrier layer is formed by thermally fusing the heat-sealable resin layer of the exterior material for the power storage device and a polypropylene plate at a position where the thickness of the heat-sealable resin layer is 20% or more and 80% or less. For a cross-section obtained by cutting the barrier layer perpendicularly from the surface of the barrier layer in a direction perpendicular to the rolling direction of the barrier layer, the area average angular difference of GOS (grain orientation spread) when the grain boundary is defined as 5° is 2.50° or less, which is obtained by performing crystal analysis by the EBSD method. Method for manufacturing an exterior material for a power storage device. Item 8B. A power storage device in which a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for a power storage device according to any one of Items 1B to 6B.

Explanation of Signs

[0292] 10 Power storage device 20 Electrode body 30 Electrode terminal 40 Exterior body 50 Exterior film 51 Base material layer 52 Barrier layer 53 Heat-sealable resin layer 54 Adhesive layer 55 Adhesion layer 60 Cover body 61 Cover main body 62 Coating body 70 First sealing part 80 Second sealing part

Claims

1. An electricity storage device, An electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body; a lid that seals the electrode body together with the exterior film, the exterior film is composed of a laminate including at least a barrier layer and a heat-sealable resin layer, the barrier layer has an area-average angle difference of GOS (grain orientation dispersion) of 2.50° or less when a grain boundary is defined as 5°, the area-average angle difference being obtained by performing crystal analysis by an EBSD method on a cross section obtained by cutting the barrier layer in a direction perpendicular to a rolling direction of the barrier layer and perpendicular to a surface of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid; Energy storage device.

2. The electricity storage device according to claim 1 , wherein the barrier layer is formed of stainless steel, a steel plate, or an aluminum alloy.

3. The lid body has a lid main body and a cover body that joins the lid main body and the exterior film, The electricity storage device according to claim 1 , wherein the covering comprises a resin.

4. The electricity storage device according to claim 1 , further comprising an adhesive layer between the barrier layer and the thermally adhesive resin layer.

5. The electricity storage device according to claim 1 , further comprising a base material layer on the side of the barrier layer opposite to the thermally adhesive resin layer side.

6. The electricity storage device according to claim 5 , further comprising an adhesive layer between the base layer and the barrier layer.

7. The electricity storage device according to claim 1 , wherein the exterior film has a Young's modulus of 6000 MPa or more.

8. A method for manufacturing an electricity storage device, comprising: The power storage device is An electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body; a lid that seals the electrode body together with the exterior film, the exterior film is composed of a laminate including at least a barrier layer and a heat-sealable resin layer, the barrier layer has an area-average angle difference of GOS (grain orientation dispersion) of 2.50° or less when a grain boundary is defined as 5°, the area-average angle difference being obtained by performing crystal analysis by an EBSD method on a cross section obtained by cutting the barrier layer in a direction perpendicular to a rolling direction of the barrier layer and perpendicular to a surface of the barrier layer at a position where the heat-sealable resin layer of the exterior film is heat-sealed to the lid, The electrode body is sealed with the outer casing. A method for manufacturing an electricity storage device.