Power storage device, barrier film, cover unit and method for manufacturing cover unit

Abstract

This electricity storage device is provided with an electrode body, an exterior body for sealing the electrode body, and a barrier film. The exterior body includes an exterior film that covers the electrode body so as to form an opening, and a cover body that is disposed in the opening. The cover body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface. The barrier film is joined to the cover body so as to cover at least a portion of the sealing surface.

Description

Technical Field

[0001] The present invention relates to a power storage device, a barrier film, a cover unit, and a method for manufacturing the cover unit. Background Art

[0002] Patent Document 1 discloses an all-solid-state battery as an example of an electrical storage device. The all-solid-state battery includes an electrode assembly and an outer casing that seals the electrode assembly. The outer casing comprises an outer film wrapped around the electrode assembly with an opening, and a cover disposed over the opening. The opposing surfaces of the outer film are heat-sealed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-153504. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned electricity storage device, there is a possibility that moisture and gas may infiltrate the interior through the gap between the cover and the exterior film. Therefore, the above-mentioned electricity storage device still has room for improvement in terms of suppressing the intrusion of moisture and gas.

[0008] An object of the present invention is to provide an electricity storage device capable of suppressing the intrusion of at least one of moisture and gas, a barrier film for the electricity storage device, a cap unit for the electricity storage device, and a method for manufacturing the cap unit.

[0009] Technical means to solve the problem

[0010] The first aspect of the present invention provides a storage device comprising: an electrode body; an outer casing for sealing the electrode body; and a barrier film, wherein the outer casing comprises: an outer casing covering the electrode body in a manner that forms an opening; and a cover body arranged at the opening, the cover body having a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface, and the barrier film is joined to the cover body in a manner that covers at least a portion of the sealing surface.

[0011] A power storage device according to a second aspect of the present invention is the power storage device according to the first aspect, wherein the barrier film is joined to the lid so as to cover at least a portion of the first surface.

[0012] In the power storage device according to the third aspect of the present invention, the barrier film includes a barrier layer and an outer layer laminated on the opposite side of the cover relative to the barrier layer.

[0013] The fourth aspect of the present invention is a storage device. In the storage device according to the second aspect, the barrier film includes a barrier layer and an outer layer stacked on the opposite side of the cover body relative to the barrier layer, and in the barrier film, the portion covering at least a portion of the sealing surface is connected to the portion covering at least a portion of the first surface, and the end portion is located at the portion covering at least a portion of the sealing surface.

[0014] A power storage device according to a fifth aspect of the present invention is the power storage device according to any one of the first to third aspects, wherein the barrier film is joined to the lid so as to cover at least a portion of the second surface.

[0015] A sixth aspect of the present invention provides the power storage device according to the fifth aspect, wherein the barrier film comprises a portion covering at least a portion of the sealing surface and a portion covering at least a portion of the second surface, and the end portions are covered by the covering portion.

[0016] According to a seventh aspect of the present invention, in the power storage device according to the first aspect, the end portion of the barrier film is located in a portion covering at least a portion of the sealing surface and is located closer to the second surface than a boundary between the first surface and the sealing surface.

[0017] According to an eighth aspect of the present invention, in the power storage device according to the first aspect, the barrier film has a portion connected to a portion bonded to the cover and folded back toward the second surface, and an end portion of the barrier film is located in the portion folded back toward the second surface.

[0018] The storage device according to the ninth aspect of the present invention, in the storage device according to any one of the first to eighth aspects, further includes an electrode terminal electrically connected to the electrode body, the cover body is constructed in a manner covering a portion of the electrode terminal, and the barrier film is arranged at least in a portion between the cover body and the electrode terminal.

[0019] A power storage device according to a tenth aspect of the present invention is the power storage device according to any one of the first to eighth aspects, wherein the barrier film is disposed in at least a portion of the interior of the lid.

[0020] According to an eleventh aspect of the present invention, in the electricity storage device according to any one of the first to tenth aspects, the barrier film is bonded to the exterior film so as to cover at least a portion of the sealing surface outside the exterior film.

[0021] The cover unit of the twelfth aspect of the present invention is a cover unit for a storage device including an electrode body and an outer film covering the electrode body in a manner forming an opening portion, which includes: a cover body arranged at the opening portion; and a barrier film, the cover body having a first surface, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface, and the barrier film is joined to the cover body in a manner covering at least a portion of the sealing surface.

[0022] A cover unit according to a thirteenth aspect of the present invention is the cover unit according to the twelfth aspect, further comprising an electrode terminal joined to the cover body.

[0023] The barrier film according to the fourteenth aspect of the present invention is used for the power storage device according to any one of the first to eleventh aspects.

[0024] The barrier film according to the fifteenth aspect of the present invention is used in the cover unit according to the twelfth aspect or the thirteenth aspect.

[0025] A sixteenth aspect of the present invention relates to a method for manufacturing a cap unit for a power storage device comprising an electrode body and an exterior film covering the electrode body so as to form an opening. The cap unit comprises: a cap body positioned in the opening; and a barrier film, the cap body having a first surface facing the electrode body, a second surface opposite the first surface, and a sealing surface connecting the first and second surfaces, the barrier film being bonded to the cap body so as to cover at least a portion of the sealing surface. The cap unit manufacturing method includes insert-molding the cap body into the barrier film.

[0026] A seventeenth aspect of the present invention provides a method for manufacturing a cap unit for a power storage device comprising an electrode body and an exterior film covering the electrode body so as to form an opening. The cap unit comprises: a cap body positioned in the opening; and a barrier film, wherein the cap body has a first surface facing the electrode body, a second surface opposite the first surface, and a sealing surface connecting the first and second surfaces, the barrier film being bonded to the cap body so as to cover at least a portion of the sealing surface. The cap unit manufacturing method includes bonding the barrier film to the cap body.

[0027] Effects of the Invention

[0028] According to the electricity storage device, the barrier film used therefor, the cap unit used therefor, and the method for manufacturing the electricity storage device of the present invention, it is possible to suppress the intrusion of at least one of moisture and gas into the interior of the electricity storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1AIt is a plan view schematically showing the power storage device according to the first embodiment.

[0030] Figure 1B It's about Figure 1A A diagram illustrating a method for measuring the sealing strength of a second sealing portion of a power storage device.

[0031] Figure 2 Yes Figure 1A sectional view showing an example of the layer structure of an exterior film included in a power storage device.

[0032] Figure 3 yes Figure 1A FIG. 1 is a diagram showing an expanded state of an exterior film included in a power storage device.

[0033] Figure 4 yes Figure 1A A three-dimensional view of a cover body included in the power storage device.

[0034] Figure 5 It is along Figure 1A Cross-sectional view of line D5-D5.

[0035] Figure 6 yes Figure 5 Partial cross-sectional view of the cover unit.

[0036] Figure 7 yes Figure 1A A cross-sectional view showing an example of the layer structure of a barrier film included in a power storage device.

[0037] Figure 8 yes Figure 1A A cross-sectional view showing another example of the layer structure of the barrier film included in the power storage device.

[0038] Figure 9 yes Figure 1A A cross-sectional view showing another example of the layer structure of the barrier film included in the power storage device.

[0039] Figure 10 Yes Figure 1A A flowchart of an example of a manufacturing process of an electricity storage device.

[0040] Figure 11 It is a partial cross-sectional view of a cover unit included in the power storage device according to the second embodiment.

[0041] Figure 12 It is a partial cross-sectional view of a cover unit included in the power storage device according to the third embodiment.

[0042] Figure 13 It is a partial cross-sectional view of a cover unit included in the power storage device according to the fourth embodiment.

[0043] Figure 14It is a partial cross-sectional view of a cover unit included in the power storage device according to the fifth embodiment.

[0044] Figure 15 It is a cross-sectional view of a power storage device according to a sixth embodiment. DETAILED DESCRIPTION

[0045] The following describes an electric storage device according to one embodiment of the present invention with reference to the accompanying drawings. It should be noted that in this specification, the numerical range indicated by "to" means "above" or "below." For example, the expression "2 to 15 mm" means "above 2 mm and below 15 mm."

[0046] [1. First embodiment]

[0047] <1-1. Structure of Power Storage Device>

[0048] Figure 1A It is a plan view schematically showing the power storage device 10 according to the first embodiment. Figure 1B This is a diagram illustrating a method for measuring the sealing strength of the second sealing portion 80 of the power storage device 10 . Figure 2 Yes Figure 1A 1 is a cross-sectional view showing a layer structure of an exterior film 50 included in the power storage device 10 . Figure 3 yes Figure 1A FIG. 1 is a diagram showing a state in which the outer film 50 included in the power storage device 10 is unfolded. Figure 4 yes Figure 1A A perspective view of the cover 60 included in the power storage device 10, Figure 5 It is along Figure 1A Cross-sectional view of line D5-D5. Figure 6 yes Figure 5 A partial cross-sectional view of the cover unit 110. Figure 1A , arrow UD indicates the thickness direction of the power storage device 10, arrow LR indicates the width direction of the power storage device 10, and arrow FB indicates the depth direction of the power storage device 10. The directions indicated by arrows UD, LR, and FB are common to the following figures.

[0049] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an outer body 40. The electrode body 20 includes, for example, electrodes (positive and negative electrodes) and a separator that constitute a power storage component such as a lithium-ion battery, a capacitor, an all-solid battery, a semi-solid battery, a pseudo-solid 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-zinc oxide battery, a metal-air battery, a multivalent cation battery, or a capacitor. In this embodiment, the shape of the electrode body 20 is roughly rectangular. Here, "roughly rectangular" includes not only a complete rectangular parallelepiped but also a three-dimensional shape that can be regarded as a rectangular parallelepiped by modifying the shape of a portion of the outer surface. The shape of the electrode body 20 can be, for example, a cylinder or a polygonal prism.

[0050] In this embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminal 30 is a metal terminal used for inputting and outputting electric power in the electrode body 20. One end of the electrode terminal 30 is electrically connected to the electrode (positive electrode or negative electrode) contained in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from the end edge of the outer casing 40, for example. In addition, the electrode terminal 30 only needs to be able to input and output electric power to and from the electrode body 20, and, for example, it does not need to protrude from the outer casing 40. In the case where the cover body 60 described later is made of metal, for example, the cover body 60 sometimes also has the function of the electrode terminal 30. In this case, the cover body 60 having the function of the electrode terminal may or may not protrude from the outer casing 40.

[0051] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, or copper. For example, in the case of a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is typically made of aluminum, while the electrode terminal 30 connected to the negative electrode is typically made of copper, nickel, or the like. Furthermore, the outermost layer of the electrode body 20 does not necessarily have to be an electrode; for example, it may also be a protective tape or a separator.

[0052] The outer casing 40 seals the electrode body 20. The outer casing 40 includes an outer film 50 and a cover 60. The outer film 50 covers the electrode body 20 so as to have an opening 40A. In this embodiment, the outer film 50 is wound around the electrode body 20 so as to have an opening 40A. The cover 60 is arranged on the side of the electrode body 20 so as to close the opening 40A. Alternatively, the electrode body 20 may be housed inside the outer film 50 which is cylindrical in shape so as to form the opening 40A, and the opening 40A may be closed by the cover 60.

[0053] From the perspective of good bonding with the cover 60, it is preferred that an adhesive film 31 be bonded to the electrode terminal 30. The adhesive film 31 can be arbitrarily selected as long as it is a film that can bond the electrode terminal 30 made of metal to the cover 60 made of resin. The adhesive film 31 can be made of, for example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, a cyclic polyolefin resin, or an acid-modified polyolefin resin obtained by grafting these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or a film of two or more layers of these materials. In the present embodiment, the adhesive film 31 is bonded to substantially the entire portion of the electrode terminal 30 covered by the cover 60.

[0054] For example, there is a method of forming a housing portion (recess) for housing the electrode body 20 in the outer film 50 by cold forming. However, it is not necessarily easy to form a deep housing portion by such a method. If you want to form the housing portion (recess) deeply by cold forming (for example, a forming depth of 15 mm), there is a possibility of pinholes or cracks in the outer film 50, which increases the possibility of reduced battery performance. On the other hand, the outer body 40 seals the electrode body 20 by winding the outer film 50 around the electrode body 20, so the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In addition, in order to reduce the ineffective area between the electrode body 20 and the outer film 50 to increase the volume energy density of the power storage device 10, it is preferred that the outer film 50 is wound in a manner in contact with the outer surface of the electrode body 20. In addition, in an all-solid-state battery, from the perspective of applying high pressure uniformly to the outer surface of the battery in order to exert battery performance, it is also necessary to eliminate the space between the electrode body 20 and the outer film 50. Therefore, it is preferred that the outer film 50 is wound in a manner that contacts the outer surface of the electrode body 20.

[0055] The exterior film 50 is, for example, a laminate (laminated film) comprising a base material layer 51, a barrier layer 52, and a heat-fusible resin layer 53 in this order. Alternatively, the exterior film 50 may be laminated with the heat-fusible resin layer 53, base material layer 51, barrier layer 52, and heat-fusible resin layer 53 in this order. Alternatively, the exterior film 50 may be laminated with the heat-fusible resin layer 53, barrier layer 52, and heat-fusible resin layer 53 in this order. Furthermore, the exterior film 50 need not include all of these layers; for example, the barrier layer 52 may not be included. Specifically, the exterior film 50 may be made of a flexible and easily bendable material, such as a resin film. Furthermore, the exterior film 50 is preferably heat-sealable.

[0056] The base layer 51 included in the exterior film 50 is used to impart heat resistance to the exterior film 50 and to suppress the formation of pinholes that may occur during processing or distribution. The base layer 51 is composed, for example, of at least one of a stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one of the stretched polyester resin layer and the stretched polyamide resin layer in the base layer 51, the barrier layer 52 can be protected during processing of the exterior film 50, thereby suppressing breakage of the exterior film 50. Furthermore, to increase the tensile elongation of the exterior film 50, the stretched polyester resin layer is preferably a biaxially stretched polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially stretched polyamide resin layer. Furthermore, to provide excellent puncture strength and impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. Alternatively, the base layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. From the viewpoint of film strength, the thickness of the base material layer 51 is, for example, preferably 5 to 300 μm, and more preferably 5 to 150 μm.

[0057] The barrier layer 52 is a layer that at least inhibits moisture intrusion. The barrier layer 52 is bonded to the substrate layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor-deposited films, and resin layers having barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers based on fluoroalkyl units, such as fluororesins and ethylene-vinyl alcohol copolymers. Furthermore, examples of the barrier layer 52 include resin films having at least one of these vapor-deposited films and resin layers. The barrier layer 52 may also be a multi-layered layer. The barrier layer 52 preferably includes a layer composed of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it preferably contains at least one of aluminum alloy foil and stainless steel foil.

[0058] In the barrier layer 52, the layer composed of the above-mentioned metal material may also contain recycled materials of the metal material. As recycled materials of the metal material, for example, recycled materials of aluminum alloy, stainless steel, titanium steel, or steel plate can be cited. These recycled materials can be obtained by known methods respectively. Recycled materials of aluminum alloy can be obtained, for example, by the manufacturing 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 mixture of recycled materials and virgin materials (virgin materials). Among them, recycled materials of metal materials refer to metal materials that are recycled, separated, refined, etc. from various products used in the so-called market and waste from the manufacturing process to become reusable. In addition, virgin materials of metal materials refer to new metal materials refined from natural resources (raw materials) of metals, and are not recycled materials.

[0059] To improve the formability and conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil, such as one made from an annealed aluminum alloy. To further improve formability and conformability, an aluminum alloy foil containing iron is preferred. In an aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. An iron content of 0.1% or greater can provide an exterior film 50 with even better formability. An iron content of 9.0% or less can provide an exterior film 50 with even greater flexibility. Examples of soft aluminum alloy foil include aluminum alloy foil having the composition specified in JIS H 4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000: 2014 A8021P-O, or JIS H4000: 2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may also be added as needed. Softening can be achieved through annealing or other treatments. To enhance the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil, such as one made of a work-hardened aluminum alloy. Examples of the hard aluminum alloy foil include aluminum alloy foil having a composition specified in JIS H4160: 1994 A8021H-H18, JIS H4160: 1994 A8079H-H18, JIS H4000: 2014 A8021P-H14, or JIS H4000: 2014 A8079P-H14.

[0060] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. Furthermore, the stainless steel foil is preferably made of austenitic stainless steel from the perspective of providing an exterior film 50 having excellent formability and conformability.

[0061] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS 304, SUS 301, and SUS 316 L. Among them, SUS 304 is particularly preferred.

[0062] In the case of a metal foil, the thickness of the barrier layer 52 is sufficient as long as it at least functions as a barrier layer to inhibit moisture intrusion, and can be, for example, approximately 9 to 200 μm. The thickness of the barrier layer 52 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. Furthermore, the thickness of the barrier layer 52 is preferably approximately 10 μm or greater, more preferably approximately 20 μm or greater, and even more preferably approximately 25 μm or greater. Preferred ranges for the thickness of the barrier layer 52 include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above range is particularly preferred. In addition, from the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, and even more preferably about 55 μm or more. In addition, it is preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferred range is 35 to 200 μm. The outer film 50 has a high formability, which facilitates deep drawing and can contribute to a higher capacity of the power storage device. In addition, since the rigidity of the outer film 50 is improved, the outer film 50 can be easily wound around the electrode body 20 when it is wound around the electrode body 20. Furthermore, while increasing the capacity of an electricity storage device increases its weight, increasing the rigidity of the exterior film 50 can contribute to improved sealing performance of the electricity storage device. Furthermore, particularly when the barrier layer 52 is formed of stainless steel foil, the thickness of the stainless steel foil is preferably approximately 60 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, even more preferably approximately 30 μm or less, and particularly preferably approximately 25 μm or less. Furthermore, the thickness of the stainless steel foil is preferably approximately 10 μm or greater, and more preferably approximately 15 μm or greater.Preferred ranges of the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0063] Furthermore, when the barrier layer 52 is aluminum foil, it is preferably coated with a corrosion-resistant film on at least the surface opposite the base layer 51 to prevent dissolution and corrosion. The barrier layer 52 may have a corrosion-resistant film on both surfaces. Here, a corrosion-resistant film refers to a thin film imparting corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer 52 by undergoing an anti-corrosion treatment such as a hot water conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing, plating with nickel or chromium, or coating with a coating agent. Specifically, a corrosion-resistant film includes a film that improves the acid resistance of the barrier layer 52 (acid-resistant film) or a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film). The corrosion-resistant film can be formed using a single treatment or a combination of two or more. Furthermore, the film may be formed using not only a single layer but also multiple layers. Furthermore, hot water conversion and anodizing are treatments in which a treatment agent dissolves the surface of the metal foil to form a metal compound with excellent corrosion resistance. In addition, these treatments may also be included in the definition of chemical conversion treatment. In addition, when the barrier layer 52 has a corrosion-resistant film, it is regarded as the barrier layer 52 including the corrosion-resistant film.

[0064] The corrosion-resistant coating has the following effects: it prevents delamination between the barrier layer 52 (for example, aluminum alloy foil) and the base layer 51 during the forming or winding of the exterior film 50, prevents hydrogen fluoride generated by the reaction between the electrolyte and moisture from dissolving and corroding the surface of the barrier layer 52, and particularly prevents aluminum oxide present on the surface of the barrier layer 52 from dissolving and corroding when the barrier layer 52 is an aluminum alloy foil, improves the adhesion (wettability) of the surface of the barrier layer 52, prevents delamination between the base layer 51 and the barrier layer 52 during heat sealing, and prevents delamination between the base layer 51 and the barrier layer 52 during forming.

[0065] The heat-fusible resin layer 53 is bonded to the barrier layer 52 via, for example, an adhesive layer 55. The heat-fusible resin layer 53 included in the exterior film 50 is a layer that imparts heat-sealing sealability to the exterior film 50. Examples of the heat-fusible resin layer 53 include resin films composed of polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, polyolefin resins such as polyethylene resins and polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. From the perspective of sealability and strength, the thickness of the heat-fusible resin layer 53 is preferably 20 to 300 μm, and more preferably 40 to 150 μm.

[0066] The exterior film 50 preferably includes one or more layers having a buffering function (hereinafter referred to as "buffer layers") located outside the thermally fusible resin layer 53, and more preferably located outside the barrier layer 52. The buffer layer may be laminated outside the base layer 51, or the base layer 51 may also function as a buffer layer. If the exterior film 50 includes multiple buffer layers, the multiple buffer layers may be adjacent to each other or laminated with the base layer 51 or the barrier layer 52 interposed therebetween.

[0067] The material constituting the buffer layer can be arbitrarily selected from materials having buffering properties. Examples of materials having buffering properties are rubber, non-woven fabric, or foam sheet. Examples of rubber are natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the non-woven fabric is preferably a material having excellent heat resistance. In the case where the buffer layer is composed of a non-woven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and more preferably 1000 μm. In the case where the buffer layer is composed of a non-woven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and more preferably 3000 μm. The preferred range of the thickness of the buffer layer is 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm. The most preferred thickness range of the buffer layer is 1000 μm to 3000 μm.

[0068] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 1 mm to 10 mm, 1 mm to 5 mm, 1 mm to 2 mm, 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0069] When the exterior film 50 includes a buffer layer, the buffer layer functions as a shock absorber, thereby preventing the exterior film 50 from being damaged by an impact when the power storage device 10 is dropped or by handling during the manufacture of the power storage device 10 .

[0070] Figure 4 The illustrated cover 60 is, for example, a rectangular parallelepiped and is a resin molded article made of a resin material. Alternatively, the cover 60 can be formed by, for example, cold forming the exterior film 50, or can be a metal molded article. The material constituting the cover 60 can include at least two or more of a metal oxide, a carbon material, and a rubber material, or can include a metal oxide, a carbon material, and a rubber material.

[0071] The cover 60 is preferably composed of a resin material. Here, "composed of a resin material" means that, when the total mass of the material constituting the cover 60 is taken as 100 mass%, the resin material content is 50 mass% or greater, preferably 80 mass% or greater, more preferably 90 mass% or greater, and even more preferably 95 mass% or greater. In other words, the material constituting the cover 60 may contain materials other than resin.

[0072] Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified forms of these resins. Furthermore, the resin material may be a mixture of these resins, a copolymer, or a modified form of a copolymer. The resin material is preferably a heat-fusible resin such as polyester or polyolefin, with polyolefin being more preferred. When the resin material is a resin, the cover 60 may be formed using any molding method.

[0073] Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyesters. Copolyesters include those having ethylene terephthalate as a main repeating unit. Specific examples include polyester copolymers composed mainly of ethylene terephthalate and ethylene isophthalate (hereinafter referred to as poly(ethylene terephthalate / isophthalate)), poly(ethylene terephthalate / adipate), poly(ethylene terephthalate / sodium sulfoisophthalate), poly(ethylene terephthalate / sodium isophthalate), poly(ethylene terephthalate / phenyl dicarboxylate), and poly(ethylene terephthalate / sebacyl carboxylate). Among these, polybutylene terephthalate is a preferred resin material from the perspective of improving heat resistance and pressure resistance.

[0074] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes 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, and propylene. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. Among these, polypropylene is preferred due to its excellent thermal sealability and electrolyte resistance.

[0075] The resin material may contain fillers as needed. Specific examples of fillers include glass beads, graphite, glass fibers, and carbon fibers. By including such fillers in the resin material, the deformation resistance of the cover 60 to temperature changes can be improved.

[0076] The melt flow rate of the resin material included in the material constituting the cover 60 is preferably within the range of 1 g / 10 min to 80 g / 10 min, more preferably within the range of 5 g / 10 min to 60 g / 10 min. The melt flow rate is measured in accordance with JIS K7210-1:2014.

[0077] The cover 60 may also be constructed from a conductive material. "Containing a conductive material" means that, when the total mass of the material constituting the cover 60 is taken as 100%, the conductive material content is 50% by mass or greater, preferably 80% by mass or greater, more preferably 90% by mass or greater, and even more preferably 95% by mass or greater. In other words, the material constituting the cover 60 may contain materials other than the conductive material.

[0078] The conductive material constituting the cover 60 is, for example, a metal material. The metal material constituting the cover 60 is, for example, aluminum, an aluminum alloy, nickel, copper, or a copper alloy. For example, in the case where the electrode body 20 is a lithium-ion battery, the cover 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The cover 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the cover 60 connected to the negative electrode may also be copper plated with nickel. The material constituting the cover 60 may also include recycled materials of metal materials. In the case where the cover 60 is composed of a conductive material, the cover 60 also has the function of the electrode terminal 30. Since the electrode terminal 30 can be omitted from the power storage device 10, the structure of the power storage device 10 can be simplified.

[0079] In the case where the cover body 60 is composed of a conductive material, the cover body 60 can also be bonded to the outer film 50 and the barrier film 90 described later via an adhesive film. The adhesive film can be arbitrarily selected as long as it is a film that can bond the outer film 50 and the barrier film 90 to the cover body 60. The adhesive film is preferably a laminated film having at least a heat-melting resin layer, a heat-resistant base material layer and a heat-melting resin layer in this order. The specifications for the heat-melting resin layer 53 can be applied to the specifications of the heat-melting resin layer of the adhesive film. The materials constituting the heat-melting resin layers on both sides of the adhesive film can be the same material or different materials, and can be appropriately selected according to the materials constituting the heat-melting resin layers of the outer film 50 and the barrier film 90 and the materials constituting the cover body 60. The material constituting the heat-melting resin layer on the side of the adhesive film bonded to the cover body 60 is preferably an acid-modified polyolefin resin obtained by grafting and modifying with an acid such as maleic anhydride. The heat-fusible resin layer on the side of the adhesive film that is bonded to the exterior film 50 and the barrier film 90 is preferably made of the same material as that constituting the heat-fusible resin layer of the exterior film 50 and the barrier film 90 .

[0080] The heat-resistant substrate layer may be any film made of a heat-resistant resin, and examples thereof include unstretched or stretched films of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal, cyclic polyolefin, polyethylene, and polypropylene. Of these, polyethylene terephthalate is particularly preferred due to its low cost and high strength.

[0081] The adhesive film preferably has tackiness. When the second sealing portion 80 (described later) is formed with the adhesive film positioned between the barrier film 90 and the cover 60, the adhesive film is less likely to shift relative to the cover 60 and the barrier film 90. Furthermore, when the barrier film 90 and the cover 60 are bonded together with the adhesive film positioned between them, the adhesive film is less likely to shift relative to the cover 60 and the barrier film 90. Furthermore, by incorporating a tackifying resin into the heat-fusible resin layer of the adhesive film, the adhesive film can be imparted with tackiness. Examples of the tackifying resin include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene and copolymers of amorphous propylene and other α-olefins. The content of the tackifying resin relative to the base material constituting the heat-fusible resin is preferably 10 to 20% by weight or less.

[0082] The lid 60 has a first surface 61, a second surface 62, and a sealing surface 63. The first surface 61 faces the electrode assembly 20. The second surface 62 is the surface opposite the first surface 61. The sealing surface 63 is connected to the first surface 61 and the second surface 62, and is bonded to the heat-fusible resin layer 53 of the exterior film 50 via a barrier film 90 (described later).

[0083] The sealing surface 63 includes a first sealing surface 63A, a second sealing surface 63B, a third sealing surface 63C, and a fourth sealing surface 63D. The first sealing surface 63A constitutes the upper surface of the cover 60. The first sealing surface 63A extends in a first direction (in this embodiment, the LR direction) in a front view of the cover 60. The second sealing surface 63B and the third sealing surface 63C are connected to the first sealing surface 63A and constitute the side surface of the cover 60. In a front view of the cover 60, the second sealing surface 63B and the third sealing surface 63C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction. In this embodiment, when the cover 60 is viewed from the front, the first direction and the second direction are orthogonal. The first and second directions do not necessarily need to be orthogonal in a front view of the cover 60. The fourth sealing surface 63D constitutes the lower surface of the cover 60. The fourth sealing surface 63D extends in the first direction (in this embodiment, the LR direction) in a front view of the cover 60.

[0084] When the cover 60 is plate-shaped, even when the power storage device 10 is arranged in an overlapping manner, the cover 60 preferably has a certain degree of thickness to suppress deformation of the outer body 40. From another perspective, when the cover 60 is plate-shaped, the sealing surface 63 of the cover 60 preferably has a certain degree of thickness in order to properly heat-seal the sealing surface 63 of the cover 60 with the outer film 50 when forming the second sealing portion 80 described later. The minimum thickness of the cover 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum thickness of the cover 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum thickness of the cover 60 may also be 20 mm or more. The preferred thickness ranges for the material constituting the cover 60 are 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, and 4.0 mm to 10 mm. In this embodiment, when the cover 60 is described as plate-shaped, the material constituting the cover 60 does not include films specified in the JIS (Japanese Industrial Standards) "Packaging Terms" standard. Furthermore, the thickness of the cover 60 may vary depending on the location of the cover 60. If the thickness of the cover 60 varies depending on the location, the thickness of the cover 60 is the thickness of the thickest portion.

[0085] The cover body 60 also includes boundaries 64, 65, 66, and 67. Boundary 64 is the boundary between the first sealing surface 63A and the second sealing surface 63B. Boundary 65 is the boundary between the first sealing surface 63A and the third sealing surface 63C. Boundary 66 is the boundary between the fourth sealing surface 63D and the second sealing surface 63B. Boundary 67 is the boundary between the fourth sealing surface 63D and the third sealing surface 63C. The cross-sectional shape of boundaries 64 to 67 viewed from the FB direction can be angular or have rounded corners by performing R processing. In this embodiment, boundaries 64 to 67 have angular shapes.

[0086] From the perspective of achieving a good heat seal between the lid 60 and the exterior film 50, it is preferable that the material constituting the sealing surface 63 of the lid 60 and the material constituting the heat-fusible resin layer 53 of the exterior film 50 be the same as the main material. In this embodiment, the material constituting the lid 60 and the material constituting the heat-fusible resin layer 53 are mainly polypropylene. Here, the main material refers to, for example, a material that accounts for 50% or more of the materials included in the component.

[0087] In this embodiment, a through hole 60X is formed in the cover 60 for inserting the electrode terminal 30. The through hole 60X penetrates the first surface 61 and the second surface 62. When the electrode body 20 is covered by the outer film 50, the electrode terminal 30 protrudes to the outside of the outer body 40 through the through hole 60X formed in the cover 60. The small gap between the through hole 60X of the cover 60 and the electrode terminal 30 is filled with, for example, resin. In addition, in the power storage device 10, the position where the electrode terminal 30 protrudes to the outside can be selected arbitrarily. For example, the electrode terminal 30 may protrude to the outside from a hole formed on any of the six surfaces of the outer body 40. In this case, the small gap between the outer body 40 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the cover 60 and the electrode terminal 30 are provided separately, but the cover 60 and the electrode terminal 30 may also be formed integrally. When the cover 60 also functions as an electrode terminal, or when the electrode terminal 30 is disposed between the cover 60 and the exterior film 50 , the through hole 60X may not be formed in the cover 60 .

[0088] In this embodiment, with the exterior film 50 wound around the electrode assembly 20 with the opening 40A, the facing surfaces (thermo-fusible resin layers 53 ) of the exterior film 50 are heat-sealed to form the first sealing portion 70 .

[0089] The first sealing portion 70 is formed by Figure 3The portion including the first edge 50A and the portion including the second edge 50B of the outer film 50 shown are heat-sealed. The first sealing portion 70 extends in the longitudinal direction (FB direction) of the outer body 40. In the outer body 40, the position where the first sealing portion 70 is formed can be selected arbitrarily. In the present embodiment, the root 70X of the first sealing portion 70 is preferably located on the edge 43 of the boundary between the first surface 41 and the second surface 42 of the outer body 40. The area of ​​the first surface 41 is larger than the area of ​​the second surface 42. The root 70X of the first sealing portion 70 may also be located on any surface of the outer body 40. In the present embodiment, the first sealing portion 70 extends outward compared to the electrode body 20 when viewed from above. The first sealing portion 70 may be folded toward the second surface 42 of the outer body 40, or may be folded toward the first surface 41.

[0090] like Figure 5 Alternatively, as shown in Figure 6, in this embodiment, a barrier film 90 is bonded to the lid 60 to prevent at least one of moisture and gas from intruding into the interior of the exterior body 40 from between the lid 60 and the exterior film 50. In this embodiment, the barrier film 90 prevents at least one of moisture and gas from intruding into the interior of the exterior body 40. The barrier film 90 only needs to cover at least a portion of the sealing surface 63 of the lid 60. In this embodiment, the barrier film 90 covers a portion of the sealing surface 63, the entire second surface 62, and a portion of the interior of the through-hole 60X of the lid 60. The barrier film 90 may also cover the boundaries 64 to 67. By covering not only the sealing surface 63 and the boundaries 64 to 67, but also the second surface 62 and the interior of the through-hole 60X, the barrier film 90 can prevent moisture from intruding into the interior of the exterior body 40 from between the electrode terminal 30 and the through-hole 60X. The barrier film 90 may be formed of a single film, and for example, the portion covering the sealing surface 63 and the portion covering the second surface 62 may be formed separately. In other words, the barrier film 90 may be a film divided into a plurality of parts.

[0091] The position of the end 90A of the portion of the barrier film 90 covering the sealing surface 63 and the position of the end 90B of the portion covering the interior of the through-hole 60X of the lid 60 can be arbitrarily selected. When the power storage device 10 is a battery containing an electrolyte, such as a lithium-ion battery, the ends 90A and 90B of the barrier film 90 come into contact with gas such as hydrogen fluoride generated from the electrolyte, and there is a possibility that a barrier layer 91 included in the barrier film 90, which will be described later, may corrode.

[0092] Therefore, from the perspective of suppressing corrosion of the barrier layer 91, the end portion 90A is preferably located closer to the second surface 62 than the boundary between the sealing surface 63 and the first surface 61. From the same perspective, the end portion 90B is preferably located closer to the opening on the second surface 62 side than the opening on the first surface 61 side of the through-hole 60X. In addition, the end portion 90A may be located at the boundary between the sealing surface 63 and the first surface 61, or may extend to a position closer to the electrode body 20 than the cover 60. The end portion 90B may be located near the opening on the first surface 61 side of the through-hole 60X, or may extend to a position closer to the electrode body 20 than the cover 60.

[0093] Figures 7 to 9 It is a cross-sectional view showing an example of the layer structure of the barrier film 90 .

[0094] like Figure 7 As shown, the barrier film 90 only needs to include at least a barrier layer 91. The specifications for the barrier layer 91 are the same as those for the barrier layer 52 of the exterior film 50. The barrier layer 91 may be thinner than the barrier layer 52 of the exterior film 50. When the barrier film 90 comprises only a single layer of the barrier layer 91, one surface of the barrier layer 91 is bonded to the lid 60 using an adhesive or the like. When the barrier film 90 comprises only a single layer of the barrier layer 91, the other surface of the barrier layer 91 is bonded to the heat-fusible resin layer 53 of the exterior film 50 using an adhesive or the like.

[0095] like Figure 8As shown, the barrier film 90 may also include an outer layer 92 laminated on the surface of the barrier layer 91 opposite to the surface bonded to the lid 60. The outer layer 92 functions as, for example, a base layer or a heat-fusible resin layer. As a base layer, it protects the barrier layer 91. As a heat-fusible resin layer, it heat-fusibles the outer film 50 with the heat-fusible resin layer 53. When the outer layer 92 functions as a base layer, the specifications for the outer layer 92 as a base layer are the same as those for the base layer 51 of the outer film 50. When the outer layer 92 functions as a heat-fusible resin layer, the specifications for the outer layer 92 as a heat-fusible resin layer are the same as those for the heat-fusible resin layer 53 of the outer film 50. When the outer layer 92 functions as a heat-fusible resin layer, it enables good bonding with the adhesive film 31. When the outer layer 92 functions as a heat-fusible resin layer, the outer layer 92 can be thinner than the heat-fusible resin layer 53. When outer layer 92 functions as a heat-sensitive adhesive resin layer, the thickness of outer layer 92 can be, for example, 5 to 20 μm. When outer layer 92 serves as a substrate layer, barrier layer 91 is protected. When outer layer 92 serves as a substrate layer, outer layer 92 and heat-sensitive adhesive resin layer 53 are bonded together, for example, using an adhesive. When outer layer 92 serves as a heat-sensitive adhesive resin layer, heat fusion can effectively bond outer layer 92 and heat-sensitive adhesive resin layer 53. Barrier layer 91 and outer layer 92 may also be bonded together using adhesive layer 54. When outer layer 92 is adhesive to barrier layer 91, adhesive layer 54 can be omitted.

[0096] like Figure 9 As shown, the barrier film 90 may also include a heat-fusible resin layer 93 laminated on the surface of the barrier layer 91 that is bonded to the cover 60. The specifications of the heat-fusible resin layer 93 are the same as those of the heat-fusible resin layer 53 of the exterior film 50. The heat-fusible resin layer 93 may be thinner than the heat-fusible resin layer 53. The thickness of the heat-fusible resin layer 93 may be, for example, 5 to 20 μm. When the barrier film 90 includes the heat-fusible resin layer 93, the barrier film 90 and the cover 60 can be well bonded by heat welding. The barrier layer 91 and the heat-fusible resin layer 93 may also be bonded by the adhesive layer 55.

[0097] In this embodiment, the barrier film 90 is Figure 9 In the structure shown, the outer layer 92 is a heat-melting resin layer. Therefore, in this embodiment, the heat-melting resin layer 53 of the outer film 50 and the sealing surface 63 of the cover body 60 are joined via the barrier film 90 to form a second sealing portion 80. Hereinafter, the sealing strength between the heat-melting resin layer 53 of the outer film 50 and the sealing surface 63 of the cover body 60 is sometimes referred to as the sealing strength of the second sealing portion 80. In addition, the sealing strength of the second sealing portion 80 is the long side portion of the sealing surface 63, i.e., Figure 1AThe sealing strength between the heat-fusible resin layer 53 and the lid 60 on the sealing surface 63 extending in the LR (width) direction is measured.

[0098] The sealing strength of the second sealing portion 80 is measured as follows. First, a cut is made in the portion of the first surface 41 of the outer body 40 in the outer film 50 to form three strip-shaped parts 41X, 41Y, and 41Z arranged in the LR direction (see FIG. Figure 1B (Double-dashed line). The width of the three strips 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strips 41X, 41Y, and 41Z are joined to the cover 60 in the second sealing portion 80. The length of the cover 60 in the LR direction is 45 mm or longer. Next, the sealing strength of each strip 41X, 41Y, and 41Z is measured by pulling the ends of the strips 41X, 41Y, and 41Z opposite to the ends joined to the cover 60 upward in the UD direction (in the direction opposite to the first surface 41B). In this embodiment, the sealing strength of the second sealing portion 80 is the average of the sealing strengths of the strips 41X, 41Y, and 41Z. If the length of the cover 60 in the LR direction is less than 45 mm, three strips of any width X mm less than 15 mm are formed and the sealing strength of the three strips is measured using the same method as when the length of the cover 60 in the LR direction is 45 mm or longer. The obtained seal strengths are divided by an arbitrary width X mm, and then multiplied by 15 to convert the seal strengths of the three strip-shaped components to a width of 15 mm. The seal strength of the second seal portion 80 is the average of the seal strengths of the three strip-shaped components converted to a width of 15 mm. Furthermore, when the lid body 60 is divided into multiple sections containing long and short sides, the seal strength of the second seal portion 80 is the seal strength of the long side of the multiple lid seal portions 63.

[0099] From the perspective of properly maintaining the state in which the electrode body 20 is sealed by the outer casing 40, the sealing strength of the second sealing portion 80 is preferably 40 N / 15 mm or greater, more preferably 50 N / 15 mm or greater, further preferably 60 N / 15 mm or greater, further preferably 70 N / 15 mm or greater, and even further preferably 85 N / 15 mm or greater. When the sealing strength of the second sealing portion 80 is 40 N / 15 mm or greater, the state in which the electrode body 20 is sealed by the outer casing 40 can be properly maintained even if the power storage device 10 is used for, for example, several years (less than 10 years). When the sealing strength of the second sealing portion 80 is 85 N / 15 mm or greater, the state in which the electrode body 20 is sealed by the outer casing 40 can be properly maintained even if the power storage device 10 is used for, for example, more than 10 years. The sealing strength of the second sealing portion 80 is preferably 300 N / 15 mm or less. The sealing strength of the second sealing portion 80 preferably ranges from 40 N / 15 mm to 300 N / 15 mm, 50 N / 15 mm to 300 N / 15 mm, 60 N / 15 mm to 300 N / 15 mm, 70 N / 15 mm to 300 N / 15 mm, or 85 N / 15 mm to 300 N / 15 mm.

[0100] <1-2. Method for Manufacturing Power Storage Device>

[0101] Figure 10 This is a flowchart illustrating an example of a method for manufacturing the power storage device 10. The method for manufacturing the power storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, a fifth step, a sixth step, a seventh step, and an eighth step. The first through eighth steps are performed, for example, by a device for manufacturing the power storage device 10. The following names of the first through eighth steps in the method for manufacturing the power storage device 10 are given for convenience only and do not necessarily indicate the order of the steps.

[0102] In the first process of step S11 , the manufacturing apparatus insert-moldes the lid body 60 into the barrier film 90 .

[0103] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus joins the electrode terminal 30 to the cover 60 to which the barrier film 90 is joined. The second step completes the cover unit 110, in which the barrier film 90 and the electrode terminal 30 are joined to the cover 60. In other words, the first and second steps constitute the manufacturing method of the cover unit 110.

[0104] The third process of step S13 is performed before or after the second process. In the third process, the manufacturing apparatus arranges the cover unit 100 on the side of the electrode body 20 and joins the electrode terminal 30 to the electrode body 20. In addition, the manufacturing method of the power storage device 10 may replace the first to third processes, first join the electrode body 20 to the electrode terminal 30, and then join the cover body 60 to the electrode terminal 30 joined to the electrode body 20. In this modified example, the electrode terminal 30 may also protrude to the outside of the outer body 40 from between any of the sealing surfaces 63A to 63D and the outer film 50. In addition, the barrier film 90 may be joined to the cover body 60 after the cover body 60 is joined to the electrode terminal 30, or may be joined to the cover body 60 before the cover body 60 is joined to the electrode terminal 30.

[0105] The fourth process of step S14 is implemented after the third process. In the fourth process, the manufacturing device winds the outer film 50 around the electrode body 20 and the cover body 60. In the fourth process, the manufacturing device winds the outer film 50 around the electrode body 20 and the cover body 60 while limiting the movement of the electrode body 20 and the cover body 60 using a limiting unit. The limiting unit is, for example, a groove for embedding the electrode body 20 and the cover body 60. The limiting unit may also be a device that applies an external force to the electrode body 20 and the cover body 60 in a manner that does not move the electrode body 20 and the cover body 60. The limiting unit may also be a device that applies a force in a direction opposite to the direction in which the outer film 50 is stretched to the electrode body 20 and the cover body 60. In addition, in order to remove wrinkles on the outer film 50, the limiting unit may also include a roller that travels on the outer film 50 while the outer film 50 is stretched.

[0106] The fifth step, step S15, is performed after the fourth step. In the fifth step, the manufacturing apparatus forms a first sealed portion (hereinafter referred to as a "temporary first sealed portion") having an unsealed portion formed in a portion for injecting the electrolyte. If the power storage device 10 is, for example, an all-solid-state battery, the electrolyte injection step is unnecessary, so the manufacturing apparatus forms the first sealed portion 70 in the fourth step.

[0107] The sixth step of step S16 is performed after the fifth step. In the sixth step, the manufacturing apparatus heat-seals the heat-fusible resin layer 53 of the exterior film 50 and the sealing surface 63 of the lid 60 via the barrier film 90 to form the second seal portion 80 .

[0108] The seventh step of step S17 is performed after the sixth step. In the seventh step, the electrolyte is injected from the unsealed portion formed in the temporary first sealed portion. After the seventh step, an aging step and an exhaust step are performed.

[0109] The eighth step, step S18, is performed after the seventh step, the aging step, and the exhaust step are completed. In the eighth step, the manufacturing apparatus heat-seals the temporary first sealed portion, including the unsealed portion, to form the first sealed portion 70. If the power storage device 10 is, for example, an all-solid-state battery, the seventh and eighth steps are omitted.

[0110] <1-3. Functions and Effects of the Power Storage Device>

[0111] According to the power storage device 10 , the barrier film 90 covers at least a portion of the sealing surface 63 of the lid 60 , thereby suppressing the intrusion of at least one of moisture and gas from between the exterior film 50 and the lid 60 .

[0112] [2. Second embodiment]

[0113] The power storage device 200 of the second embodiment differs from the power storage device 10 of the first embodiment in that it includes a cover unit 210. The remaining configuration is the same as that of the power storage device 10 of the first embodiment. The following description of the power storage device 200 of the second embodiment focuses on the differences from the power storage device 10 of the first embodiment.

[0114] <2-1. Structure of Power Storage Device>

[0115] Figure 11 This is a partial cross-sectional view of the cover unit 210 included in the power storage device 200 of the second embodiment. In this embodiment, the barrier film 90 covers the sealing surface 63 and the boundaries 64 to 67 (see Figure 4 ), the interior of the through-hole 60X of the cover body 60, and the first surface 61 are joined to the cover body 60. The positions of the end portion 90A and the end portion 90B can be arbitrarily selected. In this embodiment, the end portion 90A is located at the boundary between the sealing surface 63 and the second surface 62. The end portion 90B is located near the opening on the second surface 62 side of the through-hole 60X. The end portion 90B may also be located in the middle of the first surface 61 and the second surface 62 in the through-hole 60X.

[0116] In the power storage device 200 of the second embodiment, the barrier film 90 covers the first surface 61 of the cover 60 facing the electrode body 20. Therefore, for example, when the power storage device 200 is a battery containing an electrolyte such as a lithium ion battery, the portion of the barrier film 90 covering the first surface 61 comes into contact with gas such as hydrogen fluoride generated from the electrolyte, which may corrode the barrier layer 91. Therefore, from the perspective of protecting the barrier layer 91, the barrier film 90 is preferably Figure 8 and Figure 9 As shown, a structure including an outer layer 92 as a base material layer is preferred.

[0117] <2-2. Functions and Effects of the Power Storage Device>

[0118] According to the power storage device 200, the barrier film 90 covers at least a portion of the sealing surface 63 of the lid 60, thereby suppressing the intrusion of at least one of moisture and gas from between the exterior film 50 and the lid 60. Furthermore, the end portions 90A and 90B are less likely to come into contact with the electrolyte, thereby suppressing corrosion of the barrier layer 91.

[0119] [3. Third embodiment]

[0120] The power storage device 300 of the third embodiment differs from the power storage device 10 of the first embodiment in that it includes a cover unit 310. The remaining configuration is the same as that of the power storage device 10 of the first embodiment. The following description of the power storage device 300 of the third embodiment focuses on the differences from the power storage device 10 of the first embodiment.

[0121] <3-1. Structure of Power Storage Device>

[0122] Figure 12 This is a partial cross-sectional view of the cover unit 310 included in the power storage device 300 of the third embodiment. In this embodiment, the barrier film 90 covers the sealing surface 63 and the boundaries 64 to 67 (see Figure 4 ), the interior of the through hole 60X of the cover body 60 and the second surface 62 are joined to the cover body 60. The positions of the end portion 90A and the end portion 90B can be selected arbitrarily. In the present embodiment, the end portion 90A is located at the boundary between the sealing surface 63 and the first surface 61. The end portion 90A may also extend to a position closer to the electrode body 20 than the cover body 60. The end portion 90B is located near the opening on the first surface 61 side of the through hole 60X. The end portion 90B may also extend to a position closer to the electrode body 20 than the through hole 60X.

[0123] In the third embodiment, when the power storage device 300 is a battery containing an electrolyte such as a lithium ion battery, the end portions 90A and 90B of the barrier film 90 come into contact with gas such as hydrogen fluoride generated from the electrolyte. Figure 8 and Figure 9 As shown, even if the barrier film 90 includes an outer layer 92 serving as a base layer, the barrier layer 91 may corrode due to contact between the end portions 90A and 90B and gases such as hydrogen fluoride. Therefore, in this embodiment, the end portions 90A and 90B are covered by a covering portion 330. The material constituting the covering portion 330 can be selected as any material as long as it can protect the end portions 90A and 90B. In this embodiment, the material constituting the covering portion 330 is a resin. Furthermore, the covering portion 330 only needs to cover at least one of the end portions 90A and 90B.

[0124] <3-2. Functions and Effects of the Power Storage Device>

[0125] According to the power storage device 300 , in addition to the effects obtained by the power storage device 10 according to the first embodiment, the following effects can be obtained.

[0126] The end portions 90A and 90B of the barrier film 90 are covered by the covering portion 330. Therefore, even when the end portions 90A and 90B of the barrier film 90 come into contact with gas such as hydrogen fluoride generated from the electrolyte, corrosion of the barrier layer 91 can be suppressed.

[0127] [4. Fourth embodiment]

[0128] The power storage device 400 of the fourth embodiment differs from the power storage device 10 of the first embodiment in that it includes a cover unit 410. The remaining configuration is the same as that of the power storage device 10 of the first embodiment. The following description of the power storage device 400 of the fourth embodiment focuses on the differences from the power storage device 10 of the first embodiment.

[0129] <4-1. Structure of Power Storage Device>

[0130] Figure 13 This is a partial cross-sectional view of a cover unit 410 included in a power storage device 400 according to the fourth embodiment. In this embodiment, the barrier film 90 is bonded to the cover 60 to cover the sealing surface 63 , the interior of the through-hole 60X, and the second surface 62 of the cover 60 .

[0131] When power storage device 10 is a battery containing an electrolyte, such as a lithium-ion battery, end 90A of barrier film 90 may come into contact with gas such as hydrogen fluoride generated from the electrolyte, corroding barrier layer 91. In this embodiment, the position of end 90A is considered to suppress corrosion of barrier layer 91.

[0132] The barrier film 90 includes a joining portion 90X joined to the sealing surface 63, and a folded portion 90Y connected to the joining portion 90X and folded back toward the second surface 62. An end 90A of the portion of the barrier film 90 that covers the sealing surface 63 is located in the folded portion 90Y. The folded portion 90Y may extend further outward than the lid 60 in the FB direction. In this embodiment, the barrier layer 91 or the heat-fusible resin layer 93 of the folded portion 90Y of the barrier film 90 is joined to the heat-fusible resin layer 53 of the outer film 50.

[0133] The position of the end portion 90B can be selected arbitrarily. In the present embodiment, the end portion 90B is located inside the through-hole 60X. Therefore, it is possible to suppress the end portion 90B from contacting gases such as hydrogen fluoride. The end portion 90B may also be located at a position closer to the opening on the second side 62 side than the opening on the first side 61 side of the through-hole 60X. The end portion 90B may also be located at a position closer to the opening on the first side 61 side than the opening on the second side 62 side of the through-hole 60X. The end portion 90B may be located near the opening on the first side 61 side of the through-hole 60X, or may extend to a position closer to the electrode body 20 than the cover 60. The end portion 90B may also be located outside the through-hole 60X on the second side 62 side. In the case where the end portion 90B is located outside the through-hole 60X on the second side 62 side, the portion of the barrier film 90 located outside the through-hole 60X may also be bent.

[0134] <4-2. Functions and Effects of the Power Storage Device>

[0135] According to the power storage device 400 , in addition to the effects obtained by the power storage device 10 according to the first embodiment, the following effects can be obtained.

[0136] Since the end portion 90A is located in the folded portion 90Y folded back toward the side opposite to the electrode body 20 , the end portion 90A can be prevented from coming into contact with a gas such as hydrogen fluoride. Therefore, corrosion of the barrier layer 91 can be suppressed.

[0137] [5. Fifth embodiment]

[0138] The power storage device 500 of the fifth embodiment differs from the power storage device 10 of the first embodiment in that it includes a cover unit 510. The remaining configuration is the same as that of the power storage device 10 of the first embodiment. The following description of the power storage device 500 of the fifth embodiment focuses on the differences from the power storage device 10 of the first embodiment.

[0139] <5-1. Structure of Power Storage Device>

[0140] Figure 14 This is a partial cross-sectional view of a cover unit 510 included in an electricity storage device 500 according to Embodiment 5. In this embodiment, the barrier film 90 is bonded to the cover 60 so as to cover a portion of the sealing surface 63 and the interior of the through-hole 60X of the cover 60 .

[0141] The barrier film 90 includes an inner portion 90Z disposed within at least a portion of the interior of the lid 60. The inner portion 90Z is the portion between a portion of the sealing surface 63 and the portion covering the interior of the through-hole 60X of the lid 60. The lid unit 510 of this embodiment can be manufactured, for example, by insert-molding the barrier film 90 within the lid 60.

[0142] The positions of the end portion 90A and the end portion 90B can be selected arbitrarily. As in the first embodiment, from the viewpoint of suppressing the corrosion of the barrier layer 91, it is preferred that the end portion 90A is located closer to the second surface 62 than the boundary between the sealing surface 63 and the first surface 61. The end portion 90A may be located at the boundary between the sealing surface 63 and the first surface 61, or it may extend to a position closer to the electrode body 20 than the cover 60. From the same viewpoint, the end portion 90B is preferably located closer to the opening on the second surface 62 side than the opening on the first surface 61 side in the through hole 60X. The end portion 90B may be located near the opening on the first surface 61 side in the through hole 60X, or it may extend to a position closer to the electrode body 20 than the cover 60.

[0143] <5-2. Functions and Effects of the Power Storage Device>

[0144] According to the power storage device 500 , it is possible to obtain effects based on the effects obtained by the power storage device 10 according to the first embodiment.

[0145] [6. Sixth embodiment]

[0146] The power storage device 600 of the sixth embodiment differs from the power storage device 10 of the first embodiment in that it includes a cover unit 610. The remaining configuration is the same as that of the power storage device 10 of the first embodiment. The following description of the power storage device 600 of the sixth embodiment focuses on the differences from the power storage device 10 of the first embodiment.

[0147] <6-1. Structure of Power Storage Device>

[0148] Figure 15 This is a cross-sectional view of a power storage device 600 according to a sixth embodiment. In this embodiment, the heat-fusible resin layer 53 of the exterior film 50 is bonded to the sealing surface 63 of the lid 60. The exterior film 50 has a folded-back portion 50X that is connected to the portion bonded to the sealing surface 63 of the lid 60 and folded back toward the electrode body 20. The folded-back portion 50X covers the lid 60. The barrier film 90 is bonded to the exterior film 50 on the outside of the exterior film 50 so as to cover the sealing surface 63. In this embodiment, the barrier film 90 covers the sealing surface 63, the boundaries 64 to 67, the second surface 62, and the electrode terminal 30. The end 90A of the portion of the barrier film 90 covering the sealing surface 63 is located, for example, on the folded-back portion 50X. The end 90A may not be located on the folded-back portion 50X.

[0149] <6-2. Functions and Effects of the Power Storage Device>

[0150] According to the power storage device 600 , in addition to the effects obtained by the power storage device 10 according to the first embodiment, the following effects can be obtained.

[0151] The barrier film 90 is bonded to the lid 60 via the exterior film 50, covering the sealing surface 63 on the outside of the exterior film 50. Therefore, the end 90A is located outside the exterior film 50. This prevents the end 90A from coming into contact with gases such as hydrogen fluoride, thereby suppressing corrosion of the barrier layer 91.

[0152] [7. Modifications]

[0153] The above-described embodiments are examples of possible methods of manufacturing the power storage device, barrier film, cover unit, and power storage device of the present invention, and are not intended to limit the methods. The power storage device, barrier film, cover unit, and power storage device manufacturing method of the present invention may be implemented in a manner different from that illustrated in the embodiments. One example is a method of replacing, changing, or omitting a portion of the structure of the embodiment, or a method of adding a new structure to the embodiment. Several examples of variations of the embodiment are shown below. In addition, the following variations can be combined with each other as long as they are not technically inconsistent.

[0154] <7-1>

[0155] In the electricity storage device 10 of the first embodiment, the barrier film 90 may cover the electrode terminal 30. This modification is also applicable to the electricity storage devices 200, 300, 400, and 500 of the second to fifth embodiments.

[0156] <7-2>

[0157] The manufacturing method of the power storage device 10 of the first embodiment can be modified arbitrarily. For example, in the first process of step S11, the cover body 60 and the barrier film 90 may be prepared in advance, and the barrier film may be bonded to the cover body 60. In the first example of this modification, for example, it is preferable to form folds in the barrier film 90 corresponding to the first surface 61 and each sealing surface 63A to 63D of the covered surface of the cover body 60. When the barrier film 90 is folded, the cover body 60 and the barrier film 90 can be easily and tightly adhered to each other. In the second example of this modification, a recess may be formed in the pre-prepared barrier film 90, the pre-prepared cover body 60 may be accommodated in the recess, and the barrier film 90 and the cover body 60 may be bonded.

[0158] <7-3>

[0159] In the electricity storage device 10 of the first embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover the first surface 61 of the cover 60. In the electricity storage device 200 of the second embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover the second surface 62 of the cover 60. In the electricity storage device 300 of the third embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover the first surface 61 of the cover 60. In the electricity storage device 400 of the fourth embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover the first surface 61 of the cover 60. In the electricity storage device 500 of the fifth embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover at least one of the first surface 61 and the second surface 62 of the cover 60. In the electricity storage device 600 of the sixth embodiment, the barrier film 90 may be bonded to the cover 60 so as to cover the first surface 61 of the cover 60.

[0160] <7-4>

[0161] In the power storage device 10 of the first embodiment, the position of the electrode terminal 30 can be arbitrarily selected. For example, the electrode terminal 30 may protrude from at least one of the first sealing portion 70 and the second sealing portion 80. This modification is also applicable to the power storage devices 200, 300, 400, 500, and 600 of the second to sixth embodiments.

[0162] [8. Example]

[0163] <8-1. First Test>

[0164] The inventors of the present application conducted a first test to confirm the water vapor barrier properties of the power storage devices of Examples 1 and 2 and Comparative Examples 1 and 2. For ease of description, the elements constituting the power storage devices of the Examples and Comparative Examples that are identical to those in the embodiment are denoted by the same reference numerals as in the embodiment.

[0165] The power storage devices of Examples 1 and 2 have a similar structure to the power storage device of the first embodiment. They include a dummy electrode assembly in place of electrode assembly 20. They do not include electrode terminals 30. The specifications of the power storage devices of Examples 1 and 2 are as follows.

[0166] The barrier film is a laminated film composed of a first outer layer, a barrier layer, and a second outer layer laminated in this order. The first and second outer layers are made of unstretched polypropylene. The barrier layer is made of aluminum. The thickness of the first and second outer layers is 60 μm. The thickness of the barrier layer is 80 μm. The first and barrier layers are bonded together by dry lamination. The second outer layer and barrier layer are also bonded together by dry lamination.

[0167] The cover 60 is made of polypropylene and has a length (height) of 30 mm in the UD direction, a length (width) of 100 mm in the LR direction, and a length (thickness) of 5 mm in the FB direction.

[0168] The power storage devices of Examples 1 and 2 are manufactured by injection molding a cover 60 onto a barrier film placed in a mold. In the power storage device of Example 1, the exterior film 50 entirely covers the second surface 62 and sealing surface 63 of the cover 60. In the power storage device of Example 2, the exterior film 50 entirely covers the first surface 61 and sealing surface 63 of the cover 60.

[0169] The energy storage device of Comparative Example 1 has the same structure as the energy storage device of Example 1 or Example 2, except that it lacks a barrier film. The energy storage device of Comparative Example 2 has the same structure as the energy storage device of Example 1, except that the barrier film is bonded only to the second surface 62 of the lid 60, and the layer structure of the barrier film. The first outer layer of the barrier film in the energy storage device of Comparative Example 2 is made of a laminate of polyethylene terephthalate and nylon. The polyethylene terephthalate layer in the first outer layer is 12 μm thick, and the nylon layer is 25 μm thick. The barrier layer of the barrier film in the energy storage device of Comparative Example 2 is made of aluminum. The thickness of the barrier layer is 40 μm. The second outer layer of the barrier film in the energy storage device of Comparative Example 2 is made of polypropylene. The thickness of the second outer layer is 80 μm. The second outer layer of the energy storage device of Comparative Example 2 is bonded to the second surface 62 of the lid 60. In the power storage device of Comparative Example 2, the barrier film was not bonded to the sealing surface 63 of the lid 60. In the power storage device of Comparative Example 2, the first outer layer or the second outer layer was in contact with the second surface 62 of the lid 60, and then the layers were held at 180°C under vacuum for 60 seconds, and then bonded by applying pressure at 5 kN for 15 seconds.

[0170] The energy storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured by wrapping an exterior film 50 around two lids 60 and a dummy electrode assembly to form a first sealing portion 70 and a second sealing portion 80. The sealing conditions for the first sealing portion 70 were a temperature of 220°C, a surface pressure of 1.1 MPa, and a duration of 7 seconds. The sealing conditions for the second sealing portion 80 were a temperature of 180°C, a surface pressure of 0.78 MPa, and a duration of 5 seconds. The exterior film 50 had a width of 160 mm and a length of 300 mm.

[0171] Next, the energy storage devices of Examples 1 and 2, as well as Comparative Examples 1 and 2, were cut in the center along the FB direction. 20 g of salt-free electrolyte was introduced through the resulting opening, and the opening was sealed to form an opening seal. The salt-free electrolyte used was Purelight (manufactured by Ube Industries), with EC:DMC:DEC = 1:1:1 = (v / v / v). The opening seal was formed 70 to 80 mm from the outer end of the lid 60 in the FB direction. The width of the opening seal was 10 mm. The opening seal was formed by heat-sealing twice using a 7 mm wide heat seal strip, offset by 3 mm. The sealing conditions for the opening seal were a temperature of 190°C, a surface pressure of 1 MPa, and a time of 5 seconds.

[0172] Next, the power storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 with the opening sealed portions formed therein were stored in a constant temperature and humidity layer for 7 days with the lid 60 facing downward. The constant temperature and humidity layer had a temperature of 65° C. and a relative humidity of 90%.

[0173] Next, the power storage devices of Examples 1 and 2, as well as Comparative Examples 1 and 2, were removed from the constant temperature and humidity chamber and cooled at room temperature for 2 hours. A 0.5 ml sample of the liquid was then taken using a Karl Fischer moisture analyzer in a drying chamber to measure the moisture content and calculate the water permeation rate. An example of a Karl Fischer moisture analyzer is a moisture vaporizer ADP-611 (manufactured by Kyoto Electronics Co., Ltd.). The calculated water permeation rate is per cover 60.

[0174] The water permeation rate of the power storage device of Example 1 was 1.18 mg. The water permeation rate of the power storage device of Example 2 was 0.711 mg. The water permeation rate of the power storage device of Comparative Example 1 was 25.5 mg. The water permeation rate of the power storage device of Comparative Example 2 was 3.85 mg. The results of the first test confirmed that the water permeation rate was reduced by placing a barrier film on the sealing surface 63 of the cover 60. Furthermore, the results of Examples 1 and 2 confirmed that the water permeation rate was reduced when the barrier film was placed on the first surface 61 of the cover 60, compared to the second surface 62 of the cover 60.

[0175] <8-2. Second Test>

[0176] The inventors of the present application conducted a second test to confirm the insulation and corrosive properties of the barrier film on the power storage devices of Examples 3 and 4. For ease of description, the elements constituting the power storage devices of Examples and Comparative Examples that are identical to those in the embodiment are denoted by the same reference numerals as in the embodiment.

[0177] The energy storage device of Example 3 has the same structure as that of Example 1. The energy storage device of Example 4 has the same structure as that of Example 2. In the energy storage device of Example 3, the outermost layer (first outer layer or second outer layer) of the barrier film in contact with the second surface 62 of the lid 60 is scraped off to expose the barrier layer. The sealing conditions for the first sealing portion 70 of the energy storage devices of Examples 3 and 4 are a temperature of 220°C, a surface pressure of 1.1 MPa, and a duration of 7 seconds. The sealing conditions for the second sealing portion 80 are a temperature of 180°C, a surface pressure of 1.56 MPa, and a duration of 7 seconds.

[0178] After the electricity storage devices of Examples 3 and 4 were manufactured, they were cut at the center in the FB direction to form an opening. The barrier layer 52 of the exterior film 50 exposed in the opening was covered with an insulating tape.

[0179] Next, for the energy storage device of Example 3, the exposed barrier layer was bonded to one end of the lead wire using solder and conductive adhesive (Dotite). The junction between the barrier layer and the lead wire was protected with insulating tape. For the energy storage device of Example 4, the ridgeline of the second sealing portion 80 was cut with a cutter to expose end 90A of the barrier film. This exposed end 90A was then bonded to the end of one lead wire using conductive adhesive (Dotite). The junction between end 90A and the lead wire was protected with insulating tape. The conductive adhesive (Dotite) used in the second test was DOTITE D-500 (manufactured by Fujikura Chemicals, Ltd.).

[0180] <8-2-1. Confirmation of insulation properties>

[0181] Approximately 15-20 ml of acetone (enough to immerse the entire lid 60) was injected through the opening of the power storage devices of Examples 3 and 4 and allowed to stand for approximately 1 minute. Next, the other end of the lead wire bonded to the barrier layer of the barrier film of the power storage devices of Examples 3 and 4 was connected to one terminal fixture of a resistance meter. A rod-shaped terminal was used as the other terminal of the resistance meter and immersed in acetone. The acetone used in the second test had a purity of 99.8%. For example, the resistance meter was a 3154 Digital MΩ HiTESTER (manufactured by Hioki Electric Co., Ltd.).

[0182] Next, the resistance value was measured at an applied voltage of 100 V. The resistance value of the power storage device of Example 3 was 4.2 MΩ. The resistance value of the power storage device of Example 4 was overflow. It was confirmed that the power storage device of Example 3 had higher insulation properties of the barrier film than the power storage device of Example 4.

[0183] <8-2-2. Confirmation of Corrosiveness>

[0184] 100 g of salt-containing electrolyte was injected through the opening of the power storage device of Examples 3 and 4. A lithium disk electrode was then placed, and the opening was sealed with tape. The cathode of an electrochemical measuring device was then connected to the lithium disk electrode, and the anode of the electrochemical measuring device was connected to the other end of the lead wire. An example of an electrochemical measuring device is a VMP3 (manufactured by BioLogic). After 5 minutes of OCV (open circuit voltage), chronoamperometry was performed under the following conditions, and the current flowing for 1200 minutes was accumulated.

[0185] •Set voltage: 0.100V (vs. Ref)

[0186] •Test time: 24 hours

[0187] The cumulative value of the corrosion current of the power storage device of Example 3 up to 1200 minutes was 13.6 C. The cumulative value of the corrosion current of the power storage device of Example 4 up to 1200 minutes was 9.6×10 -4 C. In the electricity storage device of Example 4, it was confirmed that the corrosion of the barrier film was suppressed compared with the electricity storage device of Example 3. That is, it was confirmed that the electricity storage device 10 of Example 4 was able to suppress the corrosion of the barrier film.

[0188] An example of a procedure for confirming the corrosiveness of the barrier film on the finished power storage device 10 is described below.

[0189] First, the electricity storage device 10 is disassembled, and the electrode terminals 30 are cut to separate the electrode assembly 20 from the lid 60. At this point, when the lid 60 is positioned with the second surface 62 as the bottom surface, the exterior film 50 should remain at least 1.5 cm above the sealing surface 63 in the height direction. The end surfaces of the cut exterior film 50 are covered with insulating tape.

[0190] Next, similarly to the case of the power storage device of Example 3 or the power storage device of Example 4, the barrier layer is exposed by cutting or the like, and the exposed barrier layer is connected to one end of the lead wire.

[0191] The sample prepared as described above is placed in a glass container with the second surface 62 of the lid 60 as the bottom surface. The electrolyte is injected to a depth of approximately 1 cm from the first surface 61 of the lid 60. Next, a lithium disk electrode is placed on the sample. The cathode of an electrochemical measuring device is connected to the lithium disk electrode. The anode of the electrochemical measuring device is connected to the other end of a wire. Chronoamperometry is then performed to confirm the corrosiveness of the barrier film.

[0192] Description of Reference Numerals

[0193] 10, 200, 300, 400, 500, 600: Power storage device

[0194] 20: Electrode body

[0195] 30: Electrode terminal

[0196] 40: Exterior body

[0197] 40A: Opening

[0198] 50: Exterior film

[0199] 60: Cover

[0200] 61: Side 1

[0201] 62: Side 2

[0202] 63: Sealing surface

[0203] 90: Barrier film

[0204] 90A: End

[0205] 92: Outer layer

[0206] 110, 210, 310, 410, 510, 610: Cover unit

[0207] 330: Covering part.

Claims

1. A power storage device, characterized in that: include: Electrode body; an outer body for sealing the electrode body; and Barrier films, The outer body comprises: an outer film covering the electrode body so as to form an opening; and a cover body disposed at the opening, The cover has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface. The barrier film is joined to the lid so as to cover at least a portion of the sealing surface.

2. The power storage device according to claim 1, wherein: The barrier film is joined to the cover so as to cover at least a portion of the first surface.

3. The power storage device according to claim 1 or 2, wherein: The barrier film includes a barrier layer and an outer layer laminated on the opposite side of the cover relative to the barrier layer.

4. The power storage device according to claim 2, wherein: The barrier film includes a barrier layer and an outer layer laminated on the opposite side of the cover relative to the barrier layer. In the barrier film, the portion covering at least a portion of the sealing surface is connected to the portion covering at least a portion of the first surface, and the end portion is located in the portion covering at least a portion of the sealing surface.

5. The power storage device according to claim 1, wherein: The barrier film is joined to the cover so as to cover at least a portion of the second surface.

6. The power storage device according to claim 5, wherein: In the barrier film, The portion covering at least a portion of the sealing surface is connected to the portion covering at least a portion of the second surface, The end portion is covered by the covering portion.

7. The power storage device according to claim 1, wherein: The end portion of the barrier film is located in a portion covering at least a portion of the sealing surface and is located closer to the second surface than to a boundary between the first surface and the sealing surface.

8. The power storage device according to claim 1, wherein: The barrier film has a portion connected to a portion joined to the cover and folded back toward the second surface. The end portion of the barrier film is located at the portion folded back toward the second surface.

9. The power storage device according to claim 1 or 2, wherein: It also includes an electrode terminal electrically connected to the electrode body, The cover is configured to cover a portion of the electrode terminal. The barrier film is disposed at least partially between the cover and the electrode terminal.

10. The power storage device according to claim 1 or 2, wherein: The barrier film is disposed on at least a portion of the interior of the cover.

11. The power storage device according to claim 1 or 5, wherein: The barrier film is bonded to the exterior film so as to cover at least a portion of the sealing surface at a position outside the exterior film.

12. A cover unit for an electric storage device, characterized in that: The power storage device includes an electrode body and an exterior film covering the electrode body so as to form an opening. The cover unit comprises: a cover disposed at the opening; and Barrier films, The cover body has a first surface, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface. The barrier film is joined to the lid so as to cover at least a portion of the sealing surface.

13. The cover unit according to claim 12, wherein: An electrode terminal capable of being engaged with the cover is also included.

14. A barrier film, characterized in that: The invention can be used in the power storage device according to claim 2 or 5.

15. A barrier film, characterized in that: The cover unit can be used in the cover unit according to claim 12.

16. A method for manufacturing a cover unit for an electricity storage device, characterized in that: The power storage device includes an electrode body and an exterior film covering the electrode body so as to form an opening. The cover unit comprises: a cover disposed at the opening; and Barrier films, The cover has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface. The barrier film is joined to the cover so as to cover at least a portion of the sealing surface. The method for manufacturing the cover unit includes insert-molding the cover body onto the barrier film.

17. A method for manufacturing a cover unit for an electricity storage device, characterized in that: The power storage device includes an electrode body and an exterior film covering the electrode body so as to form an opening. The cover unit comprises: a cover disposed at the opening; and Barrier films, The cover has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connected to the first surface and the second surface. The barrier film is joined to the cover so as to cover at least a portion of the sealing surface. The method for manufacturing the cover unit includes the step of bonding the barrier film to the cover body.

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