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

Abstract

To provide a power storage device capable of suppressing intrusion of at least one of moisture and gas into the power storage device, a barrier film used for the power storage device, a lid unit used for the power storage device, and a method of manufacturing the lid unit.SOLUTION: The power storage device includes an electrode body, an exterior body that seals the electrode body, and a barrier film. The exterior body includes an exterior film that wraps the electrode body such that an opening is formed, and a lid body disposed in the opening. The lid has a first surface facing the electrode assembly, 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 body so as to cover at least a part of the seal surface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device, a barrier film, a lid unit, and a method for manufacturing the lid unit. [Background technology]

[0002] Patent Document 1 discloses an all-solid-state battery as an example of an electricity storage device. This all-solid-state battery includes an electrode assembly and an exterior body that seals the electrode assembly. The exterior body includes an exterior film that is wrapped around the electrode assembly to have an opening, and a lid that is placed on the opening. The surfaces of the exterior film that face each other are heat-sealed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-153504 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described electricity storage device, moisture and gas may enter the inside through the gap between the lid and the exterior film. Therefore, the above-described electricity storage device still has room for improvement in terms of suppressing the intrusion of moisture and gas.

[0005] The present invention aims to provide an electricity storage device that can suppress the intrusion of at least one of moisture and gas, a barrier film used in this electricity storage device, a lid unit used in this electricity storage device, and a method for manufacturing the lid unit. [Means for solving the problem]

[0006] An energy storage device according to a first aspect of the present invention comprises an electrode body, an exterior body that seals the electrode body, and a barrier film, wherein the exterior body includes an exterior film that wraps the electrode body so as to form an opening, and a lid body that is placed in the opening, wherein the lid body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface that connects the first surface and the second surface, and the barrier film is joined to the lid body so as to cover at least a portion of the sealing surface.

[0007] An electricity storage device according to a second aspect of the present invention is the electricity storage device according to the first aspect, wherein the barrier film is bonded to the lid so as to cover at least a part of the first surface.

[0008] In the electricity storage device according to a third aspect of the present invention, the barrier film includes a barrier layer and an outer layer laminated on the side of the barrier layer opposite to the lid.

[0009] A fourth aspect of the present invention is an electricity storage device according to the second aspect, wherein the barrier film includes a barrier layer and an outer layer laminated on the opposite side of the barrier layer from the lid, and a portion covering at least a portion of the sealing surface and a portion covering at least a portion of the first surface are connected, and an end portion is located in the portion covering at least a portion of the sealing surface.

[0010] An electricity storage device according to a fifth aspect of the present invention is the electricity storage device according to any one of the first to third aspects, wherein the barrier film is bonded to the lid so as to cover at least a part of the second surface.

[0011] An electricity storage device according to a sixth aspect of the present invention is the electricity storage device according to the fifth aspect, wherein the barrier film has a portion covering at least a part of the sealing surface and a portion covering at least a part of the second surface that are connected together, and the ends are covered by covering portions.

[0012] An electricity storage device according to a seventh aspect of the present invention is the electricity storage device according to the first aspect, wherein the end of the barrier film is located in a portion that covers at least a part of the sealing surface and is located closer to the second surface than the boundary between the first surface and the sealing surface.

[0013] An eighth aspect of the present invention is an electricity storage device according to the first aspect, wherein the barrier film has a portion that is connected to the portion that is joined to the lid and that is folded back toward the second surface, and an end of the barrier film is located in the portion that is folded back toward the second surface.

[0014] An electricity storage device according to a ninth aspect of the present invention is the electricity storage device according to any one of the first to eighth aspects, further comprising an electrode terminal electrically connected to the electrode body, the lid body being configured to cover a portion of the electrode terminal, and the barrier film being disposed at least partially between the lid body and the electrode terminal.

[0015] An electricity storage device according to a tenth aspect of the present invention is the electricity storage device according to any one of the first to eighth aspects, wherein the barrier film is disposed in at least a part of the inside of the lid.

[0016] An electricity storage device according to an eleventh aspect of the present invention is the electricity storage device according to any one of the first to tenth aspects, wherein the barrier film is joined to the exterior film so as to cover at least a portion of the sealing surface outside the exterior film.

[0017] A twelfth aspect of the present invention provides a lid unit for use in an electricity storage device comprising an electrode body and an exterior film that wraps the electrode body so as to form an opening, the lid unit comprising a lid body that is placed in the opening, and a barrier film, the lid body having a first surface, a second surface opposite the first surface, and a sealing surface that connects the first surface and the second surface, and the barrier film is joined to the lid body so as to cover at least a portion of the sealing surface.

[0018] A lid unit according to a thirteenth aspect of the present invention is the lid unit according to the twelfth aspect, further comprising an electrode terminal joined to the lid body.

[0019] A barrier film according to a fourteenth aspect of the present invention is used in an electricity storage device according to any one of the first to eleventh aspects.

[0020] The barrier film according to the fifteenth aspect of the present invention is used in the lid unit according to the twelfth or thirteenth aspect.

[0021] A sixteenth aspect of the present invention relates to a method for manufacturing a lid unit for use in an electricity storage device including an electrode assembly and an exterior film that encases the electrode assembly so as to form an opening. The lid unit includes a lid body to be placed in the opening, and a barrier film, the lid body having a first surface facing the electrode assembly, a second surface opposite the first surface, and a sealing surface connecting the first surface and the second surface, and the barrier film is joined to the lid body so as to cover at least a portion of the sealing surface. The method for manufacturing the lid unit includes the step of insert-molding the lid body into the barrier film.

[0022] A seventeenth aspect of the present invention relates to a method for manufacturing a lid unit for use in an electricity storage device including an electrode assembly and an exterior film that encases the electrode assembly so as to form an opening. The lid unit includes a lid body to be placed in the opening, and a barrier film, the lid body having a first surface facing the electrode assembly, a second surface opposite the first surface, and a sealing surface connecting the first surface and the second surface, and the barrier film is joined to the lid body so as to cover at least a portion of the sealing surface. The method for manufacturing the lid unit includes the step of joining the barrier film to the lid body. [Effects of the Invention]

[0023] The electricity storage device, the barrier film used in the electricity storage device, the lid unit used in the electricity storage device, and the method for manufacturing the electricity storage device according to the present invention can prevent at least one of moisture and gas from penetrating into the interior of the electricity storage device. [Brief explanation of the drawings]

[0024] [Figure 1A] FIG. 1 is a plan view schematically showing an electricity storage device according to a first embodiment. [Figure 1B] 1B is a diagram showing a method for measuring the seal strength of the second sealing portion of the electricity storage device in FIG. 1A. FIG. [Figure 2] 1B is a cross-sectional view showing an example of a layer structure of an exterior film included in the electricity storage device of FIG. 1A. [Figure 3] FIG. 1B is a diagram showing the state in which the exterior film provided on the electricity storage device of FIG. 1A is unfolded. [Figure 4] FIG. 1B is a perspective view of a lid provided in the electricity storage device of FIG. 1A. [Figure 5] 1B is a cross-sectional view taken along line D5-D5 in FIG. 1A. [Figure 6] FIG. 6 is a partial cross-sectional view of the lid unit of FIG. 5. [Figure 7] 1B is a cross-sectional view showing an example of the layer structure of a barrier film included in the electricity storage device of FIG. 1A. [Figure 8] FIG. 1B is a cross-sectional view showing another example of the layer structure of the barrier film included in the electricity storage device of FIG. 1A. [Figure 9] FIG. 1B is a cross-sectional view showing yet another example of the layer structure of the barrier film included in the electricity storage device of FIG. 1A. [Figure 10] 1B is a flowchart showing an example of a manufacturing process for the electricity storage device of FIG. 1A. [Figure 11] FIG. 10 is a partial cross-sectional view of a lid unit included in an electricity accumulation device according to a second embodiment. [Figure 12] FIG. 11 is a partial cross-sectional view of a lid unit included in an electricity accumulation device according to a third embodiment. [Figure 13] FIG. 10 is a partial cross-sectional view of a lid unit included in an electricity accumulation device according to a fourth embodiment. [Figure 14] FIG. 11 is a partial cross-sectional view of a lid unit included in an electricity accumulation device according to a fifth embodiment. [Figure 15] FIG. 13 is a cross-sectional view of an electricity storage device according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an electricity storage device according to one embodiment of the present invention will be described with reference to the drawings. In this specification, a numerical range indicated by "to" means "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0026] [1. First embodiment] <1-1. Configuration of the power storage device> FIG. 1A is a plan view schematically showing an electricity storage device 10 of a first embodiment. FIG. 1B is a diagram relating to a method for measuring the seal strength of a second sealing portion 80 of the electricity storage device 10. FIG. 2 is a cross-sectional view showing the layer structure of an exterior film 50 included in the electricity storage device 10 of FIG. 1A. FIG. 3 is a view showing the exterior film 50 included in the electricity storage device 10 of FIG. 1A in an unfolded state. FIG. 4 is a perspective view of a lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 5 is a cross-sectional view taken along line D5-D5 in FIG. 1A. FIG. 6 is a partial cross-sectional view of the lid unit 110 of FIG. 5. In FIG. 1A, the direction of arrow UD indicates the thickness direction of the electricity storage device 10, the direction of arrow LR indicates the width direction of the electricity storage device 10, and the direction of arrow FB indicates the depth direction of the electricity storage device 10. The directions indicated by the arrows UD, LR, and FB are common to the subsequent figures.

[0027] The electricity storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes electrodes (positive and negative electrodes) constituting an electricity storage member such as a lithium-ion battery, a capacitor, an all-solid-state battery, a semi-solid battery, a quasi-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 oxide-zinc battery, a metal-air battery, a polycation battery, or a capacitor, as well as a separator. In this embodiment, the electrode body 20 has a substantially rectangular parallelepiped shape. Note that the term "substantially rectangular parallelepiped" includes not only a perfect rectangular parallelepiped, but also a solid that can be considered a rectangular parallelepiped by modifying the shape of a portion of its outer surface, for example. The electrode body 20 may have a cylindrical or polygonal prism shape, for example.

[0028] In this embodiment, the electricity storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting electric power to and from the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from, for example, an edge of the exterior body 40. Note that the electrode terminal 30 may be any terminal as long as it is capable of inputting and outputting electric power to and from the electrode body 20, and may not, for example, protrude from the exterior body 40. When the lid body 60 described below is made of, for example, metal, the lid body 60 may also function as the electrode terminal 30. In this case, the lid body 60, which functions as an electrode terminal, may or may not protrude from the exterior body 40.

[0029] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, etc. For example, when the electrode body 20 is a lithium ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum, etc., and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, etc. Note that the outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator.

[0030] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a lid 60. The exterior film 50 wraps the electrode body 20 so as to have an opening 40A. In this embodiment, the exterior film 50 is wrapped around the electrode body 20 so as to have the opening 40A. The lid 60 is placed on the side of the electrode body 20 so as to close the opening 40A. Note that the electrode body 20 may be housed inside the exterior film 50 that is configured in a cylindrical shape so as to form the opening 40A, and the opening 40A may be closed by the lid 60.

[0031] An adhesive film 31 is preferably bonded to the electrode terminal 30 from the viewpoint of favorable adhesion to the lid 60. The adhesive film 31 can be any film that can bond the metal electrode terminal 30 and the resin lid 60. For example, the adhesive film 31 can be a polyolefin resin such as a polyethylene resin or a polypropylene resin, a cyclic polyolefin resin, or an acid-modified polyolefin resin obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single-layer film or a film of two or more layers. In this embodiment, the adhesive film 31 is bonded to substantially the entire portion of the electrode terminal 30 that is covered by the lid 60.

[0032] For example, there is a method of forming a storage portion (recess) in the exterior film 50 through cold forming to store the electrode assembly 20. However, it is not necessarily easy to form a deep storage portion using this method. Attempting to form a deep storage portion (recess) through cold forming (for example, a forming depth of 15 mm) increases the likelihood of pinholes or cracks occurring in the exterior film 50, resulting in a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode assembly 20 by wrapping the exterior film 50 around the electrode assembly 20, and therefore can easily seal the electrode assembly 20 regardless of the thickness of the electrode assembly 20. Note that in order to reduce the dead space between the electrode assembly 20 and the exterior film 50 and improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 be wrapped so as to contact the outer surface of the electrode assembly 20. Furthermore, in all-solid-state batteries, it is necessary to apply a high pressure uniformly from the outer surface of the battery to maximize battery performance, so it is necessary to eliminate the space between the electrode assembly 20 and the exterior film 50. Therefore, it is preferable that the exterior film 50 be wrapped so as to contact the outer surface of the electrode assembly 20.

[0033] The exterior film 50 is, for example, a laminate (laminate film) having a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The exterior film 50 may be formed by laminating the heat-sealable resin layer 53, the base material layer 51, the barrier layer 52, and the heat-sealable resin layer 53 in this order. The exterior film 50 may be formed by laminating the heat-sealable resin layer 53, the barrier layer 52, and the heat-sealable resin layer 53 in this order. Note that the exterior film 50 does not need to include all of these layers; for example, it may not include the barrier layer 52. In other words, the exterior film 50 may be formed by any material that is flexible and easily bendable, and may be formed by, for example, a resin film. Note that the exterior film 50 is preferably heat-sealable.

[0034] The substrate layer 51 included in the exterior film 50 is a layer that imparts heat resistance to the exterior film 50 and prevents pinholes from occurring during processing or distribution. The substrate layer 51 is composed of, for example, at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer in the substrate layer 51, the barrier layer 52 can be protected during processing of the exterior film 50, and breakage of the exterior film 50 can be prevented. Furthermore, from the viewpoint of increasing 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, from the viewpoint of excellent puncture strength or 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. The substrate layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0035] The barrier layer 52 is a layer that prevents at least moisture from penetrating. The barrier layer 52 is bonded to the base layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foils, vapor-deposited films, and resin layers with barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Other 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 be formed of multiple layers. The barrier layer 52 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that the metal material contains at least one of an aluminum alloy foil and a stainless steel foil.

[0036] In the barrier layer 52, the layer made of the aforementioned metallic material may contain recycled metallic material. Examples of recycled metallic material include recycled aluminum alloy, stainless steel, titanium steel, and steel plate. These recycled materials can be obtained by known methods. Recycled aluminum alloy material can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be made solely of recycled material, or may be made of a mixture of recycled and virgin material. Note that recycled metallic material refers to metallic material that has been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metallic material refers to new metallic material refined from natural metallic resources (raw materials) and is not recycled material.

[0037] From the viewpoint of improving the formability or conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability or conformability, an aluminum alloy foil containing iron is preferable. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By setting the iron content to 0.1% by mass or more, an exterior film 50 with better formability can be obtained. By setting the iron content to 9.0% by mass or less, an exterior film 50 with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, and the like may also be added as needed. Softening can be achieved by annealing or other methods. From the perspective of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably a hard aluminum alloy foil made of, for example, a work-hardened aluminum alloy. Examples of hard aluminum alloy foils include aluminum alloy foils 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.

[0038] Examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. Furthermore, from the viewpoint of providing an exterior film 50 with excellent formability or conformability, the stainless steel foil is preferably made of austenitic stainless steel.

[0039] Specific examples of austenitic stainless steels that can be used to form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0040] In the case of a metal foil, the thickness of the barrier layer 52 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and may 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. The thickness of the barrier layer 52 is preferably approximately 10 μm or more, even more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred thickness ranges for 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 an aluminum alloy foil, the above-mentioned range is particularly preferable. 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, and 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. Preferred ranges are approximately 35 to 200 μm, approximately 35 to 85 μm, approximately 35 to 75 μm, approximately 35 to 70 μm, approximately 45 to 200 μm, approximately 45 to 85 μm, approximately 45 to 75 μm, approximately 45 to 70 μm, approximately 50 to 200 μm, approximately 50 to 85 μm, approximately 50 to 75 μm, approximately 50 to 70 μm, approximately 55 to 200 μm, approximately 55 to 85 μm, approximately 55 to 75 μm, and approximately 55 to 70 μm. The high formability of the exterior film 50 facilitates deep drawing, which can contribute to increasing the capacity of the electricity storage device. Furthermore, the increased rigidity of the exterior film 50 allows the exterior film 50 to be suitably wrapped around the electrode body 20 when the exterior film 50 is to be wrapped around the electrode body 20. Furthermore, when the capacity of the electricity storage device is increased, the weight of the electricity storage device increases, but increasing the rigidity of the exterior film 50 can contribute to high sealing performance of the electricity storage device.In particular, when the barrier layer 52 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0041] Furthermore, when the barrier layer 52 is an aluminum foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the substrate layer 51 to prevent dissolution and corrosion. The barrier layer 52 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) by performing, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, an anodizing treatment, a plating treatment using nickel or chromium, or a corrosion prevention treatment such as applying a coating agent on the surface of the barrier layer 52. Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer 52 (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer 52 (alkali-resistant coating), or the like. The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, the barrier layer 52 may be formed not only as a single layer but also as a multi-layer. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the surface of the metal foil is dissolved using a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Furthermore, if the barrier layer 52 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 52.

[0042] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 when the exterior film 50 is formed or wound, prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride produced by a reaction between an electrolyte and water, and particularly prevents dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52 when the barrier layer 52 is an aluminum alloy foil, and also improves the adhesion (wettability) of the surface of the barrier layer 52, thereby preventing delamination between the base layer 51 and the barrier layer 52 during heat sealing and between the base layer 51 and the barrier layer 52 during forming.

[0043] The heat-sealable resin layer 53 is bonded to the barrier layer 52 via, for example, an adhesive layer 55. The heat-sealable resin layer 53 included in the exterior film 50 is a layer that provides heat-sealing properties to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made 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 viewpoints of sealability and strength, the thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm.

[0044] The exterior film 50 preferably has one or more layers with a buffer function (hereinafter referred to as "buffer layer") outside the heat-sealable resin layer 53, more preferably outside the barrier layer 52. The buffer layer may be laminated on the outside of the base material layer 51, or the base material layer 51 may also function as a buffer layer. When the exterior film 50 has multiple buffer layers, the multiple buffer layers may be adjacent to each other, or may be laminated with the base material layer 51, the barrier layer 52, or the like interposed therebetween.

[0045] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Examples of the material having cushioning properties include rubber, nonwoven fabric, and foam sheet. Examples of rubber include natural rubber, fluororubber, and silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the nonwoven fabric is preferably a material having excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and even more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and even more preferably 3000 μm. The thickness of the buffer layer is preferably in the range of 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, and most preferably in the range of 1000 μm to 3000 μm.

[0046] 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 ranges of the buffer layer thickness are 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, and 0.5 mm to 2 mm.

[0047] When the exterior film 50 has a buffer layer, the buffer layer functions as a cushion, thereby preventing the exterior film 50 from being damaged by impact when the energy storage device 10 is dropped or by handling during the manufacture of the energy storage device 10.

[0048] 4 has, for example, a rectangular parallelepiped shape and is, for example, a resin molded product made of a resin material. The lid 60 may be formed by, for example, cold forming the exterior film 50, or may be a metal molded product. The material constituting the lid 60 may include at least two or more materials selected from a metal oxide, a carbon material, and a rubber material, or may include a metal oxide, a carbon material, and a rubber material.

[0049] The lid 60 is preferably made up of a resin material. Here, "made up of a resin material" means that, when the entire material constituting the lid 60 is taken as 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In other words, the material constituting the lid 60 can contain materials other than the resin material in addition to the resin material.

[0050] 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 versions of these resins. The resin material may be a mixture of these resins, a copolymer, or a modified copolymer. Among these, the resin material is preferably a heat-sealable resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the lid 60 may be molded using any molding method.

[0051] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Examples of copolymer polyesters include copolymer polyesters whose repeating units are primarily ethylene terephthalate. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl dicarboxylate), and polyethylene (terephthalate / decane dicarboxylate). Among these, polybutylene terephthalate is preferred as the resin material from the viewpoint of improving heat resistance and pressure resistance.

[0052] 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 ethylene-butene-propylene terpolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. Among these, polypropylene is preferred as the resin material because of its excellent heat-sealing properties and electrolyte resistance.

[0053] The resin as the resin material may contain a filler as needed. Specific examples of the filler include glass beads, graphite, glass fiber, and carbon fiber. By including the filler in the resin as the resin material, the deformation resistance of the lid 60 against temperature changes can be improved.

[0054] The melt mass flow rate of the resin material contained in the material constituting the lid body 60 is preferably in the range of 1 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0055] The lid 60 may be configured to contain a conductive material. "Containing a conductive material" means that, when the entire material constituting the lid 60 is taken as 100% by mass, the content of the conductive material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In other words, the material constituting the lid 60 can contain, in addition to the conductive material, a material other than the conductive material.

[0056] The conductive material forming the lid body 60 is, for example, a metal material. The metal material forming the lid body 60 is, for example, aluminum, aluminum alloy, nickel, copper, or a copper alloy. For example, when the electrode body 20 is a lithium-ion battery, the lid body 60 connected to the positive electrode is preferably formed of aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably formed of nickel, copper, or a copper alloy. The material forming the lid body 60 connected to the negative electrode may be nickel-plated copper. The material forming the lid body 60 may contain recycled metal materials. When the lid body 60 is formed of a conductive material, the lid body 60 also functions as the electrode terminal 30. Since the electrode terminal 30 can be omitted from the electricity storage device 10, the configuration of the electricity storage device 10 can be simplified.

[0057] When the lid 60 contains a conductive material, the lid 60 may be bonded to the exterior film 50 and the barrier film 90 (described later) via an adhesive film. Any adhesive film can be selected as long as it can bond the exterior film 50 and the barrier film 90 to the lid 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant substrate layer, and a heat-sealable resin layer, in this order. The specifications for the heat-sealable resin layer of the adhesive film are the same as those for the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same or different, and are appropriately selected depending on the materials constituting the heat-sealable resin layers of the exterior film 50 and the barrier film 90, and the material constituting the lid 60. The material constituting the heat-sealable resin layer of the adhesive film on the side bonded to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer of the adhesive film on the side that is bonded to the exterior film 50 and the barrier film 90 is preferably made of the same type of material as the material that constitutes the heat-sealable resin layers of the exterior film 50 and the barrier film 90.

[0058] The heat-resistant substrate layer may be any film made of a heat-resistant resin, such as a non-stretched or stretched film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, etc. Polyethylene terephthalate is particularly preferred because it is inexpensive and has high strength.

[0059] The adhesive film preferably has adhesive properties. When the adhesive film is disposed between the barrier film 90 and the lid 60 and the second sealing portion 80 (described later) is formed, the adhesive film is less likely to shift position relative to the lid 60 and the barrier film 90. Furthermore, when the adhesive film is disposed between the barrier film 90 and the lid 60 and the barrier film 90 are joined to the lid 60, the adhesive film is less likely to shift position relative to the lid 60 and the barrier film 90. Furthermore, by incorporating a tackifier resin into the heat-sealable resin layer of the adhesive film, adhesive properties can be imparted to the adhesive film. Examples of the tackifier resin include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene and copolymers of amorphous propylene and other α-olefins. The content of the tackifier resin relative to the base material constituting the heat-sealable resin is preferably 10 to 20 wt % or less.

[0060] The lid 60 has a first surface 61, a second surface 62, and a sealing surface 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface opposite to the first surface 61. The sealing surface 63 is connected to the first surface 61 and the second surface 62, and is joined to the heat-sealable resin layer 53 of the exterior film 50 via a barrier film 90, which will be described later.

[0061] 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 lid body 60. The first sealing surface 63A extends in a first direction (the LR direction in this embodiment) when viewed from the front of the lid body 60. The second sealing surface 63B and the third sealing surface 63C are connected to the first sealing surface 63A and constitute the side surfaces of the lid body 60. The second sealing surface 63B and the third sealing surface 63C extend in a second direction (the UD direction in this embodiment) that intersects with the first direction when viewed from the front of the lid body 60. In this embodiment, the first direction and the second direction are orthogonal when viewed from the front of the lid body 60. The first direction and the second direction do not have to be orthogonal when viewed from the front of the lid body 60. The fourth sealing surface 63D constitutes the lower surface of the lid body 60. The fourth sealing surface 63D extends in a first direction (LR direction in this embodiment) when the lid 60 is viewed from the front.

[0062] When the lid body 60 is plate-shaped, it is preferable that the lid body 60 has a certain thickness so that deformation of the exterior body 40 is suppressed even when the electricity storage device 10 is placed on top of it. From another perspective, when the lid body 60 is plate-shaped, it is preferable that the sealing surface 63 of the lid body 60 has a certain thickness so that the sealing surface 63 of the lid body 60 and the exterior film 50 can be heat-sealed appropriately when forming the second sealing portion 80 described below. The minimum thickness of the lid body 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum thickness of the lid body 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum thickness of the lid body 60 may be 20 mm or more. The preferred ranges for the thickness of the material constituting the lid body 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 lid body 60 is described as being plate-shaped, films defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard are not included as materials constituting the lid body 60. The thickness of the lid body 60 may vary depending on the region of the lid body 60. When the thickness of the lid body 60 varies depending on the region, the thickness of the lid body 60 is the thickness of the thickest portion.

[0063] The cover 60 further includes boundaries 64, 65, 66, and 67. The boundary 64 is the boundary between the first seal surface 63A and the second seal surface 63B. The boundary 65 is the boundary between the first seal surface 63A and the third seal surface 63C. The boundary 66 is the boundary between the fourth seal surface 63D and the second seal surface 63B. The boundary 67 is the boundary between the fourth seal surface 63D and the third seal surface 63C. The cross-sectional shapes of the boundaries 64 to 67 when viewed from the FB direction may be angular, or may be rounded by being subjected to R processing. In this embodiment, the boundaries 64 to 67 are angular.

[0064] From the viewpoint of appropriately heat-sealing 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-sealable resin layer 53 of the exterior film 50 are mainly made of the same material. In this embodiment, the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 are mainly made of polypropylene. Note that the main material refers to, for example, a material that accounts for 50% or more of the materials contained in the constituent elements.

[0065] In this embodiment, the lid body 60 has a through hole 60X formed therein, into which the electrode terminal 30 is inserted. The through hole 60X penetrates the first surface 61 and the second surface 62. When the electrode body 20 is wrapped in the exterior film 50, the electrode terminal 30 passes through the through hole 60X formed in the lid body 60 and protrudes to the outside of the exterior body 40. A small gap between the through hole 60X of the lid body 60 and the electrode terminal 30 is filled with, for example, resin. Note that, in the energy storage device 10, the position from which 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 in any one of the six surfaces of the exterior body 40. In this case, a small gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. In the energy storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies; however, the lid body 60 and the electrode terminal 30 may be integrally formed. In addition, when the lid body 60 also functions as an electrode terminal, or when the electrode terminal 30 is disposed between the lid body 60 and the exterior film 50, the lid body 60 does not need to have a through-hole 60X formed therein.

[0066] In this embodiment, the first sealing portion 70 is formed by wrapping the exterior film 50 around the electrode body 20 so as to have an opening 40A, and then heat-sealing the opposing surfaces of the exterior film 50 (heat-fusible resin layers 53).

[0067] The first sealed portion 70 is formed by heat-sealing a portion of the exterior film 50 including the first edge 50A and a portion of the exterior film 50 including the second edge 50B shown in FIG. 3 . The first sealed portion 70 extends in the longitudinal direction (FB direction) of the exterior body 40. The position at which the first sealed portion 70 is formed in the exterior body 40 can be selected arbitrarily. In the present embodiment, the base 70X of the first sealed portion 70 is preferably located on the side 43 at the boundary between the first surface 41 and the second surface 42 of the exterior body 40. The first surface 41 has a larger area than the second surface 42. The base 70X of the first sealed portion 70 may be located on any surface of the exterior body 40. In the present embodiment, the first sealed portion 70 protrudes outward beyond the electrode assembly 20 in a plan view. The first sealed portion 70 may be folded, for example, toward the second surface 42 or the first surface 41 of the exterior body 40.

[0068] As shown in FIGS. 5 and 6 , in this embodiment, a barrier film 90 is bonded to the lid 60 to prevent at least one of moisture and gas from penetrating into the interior of the exterior body 40 through the gap 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 penetrating 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. Because the barrier film 90 covers the sealing surface 63 and the boundaries 64 to 67, as well as the second surface 62 and the interior of the through-hole 60X, the barrier film 90 prevents moisture from penetrating into the interior of the exterior body 40 through the gap between the electrode terminal 30 and the through-hole 60X. The barrier film 90 may be formed from a single film, or, 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 formed from a plurality of divided films.

[0069] The position of the end 90A of the portion of the barrier film 90 that covers the sealing surface 63 and the position of the end 90B of the portion that covers the inside of the through-hole 60X of the lid 60 can be selected arbitrarily. When the electricity storage device 10 is a battery containing an electrolyte solution such as a lithium ion battery, the ends 90A and 90B of the barrier film 90 may come into contact with gas such as hydrogen fluoride generated from the electrolyte solution, which may corrode a barrier layer 91 provided in the barrier film 90, which will be described later.

[0070] For this reason, from the viewpoint of suppressing corrosion of the barrier layer 91, it is preferable that the end 90A be located closer to the second surface 62 than to the boundary between the sealing surface 63 and the first surface 61. From the same viewpoint, it is preferable that the end 90B be located closer to the opening of the through-hole 60X on the second surface 62 side than to the opening of the through-hole 60X on the first surface 61 side. Note that the end 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 to the lid body 60. The end 90B may be located near the opening of the through-hole 60X on the first surface 61 side, or may extend to a position closer to the electrode body 20 than to the lid body 60.

[0071] 7 to 9 are cross-sectional views showing examples of the layer structure of the barrier film 90. FIG. As shown in Fig. 7, the barrier film 90 only needs to include at least a barrier layer 91. The specifications of the barrier layer 91 are the same as those of 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 is a single layer consisting of only the barrier layer 91, one surface of the barrier layer 91 is bonded to the lid 60 with an adhesive or the like. When the barrier film 90 is a single layer consisting of only the barrier layer 91, the other surface of the barrier layer 91 is bonded to the heat-sealable resin layer 53 of the exterior film 50 with an adhesive or the like.

[0072] As shown in FIG. 8 , the barrier film 90 may 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 serves, for example, as a base layer or a heat-sealable resin layer. As a base layer, it protects the barrier layer 91. As a heat-sealable resin layer, it is heat-sealed to the heat-sealable resin layer 53 of the exterior film 50. When the outer layer 92 serves as a base layer, the specifications of the outer layer 92 as a base layer are the same as the specifications of the base layer 51 of the exterior film 50. When the outer layer 92 serves as a heat-sealable resin layer, the specifications of the outer layer 92 as a heat-sealable resin layer are the same as the specifications of the heat-sealable resin layer 53 of the exterior film 50. When the outer layer 92 serves as a heat-sealable resin layer, it can be suitably bonded to the adhesive film 31. When the outer layer 92 functions as a heat-sealable resin layer, the outer layer 92 may be thinner than the heat-sealable resin layer 53. When the outer layer 92 functions as a heat-sealable resin layer, the thickness of the outer layer 92 may be, for example, 5 to 20 μm. When the outer layer 92 is a base layer, the barrier layer 91 is protected. When the outer layer 92 is a base layer, the outer layer 92 and the heat-sealable resin layer 53 are bonded together, for example, with an adhesive or the like. When the outer layer 92 is a heat-sealable resin layer, the outer layer 92 and the heat-sealable resin layer 53 can be suitably bonded together by heat fusion. The barrier layer 91 and the outer layer 92 may be bonded together with an adhesive layer 54. When the outer layer 92 has adhesive properties to the barrier layer 91, the adhesive layer 54 can be omitted.

[0073] As shown in FIG. 9 , the barrier film 90 may include a heat-sealable resin layer 93 laminated on the surface of the barrier layer 91 that is to be bonded to the lid 60. The specifications of the heat-sealable resin layer 93 are the same as those of the heat-sealable resin layer 53 of the exterior film 50. The heat-sealable resin layer 93 may be thinner than the heat-sealable resin layer 53. The thickness of the heat-sealable resin layer 93 may be, for example, 5 to 20 μm. When the barrier film 90 includes the heat-sealable resin layer 93, the barrier film 90 and the lid 60 can be suitably bonded together by heat fusion. The barrier layer 91 and the heat-sealable resin layer 93 may be bonded together by an adhesive layer 55.

[0074] In this embodiment, the barrier film 90 has a configuration shown in Fig. 9, and the outer layer 92 is a heat-sealable resin layer. Therefore, in this embodiment, the heat-sealable resin layer 53 of the exterior film 50 and the sealing surface 63 of the lid 60 are joined via the barrier film 90 to form a second sealing portion 80. Hereinafter, the seal strength between the heat-sealable resin layer 53 of the exterior film 50 and the sealing surface 63 of the lid 60 may be referred to as the seal strength of the second sealing portion 80. Note that the seal strength of the second sealing portion 80 refers to the seal strength between the heat-sealable resin layer 53 and the lid 60 at the long side portion of the sealing surface 63, i.e., the sealing surface 63 extending in the L-R (width) direction in Fig. 1A.

[0075] The seal strength of the second sealing portion 80 is measured as follows. First, a slit is made in the portion of the exterior film 50 that constitutes the first surface 41 of the exterior body 40, forming three strip-shaped members 41X, 41Y, and 41Z (see the two-dot chain lines in FIG. 1B) aligned in the L-R direction. The width of the three strip-shaped members 41X, 41Y, and 41Z in the L-R direction is 15 mm. The ends of the strip-shaped members 41X, 41Y, and 41Z are joined to the lid body 60 at the second sealing portion 80. The length of the lid body 60 in the L-R direction is 45 mm or more. Next, the end of each of the strip-shaped members 41X, 41Y, and 41Z opposite the end joined to the lid body 60 is pulled upward in the UD direction (away from the first surface 41B), thereby measuring the seal strength of each of the strip-shaped members 41X, 41Y, and 41Z. In this embodiment, the seal strength of the second sealing portion 80 is the average value of the seal strengths of the strip-shaped members 41X, 41Y, and 41Z. When the length of the lid 60 in the L-R direction is less than 45 mm, three strip-shaped members with an arbitrary width X mm, less than 15 mm, are formed. The seal strengths of the three strip-shaped members are measured in the same manner as when the length of the lid 60 in the L-R direction is 45 mm or more. The obtained seal strengths are each divided by the arbitrary width X mm and multiplied by 15 to convert them to the seal strengths of the three strip-shaped members in a 15 mm width. The seal strength of the second sealing portion 80 is the average value of the seal strengths of the three strip-shaped members converted to a 15 mm width. Note that when the lid 60 is divided into multiple parts including long and short sides, the seal strength of the second sealing portion 80 is the seal strength of the long sides of the sealing surfaces 63 of the multiple parts.

[0076] From the viewpoint of suitably maintaining the state in which the electrode assembly 20 is sealed by the exterior housing 40, the seal strength of the second sealing unit 80 is preferably 40 N / 15 mm or more, more preferably 50 N / 15 mm or more, even more preferably 60 N / 15 mm or more, even more preferably 70 N / 15 mm or more, and even more preferably 85 N / 15 mm or more. When the seal strength of the second sealing unit 80 is 40 N / 15 mm or more, the state in which the electrode assembly 20 is sealed by the exterior housing 40 is suitably maintained even after the electricity storage device 10 has been used for, for example, several years (less than 10 years). When the seal strength of the second sealing unit 80 is 85 N / 15 mm or more, the state in which the electrode assembly 20 is sealed by the exterior housing 40 is suitably maintained even after the electricity storage device 10 has been used for, for example, 10 years or more. The seal strength of the second sealing unit 80 is preferably 300 N / 15 mm or less. A preferred range for the seal strength of the second sealing portion 80 is 40N / 15mm to 300N / 15mm, 50N / 15mm to 300N / 15mm, 60N / 15mm to 300N / 15mm, 70N / 15mm to 300N / 15mm, or 85N / 15mm to 300N / 15mm.

[0077] <1-2. Method for manufacturing electricity storage devices> 10 is a flowchart showing an example of a method for manufacturing the electricity storage device 10. The method for manufacturing the electricity 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 step to the eighth step are performed, for example, by a manufacturing apparatus for the electricity storage device 10. Note that the following first step to eighth step are simply names of the steps in the method for manufacturing the electricity storage device 10 specified for convenience, and do not necessarily refer to the order of the steps.

[0078] In the first step of step S11, the manufacturing device insert-moldes the lid body 60 into the barrier film 90.

[0079] The second step of step S12 is performed after the first step. In the second step, the manufacturing equipment joins the electrode terminal 30 to the lid body 60 to which the barrier film 90 has been joined. Completion of the second step completes the lid unit 110 in which the barrier film 90 and the electrode terminal 30 are joined to the lid body 60. In other words, the first and second steps correspond to a method for manufacturing the lid unit 110.

[0080] The third step of step S13 is performed before or after the second step. In the third step, the manufacturing apparatus places the lid unit 100 beside the electrode assembly 20 and bonds the electrode terminal 30 to the electrode assembly 20. Note that, instead of the first to third steps, the manufacturing method of the electricity storage device 10 may first bond the electrode assembly 20 to the electrode terminal 30, and then bond the lid body 60 to the electrode terminal 30 bonded to the electrode assembly 20. In this modification, the electrode terminal 30 may protrude to the outside of the exterior body 40 from between any of the sealing surfaces 63A to 63D and the exterior film 50. Furthermore, the barrier film 90 may be bonded to the lid body 60 after the lid body 60 and the electrode terminal 30 are bonded, or may be bonded to the lid body 60 before the lid body 60 and the electrode terminal 30 are bonded.

[0081] The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus wraps the exterior film 50 around the electrode assembly 20 and the lid body 60. In the fourth step, the manufacturing apparatus wraps the exterior film 50 around the electrode assembly 20 and the lid body 60 while tension is applied to the exterior film 50, while restricting the movement of the electrode assembly 20 and the lid body 60 with a restricting means. The restricting means is, for example, a groove into which the electrode assembly 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode assembly 20 and the lid body 60 to prevent the electrode assembly 20 and the lid body 60 from moving. The restricting means may be a device that applies a force to the electrode assembly 20 and the lid body 60 in a direction opposite to the direction in which the exterior film 50 is pulled. The restricting means may include a roller that runs on the exterior film 50 while the exterior film 50 is being pulled, in order to remove wrinkles in the exterior film 50.

[0082] The fifth step of step S15 is performed after the fourth step. In the fifth step, the manufacturing equipment forms a first sealing portion (hereinafter referred to as a "temporary first sealing portion") having an unsealed portion formed in a part thereof for injecting an electrolyte solution. Note that if the power storage device 10 is, for example, an all-solid-state battery, the step of injecting an electrolyte solution is not necessary, and therefore, in the fourth step, the manufacturing equipment forms the first sealing portion 70.

[0083] The sixth step of step S16 is performed after the fifth step. In the sixth step, the manufacturing apparatus forms the second sealing portion 80 by heat-sealing 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.

[0084] The seventh step of step S17 is performed after the sixth step. In the seventh step, an electrolyte is injected through the unsealed portion formed in the temporary first sealing portion. After the seventh step, an aging step and a degassing step are performed.

[0085] The eighth step of step S18 is performed after the seventh step, the aging step, and the degassing step are completed. In the eighth step, the manufacturing equipment heat-seals the portion of the temporary first sealed portion, including the unsealed portion, to form the first sealed portion 70. Note that, when the power storage device 10 is, for example, an all-solid-state battery, the seventh and eighth steps are omitted.

[0086] <1-3. Actions and Effects of Electricity Storage Devices> In the electricity storage device 10, the barrier film 90 covers at least a portion of the sealing surface 63 of the lid 60, thereby preventing at least one of moisture and gas from penetrating between the exterior film 50 and the lid 60.

[0087] [2. Second Embodiment] The electricity storage device 200 of the second embodiment differs from the electricity storage device 10 of the first embodiment in that it includes a lid unit 210, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The following describes the electricity storage device 200 of the second embodiment, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0088] <2-1. Configuration of the energy storage device> FIG. 11 is a partial cross-sectional view of a lid unit 210 included in an electricity storage device 200 of a second embodiment. In this embodiment, the barrier film 90 is joined to the lid 60 so as to cover the sealing surface 63, the boundaries 64 to 67 (see FIG. 4), the inside of the through-hole 60X of the lid 60, and the first surface 61. The positions of the end 90A and the end 90B can be selected arbitrarily. In this embodiment, the end 90A is located at the boundary between the sealing surface 63 and the second surface 62. The end 90B is located near the opening of the through-hole 60X on the second surface 62 side. The end 90B may be located in an intermediate portion of the through-hole 60X between the first surface 61 and the second surface 62.

[0089] In the electricity storage device 200 of the second embodiment, the barrier film 90 covers a first surface 61 of the lid body 60 that faces the electrode body 20. Therefore, for example, if the electricity storage device 200 is a battery containing an electrolyte solution, such as a lithium ion battery, the part of the barrier film 90 that covers the first surface 61 may come into contact with gas such as hydrogen fluoride generated from the electrolyte solution, which may corrode the barrier layer 91. Therefore, from the viewpoint of protecting the barrier layer 91, the barrier film 90 preferably has a configuration including an outer layer 92 as a base layer, as shown in FIGS. 8 and 9 .

[0090] <2-2. Actions and Effects of Electricity Storage Devices> In the electricity storage device 200, the barrier film 90 covers at least a portion of the sealing surface 63 of the lid 60, thereby preventing at least one of moisture and gas from penetrating between the exterior film 50 and the lid 60. Furthermore, the end 90A and the end 90B are less likely to come into contact with the electrolyte, thereby preventing corrosion of the barrier layer 91.

[0091] 3. Third Embodiment The electricity storage device 300 of the third embodiment differs from the electricity storage device 10 of the first embodiment in that it includes a lid unit 310, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The following describes the electricity storage device 300 of the third embodiment, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0092] <3-1. Configuration of the energy storage device> FIG. 12 is a partial cross-sectional view of a lid unit 310 included in an electricity storage device 300 of a third embodiment. In this embodiment, the barrier film 90 is joined to the lid body 60 so as to cover the sealing surface 63, the boundaries 64 to 67 (see FIG. 4), the inside of the through-hole 60X of the lid body 60, and the second surface 62. The positions of the end 90A and the end 90B can be selected arbitrarily. In this embodiment, the end 90A is located at the boundary between the sealing surface 63 and the first surface 61. The end 90A may extend to a position closer to the electrode body 20 than the lid body 60. The end 90B is located near the opening of the through-hole 60X on the first surface 61 side. The end 90B may extend to a position closer to the electrode body 20 than the through-hole 60X.

[0093] In the third embodiment, when the power storage device 300 is a battery containing an electrolyte solution, such as a lithium-ion battery, the ends 90A and 90B of the barrier film 90 may come into contact with gases such as hydrogen fluoride generated from the electrolyte solution. Therefore, even if the barrier film 90 includes an outer layer 92 as a base layer, as shown in FIGS. 8 and 9 , contact between the ends 90A and 90B and gases such as hydrogen fluoride may cause corrosion of the barrier layer 91. For this reason, in this embodiment, the ends 90A and 90B are covered with a covering portion 330. The material of the covering portion 330 can be selected arbitrarily as long as it can protect the ends 90A and 90B. In this embodiment, the material of the covering portion 330 is a resin. It is sufficient that the covering portion 330 covers at least one of the ends 90A and 90B.

[0094] <3-2. Actions and Effects of Electricity Storage Devices> According to the power storage device 300, in addition to the effects equivalent to those obtained by the power storage device 10 of the first embodiment, the following effects can be obtained.

[0095] The ends 90A and 90B of the barrier film 90 are covered with the covering portion 330. Therefore, even if the ends 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.

[0096] [4. Fourth Embodiment] The electricity storage device 400 of the fourth embodiment differs from the electricity storage device 10 of the first embodiment in that it includes a lid unit 410, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The electricity storage device 400 of the fourth embodiment will be described below, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0097] <4-1. Configuration of the energy storage device> 13 is a partial cross-sectional view of a lid unit 410 included in an electricity storage device 400 of the fourth embodiment. In this embodiment, the barrier film 90 is bonded to the lid 60 so as to cover the sealing surface 63, the inside of the through-hole 60X of the lid 60, and the second surface 62.

[0098] When the electricity storage device 10 is a battery containing an electrolyte solution, such as a lithium ion battery, the end 90A of the barrier film 90 may come into contact with gas such as hydrogen fluoride generated from the electrolyte solution, which may corrode the barrier layer 91. In this embodiment, the position of the end 90A is devised to prevent corrosion of the barrier layer 91.

[0099] The barrier film 90 includes a joining portion 90X that is joined to the sealing surface 63, and a folded portion 90Y that is connected to the joining portion 90X and is folded back toward the second surface 62. An end portion 90A of the portion of the barrier film 90 that covers the sealing surface 63 is located at 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-sealable resin layer 93 of the folded portion 90Y of the barrier film 90 is joined to the heat-sealable resin layer 53 of the exterior film 50.

[0100] The position of the end 90B can be selected arbitrarily. In the present embodiment, the end 90B is located inside the through-hole 60X. This prevents the end 90B from coming into contact with gases such as hydrogen fluoride. The end 90B may be located closer to the opening of the through-hole 60X on the second surface 62 side than the opening of the through-hole 60X on the first surface 61 side. The end 90B may be located closer to the opening of the through-hole 60X on the first surface 61 side than the opening of the through-hole 60X on the second surface 62 side. The end 90B may be located near the opening of the through-hole 60X on the first surface 61 side, or may extend to a position closer to the electrode assembly 20 than the lid 60. The end 90B may be located outside the through-hole 60X on the second surface 62 side. When the end 90B is located outside the through-hole 60X on the second surface 62 side, the portion of the barrier film 90 located outside the through-hole 60X may be folded.

[0101] <4-2. Actions and Effects of Electricity Storage Devices> According to the power storage device 400, in addition to the effects similar to those obtained by the power storage device 10 of the first embodiment, the following effects can be obtained.

[0102] The end 90A is located at the folded portion 90Y folded back to the opposite side of the electrode body 20, which prevents the end 90A from coming into contact with gases such as hydrogen fluoride, thereby preventing corrosion of the barrier layer 91.

[0103] [5. Fifth Embodiment] The electricity storage device 500 of the fifth embodiment differs from the electricity storage device 10 of the first embodiment in that it includes a lid unit 510, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The following describes the electricity storage device 500 of the fifth embodiment, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0104] <5-1. Configuration of the energy storage device> 14 is a partial cross-sectional view of a lid unit 510 included in an electricity storage device 500 of the fifth embodiment. In this embodiment, the barrier film 90 is joined to the lid 60 so as to cover a part of the sealing surface 63 and the inside of the through-hole 60X of the lid 60.

[0105] The barrier film 90 includes an inner portion 90Z that is disposed in at least a portion of the interior of the lid 60. The inner portion 90Z is a portion between a part of the sealing surface 63 and a portion that covers 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 lid 60 into the barrier film 90.

[0106] The positions of the end 90A and the end 90B can be selected arbitrarily. As in the first embodiment, from the viewpoint of suppressing corrosion of the barrier layer 91, the end 90A is preferably located closer to the second surface 62 than to the boundary between the sealing surface 63 and the first surface 61. The end 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 assembly 20 than to the lid 60. From the same viewpoint, the end 90B is preferably located closer to the opening of the through-hole 60X on the second surface 62 side than to the opening of the through-hole 60X on the first surface 61 side. The end 90B may be located near the opening of the through-hole 60X on the first surface 61 side, or may extend to a position closer to the electrode assembly 20 than to the lid 60.

[0107] <5-2. Actions and Effects of Electricity Storage Devices> The power storage device 500 provides effects similar to those provided by the power storage device 10 of the first embodiment.

[0108] [6. Sixth Embodiment] The electricity storage device 600 of the sixth embodiment differs from the electricity storage device 10 of the first embodiment in that it includes a lid unit 610, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The following describes the electricity storage device 600 of the sixth embodiment, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0109] <6-1. Configuration of the energy storage device> FIG. 15 is a cross-sectional view of an electricity storage device 600 of a sixth embodiment. In this embodiment, a heat-sealable resin layer 53 of an exterior film 50 is joined to a sealing surface 63 of a lid 60. The exterior film 50 has a folded portion 50X that is connected to a portion that is joined to the sealing surface 63 of the lid 60 and is folded back toward the electrode assembly 20. The folded portion 50X covers the lid 60. A barrier film 90 is joined to the exterior film 50 on the outer side 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. An end 90A of the portion of the barrier film 90 that covers the sealing surface 63 is located on, for example, the folded portion 50X. The end 90A does not have to be located on the folded portion 50X.

[0110] <6-2. Actions and Effects of Electricity Storage Devices> According to the power storage device 600, in addition to the effects similar to those obtained by the power storage device 10 of the first embodiment, the following effects can be obtained.

[0111] The barrier film 90 is bonded to the lid 60 via the exterior film 50 so as to cover the sealing surface 63, on the outer side of the exterior film 50. Therefore, the end 90A is located outside the exterior film 50. Since contact between the end 90A and gases such as hydrogen fluoride is suppressed, corrosion of the barrier layer 91 is suppressed.

[0112] [7. Variations] The above-described embodiments are examples of possible forms of the electricity storage device, barrier film, lid unit, and method for manufacturing an electricity storage device according to the present invention, and are not intended to limit the forms. The electricity storage device, barrier film, lid unit, and method for manufacturing an electricity storage device according to the present invention may take forms different from those exemplified in the embodiments. Examples include forms in which part of the configuration of the embodiments is replaced, modified, or omitted, or forms in which a new configuration is added to the embodiments. Some examples of modified embodiments are shown below. Note that the following modified forms can be combined with each other as long as there is no technical contradiction.

[0113] <7-1> In the electricity storage device 10 of the first embodiment, the barrier film 90 may cover the electrode terminals 30. This modification can also be applied to the electricity storage devices 200, 300, 400, and 500 of the second to fifth embodiments.

[0114] <7-2> The manufacturing method of the electricity storage device 10 of the first embodiment can be modified as desired. For example, in the first process of step S11, the lid body 60 and the barrier film 90 may be prepared in advance, and the barrier film may be bonded to the lid body 60. In a first example of this modification, for example, it is preferable to form folds in the barrier film 90 corresponding to the first surface 61, which is the surface of the lid body 60 to be covered, and the sealing surfaces 63A to 63D. When folds are formed in the barrier film 90, the lid body 60 and the barrier film 90 can be easily brought into close contact. In a second example of this modification, a recess may be formed in a barrier film 90 that has been prepared in advance, and the lid body 60 that has been prepared in advance may be placed in this recess, and the barrier film 90 and the lid body 60 may then be bonded to each other.

[0115] <7-3> In the electricity storage device 10 of the first embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover the first surface 61 of the lid body 60. In the electricity storage device 200 of the second embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover the second surface 62 of the lid body 60. In the electricity storage device 300 of the third embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover the first surface 61 of the lid body 60. In the electricity storage device 400 of the fourth embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover the first surface 61 of the lid body 60. In the electricity storage device 500 of the fifth embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover at least one of the first surface 61 and the second surface 62 of the lid body 60. In the electricity storage device 600 of the sixth embodiment, the barrier film 90 may be bonded to the lid body 60 so as to cover the first surface 61 of the lid body 60.

[0116] <7-4> In the electricity storage device 10 of the first embodiment, the position at which the electrode terminal 30 is arranged can be selected arbitrarily. 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 can also be similarly applied to the electricity storage devices 200, 300, 400, 500, and 600 of the second to sixth embodiments.

[0117] 8. Working Example <8-1. First Exam> The inventors of the present application conducted a first test to confirm the water vapor barrier properties of the electricity storage devices of Examples 1 and 2 and Comparative Examples 1 and 2. For ease of explanation, the following description will be given by assigning the same reference numerals as in the embodiment to the elements constituting the electricity storage devices of Examples and Comparative Examples that are the same as in the embodiment.

[0118] The power storage devices of Examples 1 and 2 have a configuration similar to that of the power storage device of the first embodiment. The power storage devices of Examples 1 and 2 have a pseudo electrode body instead of the electrode body 20. The power storage devices of Examples 1 and 2 do not have an electrode terminal 30. The specifications of the power storage devices of Examples 1 and 2 are as follows.

[0119] The barrier film is a laminate film in which a first outer layer, a barrier layer, and a second outer layer are laminated in this order. The material constituting the first outer layer and the second outer layer is unstretched polypropylene. The material constituting the barrier layer is aluminum. The thickness of the first outer layer and the second outer layer is 60 μm. The thickness of the barrier layer is 80 μm. The first outer layer and the barrier layer are joined by dry lamination. The second outer layer and the barrier layer are joined by dry lamination.

[0120] The material that constitutes the lid body 60 is polypropylene. The length (height) of the lid body 60 in the UD direction is 30 mm, the length (width) in the LR direction is 100 mm, and the length (thickness) in the FB direction is 5 mm.

[0121] The electricity storage devices of Examples 1 and 2 are manufactured by injecting a lid 60 onto a barrier film placed in a forming mold. In the electricity storage device of Example 1, the exterior film 50 covers the entire second surface 62 and sealing surface 63 of the lid 60. In the electricity storage device of Example 2, the exterior film 50 covers the entire first surface 61 and sealing surface 63 of the lid 60.

[0122] The electricity storage device of Comparative Example 1 has the same configuration as the electricity storage device of Example 1 or Example 2, except that it does not have a barrier film. The electricity storage device of Comparative Example 2 has the same configuration as the electricity 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 configuration of the barrier film. The material constituting the first outer layer of the barrier film in the electricity storage device of Comparative Example 2 is a laminate of polyethylene terephthalate and nylon. The thickness of the polyethylene terephthalate layer in the first outer layer is 12 μm, and the thickness of the nylon layer is 25 μm. The material constituting the barrier layer of the barrier film in the electricity storage device of Comparative Example 2 is aluminum. The thickness of the barrier layer is 40 μm. The material constituting the second outer layer of the barrier film in the electricity storage device of Comparative Example 2 is polypropylene. The thickness of the second outer layer is 80 μm. In the electricity storage device of Comparative Example 2, the second outer layer is bonded to the second surface 62 of the lid 60. In the electricity storage device of Comparative Example 2, the barrier film is not bonded to the sealing surface 63 of the lid body 60. In the electricity storage device of Comparative Example 2, the first outer layer or the second outer layer and the second surface 62 of the lid body 60 are held in contact with each other at a temperature of 180°C under vacuum for 60 seconds, and then pressed with 5 kN for 15 seconds to bond them together.

[0123] The power storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured by wrapping an exterior film 50 around two lid bodies 60 and a pseudo electrode body to form a first sealed portion 70 and a second sealed portion 80. The sealing conditions for the first sealed portion 70 were a temperature of 220°C, a surface pressure of 1.1 MPa, and a time of 7 seconds. The sealing conditions for the second sealed portion 80 were a temperature of 180°C, a surface pressure of 0.78 MPa, and a time of 5 seconds. The width and length of the exterior film 50 were 160 mm and 300 mm, respectively.

[0124] Next, the power storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 were cut in the center in the FB direction, and 20 g of salt-free electrolyte was poured into the formed opening, and the opening was sealed to form an opening sealing portion. The salt-free electrolyte was Purelite (manufactured by Ube Industries) and had a composition of EC:DMC:DEC=1:1:1=(v / v / v). The opening sealing portion was formed at a position 70 mm to 80 mm from the outer edge of the lid 60 in the FB direction. The opening sealing portion had a width of 10 mm. The opening sealing portion was formed by heat sealing twice with a 7 mm wide heat seal bar, offset by 3 mm. The sealing conditions for the opening sealing portion were a temperature of 190°C, a surface pressure of 1 MPa, and a time of 5 seconds.

[0125] Next, the electricity storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 in which the opening sealing portion was formed were stored in a constant temperature and humidity chamber for 7 days with the lid 60 facing downwards. The temperature of the constant temperature and humidity chamber was 65°C, and the relative humidity was 90%.

[0126] Next, the electricity storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 were removed from the constant temperature and humidity chamber and cooled at room temperature for 2 hours. After that, 0.5 ml of the liquid inside was sampled using a Karl Fischer in a dry room, the moisture content was measured, and the moisture permeation rate was calculated. The Karl Fischer is, for example, a moisture vaporizer ADP-611 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The calculated moisture permeation rate is the amount per one lid 60.

[0127] The moisture permeation amount of the electricity storage device of Example 1 was 1.18 mg. The moisture permeation amount of the electricity storage device of Example 2 was 0.711 mg. The moisture permeation amount of the electricity storage device of Comparative Example 1 was 25.5 mg. The moisture permeation amount of the electricity storage device of Comparative Example 2 was 3.85 mg. The results of the first test confirmed that the moisture permeation amount was reduced by arranging a barrier film on the sealing surface 63 of the lid 60. Furthermore, the results of Examples 1 and 2 confirmed that the moisture permeation amount was reduced more when the barrier film was arranged on the first surface 61 of the lid 60 than on the second surface 62.

[0128] <8-2. Second Exam> The inventors of the present application conducted a second test to confirm the insulating properties and corrosion properties of the barrier films of the electricity storage devices of Examples 3 and 4. For ease of explanation, the following description will be given by assigning the same reference numerals as in the embodiment to the elements constituting the electricity storage devices of Examples and Comparative Examples that are the same as in the embodiment.

[0129] The electricity storage device of Example 3 has the same configuration as the electricity storage device of Example 1. The electricity storage device of Example 4 has the same configuration as the electricity storage device of Example 2. In the electricity storage device of Example 3, the outermost layer (first outer layer or second outer layer) of the barrier film at the portion bonded to the second surface 62 of the lid 60 was scraped off to expose the barrier layer. The sealing conditions for the first sealing portion 70 of the electricity storage devices of Examples 3 and 4 were a temperature of 220°C, a surface pressure of 1.1 MPa, and a time of 7 seconds. The sealing conditions for the second sealing portion 80 were a temperature of 180°C, a surface pressure of 1.56 MPa, and a time of 7 seconds.

[0130] After manufacturing the electricity storage devices of Examples 3 and 4, they were cut in the center in the FB direction so as to form openings. The barrier layer 52 of the exterior film 50 exposed in the openings was covered with insulating tape.

[0131] Next, for the electricity storage device of Example 3, the exposed barrier layer and one end of the conductor were soldered and joined with Dotite. The joint between the barrier layer and the conductor was protected with insulating tape. For the electricity storage device of Example 4, the ridge of the second sealing portion 80 was scraped with a cutter to expose an end 90A of the barrier film, and the exposed end 90A was joined to an end of one of the conductors with Dotite. The joint between the end 90A and the conductor was protected with insulating tape. The Dotite used in the second test was DOTITE D-500 (manufactured by Fujikura Kasei Co., Ltd.).

[0132] <8-2-1. Checking insulation> Approximately 15 ml to 20 ml of acetone (enough to immerse the entire lid 60) was poured into the opening of the electricity storage devices of Examples 3 and 4, and left to stand for approximately 1 minute. Next, for the electricity storage devices of Examples 3 and 4, the other end of the conducting wire bonded to the barrier layer of the barrier film was connected to one terminal clip of a resistance meter. A rod-shaped terminal was used as the other terminal of the resistance meter, and it was immersed in acetone. The purity of the acetone used in the second test was 99.8%. The resistance meter was, for example, a 3154 DIGITAL MΩ HiTESTER (manufactured by Hioki E.E. Corporation).

[0133] Next, the resistance value was measured at an applied voltage of 100 V. The resistance value of the electricity storage device of Example 3 was 4.2 MΩ. The resistance value of the electricity storage device of Example 4 was overflow. It was confirmed that the insulation property of the barrier film of the electricity storage device of Example 3 was higher than that of the electricity storage device of Example 4.

[0134] <8-2-2. Checking for corrosiveness> 100 g of electrolyte solution containing salt was poured into the opening of the electricity storage device of Examples 3 and 4. Next, a lithium disk electrode was placed, and the opening was sealed with tape. Next, the cathode of the electrochemical measurement device was connected to the lithium disk electrode, and the anode of the electrochemical measurement device was connected to the other end of the lead. The electrochemical measurement device was, for example, a VMP3 (manufactured by BioLogic). After 5 minutes of OCV (open circuit voltage), chronoamperometry was performed under the following setting conditions, and the current flowing up to 1200 minutes was integrated. Set voltage: 0.100V (vs. Ref) Testing time: 24 hours

[0135] The electricity storage device of Example 3 had an integrated value of the corrosion current up to 1200 minutes was 13.6 C. The electricity storage device of Example 4 had an integrated value of the corrosion current up to 1200 minutes was 9.6×10 -4 C. It was confirmed that corrosion of the barrier film was suppressed more in the electricity storage device of Example 4 than in 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 corrosion of the barrier film.

[0136] An example of a procedure for checking the corrosiveness of the barrier film in the completed electricity storage device 10 is shown below.

[0137] First, the electricity storage device 10 is disassembled, and the electrode terminals 30 are cut to separate the electrode body 20 and the lid body 60. At this time, when the lid body 60 is placed so that the second surface 62 thereof serves as the bottom surface, the exterior film 50 is left 1.5 cm or more above the sealing surface 63 in the height direction. The end surfaces of the cut exterior film 50 are covered with insulating tape.

[0138] Next, as in the case of the electricity storage device of Example 3 or the electricity 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 a conductor, taking care not to conduct electricity to the electrode terminal 30.

[0139] The sample prepared as described above is placed in a glass container with the second surface 62 of the lid 60 facing downward, and the electrolyte is poured into the container 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 the electrochemical measurement device is connected to the lithium disk electrode. The anode of the electrochemical measurement device is connected to the other end of the lead. Chronoamperometry can then be performed to confirm the corrosion properties of the barrier film. [Explanation of symbols]

[0140] 10, 200, 300, 400, 500, 600: Energy storage device 20: Electrode body 30: Electrode terminal 40: Exterior body 40A: Opening 50: Exterior film 60: Lid 61: 1st page 62:Second side 63: Sealing surface 90: Barrier film 90A: End 92: Outer layer 110, 210, 310, 410, 510, 610: Lid unit 330: Covering part

Claims

1. An electrode body; an exterior body that seals the electrode body; a barrier film, The outer casing is an exterior film that wraps the electrode body so that an opening is formed; a lid body disposed in the opening, the lid body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface; The barrier film is bonded to the lid so as to cover at least a portion of the sealing surface. Energy storage device.

2. The barrier film is bonded to the lid so as to cover at least a portion of the first surface. The electricity storage device according to claim 1 .

3. The barrier film is a barrier layer; and an outer layer laminated on the opposite side of the barrier layer from the lid. The electricity storage device according to claim 1 or 2.

4. The barrier film is a barrier layer and an outer layer laminated on the barrier layer on the opposite side of the lid body, The portion covering at least a part of the sealing surface and the portion covering at least a part of the first surface are connected, and an end portion is located in the portion covering at least a part of the sealing surface. The electricity storage device according to claim 2 .

5. The barrier film is bonded to the lid so as to cover at least a portion of the second surface. The electricity storage device according to claim 1 .

6. The barrier film is a portion covering at least a portion of the sealing surface and a portion covering at least a portion of the second surface are connected to each other; The end is covered by a covering portion. The electricity storage device according to claim 5 .

7. The end of the barrier film is located in a portion that covers at least a part of the sealing surface and is located closer to the second surface than the boundary between the first surface and the sealing surface. The electricity storage device according to claim 1 .

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

9. further comprising an electrode terminal electrically connected to the electrode body, the lid is configured to cover a portion of the electrode terminal, The barrier film is disposed at least partially between the lid and the electrode terminal. The electricity storage device according to claim 1 or 2.

10. The barrier film is disposed on at least a portion of the inside of the lid. The electricity storage device according to claim 1 or 2.

11. 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. The electricity storage device according to claim 1 or 5.

12. An electrode body; an exterior film that wraps the electrode body so as to form an opening, a lid placed on the opening; a barrier film, the lid body has a first surface, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface; The barrier film is bonded to the lid so as to cover at least a portion of the sealing surface. Lid unit.

13. The cover further includes an electrode terminal joined to the cover. A lid unit according to claim 12.

14. A barrier film for use in the electricity storage device according to claim 2 or 5.

15. A barrier film used in the lid unit according to claim 12.

16. An electrode body; an exterior film that wraps the electrode body so as to form an opening, The lid unit is a lid placed on the opening; a barrier film, the lid body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface; the barrier film is bonded to the lid so as to cover at least a portion of the sealing surface, The method for manufacturing the lid unit includes: and insert-molding the lid body into the barrier film. Method for manufacturing the lid unit.

17. An electrode body; an exterior film that wraps the electrode body so as to form an opening, The lid unit is a lid placed on the opening; a barrier film, the lid body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface; the barrier film is bonded to the lid so as to cover at least a portion of the sealing surface, The method for manufacturing the lid unit includes: and joining the barrier film to the lid. Method for manufacturing the lid unit.

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