Electric storage device, lid, lid unit, and method for manufacturing electric storage device

Abstract

To provide an electric storage device capable of suitably sealing an electrode body with a casing, a lid used for the electric storage device, a lid unit including the lid, and a method for manufacturing the electric storage device.SOLUTION: The electric storage device includes an electrode body and a casing for sealing the electrode body. The casing includes: an exterior film wrapping the electrode body to form an opening part; a lid disposed at the opening part; a projecting part protruding outward beyond a portion of the exterior film which wraps the electrode body; and a first sealing part in which opposing surfaces of the exterior film of the projecting part are sealed. The projecting part is folded starting from a position away from the root part of the first sealing part.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device, a lid body, a lid unit, and a method for manufacturing an electricity storage device. [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, in order to miniaturize the configuration, it is preferable that the portion where the opposing surfaces of the exterior film are heat-sealed is folded starting from the base. However, because the base may be heat-sealed multiple times during the manufacturing process of the electricity storage device, the base and its surrounding area are damaged by the heat sealing. In addition, the sealant layer at the base and its surrounding area is thinned by the heat sealing. Furthermore, because the portion where the opposing surfaces of the exterior film are heat-sealed is movable, material fatigue is likely to occur, and the folding is therefore likely to damage the portion even if the heat sealing is not performed multiple times. Therefore, if the exterior film is folded starting from the base, the portion of the exterior film that constitutes the base and its surrounding area may be damaged, which may reduce the airtightness of the electricity storage device.

[0005] The present invention aims to provide an electricity storage device in which an electrode body can be suitably sealed with an exterior body, a lid body used in this electricity storage device, a lid unit including this lid body, and a method for manufacturing the electricity storage device. [Means for solving the problem]

[0006] An energy storage device according to a first aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, wherein the exterior body includes an exterior film that wraps the electrode body so as to form an opening, a lid that is placed in the opening, a protrusion that protrudes outward from a portion of the exterior film that wraps the electrode body, and a first sealing portion in which opposing surfaces of the protrusion of the exterior film are sealed, and the protrusion is folded starting from a position away from the base of the first sealing portion.

[0007] An energy storage device according to a second aspect of the present invention is the energy storage device according to the first aspect, wherein the first sealing portion includes a film thickness portion that increases in thickness toward the base, the film thickness portion has a starting point and an end point that is farther from the base than the starting point, and the protrusion portion is folded toward the electrode body starting from the end point or between the end point and the starting point.

[0008] An electricity storage device according to a third aspect of the present invention is the electricity storage device according to the first or second aspect, wherein the protruding portion has a fold formed at a position away from a base of the first sealing portion.

[0009] An electricity storage device according to a fourth aspect of the present invention is the electricity storage device according to the third aspect, wherein the fold is formed as a slit that does not penetrate through the exterior film.

[0010] An energy storage device according to a fifth aspect of the present invention is an energy storage device according to any one of the first to fourth aspects, wherein the exterior body includes a second sealing portion where the lid body and the exterior film are sealed together, the lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, and the first sealing portion seals the opposing surfaces of the exterior film with the protrusion sandwiched between them.

[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 protrusion becomes thicker toward the lid seal portion.

[0012] An electricity storage device according to a seventh aspect of the present invention is the electricity storage device according to the fifth or sixth aspect, wherein the melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion.

[0013] An electricity accumulation device according to an eighth aspect of the present invention is the electricity accumulation device according to any one of the fifth to seventh aspects, wherein the length of the protrusion is 20 mm or less.

[0014] A lid body according to a ninth aspect of the present invention is a lid body used as an exterior body for an electricity storage device, the exterior body including an exterior film that wraps an electrode body so as to form an opening, the lid body including a lid seal portion that is positioned at the opening and sealed to the exterior film, and a protrusion that protrudes from the lid seal portion.

[0015] A lid according to a tenth aspect of the present invention is the lid according to the ninth aspect, wherein the protruding portion becomes thicker toward the lid seal portion.

[0016] A lid according to an eleventh aspect of the present invention is the lid according to the ninth or tenth aspect, wherein the melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion.

[0017] A lid according to a twelfth aspect of the present invention is the lid according to any one of the ninth to eleventh aspects, wherein the length of the protrusion is 20 mm or less.

[0018] A lid unit according to a thirteenth aspect of the present invention comprises the lid according to any one of the ninth to twelfth aspects, and an electrode terminal joined to the lid.

[0019] A fourteenth aspect of the present invention relates to a method for manufacturing an electricity storage device, the method comprising: an electrode body; and an outer casing that seals the electrode body, the outer casing including an outer film that wraps the electrode body so as to form an opening; a lid that is placed in the opening; a protrusion that protrudes outward from a portion of the outer casing film that wraps the electrode body; and a first sealing portion in which opposing surfaces of the outer casing film in the protrusion are sealed, the method for manufacturing the electricity storage device including a step of folding the protrusion starting from a position away from a base of the first sealing portion.

[0020] A manufacturing method for an electricity storage device according to a fifteenth aspect of the present invention is the manufacturing method for an electricity storage device according to the fourteenth aspect, wherein the electricity storage device includes a second sealing portion where the lid body and the exterior film are sealed, and the first sealing portion includes a thickness portion that increases in thickness toward the base, and the manufacturing method for the electricity storage device includes a step of forming the second sealing portion using a sealing bar, and in the step of forming the second sealing portion, the second sealing portion is formed so that the sealing bar does not contact the thickness portion, or the second sealing portion is formed using the sealing bar having a sealing surface that follows the outer shape of the thickness portion so that the thickness of the thickness portion is maintained. [Effects of the Invention]

[0021] According to the electricity storage device, lid body, lid unit, and method for manufacturing an electricity storage device of the present invention, the electrode body can be suitably sealed by the exterior body. [Brief explanation of the drawings]

[0022] [Figure 1A] FIG. 1 is a perspective view of an electricity storage device according to an 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 the layer structure of an exterior film included in the electricity storage device of FIG. 1A. [Figure 3] FIG. 1B is a side view of a lid provided in the electricity storage device of FIG. 1A. [Figure 4] 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 5] FIG. 1B is a front view of the electricity storage device of FIG. 1A. [Figure 6] FIG. 6 is a front view of the electricity storage device of FIG. 5 in a state before the protruding portion is folded. [Figure 7] 1B is a flowchart showing an example of a method for manufacturing the electricity storage device of FIG. 1A. [Figure 8] 1B is a diagram showing a third step in the method for manufacturing the electricity storage device of FIG. 1A. [Figure 9] FIG. 1B is a diagram showing a fourth step in the method for producing the electricity storage device of FIG. 1A. [Figure 10] FIG. 1B is a diagram showing a fifth step in the method for producing the electricity storage device of FIG. 1A. [Figure 11] 1B is a diagram relating to the fourth and fifth steps of the method for producing the electricity storage device of FIG. 1A. [Figure 12] 1B is a diagram showing another example of the fourth step and the fifth step of the method for manufacturing the electricity storage device of FIG. 1A. [Figure 13] FIG. 1B is a diagram showing a sixth step in the method for manufacturing the electricity storage device of FIG. 1A. [Figure 14] FIG. 1B is a diagram illustrating an eighth step in the method for manufacturing the electricity storage device of FIG. 1A. [Figure 15] FIG. 10 is a cross-sectional view showing the configuration of an electricity storage device according to a second embodiment. [Figure 16] FIG. 16 is a plan view of a lid provided in the electricity storage device of FIG. [Figure 17] FIG. 10 is a diagram illustrating a third step of the method for manufacturing an electricity storage device according to a modified example of the first embodiment. [Figure 18] FIG. 18 is a perspective view of the cooling jig of FIG. [Figure 19]FIG. 19 is a perspective view of another modified cooling jig of FIG. 18. [Figure 20] FIG. 19 is a perspective view of a cooling jig according to still another modified example of the cooling jig shown in FIG. [Figure 21] FIG. 10 is a cross-sectional view showing the configuration of an electricity storage device according to a modified example of the second embodiment. [Figure 22] FIG. 11 is a cross-sectional view showing the configuration of an electricity storage device according to another modified example of the second embodiment. [Figure 23] 10 is a table showing test results of the electricity storage devices of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an electricity storage device according to an 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.

[0024] [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 sealed portion 80 of the electricity storage device of FIG. 1A. 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 side view of a lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 4 is a diagram showing the exterior film 50 included in the electricity storage device 10 of FIG. 1A in an unfolded state. FIG. 5 is a front view of the electricity storage device 10 of FIG. 1A in a state in which a portion including a protruding portion 50Y is folded. FIG. 6 is a front view of the electricity storage device 10 of FIG. 5 in a state before the protruding portion 50Y is folded. In FIGS. 1A, 3, 5, and 6, 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 UDLRFB are the same in the subsequent figures.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a pair of lid bodies 60. The exterior film 50 wraps the electrode body 20 so as to form a pair of openings 40A. In this embodiment, the exterior film 50 is wrapped around the electrode body 20 so as to form a pair of openings 40A. Note that the electrode body 20 may be housed inside the exterior film 50, which is configured in a cylindrical shape so as to form a pair of openings 40A, and the openings 40A may be closed by the lid body 60. The exterior body 40 has a main body portion 50X and a protruding portion 50Y. The main body portion 50X is a portion where at least the electrode body 20 is wrapped by the exterior film 50. In this embodiment, the main body portion 50X is a portion where the electrode body 20 and the lid body 60 are wrapped by the exterior film 50. The protruding portion 50Y is a portion of the exterior film 50 that protrudes from the main body portion 50X. The main body 50X has a pair of first surfaces 41A, 41B and a pair of second surfaces 42A, 42B. The pair of first surfaces 41A, 41B are substantially the same size. The pair of second surfaces 42A, 42B are substantially the same size. The pair of first surfaces 41A, 41B have larger areas than the pair of second surfaces 42A, 42B. The pair of lid bodies 60 are respectively disposed on the sides of the electrode body 20 so as to close the pair of openings 40A.

[0029] 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, in this embodiment, the exterior body 40 seals the electrode assembly 20 by wrapping the exterior film 50 around the electrode assembly 20, so that the electrode assembly 20 can be easily sealed 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 to improve the volumetric energy density of the electricity storage device 10 and to improve cooling efficiency, it is preferable that the exterior film 50 be wrapped so as to come into contact with the outer surface of the electrode assembly 20. Furthermore, in all-solid-state batteries, it is necessary to apply high pressure uniformly from the outer surface of the battery in order to exert battery performance, and therefore it is necessary to eliminate the space between the electrode body 20 and the exterior film 50. Therefore, it is preferable that the exterior film 50 is wrapped around the electrode body 20 so as to contact the outer surface of the electrode body 20.

[0030] As shown in FIG. 2 , the exterior film 50 is a laminate (laminate film) having, for example, a base material layer 51, a barrier layer 52, and a 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. That is, the exterior film 50 may be made of any flexible and easily bendable material, and may be made of, for example, a resin film. The interior and exterior layers of the exterior film 50 may be heat-sealable resin layers 53. In this case, the exterior film 50 may encase the electrode assembly 20 and the lid 60 by joining the outermost and innermost layers.

[0031] 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 forming 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.

[0032] 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.

[0033] 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.

[0034] From the viewpoint of improving the formability 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 formability, an aluminum alloy foil containing iron is preferred. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior film 50 with better formability can be obtained. By having an iron content of 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, etc. may also be added as necessary. Softening can be achieved by annealing or the like. From the viewpoint of improving the mechanical strength of the packaging film 50, it is more preferable that the aluminum alloy foil is 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 H4160:1994A8021H-H18, JIS H4160:1994 A8079H-H18, JISH4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14.

[0035] 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, the stainless steel foil is preferably made of austenitic stainless steel.

[0036] 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.

[0037] 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 5 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, while increasing the capacity of the electricity storage device increases the weight of the electricity storage device, 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.

[0038] 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.

[0039] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 during molding of the exterior film 50, 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 molding.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0044] 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.

[0045] The lid body 60 is, for example, plate-shaped and made of, for example, a resin material. The lid body 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 body 60 may include at least two or more materials selected from metal oxide, carbon material, and rubber material, and may include metal oxide, carbon material, and rubber material. The lid body 60 has a lid main body 60A. The lid main body 60A has a first surface 61, a second surface 62, and a lid seal portion 63. The first surface 61 faces the electrode assembly 20. The second surface 62 is the surface opposite to the first surface 61. The lid seal portion 63 is connected to the first surface 61 and the second surface 62 and is heat-sealed to the heat-sealable resin layer 53 of the exterior film 50. The lid seal portion 63 includes a first seal surface 63A, a second seal surface 63B, a third seal surface 63C, and a fourth seal surface 63D. The first seal surface 63A forms the upper surface of the lid body 60. The first seal 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 seal surface 63B and the third seal surface 63C are connected to the first seal surface 63A and form the side surfaces of the lid body 60. The second seal surface 63B and the third seal 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 seal surface 63D forms 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.

[0046] 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 lid seal portion 63 of the lid body 60 has a certain thickness so that the lid seal portion 63 of the lid body 60 and the exterior film 50 can be heat-sealed appropriately when the second sealing portion 80 is formed. 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, this does not include embodiments in which the lid body 60 is composed solely of a film defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard. 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.

[0047] The lid seal portion 63 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 shapes of the boundaries 64 to 67 may be angular, or may be rounded by applying a rounding process. In this embodiment, the boundaries 64 to 67 are angular.

[0048] In this embodiment, the lid 60 is made of a resin material. Here, "made 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In another example, the lid body 60 may be made of a metal material. Here, "made of a metal material" means that, when the entire material constituting the lid body 60 is taken as 100% by mass, the metal material content 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 body 60 may contain materials other than metal materials in addition to metal materials. The metal material constituting the lid body 60 can be selected arbitrarily. Examples of the metal material constituting the lid body 60 include aluminum, aluminum alloy, nickel, copper, and 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 made of aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the lid body 60 connected to the negative electrode may be nickel-plated copper. The material constituting the lid body 60 may include recycled metal materials.

[0055] 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 stored, 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. If the electrode terminals 30 do not protrude from the edge of the exterior body 40, the lid body 60 does not need to have the through-holes 60X formed therein.

[0056] 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 surfaces (heat-fusible resin layers 53) of the exterior film 50 facing each other in the protrusion portion 50Y.

[0057] The protruding portion 50Y includes a portion where the first edge 50A and the second edge 50B of the exterior film 50 shown in FIG. 4 are overlapped. The first sealing portion 70 extends in the longitudinal direction (FB direction) of the exterior body 40. The position where the first sealing portion 70 is formed in the exterior body 40 can be selected arbitrarily. In this embodiment, the base 70X of the first sealing portion 70 is preferably located on the side 43 at the boundary between the first surface 41A and the second surface 42A of the exterior body 40. The base 70X of the first sealing portion 70 may be located on any surface of the exterior body 40. From the viewpoint of configuring the power storage device 10 compactly, when the power storage device 10 is in use, the protruding portion 50Y is folded, for example, onto the first surface 41A or the second surface 42A of the exterior body 40. In this embodiment, as shown in FIG. 5, the protruding portion 50Y is folded toward the second surface 42A of the exterior body 40 when the electricity accumulation device 10 is in use.

[0058] In this embodiment, the second sealed portion 80 is formed by heat-sealing the heat-sealable resin layer 53 of the exterior film 50 and the lid seal portion 63 of the lid 60. The second sealed portion 80 has a second long side sealed portion 81 and a second short side sealed portion 82 (see FIG. 14 for both). The second long side sealed portion 81 is a portion where the heat-sealable resin layer 53 of the exterior film 50 is sealed to the first seal surface 63A and the fourth seal surface 63D of the lid 60. The second short side sealed portion 82 is a portion where the heat-sealable resin layer 53 of the exterior film 50 is sealed to the second seal surface 63B and the third seal surface 63C of the lid 60.

[0059] Hereinafter, the seal strength between the heat-fusible resin layer 53 of the exterior film 50 and the lid seal portion 63 of the lid 60 may be referred to as the seal strength of the second seal portion 80. The seal strength of the second seal portion 80 is the seal strength between the heat-fusible resin layer 53 and the lid 60 at the second long side seal portion 81, i.e., the lid seal portion 63 extending in the L-R (width) direction in FIG. 1A.

[0060] 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 41A 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 body 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, and the seal strengths of the three strip-shaped members are measured in the same manner as when the length of the lid body 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 body 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 lid seal portions 63 of the multiple parts.

[0061] 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.

[0062] During the manufacturing process of the electricity storage device 10, a predetermined area including the base 70X of the first sealed portion 70 is heat-sealed multiple times, resulting in significant damage. The heat-sealable resin layer 53 of the exterior film 50 is thinner at the base 70X of the first sealed portion 70. Therefore, when the protruding portion 50Y is folded from the base 70X toward the first surface 41A or the second surface 42A, the barrier layer 52 may peel from the base material layer 51 and the heat-sealable resin layer 53 in the portion including the base 70X of the first sealed portion 70, potentially causing a crack in the exterior film 50. If a crack occurs in the portion of the exterior film 50 including the base 70X, the sealing performance of the exterior body 40 may be reduced, potentially resulting in leakage of, for example, electrolyte solution. In this embodiment, to increase the strength of the base 70X and its surroundings, the first sealed portion 70 includes a portion (hereinafter referred to as a “thickness portion 90”) whose thickness HA increases toward the base 70X.

[0063] FIG. 6 is a front view of the power storage device 10 of FIG. 5 before the protruding portion 50Y of the power storage device 10 is folded. The thick portion 90 includes a starting point 90A and an end point 90B that is farther from the base 70X than the starting point 90A. In this embodiment, the starting point 90A is located outside the surface of the exterior film 50 in the second sealing portion 80. The thickness HA of the first sealing portion 70 locally increases at the starting point 90A as it moves outward from the protruding portion 50Y. The thickness HA of the first sealing portion 70 locally decreases at the end point 90B as it moves outward from the protruding portion 50Y. The power storage device 10 can be folded at the end point 90B with the protruding portion 50Y toward the first surface 41A or the second surface 42A. In another example, the protruding portion 50Y can be folded starting from any point between the end point 90B and the starting point 90A. The protruding portion 50Y is folded at a position away from the base 70X, in other words, at a position where damage due to heat sealing is relatively small, thereby suppressing the occurrence of cracks in the exterior film 50 at the base 70X. From the viewpoint of suppressing the occurrence of cracks in the exterior film 50, the protruding portion 50Y is preferably folded at a position 0.1 mm or more away from the base 70X. To facilitate the identification of the folding position of the first sealing portion 70, it is preferable that a fold 90C be formed in advance at the end point 90B or between the start point 90A and the end point 90B. The fold 90C is preferably formed over substantially the entire protruding portion 50Y in the FB direction. The fold 90C is preferably formed at a position 0.1 mm or more away from the base 70X in the LR direction. From the viewpoint of easily folding the protruding portion 50Y, it is preferable that the fold 90C be formed as a slit 90CX that does not penetrate the exterior film 50. In another example, the fold 90C may be formed by applying an additional seal to the exterior film 50.

[0064] <1-2. Method for manufacturing electricity storage devices> 7 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, an eighth step, a ninth step, and a tenth step. The first step to the tenth step are performed, for example, by a manufacturing apparatus for the electricity storage device 10. Note that the first step to the tenth step are names of the steps in the method for manufacturing the electricity storage device 10 specified for convenience, and do not necessarily indicate the order of the steps. The order of the following steps can be changed as desired.

[0065] In the first step of step S11, the manufacturing equipment places the lid body 60 (hereinafter referred to as the "lid unit 60Z") with the electrode terminals 30 attached to both ends of the electrode body 20. Completion of the first step electrically connects the electrode terminals 30 and the electrodes of the electrode body 20. Note that in the first step, the lid body 60 may be connected to the electrode terminals 30 electrically connected to the electrode body 20.

[0066] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus winds the exterior film 50 around the electrode assembly 20 and the lid body 60 while applying tension 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. In the second step, an exterior film 50 having a larger area than the exterior film 50 of the finished electricity storage device 10 is used in order to form a gas pocket 100, which will be described later.

[0067] The third process of step S13 is performed after the second process. As shown in Fig. 8, in the third process, the manufacturing equipment forms the first FB direction seal portion 71 having an unsealed portion 71Z in the center. Note that the hatched area in Fig. 8 indicates an example of the region where the first FB direction seal portion 71 is formed.

[0068] The fourth step of step S14 is performed after the third step. As shown in FIG. 9, in the fourth step, the manufacturing apparatus forms the second short side seal portion 82. As shown in FIG. 11, in the fourth step, the manufacturing apparatus preferably forms the second short side seal portion 82, for example, so that the seal bar 110 does not contact the thick film portion 90. In another example of the fourth step, as shown in FIG. 12, the manufacturing apparatus preferably forms the second short side seal portion 82 using a seal bar 110X having seal surfaces 110XA and 110XB. The seal surface 110XA is a seal surface shaped to conform to the second seal surface 63B and the third seal surface 63C. The seal surface 110XB is a seal surface shaped to conform to the outer contour of the thick film portion 90. Note that the hatched area in FIG. 9 indicates an example of the region where the second short side seal portion 82 is formed.

[0069] The fifth step of step S15 is performed after the fourth step. As shown in FIG. 10, in the fifth step, the manufacturing equipment forms the second long side seal portion 81 so that the thickness HA of the thick film portion 90 is maintained. As shown in FIG. 11, in the fifth step, the manufacturing equipment forms the second long side seal portion 81, for example, so that the seal bar 110 does not come into contact with the thick film portion 90. Note that the hatched area in FIG. 10 indicates an example of the region where the second long side seal portion 81 is formed.

[0070] The sixth step of step S16 is performed after the fifth step. As shown in FIG. 13, in the sixth step, the manufacturing apparatus forms the first LR seal portion 72. In the sixth step, the first LR seal portion 72 is formed in a portion including the root 70X so as to partially overlap the first FB seal portion 71. Completion of the sixth step results in the completion of a gas pocket 100 having a larger area in a plan view than the protruding portion 50Y of the completed electricity storage device 10. Note that the hatched portion in FIG. 13 indicates an example of the region where the first LR seal portion 72 is formed.

[0071] The seventh step of step S17 is performed after the sixth step. In the seventh step, the manufacturing equipment injects an electrolyte solution through the opening 100X of the gas pocket 100. After the electrolyte solution is injected, the edges including the opening 100X are joined. An aging step is performed after the seventh step. Gas generated by the aging step is stored in the gas pocket 100. The gas stored in the gas pocket 100 is discharged through an opening formed by cutting a portion of the gas pocket 100.

[0072] The eighth step of step S18 is performed after the seventh step and after the aging step is completed. As shown in FIG. 14, in the eighth step, the manufacturing equipment forms the first sealing portion 70. In the eighth step, the first FB direction seal portion 71 may also be resealed, or the first FB direction seal portion 71 may not be resealed. The hatched area in FIG. 14 indicates an example of the region where the first sealing portion 70 is formed.

[0073] The ninth step of step S19 is performed after the eighth step. In the ninth step, the manufacturing apparatus cuts the gas pocket 100 so as to form a protruding portion 50Y of a predetermined size. The dashed-dotted line XA shown in FIG. 14 is an example of a line indicating the position where the gas pocket 100 is cut in the ninth step.

[0074] The tenth step of step S20 is performed after the ninth step. In the tenth step, the protruding portion 50Y including the first sealed portion 70 is folded.

[0075] <1-3. Actions and Effects of Electricity Storage Devices> According to the electricity storage device 10, the protruding portion 50Y can be folded at a position away from the base 70X, which is damaged by heat sealing during the manufacturing process, and therefore the base 70X and the surrounding area of ​​the exterior film 50 are less likely to be damaged. This allows the electrode body 20 to be suitably sealed by the exterior body 40.

[0076] [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 body 260, but other configurations are similar to those of the electricity storage device 10 of the first embodiment. The following describes the electricity storage device 10 of the second embodiment, focusing on the differences from the electricity storage device 10 of the first embodiment.

[0077] <2-1. Configuration of the energy storage device> Fig. 15 is a cross-sectional view of the electricity storage device 200 of the second embodiment. Fig. 16 is a plan view of a lid 260 provided in the electricity storage device 200 of Fig. 15.

[0078] In the electricity storage device 200 of the second embodiment, in order to increase the strength of the base 70X of the first sealing portion 70 and its surroundings, the lid body 60 has a protruding portion 68 that protrudes from the lid seal portion 63. The first sealing portion 70 is sealed with the protruding portion 68 sandwiched between them.

[0079] The position where the protrusion 68 is formed in the lid seal portion 63 is determined based on the position of the root 70X of the first sealing portion 70. In this embodiment, the root 70X of the first sealing portion 70 is located at the boundary 64 of the lid body 60. Therefore, the protrusion 68 is formed at the boundary 64 in the lid seal portion 63. The protrusion 68 may be formed on the first seal surface 63A, the second seal surface 63B, the third seal surface 63C, the fourth seal surface 63D, the boundary 65, the boundary 66, or the boundary 67, depending on the position of the root 70X of the first sealing portion 70.

[0080] The direction in which the protrusion 68 extends can be selected arbitrarily. In this embodiment, the protrusion 68 extends along the first direction (in this embodiment, the LR direction). The protrusion 68 may also extend along the second direction (in this embodiment, the UD direction).

[0081] From the viewpoint of improving the sealing performance of the electrode body 20, the protrusion 68 can take a first, second, or third form. The first, second, and third forms may be independent of each other, or may be combined with each other within a range that does not cause technical contradiction.

[0082] In the first embodiment, the protrusion 68 is plate-shaped and has a shape that increases in thickness as it approaches the boundary 64, in other words, a shape that becomes thicker as it approaches the boundary 64. According to the first embodiment, the protrusion 68 has a sufficient thickness at the base 70X and its periphery, which prevents the resin that forms the protrusion 68 from flowing to the base 70X and its periphery when forming the first sealing portion 70. This prevents a decrease in the thickness HA of the first sealing portion 70 at the base 70X and its periphery. In the first embodiment, the protrusion 68 may be formed integrally with the lid main body 60A, or may be formed separately from the lid main body 60A and joined to the lid main body 60A.

[0083] In the second embodiment, the melting point of the material constituting the protrusion 68 is equal to or higher than the melting point of the material constituting the lid body 60A. According to the second embodiment, the high melting point of the material constituting the protrusion 68 prevents the resin constituting the protrusion 68 from flowing to the base 70X and its surroundings when forming the first sealing portion 70. This prevents a decrease in the thickness HA of the first sealing portion 70 at the base 70X and its surroundings. In the second embodiment, the protrusion 68 is preferably formed separately from the lid body 60A and joined to the lid body 60A. The protrusion 68 may also be formed integrally with the lid body 60A. In the second embodiment, the shape of the protrusion 68 can be selected arbitrarily. In the second embodiment, for example, the shape of the protrusion 68 may be plate-like. In the second embodiment, the thickness of the protrusion 68 can be selected arbitrarily. In the second embodiment, the thickness of the protrusion 68 may increase as it approaches the boundary 64. In the second embodiment, the thickness of the protrusion 68 may be constant or may increase with increasing distance from the boundary 64 .

[0084] In the third embodiment, the length of the protrusion 68 in the LR direction is 20 mm or less. According to the third embodiment, the short length of the protrusion 68 prevents the resin constituting the protrusion 68 from flowing to the base 70X and its surroundings when forming the first sealing portion 70. This prevents a decrease in the thickness HA of the first sealing portion 70 at the base 70X and its surroundings. In the third embodiment, the protrusion 68 may be formed integrally with the lid main body 60A, or may be formed separately from the lid main body 60A and joined to the lid main body 60A. In the third embodiment, the shape of the protrusion 68 can be selected arbitrarily. In the third embodiment, for example, the shape of the protrusion 68 may be plate-like. In the third embodiment, the thickness of the protrusion 68 can be selected arbitrarily. In the third embodiment, the thickness of the protrusion 68 may increase as it approaches the boundary 64. In the third embodiment, the thickness of the protrusion 68 may be constant or may increase with increasing distance from the boundary 64 .

[0085] <2-2. Actions and Effects of Electricity Storage Devices> According to the electricity storage device 200, the protruding portion 50Y can be folded at a position away from the base 70X, which is damaged by heat sealing in the manufacturing process, and therefore the base 70X and the surrounding area of ​​the exterior film 50 are less likely to be damaged. This allows the electrode body 20 to be suitably sealed by the exterior body 40.

[0086] [3. Modifications] The above-described embodiments are examples of possible forms of the electricity storage device, lid, 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, lid, and method for manufacturing an electricity storage device according to the present invention may take forms different from those exemplified in the embodiments. Examples of such forms include forms in which part of the configuration of each embodiment is replaced, modified, or omitted, or forms in which a new configuration is added to each embodiment. Below are some examples of modified forms of each embodiment. Note that the following modified forms can be combined with each other as long as there is no technical contradiction.

[0087] <3-1. First modified example> In the electricity storage device 10 of the first embodiment, the configuration of the first sealing portion 70 can be modified as desired, as long as the protruding portion 50Y can be folded at a position away from the base 70X of the first sealing portion 70. For example, the thick film portion 90 can be omitted from the first sealing portion 70. In the electricity storage device 10 of this modification, the thickness HA of the first sealing portion 70 may be constant or may vary partially.

[0088] <3-2. Second modified example> The manufacturing method of the electricity storage device 10 of the first embodiment can be modified as desired. For example, in the third step of the manufacturing method of the electricity storage device 10, after forming the first FB-direction seal portion 71, the cooling jig 300 may be placed on the protruding portion 50Y along the side 43. The cooling jig 300 is a jig that prevents the portion of the first FB-direction seal portion 71, including the side 43, from being heat-sealed again in the fourth and fifth steps. The cooling jig 300 also has the effect of preventing heat from being transferred to the portion of the first FB-direction seal portion 71, including the side 43, when forming the second short-side seal portion 82 and the second long-side seal portion 81. In the fourth and fifth steps, to avoid interference between the seal bar 110 and the cooling jig 300, the cooling jig 300 is placed only on the protruding portion 50Y and not on the main body portion 50X. The cooling jig 300 may be removed from the partially manufactured energy storage device 10 (hereinafter referred to as the "intermediate body of the energy storage device 10") after the fourth and fifth steps are completed, or may remain attached to the intermediate body of the energy storage device 10.

[0089] 17 is a perspective view of an intermediate body of the electricity storage device 10 to which the cooling jig 300 is attached in the third step. FIG. 18 is a perspective view of the cooling jig 300 of FIG.

[0090] 17, cooling jigs 300 are attached to both ends of the protruding portion 50Y in the FB direction of the intermediate body of the power storage device 10. The cooling jig 300 may be attached to only one end of the protruding portion 50Y in the FB direction.

[0091] The material constituting the cooling jig 300 can be selected arbitrarily. The material constituting the cooling jig 300 is, for example, a resin material, a metal material, a rubber material, a metal oxide, or a carbon material. The cooling jig 300 has a first fixing portion 310, a second fixing portion 320, and a connecting portion 330. The material constituting the first fixing portion 310, the material constituting the second fixing portion 320, and the material constituting the connecting portion 330 may be the same material or different materials. The first fixing portion 310, the second fixing portion 320, and the connecting portion 330 may be formed integrally or may be formed separately and joined together. In this embodiment, the first fixing portion 310, the second fixing portion 320, and the connecting portion 330 are formed integrally from, for example, a resin material.

[0092] The first fixing portion 310 is plate-shaped and is disposed on the first surface 50YA of the overhanging portion 50Y along the side 43. The first fixing portion 310 does not straddle the first surface 41A of the exterior body 40. The first fixing portion 310 contacts the first surface 50YA of the overhanging portion 50Y. The first fixing portion 310 also has the effect of suppressing movement of the overhanging portion 50Y (gas pocket 100) around the side 43 toward the second surface 42A. At least a portion of the first fixing portion 310 may or may not be bonded to the first surface 50YA of the overhanging portion 50Y. The first fixing portion 310 can be bonded to the first surface 50YA of the overhanging portion 50Y by any means, such as an adhesive or heat sealing. In the second modified example, the first fixing portion 310 is not bonded to the first surface 50YA of the overhanging portion 50Y.

[0093] The second fixing portion 320 is plate-shaped and is disposed so as to contact the second surface 50YB of the overhanging portion 50Y. By supporting the overhanging portion 50Y, the second fixing portion 320 also has the effect of suppressing movement of the overhanging portion 50Y (gas pocket 100) around the side 43 toward the second surface 42A. At least a portion of the second fixing portion 320 may or may not be bonded to the second surface 50YB of the overhanging portion 50Y. The second fixing portion 320 can be bonded to the second surface 50YB of the overhanging portion 50Y by any means, such as an adhesive or heat sealing. In the second modified example, the second fixing portion 320 is not bonded to the second surface 50YB of the overhanging portion 50Y.

[0094] The lengths of first fixed portion 310 and second fixed portion 320 in the FB direction can be selected arbitrarily. In the example shown in Fig. 17, the length of first fixed portion 310 in the FB direction is longer than the length of second fixed portion 320. The length of first fixed portion 310 in the FB direction may be shorter than the length of second fixed portion 320 or may be the same as the length of second fixed portion 320.

[0095] The connecting portion 330 connects the first fixing portion 310 and the second fixing portion 320. The connecting portion 330 may or may not be in contact with the side surface 50YC of the overhanging portion 50Y. In the example shown in FIG. 17, the connecting portion 330 is in contact with the side surface 50YC of the overhanging portion 50Y. At least a portion of the connecting portion 330 may or may not be bonded to the side surface 50YC of the overhanging portion 50Y. The connecting portion 330 can be bonded to the side surface 50YC of the overhanging portion 50Y by any means, such as an adhesive or heat sealing. In a second modified example, the connecting portion 330 is not bonded to the side surface 50YC of the overhanging portion 50Y.

[0096] In the second modified example, the specific configuration of the cooling jig 300 can be changed as desired as long as the configuration can prevent the portion of the first FB-direction seal portion 71, including the side 43, from being heat-sealed again in at least one of the fourth and fifth steps. For example, the cooling jig 300 may omit the first fixing portion 310 or the second fixing portion 320. The cooling jig 300 may omit the connecting portion 330. When the cooling jig 300 is configured only with the first fixing portion 310, the first fixing portion 310 is preferably joined to at least a portion of the first surface 50YA of the protruding portion 50Y. When the cooling jig 300 is configured only with the second fixing portion 320, the second fixing portion 320 is joined to at least a portion of the second surface 50YB of the protruding portion 50Y and the second surface 42A of the exterior body 40.

[0097] The cooling jig 300 also has the effect of suppressing peeling of the first sealing portion 70 and the second sealing portion 80 when the internal pressure of the exterior body 40 increases while attached to the completed power storage device 10. The larger the contact area between the first fixing portion 310 and the first surface 50YA, the more effective the cooling jig 300 is in suppressing peeling of the first sealing portion 70 and the second sealing portion 80. The larger the contact area between the second fixing portion 320 and the connecting portion 330 and the second surface 42A, the more effective the cooling jig 300 is in suppressing peeling of the second sealing portion 80 (particularly the second short side seal portion 82).

[0098] When evacuation is performed in the manufacturing process of the electricity storage device 10, the exterior body 40 may shrink. When at least a portion of the cooling jig 300 is joined to any surface of the exterior body 40, the cooling jig 300 can prevent the exterior body 40 from shrinking.

[0099] FIG. 19 is a perspective view of a cooling jig 300X according to another modification of FIG. 18. The cooling jig 300X includes a first fixing portion 310X, a pair of second fixing portions 320X, and a pair of connecting portions 330X. The first fixing portion 310X is plate-shaped and extends in the FB direction. The length of the first fixing portion 310X in the FB direction is substantially equal to the length of the protruding portion 50Y. The pair of second fixing portions 320X are plate-shaped and connected to ends of the first fixing portion 310X in the FB direction via the pair of connecting portions 330X. The length of the pair of second fixing portions 320X in the FB direction is shorter than the length of the protruding portion 50Y. The first fixing portion 310X or the second fixing portion 320X may be omitted from the cooling jig 300X. The connecting portions 330X may be omitted from the cooling jig 300X. When the cooling jig 300 is formed only by the first fixing portion 310X, the first fixing portion 310X is preferably joined to at least a part of the first surface 50YA of the protruding portion 50Y. When the cooling jig 300 is formed only by the second fixing portion 320X, the second fixing portion 320X is joined to the second surface 50YB of the protruding portion 50Y and at least a part of the second surface 42A of the exterior body 40.

[0100] When the cooling jig 300X is attached to the finished electricity storage device 10, it has the same effect as the cooling jig 300 of suppressing expansion of the exterior body 40 and suppressing peeling of the first sealing portion 70 and the second sealing portion 80. When at least a portion of the cooling jig 300X is joined to any surface of the exterior body 40, it has the effect of suppressing contraction of the exterior body 40. Because the length of the first fixing portion 310X in the FB direction is substantially equal to the length of the protruding portion 50Y, the cooling jig 300X is particularly effective in suppressing peeling of the first sealing portion 70.

[0101] FIG. 20 is a perspective view of a cooling jig 300Y according to yet another modification of FIG. 18. The cooling jig 300Y includes a first fixing portion 310Y, a second fixing portion 320Y, and a pair of connecting portions 330Y. The first fixing portion 310Y is plate-shaped and extends in the FB direction. The length of the first fixing portion 310Y in the FB direction is substantially equal to the length of the protruding portion 50Y. The second fixing portion 320Y is plate-shaped and extends in the FB direction. The length of the second fixing portion 320Y in the FB direction is substantially equal to the length of the protruding portion 50Y. The pair of connecting portions 330Y connect the end of the first fixing portion 310Y and the end of the second fixing portion 320Y in the FB direction. The first fixing portion 310Y or the second fixing portion 320Y may be omitted from the cooling jig 300Y. The connecting portions 330Y may be omitted from the cooling jig 300Y. When the cooling jig 300Y is formed only by the first fixing portion 310Y, the first fixing portion 310Y is preferably joined to at least a part of the first surface 50YA of the protruding portion 50Y. When the cooling jig 300Y is formed only by the second fixing portion 320Y, the second fixing portion 320Y is joined to the second surface 50YB of the protruding portion 50Y and at least a part of the second surface 42A of the exterior body 40.

[0102] When attached to the completed power storage device 10, the cooling jig 300Y, like the cooling jig 300, has the effect of suppressing expansion of the exterior body 40 and suppressing peeling of the first sealing portion 70 and the second sealing portion 80. When at least a portion of the cooling jig 300Y is joined to any surface of the exterior body 40, it has the effect of suppressing contraction of the exterior body 40. Because the cooling jig 300Y sandwiches the first sealing portion 70 between the first fixing portion 310Y and the second fixing portion 320Y, it is particularly effective in suppressing peeling of the first sealing portion 70. Furthermore, the cooling jig 300Y can more effectively suppress expansion of the second surface 42A the larger the contact area between the connecting portion 330Y and the second surface 42A.

[0103] <3-3.Third modified example> In the power storage device 200 of the second embodiment, the direction in which the protrusion 68 extends can be changed as desired. For example, as shown in Fig. 21 , the protrusion 68 may extend in a third direction intersecting the first direction (LR direction in the second embodiment) and the second direction (UD direction in the second embodiment) in a front view of the lid 260.

[0104] <3-4. Fourth Variation> In the electricity storage device 200 of the second embodiment, the configuration of the lid body 260 can be modified as desired. As shown in FIG. 22 , the lid body 260 may include a frame 60B that covers the lid main body 60A. In this modification, the lid main body 60A can be made of any material, such as metal or resin. The frame 60B can be made of a material that can be suitably sealed with the heat-sealable resin layer 53 of the exterior film 50, for example. In this modification, the lid seal portion 63 and the protrusion 68 of the lid body 60 are formed on the frame 60B.

[0105] <3-5. Fifth Variation> In the electricity storage device 200 of the second embodiment, the specific method for forming the protrusion 68 of the lid body 260 can be changed as desired. For example, the protrusion 68 may be formed by an adhesive film or the like that is bonded to the lid seal portion 63 of the lid main body 60A. In this modification, for example, the protrusion 68 may be formed by bonding a plurality of adhesive films to the lid seal portion 63 in an overlapping manner, or the protrusion 68 may be formed by bonding an adhesive film to the lid seal portion 63 in a flap shape.

[0106] <3-6. Sixth Variation> The electricity storage device 10 of the first embodiment may have an adhesive film disposed between the exterior film 50 and the lid body 60 to suitably bond the exterior film 50 and the lid body 60. In this modification, for example, the lid body 60 with the adhesive film adhered thereto is attached to the openings 40A at both ends of the exterior body 40, and then the second sealing portion 80 is formed. For example, the adhesive film is wrapped around the lid body 60 so as to cover the entire surface of the lid seal portion 63 of the lid body 60. The adhesive film is preferably configured to be wider overall than the lid seal portion 63 of the lid body 60. In this case, the adhesive film can be easily bonded to the lid body 60. Furthermore, since the boundaries 64 to 67 of the lid seal portion 63 are covered by the adhesive film, the adhesion between the lid body 60 and the adhesive film is enhanced.

[0107] Any adhesive film can be selected as long as it can bond the exterior film 50 and the lid 60. The adhesive film is preferably a laminate (laminate 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 according to the materials constituting the heat-sealable resin layer 53 of the exterior film 50 and the material constituting the lid 60. The material constituting the heat-sealable resin layer of the adhesive film on the side to be bonded to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably is a polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride. Specific examples of acid-modified polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred, and polypropylene is particularly preferred.

[0108] The acid-modified polyolefin may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a cyclic polyolefin by substituting an α,β-unsaturated carboxylic acid or an anhydride thereof for some of the monomers constituting the cyclic polyolefin, or by block polymerizing or graft polymerizing an α,β-unsaturated carboxylic acid or an anhydride thereof with a cyclic polyolefin.

[0109] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, cyclic alkenes are preferred, and norbornene is even more preferred. Another example of a constitutive monomer is styrene. Examples of carboxylic acids or anhydrides thereof used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride. The heat-sealable resin layer of the adhesive film on the side bonded to the exterior film 50 is preferably made of the same material as the heat-sealable resin layer 53 of the exterior film 50.

[0110] The heat-resistant substrate layer may be any film made of a heat-resistant resin, such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, or polypropylene. Polyethylene terephthalate is particularly preferred because it is inexpensive and strong. The heat-resistant substrate layer may be a heat-resistant film or nonwoven fabric. Examples of materials constituting the heat-resistant substrate layer include polyolefin resins, polyamide resins, polyester resins, epoxy resins, acrylic resins, fluororesins, silicone resins, phenolic resins, polyetherimides, polyimides, polycarbonates, and mixtures or copolymers thereof. The heat-resistant substrate layer may have the same layer structure as the heat-sealable resin layer.

[0111] The adhesive film preferably has adhesiveness. When the second sealing portion 80 is formed with the adhesive film disposed between the exterior film 50 and the lid 60, the adhesive film is less likely to shift position relative to the lid 60 and the exterior film 50. By incorporating a tackifying resin into the heat-sealable resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the tackifying resin include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene and copolymers of amorphous propylene and other α-olefins. The content of the tackifying resin relative to the base material constituting the heat-sealable resin is preferably 10 to 20 wt % or less. This modification can also be applied to the second embodiment.

[0112] <3-7. Seventh Variation> In each of the above embodiments, the exterior film 50 of the electricity storage device 10 may protrude outward in the FB direction beyond at least one of the two lid bodies 60. The electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the lid body 60. The portion of the exterior film 50 that protrudes beyond the lid body 60 may be folded inward so that the outer surfaces of the exterior film 50 come into contact with each other, as in a Goebel-top container, or may be folded toward any surface of the exterior body 40, as in a brick container.

[0113] <3-8. Eighth Variation> In each of the above embodiments, the exterior body 40 may not have one of the two lid bodies 60. In this modification, in the FB direction, in the portion of the exterior body 40 where the lid body 60 is omitted, the electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the electrode body 20. As in the seventh modification, the portion of the exterior film 50 that protrudes outward beyond the electrode body 20 may be folded like a Goebel-top container or a brick container.

[0114] <3-9. 9th Variation> In the above embodiment, the outer shape of the exterior body 40 can be changed as desired. The outer shape of the exterior body 40 may be a cylinder, a prism, or a cube.

[0115] <3-10. 10th Variation> In the above embodiment, the electrode body 20 is wrapped in one exterior film 50, but it may be wrapped in two or more exterior films 50.

[0116] 4. Working Example The inventors of the present application conducted tests to confirm the sealing properties of the exterior bodies of the electricity storage devices of Examples and Comparative Examples. Note that, for the sake of convenience of explanation, the following description will be given by assigning the same reference numerals to the elements constituting the electricity storage devices of Examples and Comparative Examples that are the same as those in the embodiment.

[0117] The electricity storage devices of Examples 1 to 8 are electricity storage devices according to the second embodiment. The electricity storage devices of Examples 1 to 8 are intermediate products of electricity storage devices in which the fifth step in the manufacturing method for the electricity storage device 10 has been completed. Hereinafter, for ease of explanation, the intermediate products of the electricity storage devices of Examples 1 to 8 will be referred to as electricity storage devices. The specifications of the electricity storage devices of Examples 1 to 8 are as follows:

[0118] The exterior film 50 is a laminate (laminate film) having a base layer 51, a barrier layer 52, and a heat-sealable resin layer 53, in this order. The base layer 51 is formed by laminating a polyethylene terephthalate film, an adhesive layer, a stretched nylon film, and another adhesive layer, in this order. The polyethylene terephthalate film has a thickness of 15 μm. The stretched nylon film has a thickness of 15 μm. The adhesive layers are both made of two-component urethane adhesives. The adhesive layer has a thickness of 3 μm after curing. The barrier layer 52 is made of aluminum foil. The barrier layer 52 has a thickness of 40 μm. The heat-sealable resin layer 53 in Examples 1 and 2 is formed by laminating maleic anhydride-modified polypropylene and random polypropylene, in this order. The maleic anhydride-modified polypropylene has a thickness of 40 μm. The random polypropylene has a thickness of 40 μm.

[0119] The lid 60 is made of polypropylene and is manufactured by injection molding. The lid 60 has a length (height) in the UD direction of 30 mm, a length (width) in the LR direction of 100 mm, and a length (thickness) in the FB direction of 5 mm. The protrusion 68 of the lid 60 is formed at the boundary 64 in the lid seal portion 63. The length of the protrusion 68 in the LR direction is 5 mm, the length in the FB direction is 2 mm, and the length in the UD direction is 0.2 mm. The thickness of the protrusion 68 in the UD direction is approximately constant.

[0120] The manufacturing method of the electricity storage devices of Examples 1 to 8 is the same as the method shown in FIG. 7. The sealing conditions for forming the first FB-direction seal portion 71 in the third step are a temperature of 226°C, a sealing time of 10 seconds, and a surface pressure of 0.25 MPa. The sealing conditions for forming the second sealing portion 80 in the fourth and fifth steps are a temperature of 180°C, a sealing time of 5 seconds, and a surface pressure of 0.78 MPa. Note that the sealing conditions, such as temperature, pressure, and time, can be changed as appropriate depending on the material and apparatus. In the electricity storage devices of Examples 1 to 4, a fold is formed at a position 1 mm away from the base 70X (side 43) of the first sealing portion 70, so after the fifth step is completed, additional sealing is performed so as to overlap the first FB-direction seal portion 71. In the electricity storage devices of Examples 5 to 8, in order to form a fold at a position away from the base 70X (side 43) of the first sealing portion 70, after the fifth step is completed, additional sealing is performed at a position 1 mm away from the side 43 in the LR direction so as to partially overlap the first FB-direction seal portion 71. The sealing conditions for the additional sealing are a temperature of 226°C, a sealing time of 10 seconds, and a surface pressure of 1.23 MPa. In the electricity storage devices of Examples 1 to 8, the protrusion 50Y is folded starting from a position away from the base 70X (side 43) of the first sealing portion 70. The electricity storage devices of Examples 1 to 4 differ from each other in the number of times a folding operation of the protrusion 50Y, which will be described later, is performed. The electricity storage devices of Examples 5 to 8 differ from each other in the number of times a folding operation of the protrusion 50Y, which will be described later, is performed.

[0121] The electricity storage devices of Comparative Examples 1 to 4 have the same configuration as the electricity storage device 10 of the second embodiment, except that the protruding portion 50Y is folded starting from the base 70X (side 43) of the first sealing portion 70. The electricity storage devices of Comparative Examples 1 to 4 are intermediate products of electricity storage devices in which the fifth step in the manufacturing method for the electricity storage device 10 has been completed. Hereinafter, for ease of explanation, the intermediate products of the electricity storage devices of Comparative Examples 1 to 4 will be referred to as electricity storage devices. The specifications of the electricity storage devices of Comparative Examples 1 to 4 are as follows:

[0122] The specifications of the exterior film 50 and the lid 60 are the same as those of the electricity storage devices of Examples 1 to 8. The manufacturing methods of the electricity storage devices of Comparative Examples 1 to 4 are the same as those of the electricity storage devices of Examples 1 to 8. However, in the electricity storage devices of Comparative Examples 1 to 4, the protruding portion 50Y is folded starting from the base 70X (side 43) of the first sealing portion 70, and therefore no additional sealing is performed after the fifth step.

[0123] In the test, the electricity storage devices of Examples 1 to 8 and Comparative Examples 1 to 4 manufactured as described above were left to stand for 30 minutes, and then the folding operation of the protruding portion 50Y was carried out. One folding operation of the protruding portion 50Y consisted of the following operations (A) to (C).

[0124] Operation (A): The protruding portion 50Y is folded from a state in which the protruding portion 50Y protrudes outward so as to come into contact with the second surface 42A of the exterior body 40. Operation (B): After operation (A), the protruding portion 50Y is folded so as to come into contact with the first surface 41A of the exterior body 40. Operation (C): After operation (B), the protruding portion 50Y is raised from the first surface 41A, and the protruding portion 50Y is again brought into a state where it protrudes outward.

[0125] In the test, the folding operation was performed once for the electricity storage devices of Example 1, Example 5, and Comparative Example 1. The folding operation was performed twice for the electricity storage devices of Example 2, Example 6, and Comparative Example 2. The folding operation was performed three times for the electricity storage devices of Example 3, Example 7, and Comparative Example 3. The folding operation was performed four times for the electricity storage devices of Example 4, Example 8, and Comparative Example 4.

[0126] In the test, before and after the folding operation, the exterior bodies of the electricity storage devices of Examples 1 to 8 and Comparative Examples 1 to 4 were cut using an ultrasonic cutter (for example, SUW30 (manufactured by Suzuki Corporation)) and scissors. Next, the inner surface of the exterior body 40 was cut using a ritratome (for example, REM-710). Next, the cross section was observed using a laser microscope (for example, ultra-deep color 3D shape measuring microscope VK-9510) to check for the presence or absence of peeling between the barrier layer 52 and the heat-sealable resin layer 53 and the presence or absence of cracks in the heat-sealable resin layer 53.

[0127] Fig. 23 is a table showing the test results. In Fig. 23, the presence or absence of peeling between the barrier layer 52 and the heat-sealable resin layer 53 is indicated as "presence or absence of peeling." In Fig. 23, the presence or absence of cracks in the heat-sealable resin layer 53 is indicated as "presence or absence of cracks." In the electricity storage devices of Examples 1 to 8, no peeling between the barrier layer 52 and the heat-sealable resin layer 53 and no cracks in the heat-sealable resin layer 53 were observed before and after the folding operation. This indicates that the electricity storage devices of Examples 1 to 8 have high sealing properties.

[0128] On the other hand, in the electricity storage devices of Comparative Examples 2 to 4, after the folding operation, peeling between the barrier layer 52 and the heat-sealable resin layer 53 and cracks in the heat-sealable resin layer 53 were observed. Furthermore, in the electricity storage device of Comparative Example 1, peeling between the barrier layer 52 and the heat-sealable resin layer 53 was observed after the folding operation. This indicates that the electricity storage devices of Comparative Examples 1 to 4 have poor sealing properties. [Explanation of symbols]

[0129] 10: Energy storage device 20: Electrode body 40: Exterior body 40A: Opening 50: Exterior film 50Y: Overhang 60: Lid 60Z: Lid unit 260: Lid 63: Lid seal 68: Protrusion 70: First sealing portion 70X: Root 80: Second sealing portion 90: Film thickness 90A:Starting point 90B: End point 90C: Fold 90D: Slit

Claims

1. An electrode body; an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so that an opening is formed; a lid body placed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film in the protruding portion that face each other are sealed together, The protruding portion is folded starting from a position away from the base of the first sealing portion. Energy storage device.

2. the first sealing portion includes a thick portion whose thickness increases toward a base thereof, the thick portion has a start point and an end point that is farther from the base than the start point, The protruding portion is folded toward the electrode assembly from the end point or from a point between the end point and the start point. The electricity storage device according to claim 1 .

3. The protruding portion has a fold formed at a position away from the base of the first sealing portion. The electricity storage device according to claim 1 or 2.

4. The fold is formed by a cut that does not penetrate the exterior film. The electricity storage device according to claim 3 .

5. the exterior body includes a second sealing portion formed by sealing the lid body and the exterior film, the lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, The first sealing portion is formed by sealing the facing surfaces of the exterior film with the protruding portion sandwiched between them. The electricity storage device according to claim 1 .

6. The protrusion becomes thicker toward the lid seal portion. The electricity storage device according to claim 5 .

7. The melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion. The electricity storage device according to claim 5 or 6.

8. The length of the protrusion is 20 mm or less. The electricity storage device according to claim 5 or 6.

9. A lid used for an exterior body of an electricity storage device, the exterior body includes an exterior film that wraps the electrode body so that an opening is formed, The lid is disposed at the opening, a lid seal portion that is sealed with the exterior film; a protrusion protruding from the lid seal portion; Lid body.

10. The protrusion becomes thicker toward the lid seal portion. The lid according to claim 9.

11. The melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion. The lid according to claim 9 or 10.

12. The length of the protrusion is 20 mm or less. The lid according to claim 9 or 10.

13. The lid according to claim 9 or 10; an electrode terminal joined to the lid; Lid unit.

14. A method for manufacturing an electricity storage device, comprising: The electricity storage device is An electrode body; an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so that an opening is formed; a lid body placed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film in the protruding portion that face each other are sealed together, The method for manufacturing the electricity storage device includes: and folding the protruding portion starting from a position away from the base of the first sealing portion. A method for manufacturing an electricity storage device.

15. The electricity storage device is a second sealing portion formed by sealing the lid and the exterior film; the first sealing portion includes a thick portion whose thickness increases toward a base thereof, The method for manufacturing the electricity storage device includes: forming the second sealing portion using a seal bar; In the step of forming the second sealing portion, The second sealing portion is formed so that the seal bar does not come into contact with the thickness portion, or The second sealing portion is formed using the sealing bar having a sealing surface that conforms to the outer shape of the thickness portion so that the thickness of the thickness portion is maintained. The method for manufacturing the electricity storage device according to claim 14 .

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