Power storage device, lid element, outer package film, and ignition prevention element

Abstract

Provided is a power storage device comprising an electrode body and an outer packaging body in which the electrode body is sealed. The outer packaging body comprises: an outer packaging film that wraps the electrode body; and a lid member that seals the electrode body and the outer packaging film. The power storage device is provided with an ignition prevention element that has at least one of a heat absorption function and a fire extinguishing function.

Description

Power storage device, lid, exterior film, fire prevention element

[0001] The present invention relates to an electricity storage device and a lid.

[0002] Patent Document 1 discloses an example of an electricity storage device. This electricity storage device includes an electrode assembly, an electrode terminal connected to the electrode assembly, and an exterior body that seals the electrode assembly. The exterior body has an exterior film that encases the electrode assembly and a lid that is joined to the exterior film.

[0003] Japanese Patent Application Laid-Open No. 2022-123686

[0004] In the above-described electricity storage device, when the electrode assembly becomes hot, the heat generated from the electrode assembly may cause, for example, damage to elements constituting the exterior body, which may result in a decrease in the sealing performance of the exterior body.

[0005] The present invention aims to provide an electricity storage device in which the electrode body is likely to remain sealed even when the electrode body becomes hot, an anti-ignition element used in this electricity storage device, and a lid and exterior film used as the exterior body of this electricity storage device.

[0006] The energy storage device according to a first aspect of the present invention is an energy storage device comprising an electrode body and an exterior body that seals the electrode body, wherein the exterior body comprises an exterior film that wraps the electrode body and a lid that seals the electrode body together with the exterior film, and the energy storage device comprises an ignition prevention element that has at least one of a heat absorption function and a fire extinguishing function.

[0007] The second aspect of the present invention relates to an energy storage device comprising an electrode body and an exterior body that seals the electrode body, wherein the exterior body comprises an exterior film that is wrapped around the electrode body and a sealing portion that seals a portion including an end of the exterior film, and the energy storage device comprises an ignition prevention element that has at least one of a heat absorption function and a fire extinguishing function.

[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 anti-ignition element is disposed at least between the electrode body and the exterior film.

[0009] An electricity storage device according to a fourth aspect of the present invention is the electricity storage device according to the first aspect, wherein the anti-ignition element is disposed at least between the electrode body and the lid body.

[0010] An electricity storage device according to a fifth aspect of the present invention is the electricity storage device according to the first or fourth aspect, wherein the lid has a housing portion that houses the fire prevention element.

[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 storage section includes a protrusion that comes into contact with the fire prevention element when the lid is deformed.

[0012] An electricity storage device according to a seventh aspect of the present invention is the electricity storage device according to the first or fourth aspect, wherein the lid includes a protrusion that comes into contact with the anti-ignition element when deformed.

[0013] An electric storage device according to an eighth aspect of the present invention is the electric storage device according to the first aspect or any one of the fourth to seventh aspects, wherein a material constituting the lid body includes the anti-ignition element.

[0014] An electricity storage device according to a ninth aspect of the present invention is the electricity storage device according to any one of the first to eighth aspects, wherein a material constituting the exterior film includes the ignition countermeasure element.

[0015] An energy storage device according to a tenth aspect of the present invention is an energy storage device according to any one of the first to ninth aspects, wherein the outer casing has a first sealing portion in which the inner surfaces of the outer casing films are joined together, and the ignition prevention element is positioned at least at the base of the first sealing portion.

[0016] An electric storage device according to an eleventh aspect of the present invention is an electric storage device according to the first aspect or any one of the fourth to eighth aspects, wherein the ignition prevention element is disposed at least between the exterior film and the lid body.

[0017] An electric storage device according to a twelfth aspect of the present invention is an electric storage device according to the first aspect or any one of the fourth to eighth aspects, further comprising an electrode terminal connected to the electrode body, and the ignition prevention element is disposed at least between the electrode terminal and the lid body.

[0018] An electricity storage device according to a thirteenth aspect of the present invention is the electricity storage device according to any one of the first to twelfth aspects, further comprising a combustion suppression element that is at least one of flame retardant and non-flammable and suppresses combustion of the exterior body.

[0019] A lid according to a fourteenth aspect of the present invention is a lid used for an exterior packaging of an electricity storage device, the electricity storage device comprising an electrode assembly and an exterior packaging that seals the electrode assembly. The exterior packaging comprises an exterior film that wraps the electrode assembly, and a lid that seals the electrode assembly together with the exterior film. The lid comprises an ignition countermeasure element having at least one of a heat absorption function and a fire extinguishing function.

[0020] A lid according to a fifteenth aspect of the present invention is the lid according to the fourteenth aspect, wherein the ignition prevention element contacts at least a part of the surface of the lid.

[0021] A lid according to a sixteenth aspect of the present invention is the lid according to the fifteenth aspect, wherein the anti-ignition element is joined to at least a part of a surface of the lid facing the electrode body.

[0022] A lid according to a seventeenth aspect of the present invention is the lid according to any one of the fourteenth to sixteenth aspects, wherein a material constituting the lid includes the ignition countermeasure element.

[0023] A lid according to an eighteenth aspect of the present invention is the lid according to any one of the fourteenth to seventeenth aspects, and has a housing portion for housing the ignition countermeasure element.

[0024] A lid body according to a 19th aspect of the present invention is a lid body according to any one of the 14th to 18th aspects, further comprising a combustion suppression element that is at least one of flame retardant and non-flammable and suppresses the combustion of the outer casing.

[0025] A twentieth aspect of the present invention provides a fire prevention element for use in an electricity storage device, the electricity storage device comprising an electrode assembly and an exterior body sealing the electrode assembly, the exterior body comprising an exterior film wrapping the electrode assembly and a lid sealing the electrode assembly together with the exterior film, and the fire prevention element has at least one of a heat absorption function and a fire extinguishing function.

[0026] A fire prevention element according to a twenty-first aspect of the present invention is an fire prevention element for use in an electricity storage device, the electricity storage device comprising: an electrode assembly; and an exterior body sealing the electrode assembly. The exterior body comprises an exterior film wrapped around the electrode assembly; and a sealing portion sealing a portion including an end of the exterior film. The fire prevention element has at least one of a heat absorption function and a fire extinguishing function.

[0027] An exterior film according to a twenty-second aspect of the present invention is an exterior film used as an exterior body for an electricity storage device, and the material constituting the exterior film includes an ignition prevention element having at least one of a heat absorption function and a fire extinguishing function.

[0028] According to the electricity storage device, lid, anti-ignition element, and exterior film of the present invention, the electrode body is likely to remain sealed even when the electrode body reaches a high temperature.

[0029] 1A . A perspective view of an electricity storage device according to an embodiment. A diagram relating to a method for measuring the seal strength of a second sealed portion of the electricity storage device of FIG. 1A. A cross-sectional view showing the layer structure of an exterior film included in the electricity storage device of FIG. 1A. A diagram showing an unfolded state of the exterior film included in the electricity storage device of FIG. 1A. A perspective view of the front side of a lid body included in the electricity storage device of FIG. 1A. A perspective view of the back side of a lid body included in the electricity storage device of FIG. 1A. A cross-sectional view taken along line D6-D6 of FIG. 1A. A cross-sectional view taken along line D7-D7 of FIG. 1A. A flowchart showing an example of a manufacturing method of the electricity storage device of FIG. 1A. A cross-sectional view of a first modified electricity storage device. A plan view of a second modified electricity storage device. A plan view of an electricity storage device of another modified version of the second modified version. A cross-sectional view of a third modified electricity storage device. A cross-sectional view of a fourth modified electricity storage device. A plan view of a fifth modified electricity storage device. A plan view of an electricity storage device of another modified version of the fifth modified version. A cross-sectional view of a sixth modified electricity storage device. A cross-sectional view of a sixth modified electricity storage device. 13 is a cross-sectional view of an electricity storage device according to a seventh modified example. FIG. 14 is a cross-sectional view of an electricity storage device according to an eighth modified example. FIG. 15 is a cross-sectional view of an electricity storage device according to a thirteenth modified example.

[0030] 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.

[0031] [Embodiments] <1-1. Configuration of Electricity Storage Device> FIG. 1A is a perspective view schematically illustrating an electricity storage device 10 according to an embodiment. FIG. 1B is a diagram illustrating a method for measuring the seal strength of a second sealed portion 100B of the electricity storage device 10 of FIG. 1A. FIG. 2 is a cross-sectional view illustrating the layer configuration of an exterior film 50 included in the electricity storage device 10 of FIG. 1A. FIG. 3 is a diagram illustrating the exterior film 50 included in the electricity storage device 10 of FIG. 1A in an unfolded state. FIG. 4 is a perspective view of the rear side of a lid body 60 included in the electricity storage device 10 of FIG. 1A. FIG. 5 is a perspective view of the front side of the lid body 60 of FIG. 4. FIG. 6 is a cross-sectional view taken along line D6-D6 in FIG. 1A. FIG. 7 is a cross-sectional view taken along line D7-D7 in FIG. 1A. In FIG. 1A, the direction of arrow UD indicates the thickness direction of the electricity storage device 10, the direction of arrow LR indicates the width direction of the electricity storage device 10, and the direction of arrow FB indicates the depth direction of the electricity storage device 10. The directions indicated by the arrows UDLRFB are the same in the subsequent drawings.

[0032] The energy storage device 10 includes an electrode assembly 20 including a current collector 30 and an exterior housing 40. The electrode assembly 20 includes electrodes (positive and negative electrodes) constituting an energy storage member such as a lithium-ion battery, capacitor, all-solid-state battery, semi-solid battery, quasi-solid battery, polymer battery, all-resin battery, lead-acid battery, nickel-metal hydride battery, nickel-cadmium battery, nickel-iron battery, nickel-zinc battery, silver oxide-zinc battery, metal-air battery, polyvalent cation battery, or capacitor, as well as a separator. In this embodiment, the electrode assembly 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 assembly 20 may have a cylindrical or polygonal prism shape, for example.

[0033] The exterior body 40 seals the electrode assembly 20. The exterior body 40 has an exterior film 50 and a lid 60. The exterior film 50 encases the electrode assembly 20. In the present embodiment, the exterior film 50 is wrapped around the electrode assembly 20. The lid 60 is disposed on the side of the electrode assembly 20 in the FB direction. In another example, the electrode assembly 20 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and the openings may be closed by the lid 60. In yet another example, the electrode assembly 20 connected to the lid 60 may be housed inside an exterior film 50 configured in a cylindrical shape so that an opening is formed, and the openings may be closed by the lid 60. The exterior body 40 has a pair of first surfaces 41A, 41B and a pair of second surfaces 42A, 42B. In the present embodiment, the pair of first surfaces 41A, 41B are substantially the same size. In the present embodiment, the pair of second surfaces 42A, 42B are substantially the same size. The pair of first surfaces 41A, 41B have a larger area than the pair of second surfaces 42A, 42B. The pair of lid bodies 60 are respectively arranged on the sides of the electrode body 20 in the FB direction (near the outsides of the two end faces of the electrode body 20 in the FB direction).

[0034] For example, there is a method of forming a storage portion (recess) in the exterior film 50 through cold forming to store the electrode assembly 20. However, it is not necessarily easy to form a deep storage portion using this method. Attempting to form a deep storage portion (recess) through cold forming (for example, a forming depth of 15 mm) increases the likelihood of pinholes or cracks occurring in the exterior film 50, resulting in a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode assembly 20 by wrapping the exterior film 50 around the electrode assembly 20, and therefore can easily seal the electrode assembly 20 regardless of the thickness of the electrode assembly 20. Note that in order to reduce the dead space between the electrode assembly 20 and the exterior film 50 in order to improve the volumetric energy density of the electricity storage device 10, it is preferable that the exterior film 50 be wrapped so as to contact the outer surface of the electrode assembly 20. Furthermore, in an all-solid-state battery, it is necessary to apply a 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, and therefore it is preferable that the exterior film 50 be wrapped so as to be in direct or indirect contact with the outer surface of the electrode body 20. When an insulating film, separator, or the like is disposed on the outer surface of the electrode body 20, the exterior film 50 is indirectly wrapped around the outer surface of the electrode body 20 via the film, separator, or the like.

[0035] 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. 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, such as a resin film. The exterior film 50 is preferably heat-sealable. 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. The exterior film 50 may have different thicknesses in parts, or may not include some layers in parts.

[0036] The exterior film 50 may be composed of a laminate including at least a barrier layer 52 and a heat-sealable resin layer 53 in this order. In this laminate, the base layer 51 is an optional layer, and the side of the barrier layer 52 opposite to the heat-sealable resin layer 53 is the outermost layer, and the heat-sealable resin layer 53 is the innermost layer.

[0037] The overall thickness of the exterior film 50 can be selected arbitrarily. From the viewpoint of strength, the thickness of the exterior film 50 is preferably 50 μm or more. From the viewpoint of formability or conformability, the thickness of the exterior film 50 is preferably 1200 μm or less. The thickness of the exterior film 50 is preferably within the range of 50 μm or more and 1200 μm or less.

[0038] The substrate layer 51 included in the exterior film 50 is a layer that imparts heat resistance to the exterior film 50 and suppresses the occurrence of pinholes that may occur 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 suppressed. 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. From the viewpoint of film strength, the thickness of the substrate layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm.

[0039] The barrier layer 52 is a layer that prevents at least moisture penetration. The barrier layer 52 is bonded to the substrate layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal 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. The barrier layer 52 may also be a resin film 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.

[0040] In the barrier layer 52, the layer made of the aforementioned metal material may contain recycled metal material. Examples of recycled metal 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 of recycled material alone, or may be made of a mixture of recycled and virgin material. Note that recycled metal material refers to metal material that has been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0041] From the viewpoint of improving the formability or conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy. From the viewpoint of further improving the formability or conformability, an iron-containing aluminum alloy foil 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 or conformability 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. Furthermore, silicon, magnesium, copper, manganese, etc. may be added as necessary. Furthermore, softening can be achieved by annealing or the like. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil made of, for example, a work-hardened aluminum alloy. Examples of hard aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably an aluminum alloy foil containing magnesium. In the aluminum alloy foil containing magnesium (100% by mass), the magnesium content is preferably 0.2 to 5.6% by mass, and more preferably 0.2 to 3.0% by mass. Examples of aluminum alloy foils containing magnesium include aluminum alloy foils having compositions defined in JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JIS H4000:2017 A5052P-O. The aluminum alloy foil is preferably an aluminum alloy foil containing manganese.In the manganese-containing aluminum alloy foil (100% by mass), the manganese content is preferably 0.3 to 1.5% by mass, more preferably 1.0 to 1.5% by mass. Examples of the manganese-containing aluminum alloy foil include aluminum alloy foils having compositions specified in JIS H4000:2017 A3003P-O, JIS H4000:2017 A3103P-O, JIS H4000:2017 A3004P-O, and JIS H4000:2017 A3104P-O.

[0042] Examples of the 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 conformability, the stainless steel foil is preferably made of austenitic stainless steel.

[0043] Specific examples of austenitic stainless steels that form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0044] 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, about 5 to 1000 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 52 is preferably about 9.0 μm or more, more preferably about 20 μm or more, and more preferably about 25 μm or more. Preferred ranges for the thickness of the barrier layer 52 include about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 85 μm, about 9.0 to 50 μm, about 9.0 to 40 μm, about 9.0 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above-mentioned ranges are particularly preferred. 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.

[0045] 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 of 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 with 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.

[0046] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the substrate 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 in particular 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 substrate layer 51 and the barrier layer 52 during heat sealing and between the substrate layer 51 and the barrier layer 52 during molding.

[0047] 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 standpoints of sealability and strength, the thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 1000 μm, and more preferably 40 to 150 μm.

[0048] The exterior film 50 preferably has one or more layers having 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.

[0049] 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, with the most preferred range being 1000 μm to 3000 μm.

[0050] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm, more preferably 1.0 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5.0 mm, and even more preferably 2.0 mm. When the buffer layer is made of rubber, the preferred ranges of the buffer layer thickness are 1.0 mm to 2.0 mm, 1.0 mm to 5.0 mm, 1.0 mm to 10 mm, 0.5 mm to 2.0 mm, 0.5 mm to 5.0 mm, and 0.5 mm to 10 mm.

[0051] 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 manufacturing of the energy storage device 10.

[0052] The lid body 60 has a lid main body 70 and a covering body 90 that covers a part of the lid main body 70. The lid body 60 can be manufactured by, for example, injection molding the covering body 90 onto the lid main body 70.

[0053] In this embodiment, the lid body 70 is composed of a conductive material. The phrase "composed of a conductive material" refers to the conductive material content being 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, when the total mass of the materials constituting the lid body 70 is taken as 100% by mass. In other words, the material constituting the lid body 70 may contain materials other than the conductive material in addition to the conductive material. The lid body 70 composed of a conductive material preferably has the corrosion-resistant coating described in connection with the barrier layer 52. The lid body 70 may include a metal molded product. A metal molded product is an element having a certain thickness, thicker than the film defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard.

[0054] The conductive material constituting the lid body 70 is, for example, a metal material. The metal material constituting the lid body 70 is, for example, aluminum, aluminum alloy, nickel, copper, or copper alloy. For example, when the electrode body 20 is a lithium-ion battery, the lid body 70 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The lid body 70 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the lid body 70 connected to the negative electrode may be nickel-plated copper. The material constituting the lid body 70 connected to the negative electrode may be stainless steel, for example, SUS300-based austenitic stainless steel. The material constituting the lid body 70 may include recycled metal materials. When the lid body 70 is made of a conductive material, it preferably has the corrosion-resistant coating described for the barrier layer 52. The lid body 70 has a base 71 and a wall 72.

[0055] The base 71 shown in FIGS. 4 and 5 is, for example, a rectangular plate having a first surface 71A and a second surface 71B. The first surface 71A faces the outside. The second surface 71B is the surface opposite the first surface 71A. The second surface 71B faces the electrode assembly 20. The lid 60 may be arranged so that the first surface 71A faces the electrode assembly 20, in other words, so that the second surface 71B faces the outside. The base 71 may have any shape, such as a cylinder, a prism, a rectangular parallelepiped, or a cube. When the base 71 is made of a conductive material, the end 31 of the current collector 30 of the electrode assembly 20 and the second surface 71B of the base 71 are connected.

[0056] The wall portion 72 is covered by a cover 90. The wall portion 72 is frame-shaped and rises from the edge of the base 71. The wall portion 72 includes a first wall portion 72A, a second wall portion 72B, a third wall portion 72C, and a fourth wall portion 72D. The first wall portion 72A constitutes the top surface of the lid main body 70. The first wall portion 72A extends in a first direction (in the present embodiment, the LR direction) in a front view of the lid main body 70. The second wall portion 72B and the third wall portion 72C are connected to the first wall portion 72A and the fourth wall portion 72D and constitute the side surfaces of the lid main body 70. The second wall portion 72B and the third wall portion 72C extend in a second direction (in the present embodiment, the UD direction) that intersects with the first direction in a front view of the lid main body 70. In the present embodiment, the first direction and the second direction are orthogonal in a front view of the lid main body 70. The first direction and the second direction do not have to be perpendicular to each other in a front view of the lid body 70. The fourth wall portion 72D forms the lower surface of the lid body 70. The fourth wall portion 72D extends in the first direction (the LR direction in this embodiment) in a front view of the lid body 70.

[0057] At least a portion of the surface 72X of the wall portion 72 is covered with the covering 90. In this embodiment, the entire surface 72X of the wall portion 72 is covered with the covering 90.

[0058] The covering 90 shown in Figures 4, 5, and 6 is composed of a resin material. Here, "composed of a resin material" means that, when the total mass of the materials constituting the covering 90 is taken as 100 mass%, the resin material content is 50 mass% or more, preferably 80 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more. In other words, the material constituting the covering 90 may contain materials other than the resin material in addition to the resin material. The covering 90 may also include a resin molded product. A resin molded product is an element having a certain thickness, and is thicker than the film defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard.

[0059] 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 covering 90 may be molded using any molding method.

[0060] The resin material contained in the material constituting the coating 90 is preferably an olefin-based random copolymer, more preferably a resin containing a polyolefin skeleton as the main component, even more preferably a polyolefin as the main component, and even more preferably a polypropylene as the main component. The polyolefin may be an acid-modified polyolefin. The resin material contained in the material constituting the coating 90 preferably contains multiple types of amide-based lubricants. Furthermore, the resin material contained in the material constituting the coating 90 preferably contains, in addition to saturated fatty acid amides, multiple types of amide-based lubricants further containing unsaturated fatty acid amides. The resin material contained in the material constituting the coating 90 may be a polyolefin resin to which a propylene-based elastomer having a melting point higher than 150°C has been added. Note that the term "main component" refers to a material that accounts for, for example, 35% by mass or more, 50% by mass or more, 90% by mass or more, or 95% by mass or more of the materials contained in the constituent elements.

[0061] 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 / decanedicarboxylate). Among these, polybutylene terephthalate is preferred as the resin material from the viewpoint of enhancing heat resistance and pressure resistance.

[0062] 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, polypropylene block copolymers (e.g., block copolymers of propylene and ethylene), and polypropylene random copolymers (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. An example of an olefin-based homopolymer is a propylene homopolymer.

[0063] 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 covering 90 against temperature changes can be improved.

[0064] The melt mass flow rate of the resin material contained in the material constituting the coating 90 is preferably in the range of 1 g / 10 min to 100 g / 10 min, and more preferably in the range of 5 g / 10 min to 80 g / 10 min. The melt mass flow rate is measured in accordance with JIS K7210-1:2014. The melt mass flow rate is measured at 230°C.

[0065] The cover 90 has a lid seal portion 91. The lid seal portion 91 is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50. The lid seal portion 91 and the exterior film 50 may be joined by any method other than heat sealing, such as welding. Specific welding methods include laser welding, ultrasonic welding, and other methods. The lid seal portion 91 includes a first seal surface 91A, a second seal surface 91B, a third seal surface 91C, and a fourth seal surface 91D. The first seal surface 91A forms the top surface of the lid 60. The first seal surface 91A is formed on the first wall portion 72A. The first seal surface 91A extends in a first direction (the LR direction in this embodiment) when viewed from the front of the lid 60. The second seal surface 91B and the third seal surface 91C are connected to the first seal surface 91A and the fourth seal surface 91D and form the side surfaces of the lid 60. The second sealing surface 91B is formed on the second wall portion 72B. The third sealing surface 91C is formed on the third wall portion 72C. The second sealing surface 91B and the third sealing surface 91C extend in a second direction (in the UD direction in this embodiment) that intersects with the first direction in a front view of the lid body 60. In this embodiment, the first direction and the second direction are orthogonal in a front view of the lid body 60. The first direction and the second direction do not have to be orthogonal in a front view of the lid body 60. The fourth sealing surface 91D forms the underside of the lid body 60. The fourth sealing surface 91D extends in the first direction (in the LR direction in this embodiment) in a front view of the lid body 60. The fourth sealing surface 91D is formed on the fourth wall portion 72D.

[0066] The lid seal portion 91 further includes boundaries 92, 93, 94, and 95. The boundary 92 is the boundary between the first seal surface 91A and the second seal surface 91B. The boundary 93 is the boundary between the first seal surface 91A and the third seal surface 91C. The boundary 94 is the boundary between the fourth seal surface 91D and the second seal surface 91B. The boundary 95 is the boundary between the fourth seal surface 91D and the third seal surface 91C. The boundaries 92 to 95 may have angular shapes or may be rounded by applying a rounded edge. In this embodiment, the boundaries 92 to 95 are angular. If the boundaries 92 to 95 have rounded shapes, the radius of curvature of the boundaries 92 to 95 is preferably in the range of more than 0 mm and not more than 2.0 mm.

[0067] The lid 60 may be bonded to the exterior film 50 via an adhesive film instead of the covering 90. Any adhesive film can be selected as long as it can bond the exterior film 50 and the lid 60 together. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant substrate layer, and a heat-sealable resin layer in this order. The specifications for the heat-sealable resin layer of the adhesive film are the same as those for the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same or different, and are appropriately selected 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 bonded to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer of the adhesive film on the side that is bonded to the exterior film 50 is preferably made of the same type of material as the material that constitutes the heat-sealable resin layer 53 of the exterior film 50 .

[0068] The heat-resistant substrate layer may be any film made of a heat-resistant resin, such as a non-stretched or stretched film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, etc. Polyethylene terephthalate is particularly preferred because it is inexpensive and has high strength.

[0069] The adhesive film preferably has adhesive properties. When the second sealing portion 100B described below 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 tackifier resin into the heat-sealable resin layer of the adhesive film, adhesive properties can be imparted to the adhesive film. Examples of the tackifier resin include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene and copolymers of amorphous propylene and other α-olefins. The content of the tackifier resin relative to the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less.

[0070] When the lid body 60 is plate-shaped, it is preferable that the lid body 60 have a certain thickness so that deformation of the exterior body 40 is suppressed even when the power 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 91 of the lid body 60 have a certain width in the FB direction so that the lid seal portion 91 of the lid body 60 and the exterior film 50 can be suitably heat-sealed when forming the second sealing portion 100B described below. The minimum width of the lid seal portion 91 of the lid body 60 is, for example, 0.3 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum width of the lid seal portion 91 of the lid body 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum width of the lid seal portion 91 of the lid body 60 may be 20 mm or more. Preferred width ranges for the lid seal portion 91 of the lid body 60 are 0.3 mm to 20 mm, 0.3 mm to 15 mm, 0.3 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 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. Note that the width of the lid seal portion 91 of the lid body 60 may vary depending on the location. When the width of the lid seal portion 91 of the lid body 60 varies depending on the location, the width of the lid seal portion 91 of the lid body 60 is the width of the widest portion.

[0071] In this embodiment, the first sealing portion 100A is formed by wrapping the exterior film 50 around the electrode body 20 and heat-sealing the opposing surfaces of the exterior film 50 (heat-fusible resin layer 53).

[0072] The first sealed portion 100A is formed by heat-sealing a portion of the exterior film 50 shown in FIG. 3 including the first edge 50A and a portion of the exterior film 50 including the second edge 50B. The first sealed portion 100A extends in the longitudinal direction of the exterior body 40. The position at which the first sealed portion 100A is formed on the exterior body 40 can be selected arbitrarily. In this embodiment, the base 70X of the first sealed portion 100A is preferably located on the edge 43 at the boundary between the first surface 41A and the second surface 42A of the exterior body 40. The base 100AX of the first sealed portion 100A may be located on any surface of the exterior body 40. In this embodiment, the first sealed portion 100A protrudes outward beyond the electrode assembly 20 in a plan view. The first sealed portion 100A may be folded, for example, toward the second surface 42A of the exterior body 40 or toward the first surface 41A.

[0073] In this embodiment, the second sealing portion 100B is formed by heat-sealing the heat-fusible resin layer 53 of the exterior film 50 and the lid seal portion 91 of the lid body 60. Hereinafter, the seal strength between the heat-fusible resin layer 53 of the exterior film 50 and the lid seal portion 91 of the lid body 60 may be referred to as the seal strength (bonding strength) of the second sealing portion 100B. Note that the seal strength of the second sealing portion 100B is the seal strength between the heat-fusible resin layer 53 and the lid body 60 at the long side portion of the lid seal portion 91, i.e., the lid seal portion 91 extending in the LR (width) direction in FIG. 1A .

[0074] The seal strength of the second sealing portion 100B is measured as follows. First, a slit is formed in the portion of the exterior film 50 that constitutes the first surface 41 of the exterior body 40, forming three strip-shaped members 41X, 41Y, and 41Z (see the two-dot chain lines in FIG. 1B ) aligned in the LR direction. The width of the three strip-shaped members 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strip-shaped members 41X, 41Y, and 41Z are joined to the lid body 60 in the second sealing portion 100B. The length of the lid body 60 in the LR 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 to measure the seal strength of each of the strip-shaped members 41X, 41Y, and 41Z. The distance between the zippers in the UD direction is 50 mm. The seal strengths of the strip-shaped members 41X, 41Y, and 41Z are the peak values ​​of their respective seal strengths. In this embodiment, the seal strength of the second sealing portion 100B is the average value of the seal strengths of the strip-shaped members 41X, 41Y, and 41Z. When the LR length of the lid body 60 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 using the same method as when the LR length of the lid body 60 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 at a 15 mm width. The seal strength of the second sealing portion 100B is the average value of the seal strengths of the three strip-shaped members converted to a 15 mm width. In addition, when the lid body 60 is divided into multiple parts including long and short sides, the sealing strength of the second sealing portion 100B is the sealing strength of the long side portion of the lid seal portion 91 of the multiple parts.

[0075] From the viewpoint of suitably maintaining the state in which the electrode assembly 20 is sealed by the exterior body 40, the seal strength of the second sealing unit 100B 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 100B is 40 N / 15 mm or more, the state in which the electrode assembly 20 is sealed by the exterior body 40 is suitably maintained even after the power storage device 10 has been used for, for example, several years (less than 10 years). When the seal strength of the second sealing unit 100B is 85 N / 15 mm or more, the state in which the electrode assembly 20 is sealed by the exterior body 40 is suitably maintained even after the power storage device 10 has been used for, for example, 10 years or more. The seal strength of the second sealing unit 100B is preferably 300 N / 15 mm or less. A preferred range of the seal strength of the second sealing portion 100B 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.

[0076] In this embodiment, the lid body 60 may have a protrusion 96 protruding from the lid seal portion 91 to prevent a gap from forming between the exterior film 50 and the lid body 60. The protrusion 96 may be formed integrally with the cover 90, or may be formed separately from the cover 90 and joined to the cover 90. In this embodiment, the protrusion 96 is formed integrally with the cover 90. The position at which the protrusion 96 is formed in the lid seal portion 91 can be selected arbitrarily. A gap between the exterior film 50 and the lid body 60 is likely to form, for example, between the base 100AX of the first sealing portion 100A and the lid body 60. In particular, when the base 100AX of the first sealing portion 100A is located between the boundary 92 and boundary 95 of the lid body 60, the resin filling ability between the base 100AX of the first sealing portion 100A and the lid body 60 is likely to decrease. For this reason, the protrusion 96 is preferably formed in the lid seal portion 91 at a location where the root 100AX of the first sealing portion 100A is located. In this embodiment, the root 100AX of the first sealing portion 100A is located at the boundary 92 of the lid body 60. For this reason, the protrusion 96 is preferably formed in the lid seal portion 91 at the boundary 92. In this embodiment, the first sealing portion 100A is sealed with the protrusion 96 sandwiched between them. Note that the protrusion 96 may be formed on at least one of the first seal surface 91A, the second seal surface 91B, the third seal surface 91C, the fourth seal surface 91D, the boundary 93, the boundary 94, and the boundary 95.

[0077] The shape of the protrusion 96 can be selected arbitrarily. In this embodiment, the shape of the protrusion 96 is plate-like. The thickness of the protrusion 96 can be selected arbitrarily. In this embodiment, the thickness of the protrusion 96 becomes thinner with increasing distance from the boundary 92. In other words, the protrusion 96 has a tapered shape with increasing distance from the boundary 92. The thickness of the protrusion 96 may be constant, or may increase with increasing distance from the boundary 92.

[0078] The direction in which the protrusion 96 extends can be selected arbitrarily. In the present embodiment, the protrusion 96 extends along a first direction (in the present embodiment, the LR direction). The protrusion 96 may extend along a second direction (in the present embodiment, the UD direction). The protrusion 96 may extend in a third direction that intersects with the first direction (in the present embodiment, the LR direction) and the second direction (in the present embodiment, the UD direction) when the lid 60 is viewed from the front.

[0079] The length of the protrusion 96 can be selected arbitrarily within a range equal to or less than the length of the first sealing portion 100A. For example, the length of the protrusion 96 may be substantially equal to the length of the first sealing portion 100A, or may be 30% to 50% of the length of the first sealing portion 100A.

[0080] The power storage device 10 of this embodiment has a relatively large capacity, and therefore generates a large amount of heat from the electrode assembly 20. For example, when an abnormality occurs in the electrode assembly 20, the electrode assembly 20 becomes hot. Therefore, the heat generated from the electrode assembly 20 may cause, for example, peeling of the first sealing portion 100A or the second sealing portion 100B, or damage to elements constituting the exterior body 40. In another example, the heat generated by another power storage device installed next to the electrode assembly 20 may cause, for example, peeling of the first sealing portion 100A or the second sealing portion 100B, or damage to elements constituting the exterior body 40. For this reason, the power storage device 10 preferably includes a combustion suppression element 120 that is at least one of flame retardant and non-flammable and suppresses combustion of the exterior body 40. The combustion suppression element 120 is disposed on the exterior body 40 and / or between the exterior body 40 and the electrode assembly 20. Flame retardant means the property of being difficult to burn, in other words, the property of resisting combustion. More specifically, flame retardant means the property of having a certain resistance to fire, being difficult to ignite, and even if ignited, burning slowly. A substance with flame retardant properties does not spread fire immediately even when it comes into contact with fire. Non-flammable means the property of not burning, or being extremely difficult to burn. More specifically, non-flammable means the property of having complete resistance to fire, not burning even when it comes into contact with fire, or being extremely difficult to burn. A substance with non-flammable properties does not burn, or is extremely difficult to burn, even when heat is applied.

[0081] In the power storage device 10, the position at which the combustion suppression element 120 is disposed can be selected arbitrarily as long as the position can suppress combustion of the exterior body 40. In the example shown in FIG. 7 , the combustion suppression element 120 is disposed between the first surface 41A of the exterior body 40 and the electrode assembly 20, and between the first surface 41B and the electrode assembly 20. This suppresses combustion of the exterior body 40 due to heat generated on a relatively large surface of the electrode assembly 20. The combustion suppression element 120 may be disposed entirely or partially between the first surface 41A of the exterior body 40 and the electrode assembly 20. The combustion suppression element 120 may be disposed entirely or partially between the first surface 41B of the exterior body 40 and the electrode assembly 20. In another example, the material constituting the lid body 60 may include the combustion suppression element 120. In yet another example, the material constituting the exterior film 50 may include the combustion suppression element 120. When the material constituting the exterior film 50 includes the combustion suppression element 120 , the combustion suppression element 120 is preferably included in the material constituting a layer closer to the electrode body 20 than the barrier layer 52 , for example.

[0082] The specific configuration of the combustion suppression element 120 can be selected arbitrarily as long as the element has at least one of flame retardancy and non-flammability. Examples of flame retardant elements include the flame retardant itself, a flame retardant resin composition containing a flame retardant and a resin, or a flame-retardant resin such as polyphenylene sulfide. Resins that are flame-retardant also include flame-retardant resins. Flame retardancy and flame-retardant properties are determined based on the test methods and standards specified in UL94 of the U.S. Underwriters Laboratories (UL) standard, with HB grade being flame-retardant and V-2 grade or higher (VTM-0 grade for thin materials) being flame-retardant.

[0083] Examples of flame-retardant resins include super engineering plastics. Among these, from the viewpoint of processability, preferred flame-retardant resins are PI (polyimide), PEEK (polyether ether ketone), PTFE (polytetrafluoroethylene), PAI (polyamide imide), PPS (polyphenylene sulfide), PPSU (polyphenylsulfone), PEI (polyetherimide), and PVDF (polyvinylidene fluoride). Among these, more preferred flame-retardant resins are PI, PEEK, PTFE, PAI, and PPS from the viewpoint of resistance to combustion. Examples of flame-retardant resins include epoxy glass, PC (polycarbonate), cloth Bakelite, PBT (polybutylene terephthalate), paper Bakelite, POM (polyacetal), PMP (polymethylpentene), PMMA (polymethyl methacrylate), nylon 6, and ABS (acrylonitrile butadiene styrene resin). From the viewpoint of retarding combustion or suitability for processing, the flame-retardant resin is preferably epoxy glass, PC, MC nylon, cloth bakelite, or PBT.

[0084] Examples of flame retardants include fibrous materials, non-combustible paper, halogen-based materials, phosphorus-based materials, metal hydroxides, antimony oxides, etc. Examples of fibrous materials include glass fibers, ceramic fibers, metal fibers, cellulose fibers, polyester fibers, carbon fibers, graphite fibers, thermosetting resin fibers, etc. Examples of halogen-based materials include bromine-based substances such as tetrabromobisphenol A (TBBA) and decabromodiphenyl ether (Deca-BDE). Examples of phosphorus-based materials include various phosphate esters such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and xylenyl diphenyl phosphate, metal phosphates such as sodium phosphate, potassium phosphate, and magnesium phosphate, metal phosphite salts such as sodium phosphite, potassium phosphite, magnesium phosphite, and aluminum phosphite, phosphorus compounds such as phosphorus atom compounds such as ammonium polyphosphate, and red phosphorus. Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, and other metal hydroxides, and examples of antimony oxides include antimony trioxide, and these can be used alone or in combination. The non-combustible element is, for example, an inorganic substance or a metal. Examples of inorganic substances include ceramics, concrete, brick, glass material, rock wool, and glass wool. Examples of metals include iron or steel.

[0085] If the electrode assembly 20 becomes too hot, there is a risk that the electrode assembly 20 or elements surrounding the electrode assembly 20, such as the separator (hereinafter referred to as the "electrode assembly 20, etc.") may catch fire. In another example, if another electricity storage device installed next to it catches fire, there is a risk that the electricity storage device 10 may catch fire. For this reason, the electricity storage device 10 preferably includes an ignition prevention element 130 that has at least one of a function of absorbing heat (hereinafter referred to as a "heat absorption function") and a function of extinguishing a fire in the event of a fire (hereinafter referred to as a "fire extinguishing function"). The ignition prevention element 130 is disposed on the exterior body 40 and / or between the exterior body 40 and the electrode assembly 20.

[0086] In the power storage device 10, the position of the fire prevention element 130 can be selected arbitrarily as long as it is a position that can absorb heat or a position that can extinguish a fire in the event of a fire. In the example shown in FIG. 7 , the fire prevention element 130 is positioned between the first surface 41A of the exterior body 40 and the electrode assembly 20, and between the first surface 41B and the electrode assembly 20. This prevents the exterior body 40 from burning due to heat generated on a relatively large surface of the electrode assembly 20. The fire prevention element 130 may be positioned entirely or partially between the first surface 41A of the exterior body 40 and the electrode assembly 20. The fire prevention element 130 may be positioned entirely or partially between the first surface 41B of the exterior body 40 and the electrode assembly 20. In another example, the material constituting the lid 60 may include the fire prevention element 130. In yet another example, the material constituting the exterior film 50 may include the fire prevention element 130. When the material constituting the exterior film 50 includes the ignition countermeasure element 130 , the ignition countermeasure element 130 is preferably included in the material constituting a layer closer to the electrode body 20 than the barrier layer 52 , for example.

[0087] The specific configuration of the fire prevention element 130 can be arbitrarily selected as long as it has at least one of a heat absorption function and a fire extinguishing function. The element having a heat absorption function is, for example, a fire-resistant resin composition containing a heat-absorbing agent and a resin. The heat-absorbing agent, for example, has a thermal decomposition onset temperature of 800°C or less and an endothermic amount of 300 J / g or more. The content of the heat-absorbing agent per 100 parts by mass of resin is, for example, 10 to 1600 parts by mass. The heat-absorbing material includes, for example, one or more selected from the group consisting of hydrated metal hydroxides, alkali metal compounds, ammonium salts, and urea. Examples of hydrated metal hydroxides include calcium-magnesium hydroxides, hydrotalcite, boehmite, talc, dawsonite, calcium sulfate hydrate, magnesium sulfate hydrate, etc. Examples of alkali metal compounds include sodium bicarbonate, potassium bicarbonate, potassium oxide, sodium carbonate, and potassium carbonate. Examples of ammonium salts include ammonium chloride, ammonium nitrate, ammonium bicarbonate, ammonium sulfate, and ammonium dihydrogen phosphate. When the material constituting the lid body 60 includes the ignition prevention element 130, the core shell may be kneaded into a resin material and used as the resin part of the lid body 60 (for example, the covering body 90).

[0088] The element having a fire-extinguishing function is, for example, a fire extinguishing agent that generates gas by collapsing a core-shell structure. The fire extinguishing agent includes a core containing a compound that releases a gas other than oxygen at a temperature of 50°C or higher and 450°C or lower, and a polymer shell surrounding the core. In another example, the element having a fire-extinguishing function includes a shell-shaped container and a fire extinguishing agent contained in the shell-shaped container. The fire extinguishing agent extinguishes a fire by its heat of vaporization and oxygen absorption function. The fire extinguishing agent includes, for example, a mixture of ammonium dihydrogen phosphate, ammonium sulfate, and silicon dioxide. The shell-shaped container melts, for example, at 90°C to 300°C. The extinguishing agent may be, for example, potassium bicarbonate, protein foam, fluoroprotein foam, surfactant foam, fluorosurfactant, sodium silicate, anhydrous sodium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, ammonium chloride, ammonium nitrate, ammonium bicarbonate, ammonium sulfate, ammonium dihydrogen phosphate, alum, or Halon 1211.

[0089] Any fire extinguishing agent can be used as long as it can ensure fire extinguishing function, such as smothering, cooling, or suppression. Smothering is a method of extinguishing a fire by cutting off the oxygen supply, cooling is a method of extinguishing a fire by removing oxygen from the burning material and lowering the temperature below the ignition point, and suppression is a method of extinguishing a fire by suppressing the oxidation chain reaction. Examples of these materials include the following, and one or more of them may be used simultaneously. These materials include carbonates, bicarbonates, urea, halogen compounds, phosphate compounds, phosphazene compounds, ammonium salts, protein foam, fluorinated protein foam, alcohol foam, aqueous film foam, synthetic surfactant foam, silicates, ethylmethylimidazole, fluoroethers, fluoroketones, and fluorocarbons. More specifically, examples of the radical generator include potassium bicarbonate, protein foam, fluoroprotein foam, surfactant foam, alcohol foam, aqueous film foam fluorosurfactant, sodium silicate, anhydrous sodium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, ammonium chloride, ammonium nitrate, ammonium bicarbonate, ammonium sulfate, ammonium dihydrogen phosphate, calcined alum, and Halon 1211. Also, examples of the radical generator include one or more of potassium chlorate, sodium chlorate, potassium perchlorate, ammonium chlorate, strontium chlorate, and magnesium chlorate, and a mixture of a potassium salt and a sodium salt. Among the radical generators, those having a decomposition initiation temperature of 100° C. or higher are preferred.

[0090] When the combustion suppression element 120 and the ignition countermeasure element 130 are arranged in a stacked manner, the order in which they are stacked can be selected arbitrarily. In the example shown in Fig. 7, the ignition countermeasure element 130 and the combustion suppression element 120 are arranged in this order from the side closest to the electrode body 20. Note that the combustion suppression element 120 may be omitted.

[0091] 8 is a flowchart showing an example of a method for manufacturing the power storage device 10. The method for manufacturing the power storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, and a fifth step. The first step to the fifth step are performed, for example, by a manufacturing apparatus for the power storage device 10. At least some of the first step to the fifth step may be performed by an operator. Note that the first step to the fifth step are names of the steps in the method for manufacturing the power storage device 10 defined for convenience, and do not necessarily refer to the order of the steps. The order of the first step to the fifth step can be changed as desired as long as it is not technically inconsistent.

[0092] In the first process of step S11, the manufacturing device places a pair of lid bodies 60 on either side of the electrode body 20 in the FB direction.

[0093] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus joins the current collector 30 of the electrode body 20 and the lid body 60 together.

[0094] The third process of step S13 is performed after the second process. In the third process, the manufacturing apparatus arranges the combustion suppression element 120 and the ignition prevention element 130. Note that at least one of the combustion suppression element 120 and the ignition prevention element 130 may be previously attached to at least one of the exterior film 50 and the lid body 60 in a process prior to the third process.

[0095] The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus winds the exterior film 50 around the electrode assembly 20 and the lid body 60 while tension is applied to the exterior film 50, while restricting the movement of the electrode assembly 20 and the lid body 60 using 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. The electrode body 20 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and after the current collector 30 of the electrode body 20 and the lid 60 are joined, the opening may be closed by the lid 60. In yet another example, the electrode body 20 connected to the lid 60 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and the opening may be closed by the lid 60.

[0096] The fifth step of step S15 is performed after the fourth step. In the fifth step, the manufacturing apparatus heat-seals the exterior film 50 and the lid 60 together to form the second sealed portion 100B.

[0097] The sixth step of step S16 is performed before or after the fifth step. In the sixth step, the manufacturing apparatus forms the first sealed portion 100A by heat-sealing the heat-sealable resin layer 53 in the portion including the first edge 50A of the exterior film 50 and the heat-sealing the heat-sealable resin layer 53 in the portion including the second edge 50B while restricting the movement of the electrode body 20 and the lid body 60 and applying tension to the exterior film 50.

[0098] <1-3. Functions and Effects of the Electricity Storage Device> Because the electricity storage device 10 is provided with the anti-ignition element 130, it is unlikely to catch fire due to heat generated from the electrode body 20, or even if a fire does break out due to heat generated from the electrode body 20, the fire is extinguished. The electricity storage device 10 is prevented from damaging the exterior body 40 due to the influence of heat generated from the electrode body 20. Therefore, the electricity storage device 10 is likely to maintain a sealed state of the electrode body 20.

[0099] [2. Modifications] The above-described embodiments are examples of possible forms of the electricity storage device, lid, fire prevention element, and exterior film of the present invention, and are not intended to limit the forms. The electricity storage device, lid, fire prevention element, and exterior film of the present invention may take forms different from those exemplified in the embodiments. Examples include forms in which part of the configuration of the embodiment is replaced, modified, or omitted, or forms in which a new configuration is added to the embodiment. Some examples of modifications of the embodiments are shown below. Note that the following modifications can be combined with each other as long as there is no technical contradiction.

[0100] 2-1. First Modification In the above embodiment, the arrangement of the combustion suppression element 120 can be modified. FIG. 9 is a cross-sectional view of an electric storage device 10 according to a first modification. The combustion suppression element 120 may be bonded to at least a portion of the surface of the lid body 60. To prevent the exterior body 40 from burning due to heat generated by the electrode assembly 20, the combustion suppression element 120 is preferably bonded to at least a portion of the surface of the lid body 60 facing the electrode assembly 20. In the example shown in FIG. 9 , the combustion suppression element 120 is bonded to the second surface 71B of the lid main body 70, the end surface of the wall portion 72 facing the electrode assembly 20, and the end surface of the cover 90 facing the electrode assembly 20. Note that in the first modification, the illustration of the ignition prevention element 130 is omitted to illustrate an example of a modification in the arrangement of the combustion suppression element 120. This also applies to the second and third modifications. The electric storage devices 10 according to the first to third modifications each include the ignition prevention element 130.

[0101] 9 , the combustion suppression element 120 is preferably arranged inside the power storage device 10 so as to cover elements containing a resin material and substantially the entire interface between the cover 90 and the lid main body 70. The elements containing a resin material are, for example, the exterior film 50 and the cover 90.

[0102] If the electrode body 20 or the like catches fire, the flame may pass between the lid body 70 and the covering body 90, exposing the exterior film 50 to the flame from outside the exterior body 40. Therefore, from the viewpoint of suppressing combustion of the exterior film 50, it is preferable that the combustion suppression element 120 be disposed at least at the boundary between the lid body 70 and the covering body 90 on the first surface 71A of the lid body 70.

[0103] 2-2. Second Modification> FIG. 10 is a plan view of an electric storage device 10 according to another modification of the second modification. From the viewpoint of suppressing combustion of the first sealed portion 100A due to heat generated from the electrode body 20, the combustion suppression element 120 is preferably arranged along the base 100AX of the first sealed portion 100A. In the example shown in FIG. 10, the combustion suppression element 120 is arranged so that its edge coincides with the base 100AX. FIG. 11 is a plan view of an electric storage device 10 according to another modification of the second modification. In the example shown in FIG. 11, the combustion suppression element 120 is arranged so as to straddle the base 100AX. In the example shown in FIG. 11, the first sealed portion 100A is formed in a state in which the combustion suppression element 120 is sandwiched between opposing heat-sealable resin layers 53 of the exterior film 50.

[0104] 12 is a cross-sectional view of an electricity storage device 10 according to a third modification. In order to prevent combustion of the exterior body 40 due to heat generated from the electrode body 20, the combustion suppression element 120 is preferably disposed between the electrode body 20 and the second surfaces 42A, 42B of the exterior body 40, in addition to between the electrode body 20 and the first surfaces 41A, 41B of the exterior body 40.

[0105] From the viewpoint of being disposed along the base 100AX of the first sealed portion 100A, the combustion suppressing element 120 may have a protrusion 121 that is sandwiched between the opposing heat-sealable resin layers 53 of the exterior film 50 in the first sealed portion 100A. The combustion suppressing element 120 may have at least one of a flat portion 122A and a flat portion 122B that follows the outer shape of the electrode body 20 near the base 100AX of the first sealed portion 100A.

[0106] 2-4. Fourth Modification In the above-described embodiment, the arrangement of the fire prevention element 130 can be changed. FIG. 13 is a cross-sectional view of an electricity storage device 10 according to a fourth modification. The fire prevention element 130 may be arranged so as to contact at least a portion of the surface of the lid body 60. In order to prevent heat generated from the electrode body 20 from being transferred to the exterior body 40, the fire prevention element 130 is preferably joined to at least a portion of the surface of the lid body 60 that faces the electrode body 20. In the example shown in FIG. 13 , the fire prevention element 130 is arranged so as to contact the second surface 71B of the lid body 70, the end face of the wall portion 72 facing the electrode body 20, and the end face of the cover 90 facing the electrode body 20.

[0107] 13 , the fire prevention element 130 is preferably arranged inside the power storage device 10 so as to cover elements containing a resin material and substantially the entire interface between the cover 90 and the lid main body 70. The elements containing a resin material are, for example, the exterior film 50 and the cover 90.

[0108] If the electrode body 20 or the like catches fire, the flame may pass between the lid body 70 and the covering body 90, exposing the exterior film 50 to the flame from outside the exterior body 40. Therefore, from the viewpoint of suppressing combustion of the exterior film 50, it is preferable that the ignition prevention element 130 be disposed at least at the boundary between the lid body 70 and the covering body 90 on the first surface 71A of the lid body 70.

[0109] The fire prevention element 130 may be disposed on the outside of the lid body 60 or may be disposed throughout the space surrounded by the wall portion 72 of the lid main body 70 .

[0110] 2-5. Fifth Modification FIG. 14 is a plan view of an electric storage device 10 according to another modification of the fifth modification. From the viewpoint of preventing the first sealing portion 100A from peeling off due to the influence of heat generated from the electrode body 20, the ignition countermeasure element 130 is preferably arranged along the base 100AX of the first sealing portion 100A. In the example shown in FIG. 14, the ignition countermeasure element 130 is arranged so that its edge coincides with the base 100AX. FIG. 15 is a plan view of an electric storage device 10 according to another modification of the fifth modification. In the example shown in FIG. 15, the ignition countermeasure element 130 is arranged so as to straddle the base 100AX. In the example shown in FIG. 15, the first sealing portion 100A is formed in a state in which the ignition countermeasure element 130 is sandwiched between opposing heat-sealable resin layers 53 of the exterior film 50.

[0111] 2-6. Sixth Modification FIG. 16 is a cross-sectional view of an electric storage device 10 according to a sixth modification. The lid 60 may have a housing 60Y that houses the fire prevention element 130. In the sixth modification, when the electrode assembly 20 becomes hot, there is a high possibility that the internal pressure will increase due to gas generated inside the electric storage device 10. When the internal pressure of the electric storage device 10 increases, the lid 60 bends away from the electrode assembly 20, rupturing a container that houses a fire extinguishing agent in the fire prevention element 130, causing the fire extinguishing agent to jump out of the housing 60Y, thereby absorbing heat from the electrode assembly 20 or, if a fire has already started, extinguishing the fire. If the housing 60Y is sealed with a resin, the resin may be configured to melt due to heat when the electrode assembly 20 becomes hot, causing the housed fire prevention element 130 to jump out. In the sixth modification, the lid 60 preferably includes a protrusion 60Z formed at a position where it can come into contact with the ignition control element 130 when the lid 60 is deformed. The protrusion 60Z preferably does not come into contact with the ignition control element 130 before the lid 60 is deformed. When the lid 60 includes the protrusion 60Z, it can facilitate rupturing of the container that contains the fire extinguishing agent in the ignition control element 130. Note that in the sixth modification, the lid 60 may omit the storage portion 60Y and have the protrusion 60Z.

[0112] Fig. 17 is a cross-sectional view of an electricity storage device 10 according to another modification of the sixth modification. As shown in Fig. 17, the storage section 60Y may be a recess formed in the lid main body 70. In the example shown in Fig. 17, the storage section 60Y preferably opens toward the electrode body 20.

[0113] 18 is a cross-sectional view of an electricity storage device 10 according to a seventh modification. The ignition countermeasure element 130 may be disposed between the exterior film 50 and the cover 60. In the seventh modification, the second sealing portion 100B is formed with the ignition countermeasure element 130 sandwiched between the exterior film 50 and the cover 90.

[0114] 19 is a cross-sectional view of an electricity storage device 10 according to an eighth modification. In order to absorb heat from the electrode body 20 and the like, or to extinguish a fire caused by heat generated from the electrode body 20, the ignition countermeasure element 130 is preferably disposed between the electrode body 20 and the second surfaces 42A, 42B, in addition to between the electrode body 20 and the first surfaces 41A, 41B of the exterior body 40.

[0115] From the viewpoint of being disposed along the base 100AX of the first sealing portion 100A, the ignition countermeasure element 130 may have a protrusion 131 that is sandwiched between the opposing heat-sealable resin layers 53 of the exterior film 50 in the first sealing portion 100A. The ignition countermeasure element 130 may have at least one of a flat portion 132A and a flat portion 132B that follows the outer shape of the electrode body 20 near the base 100AX of the first sealing portion 100A.

[0116] 2-9. Ninth Modification Fig. 20 is a cross-sectional view of an electricity storage device 10 according to a ninth modification. The electricity storage device 10 may have an electrode terminal 200 electrically connected to the electrode body 20. The current collector 30 may be connected to the electrode terminal 200. The lid body 60 may have a hole 200X formed therein through which the electrode terminal 200 passes. The ignition countermeasure element 130 may be disposed at least between the electrode terminal 200 and the lid body 60.

[0117] <2-10. Tenth Modification> In the above embodiment, the lid body 70 is configured to include a conductive material, but the lid body 70 may be configured to include a resin material. When the lid body 70 is configured to include a resin material, the cover 90 of the lid body 60 may be omitted.

[0118] <2-11. Eleventh Modification> In the above embodiment, the wall portion 72 may be omitted from the lid main body 70. When the wall portion 72 is omitted from the lid main body 70, the cover 90 may cover at least a part of the side surface of the base 71. When the wall portion 72 is omitted from the lid main body 70 and the base 71 is configured to contain a resin material, the cover 90 may be omitted and the side surface of the base 71 and the heat-sealable resin layer 53 of the exterior film 50 may be joined.

[0119] <2-12. Twelfth Modification> In the above embodiment, the exterior film 50 of the power storage device 10 may protrude outward beyond at least one of the two lid bodies 60 in the FB direction. 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 films 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. In the twelfth modification, the power storage device 10 preferably has electrode terminals that are long enough to be exposed from the closed portion of the exterior film 50 in the FB direction.

[0120] 2-13. Thirteenth Modification Fig. 21 is a cross-sectional view of the electricity storage device 10 of the thirteenth modification. In the above embodiment, the exterior body 40 may not have at least 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 twelfth 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-type container.

[0121] 2-14. Fourteenth Modification 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.

[0122] <2-15. Fifteenth Modification> 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.

[0123] 10: Electricity storage device 20: Electrode body 40: Exterior body 50: Exterior film 60: Lid body 60X: Space 70: Lid body 120: Combustion suppressing element 130: Ignition prevention element

Claims

1. An electricity storage device comprising: an electrode body; and an exterior body that seals the electrode body, wherein the exterior body comprises an exterior film that wraps the electrode body; and a lid that seals the electrode body together with the exterior film, and the electricity storage device is provided with an anti-ignition element that has at least one of a heat absorption function and a fire extinguishing function.

2. An electricity storage device comprising: an electrode body; and an exterior body that seals the electrode body, wherein the exterior body comprises an exterior film that is wrapped around the electrode body; and a sealing portion that seals a portion including an end of the exterior film, and the electricity storage device comprises an ignition prevention element that has at least one of a heat absorption function and a fire extinguishing function.

3. The electricity storage device according to claim 1 or 2, wherein the anti-ignition element is disposed at least between the electrode body and the exterior film.

4. The electricity storage device according to claim 1, wherein the anti-ignition element is disposed at least between the electrode body and the lid body.

5. The electricity storage device according to claim 1 or 4, wherein the lid has a housing portion for housing the fire prevention element.

6. The electricity storage device according to claim 5, wherein the housing portion includes a protrusion that comes into contact with the anti-ignition element when the lid body is deformed.

7. The electricity storage device according to claim 1 or 4, wherein the lid includes a protrusion that comes into contact with the anti-ignition element when the lid is deformed.

8. The electricity storage device according to claim 1 or 4, wherein the material constituting the lid includes the anti-ignition element.

9. The electricity storage device according to claim 1 or 2, wherein the material constituting the exterior film includes the anti-ignition element.

10. The energy storage device according to claim 1 or 2, wherein the exterior body has a first sealing portion where the inner surfaces of the exterior films are joined together, and the fire prevention element is positioned at least at the base of the first sealing portion.

11. The electricity storage device according to claim 1 or 4, wherein the anti-ignition element is disposed at least between the exterior film and the lid.

12. The electricity storage device according to claim 1 or 4, further comprising an electrode terminal connected to the electrode body, wherein the anti-ignition element is disposed at least between the electrode terminal and the lid body.

13. The electricity storage device according to claim 1 or 2, further comprising a combustion suppression element that is at least one of flame retardant and non-flammable and that suppresses combustion of the exterior body.

14. A lid used for the exterior of an electricity storage device, wherein the electricity storage device comprises: an electrode body; and an exterior body that seals the electrode body; the exterior body comprises an exterior film that wraps the electrode body; and a lid that seals the electrode body together with the exterior film; and the lid is provided with an anti-ignition element that has at least one of a heat absorption function and a fire extinguishing function.

15. A lid according to claim 14, wherein the fire prevention element contacts at least a portion of the surface of the lid.

16. The lid according to claim 15, wherein the anti-ignition element is bonded to at least a portion of the surface of the lid facing the electrode assembly.

17. A lid according to any one of claims 14 to 16, wherein the material constituting the lid includes the fire prevention element.

18. A lid according to claim 14 or 15, which has a storage section for storing the fire prevention element.

19. The lid according to any one of claims 14 to 16, further comprising a combustion suppression element that is at least one of flame retardant and non-flammable and that suppresses combustion of the exterior body.

20. An ignition prevention element for use in an electricity storage device, wherein the electricity storage device comprises: an electrode body; and an exterior body that seals the electrode body; the exterior body comprises an exterior film that wraps the electrode body; and a lid that seals the electrode body together with the exterior film; and the ignition prevention element has at least one of a heat absorption function and a fire extinguishing function.

21. An ignition prevention element for use in an electricity storage device, wherein the electricity storage device comprises an electrode body and an exterior body that seals the electrode body, the exterior body comprising an exterior film wrapped around the electrode body and a sealing portion that seals a portion including an end of the exterior film, and the ignition prevention element has at least one of a heat absorption function and a fire extinguishing function.

22. An exterior film used as an exterior body for an electricity storage device, wherein the material constituting the exterior film includes an anti-ignition element having at least one of a heat absorption function and a fire extinguishing function.

Images