Lid body, power storage device, lid body kit, lid unit, base part, first covering part, second covering part, and method for manufacturing power storage device

Abstract

This lid body is used for an outer casing of a power storage device. This lid body comprises: a base part which is configured to include a conductive material, and has a first surface and a second surface that is opposite to the first surface; a first covering part which is configured to include a resin material, and covers at least a part of the first surface of the base part; and a second covering part which is configured to include a resin material, and covers at least a part of the second surface of the base part.

Description

Lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and method for manufacturing electricity storage device

[0001] The present invention relates to a lid, an electricity storage device, a lid kit, a lid unit, a base part, a first covering part, a second covering part, and a method for manufacturing an electricity storage device.

[0002] Patent Document 1 discloses an example of an electricity storage device. This electricity storage device includes an 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. The lid is made of a metal material.

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

[0004] In the above-described energy storage device, in order to suitably bond the exterior film and the lid, it is conceivable to cover the lid with a cover made of a resin material and then bond the cover to the exterior film. However, when the resin material is injection-molded onto the lid, for example, the lid may be deformed. If the lid is deformed, for example, the sealing performance of the exterior may be reduced.

[0005] The present invention aims to provide a lid body that is suppressed from deforming, an energy storage device that includes this lid body, a lid body kit, a lid unit, a base part, a first covering part, a second covering part, and a method for manufacturing an energy storage device.

[0006] The lid body according to a first aspect of the present invention is a lid body used for an exterior body of an electricity storage device, and has a base part comprising a conductive material and including a first surface and a second surface opposite to the first surface, a first covering part comprising a resin material and covering at least a portion of the first surface of the base part, and a second covering part comprising a resin material and covering at least a portion of the second surface of the base part.

[0007] A lid according to a second aspect of the present invention is the lid according to the first aspect, and includes a portion where the first covering part and the second covering part come into contact with each other.

[0008] A lid according to a third aspect of the present invention is the lid according to the first aspect, wherein an edge of the base part is sandwiched between the first covering part and the second covering part.

[0009] A lid body according to a fourth aspect of the present invention is a lid body according to any one of the first to third aspects, wherein the base part has a main part, a wall part protruding from the main part, and an internal space defined by the wall part, and the first covering part includes a storage part that is stored in the internal space.

[0010] A lid according to a fifth aspect of the present invention is the lid according to any one of the first to fourth aspects, wherein the thickness of the base part is 5.0 mm or less.

[0011] An energy storage device according to a sixth aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, the exterior body having an exterior film that wraps the electrode body and a lid body that seals the electrode body together with the exterior film, the lid body having a base part that is made up of a conductive material and includes a first surface and a second surface opposite to the first surface, a first covering part that is made up of a resin material and covers at least a portion of the first surface of the base part, and a second covering part that is made up of a resin material and covers at least a portion of the second surface of the base part.

[0012] A lid body kit according to a seventh aspect of the present invention is a lid body kit for forming a lid body to be used in the exterior of an electricity storage device, and includes a base part comprising a conductive material and including a first surface and a second surface opposite to the first surface, a first covering part comprising a resin material and covering at least a portion of the first surface of the base part, and a second covering part comprising a resin material and covering at least a portion of the second surface of the base part.

[0013] The lid unit according to an eighth aspect of the present invention is a lid unit constituting a lid body used in the outer casing of an electricity storage device, and includes a base part containing a conductive material and including a first surface and a second surface opposite to the first surface, and a first covering part containing a resin material and covering at least a portion of the first surface of the base part.

[0014] The lid unit according to the ninth aspect of the present invention is a lid unit constituting a lid body used in the outer casing of an electricity storage device, and includes a base part containing a conductive material and including a first surface and a second surface opposite to the first surface, and a second covering part containing a resin material and covering at least a portion of the second surface of the base part.

[0015] A base part according to a tenth aspect of the present invention is a base part constituting a lid body used in an exterior body of an electricity storage device, the base part comprising a first surface containing a conductive material and at least a portion of which is covered by a first covering part containing a resin material, and a second surface opposite the first surface and at least a portion of which is covered by a second covering part containing a resin material.

[0016] A first covering part according to an eleventh aspect of the present invention is a first covering part constituting a lid body used in an exterior body of an electricity storage device, the lid body being constructed to include a conductive material and having a base part including a first surface and a second surface opposite to the first surface, and the first covering part being constructed to include a resin material and configured to cover at least a portion of the first surface of the lid body.

[0017] A second covering part according to a twelfth aspect of the present invention is a second covering part constituting a lid body used in an exterior body of an electricity storage device, the lid body being constructed to include a conductive material and having a base part including a first surface and a second surface opposite to the first surface, and the second covering part being constructed to include a resin material and configured to cover at least a portion of the second surface of the lid body.

[0018] A thirteenth aspect of the present invention relates to a method for manufacturing an electricity storage device, the method comprising: an electrode assembly; and an exterior body sealing the electrode assembly, the exterior body having an exterior film wrapping the electrode assembly; and a lid body sealing the electrode assembly together with the exterior film, the lid body having a base part comprising a conductive material and including a first surface and a second surface opposite to the first surface, a first covering part comprising a resin material and covering at least a portion of the first surface of the base part, and a second covering part comprising a resin material and covering at least a portion of the second surface of the base part. The method for manufacturing an electricity storage device includes a step of placing the lid body on the electrode assembly.

[0019] According to the lid body, electricity storage device, lid body kit, lid unit, base part, first covering part, second covering part, and method for manufacturing an electricity storage device related to the present invention, deformation of the lid body can be suppressed.

[0020] 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 sealing 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 the exterior film included in the electricity storage device of FIG. 1A in an unfolded state. A perspective view of a base part of a lid body included in the electricity storage device of FIG. 1A. A perspective view of a first covering part of a lid body included in the electricity storage device of FIG. 1A. A perspective view of a second covering part of a lid body included in the electricity storage device of FIG. 1A. A cross-sectional view taken along line D7-D7 of FIG. 1A. A cross-sectional view of a lid unit constituting the lid body of FIG. 1A. A cross-sectional view of another lid unit constituting the lid body 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 lid body of a first modified example. A cross-sectional view of a lid body of a second modified example. A cross-sectional view of a lid body of a third modified example.

[0021] 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.

[0022] [Embodiments] <1-1. Configuration of Electricity Storage Device> Fig. 1A is a perspective view schematically showing an electricity storage device 10 according to an embodiment. Fig. 1B is a diagram relating to 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 showing the layer configuration of an exterior film 50 included in the electricity storage device 10 of Fig. 1A. Fig. 3 is a diagram showing the exterior film 50 included in the electricity storage device 10 of Fig. 1A in an unfolded state. Fig. 4 is a perspective view of a base part 70 of a lid body 60 included in the electricity storage device 10 of Fig. 1A. Fig. 5 is a perspective view of a first covering part 80 of the lid body 60 included in the electricity storage device 10 of Fig. 1A. Fig. 6 is a perspective view of a second covering part 90 of the lid body 60 included in the electricity storage device 10 of Fig. 1A. Fig. 7 is a cross-sectional view taken along line D7-D7 in Fig. 1A. 1A, the direction of the arrow UD indicates the thickness direction of the power storage device 10, the direction of the arrow LR indicates the width direction of the power storage device 10, and the direction of the arrow FB indicates the depth direction of the power storage device 10. The directions indicated by the arrows UDLRFB are the same in the subsequent figures.

[0023] The energy storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes electrodes (positive and negative electrodes) constituting an energy storage member such as a lithium-ion battery, a capacitor, an all-solid-state battery, a semi-solid battery, a quasi-solid battery, a polymer battery, an all-resin battery, a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, or a capacitor, as well as a separator. In this embodiment, the shape of the electrode body 20 is approximately rectangular. Note that the term "approximately rectangular" 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 shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0024] In this embodiment, the energy storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting power to and from the electrode assembly 20. The shape of the electrode terminals 30 can be selected arbitrarily. In the example shown in FIG. 1A and other figures, the electrode terminals 30 are cylindrical. The electrode terminals 30 may also be prism-shaped or plate-shaped. One end of the electrode terminal 30 is electrically connected to an electrode (positive or negative electrode) included in the electrode assembly 20. The other end of the electrode terminal 30 protrudes outward from, for example, an edge of the exterior body 40. Note that the electrode terminals 30 may be any terminal as long as they are capable of inputting and outputting power to and from the electrode assembly 20, and may not, for example, protrude from the exterior body 40. When the lid body 60 described below is made of, for example, metal, the lid body 60 may also function as the electrode terminals 30. In this case, the lid body 60, which functions as an electrode terminal, may or may not protrude from the exterior body 40.

[0025] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, etc. For example, when the electrode body 20 is a lithium ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum, etc., and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, etc. The outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator.

[0026] The exterior body 40 seals the electrode body 20. The exterior body 40 has an exterior film 50 and a lid body 60. The exterior film 50 wraps the electrode body 20. In the present embodiment, the exterior film 50 is wrapped around the electrode body 20. The lid body 60 is disposed on the side of the electrode body 20 in the FB direction. In another example, 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 the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the lid body 60 may be housed inside an exterior film 50 configured in a cylindrical shape so that openings are formed, and the openings may be closed by the lid body 60.

[0027] For example, there is a method of forming a storage portion (recess) in the exterior film 50 through cold forming to accommodate the electrode assembly 20. However, it is not necessarily easy to form a deep storage portion using such a method. Attempting to form a deep storage portion (recess) by cold forming (for example, a forming depth of 15 mm) increases the likelihood of pinholes or cracks occurring in the exterior film 50, resulting in a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode assembly 20 by wrapping the exterior film 50 around the electrode assembly 20, and therefore can easily seal the electrode assembly 20 regardless of the thickness of the electrode assembly 20. Note that in order to reduce the dead space between the electrode assembly 20 and the exterior film 50 and improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 be wrapped so as to contact the outer surface of the electrode assembly 20. Furthermore, in all-solid-state batteries, it is necessary to apply a high pressure uniformly from the outer surface of the battery to exhibit battery performance, so it is necessary to eliminate the space between the electrode assembly 20 and the exterior film 50. Therefore, it is preferable that the exterior film 50 be wrapped so as to contact the outer surface of the electrode assembly 20.

[0028] 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. It is not necessary for the exterior film 50 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 material that is flexible and easily bendable, and may be made of, for example, a resin film. It is preferable that the exterior film 50 is heat-sealable. The innermost and outermost layers of the exterior film 50 may be heat-sealable resin layers 53. In this case, the exterior film 50 may encase the electrode body 20 and the lid body 60 by joining the outermost and innermost layers.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] From the viewpoint of improving the formability or conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability or conformability, an aluminum alloy foil containing iron is preferable. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior film 50 with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior film 50 with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, and the like may also be added as needed. Softening can be achieved by annealing or other methods. From the perspective of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably a hard aluminum alloy foil made of, for example, a work-hardened aluminum alloy. Examples of hard aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14. 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 specified in JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JIS H4000:2017 A5052P-O. The aluminum alloy foil is also preferably an aluminum alloy foil containing manganese. In the aluminum alloy foil containing manganese (100% by mass), the manganese content is preferably 0.3 to 1.5% by mass, and more preferably 1.0 to 1.5% by mass. Examples of aluminum alloy foils containing manganese include aluminum alloy foils having compositions defined by JIS H4000: 2017 A3003P-O, JIS H4000: 2017 A3103P-O, JIS H4000: 2017 A3004P-O, and JIS H4000: 2017 A3104P-O.

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

[0036] Specific examples of austenitic stainless steels that form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0037] In the case of a metal foil, the thickness of the barrier layer 52 should be sufficient to at least function as a barrier layer that prevents moisture penetration, and may be, for example, 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.

[0038] Furthermore, when the barrier layer 52 is an aluminum foil, it is preferable that a corrosion-resistant coating be provided on at least the surface opposite the substrate layer 51 to prevent dissolution and corrosion. The barrier layer 52 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant coating refers to a thin film that is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) by performing, for example, a hydrothermal conversion treatment such as boehmite treatment, a chemical conversion treatment, an anodizing treatment, a plating treatment 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.

[0039] 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.

[0040] The heat-sealable resin layer 53 is bonded to the barrier layer 52 via, for example, an adhesive layer 55. The heat-sealable resin layer 53 included in the exterior film 50 is a layer that provides heat-sealing properties to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, polyolefin resins such as polyethylene resins and polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. From the 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.

[0041] 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.

[0042] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Examples of the material having cushioning properties include rubber, nonwoven fabric, and foam sheet. Examples of rubber include natural rubber, fluororubber, and silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the nonwoven fabric is preferably a material having excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and even more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and even more preferably 3000 μm. The thickness of the buffer layer is preferably in the range of 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm, with the most preferred range being 1000 μm to 3000 μm.

[0043] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm, 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.

[0044] When the exterior film 50 has a buffer layer, the buffer layer functions as a cushion, thereby preventing the exterior film 50 from being damaged by impact when the energy storage device 10 is dropped or by handling during manufacturing of the energy storage device 10.

[0045] The cover body 60 has a base part 70 , a first covering part 80 , and a second covering part 90 .

[0046] The base part 70 is composed of a conductive material. "Comprised of a conductive material" means that, when the entire material constituting the base part 70 is taken as 100 mass %, the content of the conductive material 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 base part 70 can contain materials other than the conductive material in addition to the conductive material. The base part 70 composed of a conductive material preferably has the corrosion-resistant coating described for the barrier layer 52.

[0047] The conductive material constituting the base part 70 is, for example, a metal material. The metal material constituting the base part 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 base part 70 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The base part 70 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the base part 70 connected to the negative electrode may be nickel-plated copper. The material constituting the base part 70 may include recycled metal material.

[0048] The base part 70 may be a film or a metal molded product. When the base part 70 is described as a metal molded product, this does not include an embodiment in which the base part 70 is composed only of a film as defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard.

[0049] The base part 70 has a main portion 71 , a wall portion 72 and an internal space 73 .

[0050] The outer shape of the main portion 71 can be selected arbitrarily as long as it can seal the electrode body 20. In the example shown in FIG. 4 and other figures, the outer shape of the main portion 71 is rectangular. The outer shape of the main portion 71 may be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 71 has a first surface 71A and a second surface 71B. The first surface 71A faces the electrode body 20 via the first covering part 80. The second surface 71B is the surface opposite the first surface 71A in the FB direction. The second surface 71B faces the external space via the second covering part 90. Note that the lid body 60 may be arranged so that the first surface 71A faces the external space, in other words, so that the second surface 71B faces the second covering part 90.

[0051] The main portion 71 has a hole 71Z formed therein, which penetrates the first surface 71A and the second surface 71B. The electrode terminal 30 is inserted into the hole 71Z. From the viewpoint of preventing electrical conduction between the main portion 71 and the electrode terminal 30, it is preferable that an insulating member 110 (see FIG. 7 ) be disposed at least in the hole 71Z.

[0052] The wall portion 72 protrudes from the outer peripheral edge of the main portion 71. The direction in which the wall portion 72 protrudes can be selected arbitrarily. In the example shown in FIG. 4 etc., the wall portion 72 protrudes from the outer peripheral edge of the main portion 71 toward the electrode body 20 in the FB direction. The wall portion 72 may protrude from the outer peripheral edge of the main portion 71 in the opposite direction to the electrode body 20, in other words, toward the external space, in the FB direction. The wall portion 72 may protrude from the outer peripheral edge of the main portion 71 in a direction intersecting the FB direction in a side view of the lid body 60.

[0053] The wall portion 72 has a first wall surface 72X and a second wall surface 72Y. The first wall surface 72X is the surface that is covered by the second covering part 90. The second wall surface 72Y is the surface opposite to the first wall surface 72X. The second wall surface 72Y is the surface that is covered by the first covering part 80.

[0054] 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 extends in a first direction (in the present embodiment, the LR direction) in a front view of the lid body 60. 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. 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 body 60. In the present 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 wall portion 72D extends in a first direction (LR direction in this embodiment) when the cover body 60 is viewed from the front.

[0055] In this embodiment, the thicknesses of the first to fourth wall portions 72A to 72D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 72A to 72D may vary in the FB direction. For example, at least one of the first to fourth wall portions 72A to 72D may have a tapered shape in which the thickness increases or decreases in the FB direction toward the electrode assembly 20. If the first to fourth wall portions 72A to 72D have a tapered shape, the tapered shape is preferably a tapered shape in which the thickness increases toward the electrode assembly 20, from the viewpoint of suppressing an increase in the internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 72A and 72D, which are longer in the LR direction, have a constant thickness in the FB direction, in other words, do not have a tapered shape.

[0056] The wall portion 72 further includes boundaries 72E, 72F, 72G, and 72H. The boundary 72E is the boundary between the first wall portion 72A and the second wall portion 72B. The boundary 72F is the boundary between the first wall portion 72A and the third wall portion 72C. The boundary 72G is the boundary between the fourth wall portion 72D and the second wall portion 72B. The boundary 72H is the boundary between the fourth wall portion 72D and the third wall portion 72C. The boundaries 72E to 72H may have angular shapes or may be rounded by applying a rounded edge. In this embodiment, the boundaries 72E to 72H are angular. If the boundaries 72E to 72H have rounded shapes, the radius of curvature of the boundaries 72E to 72H is preferably within the range of 0 mm to 2.0 mm.

[0057] The internal space 73 is defined by the first surface 71A of the main portion 71 and the second wall surface 72Y of the wall portion 72. A part of the first covering part 80 is housed in the internal space 73.

[0058] The thickness of the base part 70 can be selected arbitrarily. When the base part 70 is a film, the thickness of the base part 70 is preferably 9 μm or more from the viewpoint of preventing breakage of the base part 70 or the occurrence of pinholes. When the base part 70 is a film, the thickness of the base part 70 is preferably 0.2 mm or less from the viewpoint of suitable molding. When the base part 70 is a film, the preferred range of the thickness of the base part 70 is 9.0 μm or more and 0.2 mm or less. The thicknesses of the first wall portion 72A and the fourth wall portion 72D are measured in the UD direction. The thicknesses of the second wall portion 72B and the third wall portion 72C are measured in the LR direction. The thickness of the main portion 71 is measured in the FB direction.

[0059] When the base part 70 is a metal molded product, from the viewpoint of suppressing deformation of the lid body 60 when an external force is applied to the lid body 60, the thickness of the base part 70 is preferably 0.2 mm or more, and more preferably 0.5 mm or more. When the base part 70 is a metal molded product, from the viewpoint of reducing the weight of the lid body 60, the thickness of the base part 70 is preferably 5.0 mm or less, and more preferably 2.0 mm or less. When the base part 70 is a metal molded product, the preferred range of the thickness of the base part 70 is 0.2 mm or more and 5.0 mm or less, 0.2 mm or more and 2.0 mm or less, 0.5 mm or more and 5.0 mm or less, or 0.5 mm or more and 2.0 mm or less. Note that when the thickness of the base part 70 varies depending on the portion, the thickness of the base part 70 is the thickness of the thickest portion. From the viewpoint of reducing the weight of the lid body 60, the thickness of the base part 70 is preferably thinner than at least one of the thickness of the first covering part 80 and the thickness of the second covering part 90. It is further preferable that the thickness of the base part 70 is thinner than the thickness of the first covering part 80 and the thickness of the second covering part 90. The thicknesses of the first wall portion 72A and the fourth wall portion 72D are measured in the UD direction. The thicknesses of the second wall portion 72B and the third wall portion 72C are measured in the LR direction. The thickness of the main portion 71 is measured in the FB direction.

[0060] The width of the base part 70 in the LR direction can be selected arbitrarily. When the base part 70 is a film, the width of the base part 70 in the LR direction is preferably 10 mm or more. When the base part 70 is a film, the width of the base part 70 in the LR direction is preferably 500 mm or less. When the base part 70 is a film, the preferred range of the width of the base part 70 in the LR direction is 10 mm or more and 500 mm or less.

[0061] The height of the base part 70 in the UD direction can be selected arbitrarily. When the base part 70 is a film, the height of the base part 70 in the UD direction is preferably 10 mm or more. When the base part 70 is a film, the height of the base part 70 in the UD direction is preferably 500 mm or less. When the base part 70 is a film, the preferred range for the height of the base part 70 in the UD direction is 10 mm or more and 500 mm or less.

[0062] The first covering part 80 covers at least a portion of the first surface 71A of the base part 70. In the present embodiment, the first covering part 80 covers the entire first surface 71A.

[0063] The first covering part 80 is made of a resin material. Here, "made of a resin material" means that, when the total mass of the materials constituting the first covering part 80 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 first covering part 80 can contain materials other than the resin material in addition to the resin material.

[0064] 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 first covering part 80 may be molded by any molding method or manufactured by cutting.

[0065] The resin material contained in the material constituting the first covering part 80 is preferably an olefin-based random copolymer, more preferably a resin containing a polyolefin skeleton as a main component, even more preferably a polyolefin as a main component, and even more preferably a polypropylene as a main component. The polyolefin may be an acid-modified polyolefin. The resin material contained in the material constituting the first covering part 80 preferably contains multiple types of amide-based lubricants. Furthermore, the resin material contained in the material constituting the first covering part 80 preferably contains, in addition to saturated fatty acid amide, multiple types of amide-based lubricants further containing unsaturated fatty acid amide. The resin material contained in the material constituting the first covering part 80 may be a polyolefin resin to which a propylene-based elastomer having a melting point higher than 150°C has been added. Note that a "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.

[0066] 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.

[0067] 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.

[0068] The resin as the resin material may contain a filler as needed. Specific examples of fillers include glass beads, graphite, glass fiber, and carbon fiber. By including the filler in the resin as the resin material, the deformation resistance of first covering part 80 to temperature changes can be improved.

[0069] The melt mass flow rate of the resin material contained in the material constituting first covering part 80 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.

[0070] The first covering part 80 may be a film or a resin molded product. When the first covering part 80 is described as a resin molded product, this does not include an embodiment in which the first covering part 80 is composed only of a film defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard.

[0071] The first covering part 80 includes a storage portion 80A and a flange portion 80B. The storage portion 80A is stored in the internal space 73 of the base part 70. The storage portion 80A has a main portion 81, a wall portion 82, and an internal space 83. The first covering part 80 may or may not be joined to the base part 70. The first covering part 80 can omit the flange portion 80B. In other words, the first covering part 80 can be composed of only the storage portion 80A.

[0072] The outer shape of the main portion 81 can be selected arbitrarily as long as it can cover at least a portion of the first surface 71A of the base part 70. In the example shown in FIG. 5 etc., the outer shape of the main portion 81 is rectangular. The outer shape of the main portion 81 may be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 81 has a first surface 81A and a second surface 81B. The first surface 81A faces the electrode body 20. The second surface 81B is the surface opposite the first surface 81A in the FB direction. The second surface 81B faces the first surface 71A of the base part 70. The main portion 81 has a hole 81Z that penetrates the first surface 81A and the second surface 81B. An electrode terminal 30 is inserted into the hole 81Z.

[0073] The wall portion 82 protrudes from the outer peripheral edge of the main portion 81. In the example shown in Fig. 5 etc., the wall portion 82 protrudes from the outer peripheral edge of the main portion 81 toward the electrode body 20 in the FB direction. The wall portion 82 has a first wall surface 82X and a second wall surface 82Y. The first wall surface 82X is a surface that comes into contact with the second wall surface 72Y of the base part 70. The second wall surface 82Y is a surface opposite to the first wall surface 82X.

[0074] The wall portion 82 includes a first wall portion 82A, a second wall portion 82B, a third wall portion 82C, and a fourth wall portion 82D. The first wall portion 82A extends along the first wall portion 72A. The second wall portion 82B and the third wall portion 82C are connected to the first wall portion 82A and the fourth wall portion 82D. The second wall portion 82B extends along the second wall portion 72B. The third wall portion 82C extends along the third wall portion 72C. The fourth wall portion 82D extends along the fourth wall portion 72D.

[0075] In this embodiment, the thicknesses of the first to fourth wall portions 82A to 82D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 82A to 82D may vary in the FB direction. For example, at least one of the first to fourth wall portions 82A to 82D may have a tapered shape in which the thickness increases or decreases in the FB direction toward the electrode assembly 20. If the first to fourth wall portions 82A to 82D have a tapered shape, the tapered shape is preferably a tapered shape in which the thickness increases toward the electrode assembly 20, from the viewpoint of suppressing an increase in the internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 82A and 82D, which are longer in the LR direction, of the wall portions 82 have a constant thickness in the FB direction, in other words, do not have a tapered shape. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are measured in the UD direction, and the thicknesses of the second wall portion 82B and the third wall portion 82C are measured in the LR direction.

[0076] The wall portion 82 further includes boundaries 82E, 82F, 82G, and 82H. The boundary 82E is the boundary between the first wall portion 82A and the second wall portion 82B. The boundary 82F is the boundary between the first wall portion 82A and the third wall portion 82C. The boundary 82G is the boundary between the fourth wall portion 82D and the second wall portion 82B. The boundary 82H is the boundary between the fourth wall portion 82D and the third wall portion 82C. The shapes of the boundaries 82E to 82H may be angular, or may be rounded by applying a rounded edge. In this embodiment, the boundaries 82E to 82H are angular. If the shapes of the boundaries 82E to 82H are rounded, the radius of curvature of the boundaries 82E to 82H is preferably in the range of more than 0 mm and not more than 2.0 mm.

[0077] The internal space 83 is defined by the first surface 81A of the main portion 81 and the second wall surface 82Y of the wall portion 82.

[0078] The flange portion 80B protrudes from the end face of the wall portion 82 opposite the main portion 81 in the FB direction. The flange portion 80B covers the end face of the wall portion 72 of the base part 70 opposite the main portion 71 in the FB direction.

[0079] The thickness of the first covering part 80 can be selected arbitrarily. When the first covering part 80 is a film, the thickness of the first covering part 80 is preferably 0.3 mm or more from the viewpoint of preventing damage to the first covering part 80 or preventing the occurrence of pinholes. When the first covering part 80 is a film, the thickness of the first covering part 80 is preferably 3.0 mm or less from the viewpoint of formability. When the first covering part 80 is a film, the preferred range of the thickness of the first covering part 80 is 0.3 mm or more and 3.0 mm or less. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are measured in the UD direction. The thicknesses of the second wall portion 82B and the third wall portion 82C are measured in the LR direction. The thickness of the main portion 81 and the flange portion 80B are measured in the FB direction.

[0080] When the first covering part 80 is a resin molded product, the thickness of the first covering part 80 is preferably 1.0 mm or more in order to prevent deformation of the lid body 60 when an external force is applied to the lid body 60. When the first covering part 80 is a resin molded product, the thickness of the first covering part 80 is preferably 3.0 mm or less in order to reduce the weight of the lid body 60. When the first covering part 80 is a resin molded product, the preferred range of the thickness of the first covering part 80 is 1.0 mm or more and 3.0 mm or less. Note that when the thickness of the first covering part 80 varies depending on the portion, the thickness of the first covering part 80 is the thickness of the thickest portion. The thicknesses of the first wall portion 82A and the fourth wall portion 82D are measured in the UD direction. The thicknesses of the second wall portion 82B and the third wall portion 82C are measured in the LR direction. The thickness of the main portion 81 and the flange portion 80B are measured in the FB direction.

[0081] The second covering part 90 covers at least a portion of the second surface 71B of the base part 70. In this embodiment, the second covering part 90 covers the entire second surface 71B. The second covering part 90 is joined to the base part 70.

[0082] The second covering part 90 is made of a resin material. The definition of "made of a resin material" with respect to the second covering part 90 is the same as that of the first covering part 80. The specifications of the resin material contained in the material constituting the second covering part 90 are the same as those of the resin material contained in the material constituting the first covering part 80. The second covering part 90 may be a film or a resin molded product. When the second covering part 90 is referred to as a resin molded product, this does not include a case in which the second covering part 90 is made of only a film as defined by the JIS (Japanese Industrial Standards) "Packaging Terminology" standard. Note that the resin material contained in the material constituting the first covering part 80 and the resin material contained in the material constituting the second covering part 90 may be the same or different. When the resin material constituting the second covering part 90 is a resin, the second covering part 90 may be molded by any molding method or may be manufactured by cutting.

[0083] The second covering part 90 has a shape similar to that of the base part 70. The second covering part 90 has a main part 91, a wall part 92, and an internal space 93.

[0084] The outer shape of the main portion 91 can be selected arbitrarily as long as it can cover at least a portion of the second surface 71B of the base part 70. In the example shown in FIG. 6 and other figures, the outer shape of the main portion 91 is rectangular. The outer shape of the main portion 91 may be circular, elliptical, square, triangular, or a polygon with pentagons or more sides. The main portion 91 has a first surface 91A and a second surface 91B. The first surface 91A faces the second surface 71B of the base part 70. The second surface 91B is the surface opposite the first surface 91A in the FB direction. The second surface 91B faces the external space. The lid 60 may be arranged so that the first surface 91A faces the external space, in other words, so that the second surface 91B faces the electrode body 20. The main portion 91 has a hole 91Z formed therein, penetrating the first surface 91A and the second surface 91B. The electrode terminal 30 is inserted into the hole 91Z.

[0085] The wall portion 92 protrudes from the outer peripheral edge of the main portion 91 so as to cover the first wall surface 72X of the wall portion 72 of the base part 70. The wall portion 92 has a first wall surface 92X and a second wall surface 92Y. The first wall surface 92X is the surface that is joined to the heat-sealable resin layer 53 of the exterior film 50. The second wall surface 92Y is the surface opposite the first wall surface 92X. The second wall surface 92Y covers the second wall surface 72Y of the wall portion 72 of the base part 70.

[0086] The wall portion 92 includes a first wall portion 92A, a second wall portion 92B, a third wall portion 92C, and a fourth wall portion 92D. The first wall portion 92A forms the top surface of the lid 60. The first wall portion 92A extends along the first wall portion 72A of the base part 70. The second wall portion 92B and the third wall portion 92C are connected to the first wall portion 92A and the fourth wall portion 92D, and form the side surfaces of the lid 60. The second wall portion 92B extends along the second wall portion 72B of the base part 70. The third wall portion 93C extends along the third wall portion 72C of the base part 70. The fourth wall portion 92D extends along the fourth wall portion 72D of the base part 70.

[0087] In this embodiment, the thicknesses of the first to fourth wall portions 92A to 92D are substantially constant in the FB direction. The thicknesses of the first to fourth wall portions 92A to 92D may vary in the FB direction. For example, at least one of the first to fourth wall portions 92A to 92D may have a tapered shape in which the thickness increases or decreases in the FB direction toward the electrode assembly 20. If the first to fourth wall portions 92A to 92D have a tapered shape, the tapered shape is preferably a tapered shape in which the thickness increases toward the electrode assembly 20, from the viewpoint of suppressing an increase in the internal pressure of the exterior body 40. From the viewpoint of suppressing a decrease in the strength of the lid body 60, it is preferable that the first and fourth wall portions 92A and 92D, which are longer in the LR direction, of the wall portions 92 have a constant thickness in the FB direction, in other words, do not have a tapered shape. The thicknesses of the first wall portion 92A and the fourth wall portion 92D are measured in the UD direction, and the thicknesses of the second wall portion 92B and the third wall portion 92C are measured in the LR direction.

[0088] The wall portion 92 further includes boundaries 92E, 92F, 92G, and 92H. The boundary 92E is the boundary between the first wall portion 92A and the second wall portion 92B. The boundary 92F is the boundary between the first wall portion 92A and the third wall portion 92C. The boundary 92G is the boundary between the fourth wall portion 92D and the second wall portion 92B. The boundary 92H is the boundary between the fourth wall portion 92D and the third wall portion 92C. The boundaries 92E to 92H may have angular shapes or may be rounded by applying a rounding process. In this embodiment, the boundaries 92E to 92H are angular. If the boundaries 92E to 92H have rounded shapes, the radius of curvature of the boundaries 92E to 92H is preferably in the range of more than 0 mm and not more than 2.0 mm.

[0089] The end face of the wall portion 92 opposite the main portion 91 in the FB direction contacts the flange portion 80B of the first covering part 80. Therefore, in the lid body 60, a boundary 60X between the first covering part 80 and the second covering part 90 can be confirmed. The boundary 60X can be observed using a scanning electron microscope or a scanning transmission electron microscope. Even if the resin material contained in the material constituting the first covering part 80 and the resin material contained in the material constituting the second covering part 90 are the same material, the boundary 60X is observed using a scanning electron microscope or a scanning transmission electron microscope because the sea-island shape or lamellar shape at the boundary 60X is different. Note that "different sea-island shapes" includes cases where the components are the same but the shape differs only due to differences in the vertical or horizontal dimensions of the sea-island shapes. "Different lamellar shapes" also includes cases where the lamellae are discontinuous or have different orientations, even if the dimensions such as thinness and length of the lamellae are the same.

[0090] The internal space 93 is defined by the first surface 91A of the main portion 91 and the second wall surface 92Y of the wall portion 92. The internal space 93 accommodates the entire base part 70 and a part of the first covering part 80. The flange portion 80B of the first covering part 80 is exposed from the internal space 93.

[0091] The thickness of the second covering part 90 can be selected arbitrarily. Whether the second covering part is a film or a resin molded product, the thickness of the second covering part 90 is preferably 50 μm or more from the viewpoint of favorable bonding with the exterior film 50. Whether the second covering part is a film or a resin molded product, the thickness of the second covering part 90 is preferably 2.0 mm or less from the viewpoint of reducing the weight of the lid body 60. A preferred range for the thickness of the second covering part 90 is 50 μm or more and 2.0 mm or less. Note that if the thickness of the second covering part 90 varies depending on the portion, the thickness of the second covering part 90 refers to the thickness of the thickest portion. The thicknesses of the first wall portion 92A and the fourth wall portion 92D are measured in the UD direction. The thicknesses of the second wall portion 92B and the third wall portion 92C are measured in the LR direction. The thickness of the main portion 91 is measured in the FB direction.

[0092] Any method can be selected as the manufacturing method for the lid body 60. An example of the manufacturing method for the lid body 60 will be described below.

[0093] In the first example, the manufacturing method for the lid 60 includes a first injection molding step and a second injection molding step. In the first injection molding step, a first covering part 80 is injection molded onto a base part 70. Note that the object obtained by injection molding the first covering part 80 onto the base part 70 corresponds to the lid unit 130. In the second injection molding step, a second covering part 90 is injection molded onto the lid unit 130. In the first example, the amount of resin used in the first injection molding step is smaller than when the first covering part 80 and the second covering part 90 are injection molded onto the base part 70 at the same time. Therefore, even if the thickness of the base part 70 is thin, deformation of the base part 70 is suppressed in the first injection molding step and the second injection molding step. In particular, when the thickness of the base part 70 is 2.0 mm or less, it is preferable to manufacture the lid 60 using the manufacturing method in the first example. Furthermore, in the first example, in the first injection molding process, the base part 70, which is easily deformed by resin pressure, is held down by a mold, so deformation of the base part 70 is suppressed even when the first covering part 80 is injection molded.

[0094] In the first example, after the first injection molding process is completed, a burr 100X (see FIG. 8A ) may be formed in a portion of the flange portion 80B of the first covering part 80 that does not cover the end face of the wall portion 72 of the base part 70. In the second injection molding process, the burr 100X is covered by the second covering part 90 or is integrated with the second covering part 90. This prevents the burr 100 from coming into contact with elements such as the electrode body 20 located inside the exterior body 40.

[0095] In the second example, the manufacturing method for the lid 60 includes a first injection molding step and a second injection molding step. In the first injection molding step, a second covering part 90 is injection molded onto a base part 70. Note that the object in which the second covering part 90 is injection molded onto the base part 70 corresponds to the lid unit 230 (see FIG. 8B ). In the second injection molding step, a first covering part 80 is injection molded onto the lid unit 230. In the second example, a smaller amount of resin is used in the first injection molding step than when the first covering part 80 and the second covering part 90 are injection molded onto the base part 70 at the same time. Therefore, even if the thickness of the base part 70 is thin, deformation of the base part 70 is suppressed in the first injection molding step and the second injection molding step. In particular, when the thickness of the base part 70 is 2.0 mm or less, the lid 60 is preferably manufactured by the manufacturing method in the second example. In addition, in the second example, in the first injection molding process, the base part 70, which is easily deformed by resin pressure, is held down by a mold, so that deformation of the base part 70 is suppressed even when the second covering part 90 is injection molded.

[0096] In a third example, the base part 70, the first covering part 80, and the second covering part 90 are manufactured separately and then combined. In the third example, the first covering part 80 and the second covering part 90 may be manufactured in the same molding machine. In the third example, the first covering part 80 and the second covering part 90 are not injection molded onto the base part 70, so deformation of the base part 70 is suppressed during the manufacturing process of the lid 60. In particular, when the thickness of the base part 70 is 2.0 mm or less, it is preferable to manufacture the lid 60 by the manufacturing method of the third example. The base part 70, the first covering part 80, and the second covering part 90, which are manufactured separately, correspond to a lid kit 140 (see FIGS. 4 to 6 ).

[0097] 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).

[0098] 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 100AX of the first sealed portion 100A is preferably located on the edge 43 at the boundary between the first surface 41 and the second surface 42 of the exterior body 40. The first surface 41 has a larger area than the second surface 42. The base 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 42 or the first surface 41 of the exterior body 40.

[0099] In this embodiment, the second sealed portion 100B is formed by heat-sealing the heat-sealable resin layer 53 of the exterior film 50 and the first wall surface 92X of the second covering part 90. Hereinafter, the seal strength between the heat-sealable resin layer 53 of the exterior film 50 and the first wall surface 92X of the second covering part 90 may be referred to as the seal strength (bonding strength) of the second sealed portion 100B. Note that the seal strength of the second sealed portion 100B is the seal strength between the heat-sealable resin layer 53 and the lid 60 at the long side portion of the first wall surface 92X, i.e., the first wall surface 92X extending in the LR (width) direction in FIG. 1A .

[0100] 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 (away from the first surface 41B), thereby measuring 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 sides and short sides, the sealing strength of the second sealing portion 100B is the sealing strength of the long side portion of the first wall surface 92X of the multiple parts.

[0101] 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.

[0102] 9 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.

[0103] 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.

[0104] The second process of step S12 is performed after the first process. In the second process, the manufacturing apparatus joins the electrode terminal 30 connected to the electrode body 20 to the lid body 60. Note that the lid body 60 with the electrode terminal 30 joined thereto may be disposed in the first process, and the electrode terminal 30 and the electrode body 20 may be connected in the second process.

[0105] The third step of step S13 is performed after the second step. In the third 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 with the electrode terminals 30 connected thereto may be housed inside the exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and after the electrode body 20 and the lid 60 are joined together, the opening may be closed by the lid 60. In yet another example, the electrode body 20 with the lid 60 connected via the electrode terminals 30 may be housed inside the 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.

[0106] The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus heat-seals the exterior film 50 and the first wall surface 82X of the lid body 60 to form the second sealed portion 110B.

[0107] The fifth step of step S15 is performed before or after the fourth step. In the fifth step, the manufacturing apparatus forms the first sealed portion 100A by heat-sealing the heat-sealable resin layer 53 in a portion including the first edge 50A of the exterior film 50 and the heat-sealing the heat-sealable resin layer 53 in a 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.

[0108] <1-3. Functions and Effects of the Power Storage Device> The lid body 60 includes a base part 70, a first covering part 80, and a second covering part 90. Because the first covering part 80 and the second covering part 90 are separate parts, the first covering part 80 and the second covering part 90 are not injection molded simultaneously with respect to the base part 70 during the manufacturing process of the lid body 60. Therefore, deformation of the lid body 60 during the manufacturing process of the lid body 60 is suppressed.

[0109] [2. Modifications] The above-described embodiments are examples of possible forms of the lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and electricity storage device manufacturing method of the present invention, and are not intended to limit the forms. The lid, electricity storage device, lid kit, lid unit, base part, first covering part, second covering part, and electricity storage device manufacturing method 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 embodiments is replaced, modified, or omitted, or forms in which a new configuration is added to the embodiments. 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.

[0110] 2-1. First Modification In the above embodiment, the configuration of lid 60 can be modified. Fig. 10 is a cross-sectional view of lid 160 of a first modification. As shown in Fig. 10, main portion 91 of second covering part 90 does not have to cover a portion of second surface 71B of base part 70.

[0111] 2-2. Second Modification FIG. 11 is a cross-sectional view of a cover body 260 of a second modification. As shown in FIG. 11 , the main portion 81 of the first covering part 80 may not cover a portion of the first surface 71A of the base part 70. The main portion 91 of the second covering part 90 may not cover a portion of the second surface 71B of the base part 70. In the example shown in FIG. 11 , the first surface 71A and the second surface 71B of the base part 70 are exposed. The exposed portion of the first surface 71A of the base part 70 may be connected to the electrode body 20. The exposed portion of the second surface 71B of the base part 70 may be connected to an external device. In the second modification, a current can be output from the base part 70. In other words, the base part 70 also functions as the electrode terminal 30, so that the electrode terminal 30 can be omitted. In the second modified example, the electrode terminal 30 may be joined to a portion of the second surface 71B that is not covered by the second covering part 90.

[0112] 12 is a cross-sectional view of a lid 360 of a third modified example. The base part 70 may have a flange portion 74 connected to the wall portion 72. An edge 74A of the flange portion 74 may be sandwiched between the first covering part 80 and the second covering part 90. In the third modified example, the first covering part 80 and the second covering part 90 do not contact each other.

[0113] 2-4. Fourth Modification In the above embodiment, the electrode terminal 30 may protrude outside the exterior body 40 from between the first wall surface 91X of the second covering part 90 and the exterior film 50. In the fourth modification, an adhesive film that can be suitably bonded to metal and resin is preferably disposed between the first wall surface 91X and the electrode terminal 30 and between the electrode terminal 30 and the exterior film 50. In the fourth modification, from the viewpoint of sealing performance, the electrode terminal 30 is preferably plate-shaped. In the fourth modification, the hole 71Z of the base part 70, the hole 81Z of the first covering part 80, and the hole 91Z of the second covering part 90 may be omitted. The fourth modification can be similarly applied to the first to third modifications.

[0114] 2-5. Fifth Modification In the above embodiment, the shape of the base part 70 can be changed as desired. The base part 70 may be, for example, cylindrical. When the base part 70 is cylindrical, for example, one side of an imaginary line that coincides with the radius of the circle of the end face can be defined as a first surface, and the other side can be defined as a second surface.

[0115] <2-6. Sixth Modification> In the above embodiment, the exterior film 50 of the power storage device 10 may protrude outward in the FB direction beyond at least one of the two lid bodies 60. The electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the lid body 60. The portion of the exterior film 50 that protrudes beyond the lid body 60 may be folded inward so that the outer surfaces of the exterior 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.

[0116] 2-7. Seventh Modification In the above embodiment, the exterior body 40 may not have one of the two lid bodies 60. In this modification, in the FB direction, in the portion of the exterior body 40 where the lid body 60 is omitted, the electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward beyond the electrode body 20. As in the sixth 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.

[0117] 2-8. Eighth 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.

[0118] <2-9. Ninth 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.

[0119] 10: Electricity storage device 20: Electrode body 40: Exterior body 50: Exterior film 60, 260, 360: Lid body 70: Base part 71: Main part 71A: First surface 71B: Second surface 72: Wall part 73: Internal space 74A: Edge 80: First covering part 80A: Storage part 90: Second covering part 130, 230: Lid unit 140: Lid body kit

Claims

1. A lid used for an exterior body of an electricity storage device, a base part comprising a conductive material and including a first surface and a second surface opposite the first surface; a first covering part including a resin material and covering at least a portion of the first surface of the base part; a second covering part that contains a resin material and covers at least a portion of the second surface of the base part, The first covered part and the second covered part are resin molded parts. Lid body.

2. The first covering part and the second covering part are in contact with each other. The lid according to claim 1 .

3. The edge of the base part is sandwiched between the first covering part and the second covering part. The lid according to claim 1 .

4. The base part comprises: The main part and a wall portion protruding from the main portion; an interior space defined by the wall portion; The first covering part includes a housing portion that is housed in the internal space. The lid according to any one of claims 1 to 3.

5. The thickness of the base part is 5.0 mm or less. The lid according to any one of claims 1 to 3.

6. An electrode body; an exterior body that seals the electrode body, The outer casing is an exterior film that wraps the electrode body; a lid that seals the electrode body together with the exterior film, The lid body is a base part including a conductive material and including a first surface facing the electrode body and a second surface opposite the first surface; a first covering part including a resin material and covering at least a portion of the first surface of the base part; a second covering part that contains a resin material and covers at least a portion of the second surface of the base part, The first covering part is disposed apart from the electrode body. Energy storage device.

7. A lid kit for constituting a lid to be used for an exterior body of an electricity storage device, a base part comprising a conductive material and including a first surface and a second surface opposite the first surface; a first covering part including a resin material and covering at least a portion of the first surface of the base part; a second covering part that contains a resin material and covers at least a portion of the second surface of the base part, The first covered part and the second covered part are resin molded parts. Lid body kit.

8. A lid unit constituting a lid body used in an exterior body of an electricity storage device, a base part comprising a conductive material and including a first surface and a second surface opposite the first surface; a first covering part containing a resin material and covering at least a portion of the first surface of the base part; and a second covering part containing a resin material and covering at least a portion of the second surface of the base part, The first covered part and the second covered part are resin molded parts. Lid unit.

9. A first covering part constituting a lid used in an exterior body of an electricity storage device, the lid body includes a base part including a conductive material and including a first surface facing an electrode body of the power storage device and a second surface opposite to the first surface; The first covering part is a resin molded product that contains a resin material and is configured to cover at least a part of the first surface of the lid. First coated part.

10. A method for manufacturing an electricity storage device, comprising: The electricity storage device is An electrode body; an exterior body that seals the electrode body, The outer casing is an exterior film that wraps the electrode body; a lid that seals the electrode body together with the exterior film, The lid body is a base part including a conductive material and including a first surface facing the electrode body and a second surface opposite the first surface; a first covering part including a resin material and covering at least a portion of the first surface of the base part; a second covering part that contains a resin material and covers at least a portion of the second surface of the base part, the first covering part is disposed apart from the electrode body, The method for manufacturing the electricity storage device includes: and a step of placing the lid body on the electrode body. A method for manufacturing an electricity storage device.