Storage device, lid, lid unit, method for manufacturing a storage device

Abstract

To provide a power storage device capable of suitably sealing an electrode body by an exterior body, a lid for use in the power storage device, a lid unit having the lid, and a method of manufacturing the power storage device.SOLUTION: A power storage device comprises an electrode body, and an exterior body for sealing the electrode body. The exterior body includes an exterior film for wrapping the electrode body so that an opening can be opened, a lid that is arranged in the opening, an overhanging part that overhangs outward with respect to a part, wrapping the electrode body, of the exterior film, and a first sealing part, in which mutually-opposed surfaces of the exterior film are sealed, of the overhanging part. The overhanging part is folded by setting a position away from a base of the first sealing part as a starting point.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a power storage device, a lid body, a lid unit, and a method for manufacturing a power storage device.

Background Art

[0002] Patent Document 1 discloses an all-solid-state battery as an example of a power storage device. This all-solid-state battery includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that is wound around the electrode body so as to have an opening, and a lid body that is disposed at the opening. The surfaces of the exterior film that face each other are heat-sealed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above power storage device, in order to miniaturize the configuration, the portion where the surfaces of the exterior film that face each other are heat-sealed is preferably folded starting from the root. However, since the root may be heat-sealed multiple times in the manufacturing process of the power storage device, the root and its periphery are damaged by heat-sealing. Also, the root and its periphery have a thinner sealant layer due to heat-sealing. Furthermore, since the portion where the surfaces of the exterior film that face each other are heat-sealed is movable, material fatigue is likely to occur, so even if it is not heat-sealed multiple times, it is likely to be damaged by folding. Therefore, when the exterior film is folded starting from the root, the portion constituting the root and its periphery of the exterior film may be damaged, and the sealing performance of the power storage device may be reduced.

[0005] The present invention aims to provide a power storage device capable of suitably sealing an electrode body with an exterior body, a lid used for this power storage device, a lid unit including this lid, and a method for manufacturing a power storage device.

Means for Solving the Problems

[0006] The power storage device according to the first aspect of the present invention includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body so that an opening is formed, a lid disposed at the opening, an overhanging portion that protrudes outward from a portion of the exterior film that wraps the electrode body, and a first sealing portion in which surfaces of the exterior film facing each other in the overhanging portion are sealed. The overhanging portion is folded starting from a position away from the base of the first sealing portion.

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

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

[0009] The power storage device according to the fourth aspect of the present invention is the power storage device according to the third aspect, wherein a cut that does not penetrate the exterior film is formed at the fold.

[0010] The power storage device according to the fifth aspect of the present invention is a power storage device according to any one of the first to fourth aspects, wherein the exterior body includes a second sealing portion in which the lid body and the exterior film are sealed, the lid body includes a lid sealing portion sealed with the exterior film and a protruding portion protruding from the lid sealing portion, and the first sealing portion seals the mutually facing surfaces of the exterior film with the protruding portion sandwiched therebetween.

[0011] The power storage device according to the sixth aspect of the present invention is a power storage device according to the fifth aspect, wherein the protruding portion becomes thicker as it approaches the lid sealing portion.

[0012] The power storage device according to the seventh aspect of the present invention is a power storage device according to the fifth or sixth aspect, wherein the melting point of the material constituting the protruding portion is equal to or higher than the melting point of the material constituting the lid sealing portion.

[0013] The power storage device according to the eighth aspect of the present invention is a power storage device according to any one of the fifth to seventh aspects, wherein the length of the protruding portion is 20 mm or less.

[0014] The lid body according to the ninth aspect of the present invention is a lid body used for the exterior body of a power storage device, wherein the exterior body includes an exterior film that wraps an electrode body so that an opening is formed, the lid body is disposed at the opening, and includes a lid sealing portion sealed with the exterior film and a protruding portion protruding from the lid sealing portion.

[0015] The lid body according to the tenth aspect of the present invention is a lid body according to the ninth aspect, wherein the protruding portion becomes thicker as it approaches the lid sealing portion.

[0016] The lid body according to the eleventh aspect of the present invention is a lid body according to the ninth or tenth aspect, wherein the melting point of the material constituting the protruding portion is equal to or higher than the melting point of the material constituting the lid sealing portion.

[0017] The lid according to the 12th aspect of the present invention is the lid according to any one of the 9th to 11th aspects, and the length of the protruding portion is 20 mm or less.

[0018] The lid unit according to the 13th aspect of the present invention includes a lid according to any one of the 9th to 12th aspects and an electrode terminal joined to the lid.

[0019] The method for manufacturing a power storage device according to the 14th aspect of the present invention includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body so that an opening is formed, a lid disposed at the opening, an overhanging portion that protrudes outward from a portion of the exterior film that wraps the electrode body, and a first sealing portion in which surfaces of the exterior film that face each other in the overhanging portion are sealed. The method for manufacturing a power storage device includes a step of folding the overhanging portion starting from a position away from the root of the first sealing portion.

[0020] The method for manufacturing a power storage device according to the 15th aspect of the present invention is the method for manufacturing a power storage device according to the 14th aspect. The power storage device includes a second sealing portion in which the lid and the exterior film are sealed. The first sealing portion includes a film thickness portion whose thickness increases toward the root. The method for manufacturing a power storage device includes a step of forming the second sealing portion using a seal bar. In the step of forming the second sealing portion, the second sealing portion is formed so that the seal bar does not contact the film thickness portion, or the second sealing portion is formed using the seal bar having a sealing surface along the outer contour shape of the film thickness portion so that the thickness of the film thickness portion is maintained.

Advantages of the Invention

[0021] According to the power storage device, lid, lid unit, and method for manufacturing a power storage device of the present invention, the electrode body can be suitably sealed by the exterior body.

Brief Description of the Drawings

[0022]

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Mode for Carrying Out the Invention

[0023] Hereinafter, a power storage device according to an embodiment of the present invention will be described with reference to the drawings. In this specification, the numerical range indicated by "~" means "above" and "below". For example, the notation 2~15 mm means 2 mm or more and 15 mm or less.

[0024] [1. First Embodiment] <1-1. Configuration of Power Storage Device> FIG. 1A is a plan view schematically showing a power storage device 10 of the first embodiment. FIG. 1B is a diagram regarding a method for measuring the seal strength of the second sealing portion 80 of the power storage device of FIG. 1A. FIG. 2 is a cross-sectional view showing the layer configuration of the exterior film 50 provided in the power storage device 10 of FIG. 1A. FIG. 3 is a side view of the lid 60 provided in the power storage device 10 of FIG. 1A. FIG. 4 is a view of the exterior film 50 provided in the power storage device 10 of FIG. 1A in a spread state. FIG. 5 is a front view of a state in which a portion including the overhanging portion 50Y of the power storage device 10 of FIG. 1A is folded. FIG. 6 is a front view of a state before the overhanging portion 50Y of the power storage device 10 of FIG. 5 is folded. In FIGS. 1A, 3, 5, and 6, 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 each of the arrows UDLRFB are common in each of the following figures.

[0025] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes, for example, electrodes (a positive electrode and a negative electrode) that constitute a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid-state battery, a quasi-solid-state battery, a polymer battery, an all-resin battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal-air battery, a polyvalent cation battery, or a capacitor, as well as a separator and the like. In the present embodiment, the shape of the electrode body 20 is a substantially rectangular parallelepiped. Note that the "substantially rectangular parallelepiped" includes, in addition to a perfect rectangular parallelepiped, a solid that can be regarded as a rectangular parallelepiped by, for example, modifying the shape of a part of the outer surface. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0026] In the present embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminal 30 is a metal terminal used for inputting and outputting power in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from, for example, the edge of the exterior body 40. Note that the electrode terminal 30 only needs to be able to input and output power of the electrode body 20, and for example, it does not need to protrude from the exterior body 40. When the lid body 60 described later is made of, for example, metal, the lid body 60 may also serve as the function of the electrode terminal 30. In this case, the lid body 60 having the function as the electrode terminal may or may not protrude from the exterior body 40.

[0027] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, or the like. 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 or the like, and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, or the like. Note that the outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator.

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

[0029] For example, there is a method of forming a housing portion (depression) for housing the electrode body 20 in the exterior film 50 through cold forming. However, it is not always easy to form a deep housing portion by such a method. If an attempt is made to deeply form the housing portion (depression) (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks are likely to occur in the exterior film 50, increasing the possibility of deterioration of battery performance. On the other hand, in the present embodiment, since the exterior body 40 seals the electrode body 20 by winding the exterior film 50 around the electrode body 20, the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In order to reduce the dead space between the electrode body 20 and the exterior film 50 and to improve the cooling efficiency in order to improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 is wound so as to be in contact with the outer surface of the electrode body 20. Also, in the all-solid-state battery, from the viewpoint that it is necessary to uniformly apply a high pressure from the outside of the battery in order to exhibit battery performance, it is necessary to eliminate the space between the electrode body 20 and the exterior film 50, so it is preferable that the exterior film 50 is wound so as to be in contact with the outer surface of the electrode body 20.

[0030] As shown in FIG. 2, the exterior film 50 is, for example, a laminate (laminate film) having a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. Note that it is not necessary for the exterior film 50 to include all of these layers. For example, the barrier layer 52 may not be included. That is, the exterior film 50 may be made of a material having flexibility and being easy to bend. For example, it may be made of a resin film. The outermost layer and the innermost layer of the exterior film 50 may be the heat-sealable resin layer 53. In this case, the exterior film 50 may wrap the electrode body 20 and the lid body 60 by joining the outermost layer and the innermost layer.

[0031] The base material layer 51 included in the exterior film 50 is a layer that imparts heat resistance to the exterior film 50 and suppresses the generation of pinholes that may occur during processing or distribution. The base material 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 base material 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. Further, 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. Note that the base material layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base material layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0032] The barrier layer 52 is a layer that at least suppresses the intrusion of moisture. The barrier layer 52 is joined to the base material layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include a metal foil having barrier properties, a vapor deposition film, and a resin layer. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, and a carbon-containing inorganic oxide vapor deposition film. Examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, and polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Further, examples of the barrier layer 52 include a resin film provided with at least one of these vapor deposition films and resin layers. A plurality of barrier layers 52 may be provided. 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 preferably includes at least one of an aluminum alloy foil and a stainless steel foil.

[0033] In the barrier layer 52, the layer made of the above-described metal material may contain a recycled material of the metal material. Examples of the recycled material of the metal material include recycled materials of aluminum alloys, stainless steel, titanium steel, or steel plates. These recycled materials can be obtained by known methods respectively. The recycled material of the aluminum alloy can be obtained, for example, by the production method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed only of the recycled material or may be composed of a mixed material of the recycled material and a virgin material. Note that the recycled material of the metal material refers to a metal material that has been recycled into a reusable state by collecting, separating, purifying, etc. various products used in the market and waste generated from the manufacturing process. Also, the virgin material of the metal material refers to a new metal material refined from natural resources (raw materials) of the metal and not a recycled material.

[0034] From the perspective of improving the formability of the exterior film 50, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the perspective of further improving the formability, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the content of iron is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, an exterior film 50 having more excellent formability can be obtained. When the iron content is 9.0% by mass or less, an exterior film 50 having more excellent flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having compositions defined by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Also, silicon, magnesium, copper, manganese, etc. may be added as necessary. Softening can be performed by annealing treatment or the like. From the perspective of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil composed of, for example, a work-hardened aluminum alloy. Examples of the hard aluminum alloy foil include aluminum alloy foils having compositions defined by JIS H4160:1994A8021H-H18, JIS H4160:1994 A8079H-H18, JISH4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14.

[0035] Also, examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Further, from the perspective of providing an exterior film 50 having excellent formability, the stainless steel foil is preferably composed of austenitic stainless steel.

[0036] Specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

[0037] In the case of a metal foil, the thickness of the barrier layer 52 only needs to exhibit the function as a barrier layer that at least suppresses the intrusion of moisture, and for example, it can be about 5 to 200 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 52 is preferably about 10 μm or more, still more preferably about 20 μm or more, and more preferably about 25 μm or more. Also, as the preferable range of the thickness of the barrier layer 52, there can be mentioned about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 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, about 25 to 35 μm. When the barrier layer 52 is composed of an aluminum alloy foil, the above-mentioned range is particularly preferable. Also, 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, still more preferably about 50 μm or more, and still more preferably about 55 μm or more, and is also preferably about 200 μm or less, more preferably about 85 μm or less, still more preferably about 75 μm or less, and still more preferably about 70 μm or less. The preferable range is about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, about 55 to 70 μm. Since the exterior film 50 has high formability, deep drawing forming becomes easy, which can contribute to increasing the capacity of the power storage device. Also, when the capacity of the power storage device is increased, the weight of the power storage device increases, but by increasing the rigidity of the exterior film 50, it can contribute to the high sealing property of the power storage device.In particular, when the barrier layer 52 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Also, the preferable range of the thickness of the stainless steel foil includes 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] When the barrier layer 52 is an aluminum foil, in order to prevent dissolution and corrosion, etc., it is preferable to provide a corrosion-resistant film on at least the surface opposite to the base material layer 51. The barrier layer 52 may be provided with corrosion-resistant films on both sides. Here, the corrosion-resistant film refers to, for example, a thin film that is subjected to a hot water conversion treatment such as a boehmite treatment, a chemical conversion treatment, an anodizing treatment, a plating treatment such as nickel or chromium, or a corrosion prevention treatment of applying a coating agent to the surface of the barrier layer 52 to impart corrosion resistance (such as acid resistance, alkali resistance, etc.) to the barrier layer 52. Specifically, the corrosion-resistant film means a film that improves the acid resistance of the barrier layer 52 (acid-resistant film), a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film), etc. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be combined. Also, it can be made into multiple layers instead of just one layer. Furthermore, among these treatments, the hot water conversion treatment and the anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound excellent in corrosion resistance. Note that these treatments may be included in the definition of the chemical conversion treatment. Also, when the barrier layer 52 is provided with a corrosion-resistant film, the barrier layer 52 including the corrosion-resistant film is used.

[0039] The corrosion-resistant film prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base material layer 51 during the molding of the outer packaging film 50, and prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride generated by the reaction of the electrolyte and moisture, particularly when the barrier layer 52 is an aluminum alloy foil, the aluminum oxide present on the surface of the barrier layer 52 is dissolved and corroded. In addition, it improves the adhesiveness (wettability) of the surface of the barrier layer 52, and shows the effect of preventing delamination between the base material layer 51 and the barrier layer 52 during heat sealing and preventing delamination between the base material layer 51 and the barrier layer 52 during molding.

[0040] The heat-sealable resin layer 53 is joined to the barrier layer 52 via, for example, the adhesive layer 55. The heat-sealable resin layer 53 contained in the outer packaging film 50 is a layer that imparts sealing properties to the outer packaging film 50 by heat sealing. Examples of the heat-sealable resin layer 53 include polyester resins such as polyethylene terephthalate-based resins and polybutylene terephthalate-based resins, polyolefin resins such as polyethylene-based resins and polypropylene-based resins, or resin films made of acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with acids such as maleic anhydride. From the viewpoints of sealing properties and strength, the thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm.

[0041] The outer packaging film 50 preferably has one or more layers having a buffering 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 outside the base material layer 51, or the base material layer 51 may also serve as the buffer layer. When the outer packaging film 50 has a plurality of buffer layers, the plurality of buffer layers may be adjacent to each other, or may be laminated via the base material layer 51 or the barrier layer 52 or the like.

[0042] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Materials having cushioning properties are, for example, rubber, non-woven fabric, or foamed sheet. Rubber is, for example, natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the non-woven fabric is preferably a material having excellent heat resistance. When the buffer layer is constituted by a non-woven fabric, the lower limit value 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 constituted by a non-woven fabric, the upper limit value of the thickness of the buffer layer is preferably 5000 μm, more preferably 3000 μm. The preferable range of the thickness of the buffer layer is 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm. Among these, the range of the thickness of the buffer layer is most preferably 1000 μm to 3000 μm.

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

[0044] When the exterior film 50 has a buffer layer, since the buffer layer functions as a cushion, it is possible to suppress the exterior film 50 from being damaged due to the impact when the power storage device 10 falls or the handling during the manufacture of the power storage device 10.

[0045] The lid body 60 is, for example, plate-shaped and is made of, for example, a resin material. Note that the lid body 60 may be formed by, for example, cold-forming the exterior film 50, or may be a metal-formed product. The material constituting the lid body 60 may contain at least two or more materials among metal oxides, carbon materials, and rubber materials, or may contain metal oxides, carbon materials, and rubber materials. The lid body 60 has a lid main body 60A. The lid main body 60A has a first surface 61, a second surface 62, and a lid seal portion 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface on the side opposite to the first surface 61. The lid seal portion 63 is connected to the first surface 61 and the second surface 62 and is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50. The lid seal portion 63 includes a first seal surface 63A, a second seal surface 63B, a third seal surface 63C, and a fourth seal surface 63D. The first seal surface 63A constitutes the upper surface of the lid body 60. The first seal surface 63A extends in a first direction (in this embodiment, the LR direction) in a front view of the lid body 60. The second seal surface 63B and the third seal surface 63C are connected to the first seal surface 63A and constitute the side surface of the lid body 60. The second seal surface 63B and the third seal surface 63C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction in a front view of the lid body 60. In this embodiment, in a front view of the lid body 60, the first direction and the second direction are orthogonal. The first direction and the second direction may not be orthogonal in a front view of the lid body 60. The fourth seal surface 63D constitutes the lower surface of the lid body 60. The fourth seal surface 63D extends in a first direction (in this embodiment, the LR direction) in a front view of the lid body 60.

[0046] When the lid body 60 is plate-shaped, even when the power storage devices 10 are stacked, it is preferable that the lid body 60 has a certain thickness so that the exterior body 40 is suppressed from deforming. From another perspective, when the lid body 60 is plate-shaped, in order to preferably heat-seal the lid seal portion 63 of the lid body 60 and the exterior film 50 when forming the second sealing portion 80, it is preferable that the lid seal portion 63 of the lid body 60 has a certain thickness. The minimum value of the thickness of the lid body 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid body 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum value of the thickness of the lid body 60 may be 20 mm or more. The preferable range of the thickness of the material constituting the lid body 60 is 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, 4.0 mm to 10 mm. In the present embodiment, when the lid body 60 is described as plate-shaped, the mode in which the lid body 60 is constituted only by a film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. Note that the thickness of the lid body 60 may vary depending on the part of the lid body 60. When the thickness of the lid body 60 varies depending on the part, the thickness of the lid body 60 is the thickness of the thickest part.

[0047] The lid seal portion 63 further includes boundaries 64, 65, 66, and 67. The boundary 64 is the boundary between the first seal surface 63A and the second seal surface 63B. The boundary 65 is the boundary between the first seal surface 63A and the third seal surface 63C. The boundary 66 is the boundary between the fourth seal surface 63D and the second seal surface 63B. The boundary 67 is the boundary between the fourth seal surface 63D and the third seal surface 63C. The shapes of the boundaries 64 to 67 may be corners, or may be rounded by R processing. In the present embodiment, the boundaries 64 to 67 are corners.

[0048] In this embodiment, the lid 60 is made of a resin material. Here, "made of a resin material" means that when the total amount of the materials constituting the lid 60 is 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. That is, the material constituting the lid 60 can contain, in addition to the resin material, materials other than the resin material.

[0049] Specific examples of the resin include resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, and thermoplastic resins such as modified products of these resins. The resin material may be a mixture of these resins, a copolymer, or a modified product of a copolymer. Among these, the resin material is preferably a heat-sealable resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the lid 60 may be molded by any molding method.

[0050] Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolyester, etc. Specific examples of the copolyester include copolyester having ethylene terephthalate as the main repeating unit. Specifically, a copolymer polyester obtained by polymerizing ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated following polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate), etc. Among these, the resin material is preferably polybutylene terephthalate from the viewpoint of enhancing heat resistance and pressure resistance.

[0051] In addition, specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and terpolymers of ethylene-butene-propylene. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. Among these, polypropylene is preferred as the resin material because it is excellent in heat sealability and electrolyte resistance.

[0052] The resin as the resin material may contain a filler as required. Specific examples of the filler include glass beads, graphite, glass fibers, and carbon fibers. By containing the above filler in the resin as the resin material, the deformation resistance of the lid body 60 against temperature changes can be improved.

[0053] The melt mass flow rate of the resin material contained in the material constituting the lid body 60 is preferably in the range of 1 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0054] In another example, the lid 60 may be made of a metal material. Here, "made of a metal material" means that when the total amount of the material constituting the lid 60 is 100% by mass, the content of the metal material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. That is, the material constituting the lid 60 can contain materials other than the metal material in addition to the metal material. The metal material constituting the lid 60 can be arbitrarily selected. The metal material constituting the lid 60 is, for example, aluminum, an aluminum alloy, nickel, copper, or a copper alloy. For example, when the electrode body 20 is a lithium-ion battery, the lid 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The lid 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the lid 60 connected to the negative electrode may be copper plated with nickel. The material constituting the lid 60 may contain a recycled material of the metal material.

[0055] In the present embodiment, a through hole 60X into which the electrode terminal 30 is inserted is formed in the lid 60. The through hole 60X penetrates the first surface 61 and the second surface 62. In a state where the electrode body 20 is housed, the electrode terminal 30 protrudes to the outside of the exterior body 40 through the through hole 60X formed in the lid 60. A slight gap between the through hole 60X of the lid 60 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the position where the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude to the outside through a hole formed in any one of the six surfaces of the exterior body 40. In this case, a slight gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the lid 60 and the electrode terminal 30 are provided as separate bodies, but the lid 60 and the electrode terminal 30 may be integrally formed. Note that when the electrode terminal 30 does not protrude from the edge of the exterior body 40, the through hole 60X may not be formed in the lid 60.

[0056] In the present embodiment, in a state where the exterior film 50 is wound around the electrode body 20 so as to have the opening 40A, the surfaces (heat-sealable resin layers 53) of the exterior film 50 facing each other in the overhanging portion 50Y are heat-sealed to form the first sealing portion 70.

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

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

[0059] Hereinafter, the sealing strength between the heat-sealable resin layer 53 of the outer film 50 and the lid seal portion 63 of the lid body 60 may be referred to as the sealing strength of the second sealing portion 80. Note that the sealing strength of the second sealing portion 80 is the sealing strength between the heat-sealable resin layer 53 and the lid body 60 in the lid seal portion 63 extending in the LR (width) direction in FIG. 1A, that is, the second long-side seal portion 81.

[0060] The sealing strength of the second sealing portion 80 is measured as follows. First, a cut is formed in a portion of the outer film 50 that constitutes the first surface 41A of the outer body 40, and three strip members 41X, 41Y, and 41Z arranged in the LR direction (see the two-dot chain line in FIG. 1B) are formed. The width of the three strip members 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strip members 41X, 41Y, and 41Z are joined to the lid body 60 at the second sealing portion 80. The length of the lid body 60 in the LR direction is 45 mm or more. Next, the sealing strengths of the strip members 41X, 41Y, and 41Z are measured respectively by pulling the ends of the strip members 41X, 41Y, and 41Z opposite to the ends joined to the lid body 60 upward in the UD direction (the direction opposite to the first surface 41B). In the present embodiment, the sealing strength of the second sealing portion 80 is the average value of the sealing strengths of the strip members 41X, 41Y, and 41Z. When the length of the lid body 60 in the LR direction is less than 45 mm, three strip members with an arbitrary width X mm less than 15 mm are formed, and the sealing strengths of the three strip members are measured in the same manner as when the length of the lid body 60 in the LR direction is 45 mm or more. By dividing the obtained sealing strengths by the arbitrary width X mm and multiplying by 15 respectively, the sealing strengths of the three strip members in a 15-mm width are converted respectively. The sealing strength of the second sealing portion 80 is the average value of the sealing strengths of the three strip members converted to a 15-mm width. Note that when the lid body 60 is divided into a plurality of parts including long sides and short sides, the sealing strength of the second sealing portion 80 is the sealing strength in the long-side portion of the lid seal portions 63 of the plurality of parts.

[0061] From the viewpoint of suitably maintaining the state in which the electrode body 20 is sealed by the outer package 40, the sealing strength of the second sealing portion 80 is preferably 40 N / 15 mm or more, more preferably 50 N / 15 mm or more, still more preferably 60 N / 15 mm or more, still more preferably 70 N / 15 mm or more, still more preferably 85 N / 15 mm or more. When the sealing strength of the second sealing portion 80 is 40 N / 15 mm or more, even if the power storage device 10 is used for, for example, several years (less than 10 years), the state in which the electrode body 20 is sealed by the outer package 40 is suitably maintained. When the sealing strength of the second sealing portion 80 is 85 N / 15 mm or more, even if the power storage device 10 is used for, for example, 10 years or more, the state in which the electrode body 20 is sealed by the outer package 40 is suitably maintained. The sealing strength of the second sealing portion 80 is preferably 300 N / 15 mm or less. The preferable range of the sealing strength of the second sealing portion 80 is 40 N / 15 mm to 300 N / 15 mm, 50 N / 15 mm to 300 N / 15 mm, 60 N / 15 mm to 300 N / 15 mm, 70 N / 15 mm to 300 N / 15 mm, or 85 N / 15 mm to 300 N / 15 mm.

[0062] In the manufacturing process of the power storage device 10, a predetermined range including the base 70X of the first sealing portion 70 is heat-sealed a plurality of times, so it is severely damaged. The base 70X of the first sealing portion 70 has a thin heat-sealing resin layer 53 of the outer film 50. Therefore, when the protruding portion 50Y is bent toward the first surface 41A or the second surface 42A starting from the base 70X, in the portion including the base 70X of the first sealing portion 70, the barrier layer 52, the base material layer 51, and the heat-sealing resin layer 53 may peel off, and the outer film 50 may crack. When a crack occurs in the portion of the outer film 50 including the base 70X, the sealing performance of the outer package 40 may decrease, and for example, an electrolytic solution or the like may leak. In the present embodiment, in order to increase the strength of the base 70X and its periphery, the first sealing portion 70 includes a portion where the thickness HA increases as it goes toward the base 70X (hereinafter, "film thickness portion 90").

[0063] FIG. 6 is a front view of the power storage device 10 before the protruding portion 50Y of the power storage device 10 in FIG. 5 is folded. The film thickness portion 90 includes a starting point 90A and an ending point 90B that is farther from the base 70X than the starting point 90A. In the present embodiment, the starting point 90A is located outside the surface of the exterior film 50 in the second sealing portion 80. The thickness HA of the first sealing portion 70 locally increases at the starting point 90A as it goes outward from the protruding portion 50Y. The thickness HA of the first sealing portion 70 locally decreases at the ending point 90B as it goes outward from the protruding portion 50Y. The power storage device 10 can fold the protruding portion 50Y toward the first surface 41A or the second surface 42A at the ending point 90B. In another example, the protruding portion 50Y can be folded starting from any point between the ending point 90B and the starting point 90A. Since the protruding portion 50Y is folded at a position far from the base 70X, in other words, at a position where damage due to heat sealing is relatively small, cracks are suppressed from occurring in the exterior film 50 at the base 70X. From the perspective of suppressing cracks from occurring in the exterior film 50, the protruding portion 50Y is preferably folded at a location more than 0.1 mm away from the base 70X. In addition, from the perspective of making it easy to grasp the folding position of the first sealing portion 70, it is preferable that a fold line 90C is formed in advance at the ending point 90B or between the starting point 90A and the ending point 90B. The fold line 90C is preferably formed generally throughout the protruding portion 50Y in the FB direction. The fold line 90C is preferably formed at a position more than 0.1 mm away from the base 70X in the LR direction. From the perspective of easily folding the protruding portion 50Y, it is preferable that a cut 90CX that does not penetrate the exterior film 50 is formed in the fold line 90C. In another example, the fold line 90C may be formed by applying an additional seal to the exterior film 50.

[0064] <1-2. Method of manufacturing a power storage device> FIG. 7 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, a fifth step, a sixth step, a seventh step, an eighth step, a ninth step, and a tenth step. The first to tenth steps are performed, for example, by a manufacturing apparatus for the power storage device 10. Note that the first to tenth steps are those defined for convenience as the names of the respective steps of the method for manufacturing the power storage device 10, and do not necessarily imply the order of the respective steps. The order of the following steps can be arbitrarily changed.

[0065] In the first step of step S11, the manufacturing apparatus arranges a lid body 60 (hereinafter referred to as “lid unit 60Z”) in a state where electrode terminals 30 are attached to both ends of the electrode body 20. By completion of the first step, the electrode terminals 30 and the electrodes of the electrode body 20 are electrically connected. Note that in the first step, the lid body 60 may be connected to the electrode terminals 30 electrically connected to the electrode body 20.

[0066] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus winds the exterior film 50 around the electrode body 20 and the lid body 60 while applying tension to the exterior film 50 while restricting the movement of the electrode body 20 and the lid body 60 by a restricting means. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force in a direction opposite to the direction in which the exterior film 50 is pulled to the electrode body 20 and the lid body 60. Note that the restricting means may include a roller that travels on the exterior film 50 in a state where the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50. Note that in the second step, an exterior film 50 having a larger area than the exterior film 50 of the completed power storage device 10 is used in order to form a gas pocket 100 described later.

[0067] The third step of step S13 is carried out after the second step. As shown in FIG. 8, in the third step, the manufacturing apparatus forms a first FB-direction seal portion 71 having an unsealed portion 71Z in the center. Note that the hatched portion in FIG. 8 shows an example of the region where the first FB-direction seal portion 71 is formed.

[0068] The fourth step of step S14 is carried out after the third step. As shown in FIG. 9, in the fourth step, the manufacturing apparatus forms a second short-side seal portion 82. As shown in FIG. 11, in the fourth step, the manufacturing apparatus preferably forms the second short-side seal portion 82 such that, for example, the seal bar 110 does not contact the film thickness portion 90. In another example of the fourth step, as shown in FIG. 12, the manufacturing apparatus preferably forms the second short-side seal portion 82 using a seal bar 110X having a seal surface 110XA and a seal surface 110XB. The seal surface 110XA is a seal surface having a shape along the second seal surface 63B and the third seal surface 63C. The seal surface 110XB is a seal surface having a shape along the outer contour of the film thickness portion 90. Note that the hatched portion in FIG. 9 shows an example of the region where the second short-side seal portion 82 is formed.

[0069] The fifth step of step S15 is carried out after the fourth step. As shown in FIG. 10, in the fifth step, the manufacturing apparatus forms a second long-side seal portion 81 such that the thickness HA of the film thickness portion 90 is maintained. As shown in FIG. 11, in the fifth step, the manufacturing apparatus forms the second long-side seal portion 81 such that, for example, the seal bar 110 does not contact the film thickness portion 90. Note that the hatched portion in FIG. 10 shows an example of the region where the second long-side seal portion 81 is formed.

[0070] The sixth step of step S16 is carried out after the fifth step. As shown in FIG. 13, in the sixth step, the manufacturing apparatus forms a first LR direction seal portion 72. In the sixth step, in the portion including the base 70X, the first LR direction seal portion 72 is formed so as to partially overlap with the first FB direction seal portion 71. By completing the sixth step, a gas pocket 100 having an area larger than that of the overhanging portion 50Y provided in the completed power storage device 10 is completed in a plan view. Note that the hatched portion in FIG. 13 shows an example of a region where the first LR direction seal portion 72 is formed.

[0071] The seventh step of step S17 is carried out after the sixth step. In the seventh step, the manufacturing apparatus injects an electrolytic solution through the opening 100X of the gas pocket 100. After the electrolytic solution is injected, the edge including the opening 100X is joined. An aging step is carried out after the seventh step. The gas generated by the aging step is stored in the gas pocket 100. The gas stored in the gas pocket 100 is discharged through an opening formed by cutting a part of the gas pocket 100.

[0072] The eighth step of step S18 is carried out after the seventh step and after the completion of the aging step. As shown in FIG. 14, in the eighth step, the manufacturing apparatus forms a first sealing portion 70. In the eighth step, the first FB direction seal portion 71 may be sealed again, or the first FB direction seal portion 71 may not be sealed again. Note that the hatched portion in FIG. 14 shows an example of a region where the first sealing portion 70 is formed.

[0073] The ninth step of step S19 is carried out after the eighth step. In the ninth step, the manufacturing apparatus cuts the gas pocket 100 so that an overhanging portion 50Y having a predetermined size is formed. The dashed-dotted line XA shown in FIG. 14 is an example of a line indicating a position where the gas pocket 100 is cut off in the ninth step.

[0074] The tenth step of step S20 is carried out after the ninth step. In the tenth step, the overhanging portion 50Y including the first sealing portion 70 is folded.

[0075] <1-3. Operation and Effect of Power Storage Device> According to the power storage device 10, since the protruding portion 50Y can be folded at a position away from the base 70X that is damaged by heat sealing in the manufacturing process, the base 70X of the outer film 50 and the portions constituting its periphery are less likely to be damaged. Therefore, the electrode body 20 can be suitably sealed by the exterior body 40.

[0076] [2. Second Embodiment] The power storage device 200 of the second embodiment is different from the power storage device 10 of the first embodiment in that it includes a lid body 260, and other configurations are the same as those of the power storage device 10 of the first embodiment. Hereinafter, the power storage device 10 of the second embodiment will be described centering on the parts different from the power storage device 10 of the first embodiment.

[0077] <2-1. Configuration of Power Storage Device> FIG. 15 is a cross-sectional view of the power storage device 200 of the second embodiment. FIG. 16 is a plan view of the lid body 260 included in the power storage device 200 of FIG. 15.

[0078] In the power storage device 200 of the second embodiment, in order to increase the strength of the base 70X of the first sealing portion 70 and its periphery, the lid body 60 has a protruding portion 68 protruding from the lid sealing portion 63. The first sealing portion 70 is sealed in a state of sandwiching the protruding portion 68.

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

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

[0081] From the viewpoint of enhancing the sealing property of the electrode body 20, the protrusion 68 can take a first aspect, a second aspect, and a third aspect. The first aspect, the second aspect, and the third aspect may be independent aspects of each other, or may be combined with each other within a range where there is no technical contradiction.

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

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

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

[0085] <2-2. Operation and Effect of Power Storage Device> According to the power storage device 200, since the overhanging portion 50Y can be folded at a position away from the base 70X that has been damaged by heat sealing in the manufacturing process, the base 70X of the outer film 50 and the portions constituting its periphery are less likely to be damaged. For this reason, the electrode body 20 can be suitably sealed by the exterior body 40.

[0086] [3. Modified Example] Each of the above embodiments is an exemplification of a form that the power storage device, the lid body, and the manufacturing method of the power storage device according to the present invention can take, and is not intended to limit the form. The power storage device, the lid body, and the manufacturing method of the power storage device according to the present invention can take forms different from those exemplified in each embodiment. One example is a form in which a part of the configuration of each embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to each embodiment. Some examples of modified examples of each embodiment are shown below. Note that the following modified examples can be combined with each other as long as there is no technical contradiction.

[0087] <3-1. First Modified Example> In the power storage device 10 of the first embodiment, within the range where the overhanging portion 50Y can be folded at a position away from the base 70X of the first sealing portion 70, the configuration of the first sealing portion 70 can be arbitrarily changed. For example, the film thickness portion 90 can also be omitted from the first sealing portion 70. In the power storage device 10 of this modified example, the thickness HA of the first sealing portion 70 may be constant or may vary partially.

[0088] <3-2. Second Modified Example> The manufacturing method of the power storage device 10 of the first embodiment can be arbitrarily changed. For example, in the third step of the manufacturing method of the power storage device 10, after forming the first FB-direction seal portion 71, on the protruding portion 50Y, the cooling jig 300 may be arranged along the side 43. The cooling jig 300 is a jig that suppresses the re-heat sealing of the portion including the side 43 of the first FB-direction seal portion 71 in the fourth and fifth steps. The cooling jig 300 also has the effect of suppressing the transfer of heat of heat sealing to the portion including the side 43 of the first FB-direction seal portion 71 when forming the second short-side seal portion 82 and the second long-side seal portion 81. In the fourth and fifth steps, in order to avoid interference between the seal bar 110 and the cooling jig 300, the cooling jig 300 is installed only on the protruding portion 50Y and not on the main body portion 50X. Note that the cooling jig 300 may be removed from the power storage device 10 during manufacturing (hereinafter referred to as the "intermediate body of the power storage device 10") after the fourth and fifth steps are completed, or may remain attached to the intermediate body of the power storage device 10.

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

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

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

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

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

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

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

[0096] In the second modification example, the specific configuration of the cooling jig 300 can be arbitrarily changed as long as it can suppress the re - heat - sealing of the portion including the side 43 of the first FB - direction seal portion 71 in at least one of the fourth step and the fifth step. For example, in the cooling jig 300, the first fixing portion 310 or the second fixing portion 320 may be omitted. In the cooling jig 300, the connecting portion 330 may be omitted. When the cooling jig 300 is composed only of the first fixing portion 310, it is preferable that the first fixing portion 310 is joined to at least a part of the first surface 50YA of the protruding portion 50Y. When the cooling jig 300 is composed only of the second fixing portion 320, the second fixing portion 320 is joined to at least a part of the second surface 50YB of the protruding portion 50Y and the second surface 42A of the exterior body 40.

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

[0098] When performing evacuation in the manufacturing process of the power storage device 10, the exterior body 40 may shrink. When at least a part of the cooling jig 300 is joined to an arbitrary surface of the exterior body 40, the cooling jig 300 can suppress the shrinkage of the exterior body 40.

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

[0100] When the cooling jig 300X is attached to the completed power storage device 10, similarly to the cooling jig 300, effects of suppressing expansion of the exterior body 40 and suppressing peeling of the first sealing portion 70 and the second sealing portion 80 can be obtained. When at least a part of the cooling jig 300X is joined to an arbitrary surface of the exterior body 40, an effect of suppressing shrinkage of the exterior body 40 can be obtained. Since the length of the first fixing portion 310X in the FB direction is substantially equal to the length of the overhanging portion 50Y, the cooling jig 300X has a particularly high effect of suppressing peeling of the first sealing portion 70.

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

[0102] When the cooling jig 300Y is attached to the completed power storage device 10, similar to the cooling jig 300, effects of suppressing the expansion of the exterior body 40 and suppressing the peeling of the first sealing portion 70 and the second sealing portion 80 can be obtained. When at least a part of the cooling jig 300Y is joined to an arbitrary surface of the exterior body 40, an effect of suppressing the shrinkage of the exterior body 40 can be obtained. Since the first sealing portion 70 is sandwiched between the first fixing portion 310Y and the second fixing portion 320Y in the cooling jig 300Y, the effect of suppressing the peeling of the first sealing portion 70 is particularly high. Also, in the cooling jig 300Y, the larger the contact area between the connecting portion 330Y and the second surface 42A, the more suitably the expansion of the second surface 42A can be suppressed.

[0103] <3-3. Third Modified Example> In the power storage device 200 of the second embodiment, the direction in which the protruding portion 68 extends can be arbitrarily changed. For example, as shown in FIG. 21, the protruding portion 68 may extend in a third direction that intersects a first direction (LR direction in the second embodiment) and a second direction (UD direction in the second embodiment) in a front view of the lid body 260.

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

[0105] <3-5. Fifth modification example> In the power storage device 200 of the second embodiment, the specific formation method of the protruding portion 68 of the lid body 260 can be arbitrarily changed. For example, the protruding portion 68 may be formed by an adhesive film or the like joined to the lid seal portion 63 of the lid main body 60A. In this modification example, for example, the protruding portion 68 may be formed by joining a plurality of adhesive films to the lid seal portion 63 so as to overlap, or the protruding portion 68 may be formed by joining the adhesive film to the lid seal portion 63 in a flap shape.

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

[0107] The adhesive film can be arbitrarily selected as long as it can adhere the exterior film 50 and the lid 60. The adhesive film is preferably a laminate (laminated film) having at least a heat-sealable resin layer, a heat-resistant base material layer, and a heat-sealable resin layer in this order. The specifications of the heat-sealable resin layer of the adhesive film can be applied to the specifications of 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 kind of material or different materials, and are appropriately selected according to the material 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 on the side of the adhesive film that is adhered to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The acid-modified polyolefin is not particularly limited as long as it is an acid-modified polyolefin, but preferably includes a polyolefin graft-modified with an unsaturated carboxylic acid or its anhydride. Specific examples of the polyolefin to be acid-modified include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylene such as homopolypropylene, block copolymers of polypropylene (for example, block copolymers of propylene and ethylene), and random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); and terpolymers of ethylene-butene-propylene. Among these polyolefins, polyethylene and polypropylene are preferably used, and polypropylene is particularly preferred.

[0108] In addition, the polyolefin to be acid-modified may be a cyclic polyolefin. For example, a carboxylic acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing them with an α,β-unsaturated carboxylic acid or its anhydride, or by block-polymerizing or graft-polymerizing an α,β-unsaturated carboxylic acid or its anhydride onto the cyclic polyolefin.

[0109] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, butadiene, isoprene, and the like. Further, examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these polyolefins, cyclic alkenes are preferable, and norbornene is more preferable. Styrene is also included as a constituent monomer. Examples of the carboxylic acid or its anhydride used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, and the like. It is preferable to use the same kind of material as the material constituting the heat-sealable resin layer 53 of the exterior film 50 for the heat-sealable resin layer on the side adhered to the exterior film 50 among the adhesive films.

[0110] The heat-resistant base material layer may be a film composed of a heat-resistant resin. For example, unstretched or stretched films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, and polypropylene can be used. Among them, polyethylene terephthalate is particularly preferable because it is inexpensive and has high strength. The heat-resistant base material layer may be a heat-resistant film or a non-woven fabric. The material constituting the heat-resistant base material layer is, for example, a polyolefin-based resin, a polyamide-based resin, a polyester-based resin, an epoxy resin, an acrylic resin, a fluororesin, a silicone resin, a phenol resin, a polyetherimide, a polyimide, a polycarbonate, and a mixture or copolymer thereof. The heat-resistant base material layer may have the same layer structure as the heat-sealable resin layer.

[0111] The adhesive film preferably has adhesiveness. When the second sealing portion 80 is formed with the adhesive film disposed between the exterior film 50 and the lid body 60, the position of the adhesive film with respect to the lid body 60 and the exterior film 50 is less likely to shift. By including an adhesion-imparting resin in the heat-sealable resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the adhesion-imparting resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene, or a copolymer of amorphous propylene and other α-olefins. The content of the adhesion-imparting resin with respect to the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less. Note that this modification can be similarly applied to the second embodiment.

[0112] <3-7. Seventh Modification> In each of the above embodiments, 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. When the portion of the exterior film 50 that protrudes outward beyond the lid body 60 is closed, the electrode body 20 is sealed. The portion of the exterior film 50 that protrudes beyond the lid body 60 may be folded inward so that the outer surfaces of the exterior film 50 contact each other, like a gable-top container, or may be folded toward an arbitrary surface of the exterior body 40, like a brick-shaped container.

[0113] <3-8. Eighth Modification> In each of the above embodiments, the exterior body 40 may not have one of the two lid bodies 60. In this modification, in the FB direction, at the portion where the lid body 60 of the exterior body 40 is omitted, when the portion of the exterior film 50 that protrudes outward beyond the electrode body 20 is closed, the electrode body 20 is sealed. The portion of the exterior film 50 that protrudes outward beyond the electrode body 20 may be folded, like a gable-top container or a brick-shaped container, in the same manner as in the seventh modification.

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

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

[0116] [4. Examples] The inventor of the present application conducted a test to confirm the airtightness of the exterior body for the power storage devices of the examples and comparative examples. Hereinafter, for convenience of explanation, among the elements constituting the power storage devices of the examples and comparative examples, the same elements as those in the embodiment are denoted by the same reference numerals as those in the embodiment and will be described.

[0117] The power storage devices of Examples 1 to 8 are power storage devices according to the second embodiment. The power storage devices of Examples 1 to 8 are intermediates of power storage devices in which the fifth step of the manufacturing method of the power storage device 10 has been completed. Hereinafter, for convenience of explanation, the intermediates of the power storage devices of Examples 1 to 8 are referred to as power storage devices. The specifications of the power storage devices of Examples 1 to 8 are as follows.

[0118] The outer film 50 is a laminate (laminated film) having a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The base material layer 51 is laminated with a polyethylene terephthalate film, an adhesive layer, a stretched nylon film, and an adhesive layer in this order. The thickness of the polyethylene terephthalate film is 15 μm. The thickness of the stretched nylon film is 15 μm. The materials constituting the adhesive layer are both two-component urethane adhesives. The thickness of the adhesive layer after curing is 3 μm. The material constituting the barrier layer 52 is an aluminum foil. The thickness of the barrier layer 52 is 40 μm. In Examples 1 and 2, the heat-sealable resin layer 53 is laminated with maleic anhydride-modified polypropylene and random polypropylene in this order. The thickness of the maleic anhydride-modified polypropylene is 40 μm. The thickness of the random polypropylene is 40 μm.

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

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

[0121] The power storage devices of Comparative Examples 1 to 4 have the same configuration as the power storage device 10 of the second embodiment, except that the overhanging portion 50Y is folded starting from the root 70X (side 43) of the first sealing portion 70. Note that the power storage devices of Comparative Examples 1 to 4 are intermediates of the power storage device in which the fifth step of the manufacturing method of the power storage device 10 is completed. Hereinafter, for convenience of explanation, the intermediates of the power storage devices of Comparative Examples 1 to 4 are referred to as power storage devices. The specifications of the power storage devices of Comparative Examples 1 to 4 are as follows.

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

[0123] In the test, for the power storage devices of Examples 1 to 8 and Comparative Examples 1 to 4 manufactured as described above, after standing for 30 minutes, the folding operation of the protruding portion 50Y was performed. One folding operation of the protruding portion 50Y is the following operations (A) to (C).

[0124] Operation (A): Fold the protruding portion 50Y from the state where it protrudes outward so that it contacts the second surface 42A of the exterior body 40. Operation (B): After operation (A), fold the protruding portion 50Y so that it contacts the first surface 41A of the exterior body 40. Operation (C): After operation (B), lift the protruding portion 50Y from the first surface 41A to reform the state where the protruding portion 50Y protrudes outward.

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

[0126] In the test, before and after the folding operation, the outer packages of the power storage devices of Examples 1 to 8 and Comparative Examples 1 to 4 were cut out using an ultrasonic cutter (e.g., SUW30 (manufactured by Suzuki Corporation)) and scissors. Next, the surface corresponding to the inside of the outer package 40 was cut by a retrotome (e.g., REM-710). Next, the cross-section was observed using a laser microscope (e.g., ultra-depth color 3D shape measurement microscope VK-9510), and the presence or absence of peeling between the barrier layer 52 and the heat-sealable resin layer 53 and the presence or absence of cracks in the heat-sealable resin layer 53 were confirmed.

[0127] Figure 23 is a table showing the test results. In Figure 23, the presence or absence of peeling between the barrier layer 52 and the heat-sealable resin layer 53 is described as "Presence or absence of peeling". In Figure 23, the presence or absence of cracks in the heat-sealable resin layer 53 is described as "Presence or absence of cracks". In the power storage devices of Examples 1 to 8, no peeling between the barrier layer 52 and the heat-sealable resin layer 53 and no cracks in the heat-sealable resin layer 53 were confirmed before and after the folding operation. Therefore, it can be understood that the power storage devices of Examples 1 to 8 have high sealing performance.

[0128] On the other hand, in the power storage devices of Comparative Examples 2 to 4, peeling between the barrier layer 52 and the heat-sealable resin layer 53 and cracks in the heat-sealable resin layer 53 were confirmed after the folding operation. Also, in the power storage device of Comparative Example 1, peeling between the barrier layer 52 and the heat-sealable resin layer 53 was confirmed after the folding operation. Therefore, it can be understood that the power storage devices of Comparative Examples 1 to 4 have low sealing performance.

Explanation of symbols

[0129] 10: Power storage device 20: Electrode body 40: Outer package 40A: Opening 50: Outer film 50Y: Overhanging portion 60: Cover 60Z: Cover unit 260: Cover 63: Cover seal portion 68: Protrusion 70: First sealing part 70X: Root 80: Second sealing part 90: Film thickness part 90A: Starting point 90B: End point 90C: Fold 90D: Notch

Claims

1. An electrode body; and an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so as to form an opening; A lid body disposed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film of the protruding portion facing each other are sealed together, The protruding portion is folded starting from a position away from a base of the first sealing portion, the protruding portion has a fold formed at a position away from a base of the first sealing portion, The fold is formed by a cut that does not penetrate the exterior film, The lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, The first sealing portion is formed by sealing the facing surfaces of the exterior film with the protruding portion sandwiched therebetween. Energy storage device.

2. An electrode body; and an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so as to form an opening; A lid body disposed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film of the protruding portion facing each other are sealed together, The protruding portion is folded starting from a position away from a base of the first sealing portion, the exterior body includes a second sealing portion in which the lid body and the exterior film are sealed together, The lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, The first sealing portion is formed by sealing the facing surfaces of the exterior film with the protruding portion sandwiched therebetween. Energy storage device.

3. The protrusion becomes thicker toward the lid seal portion. The power storage device according to claim 2 .

4. The melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion. The electricity storage device according to claim 2 or 3.

5. The length of the protrusion is 20 mm or less. The electricity storage device according to claim 2 or 3.

6. A lid body used for an exterior body of an electricity storage device, The exterior body is an exterior film that wraps the electrode body so as to form an opening; a first sealing portion in which the opposing surfaces of the exterior film are sealed together, The lid is disposed at the opening, A lid seal portion that is sealed to the exterior film; a protruding portion that is an element protruding from the lid seal portion and is configured to be sandwiched between the opposing surfaces of the exterior film that constitute the first sealing portion; The melting point of the material constituting the protrusion is equal to or higher than the melting point of the material constituting the lid seal portion. Lid body.

7. A lid for use in an exterior body of an electricity storage device, comprising: The exterior body is an exterior film that wraps the electrode body so as to form an opening; a first sealing portion in which the opposing surfaces of the exterior film are sealed together, The lid is disposed at the opening, A lid seal portion that is sealed to the exterior film; a protruding portion that is an element protruding from the lid seal portion and is configured to be sandwiched between the opposing surfaces of the exterior film that constitute the first sealing portion; The length of the protrusion is 20 mm or less. Lid body.

8. The protrusion becomes thicker toward the lid seal portion. The lid according to claim 6 or 7.

9. A lid body according to claim 6 or 7, and an electrode terminal joined to the lid. Lid unit.

10. A method for manufacturing an electricity storage device, comprising: The power storage device is An electrode body; and an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so as to form an opening; A lid body disposed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film of the protruding portion facing each other are sealed together, the protruding portion has a fold formed at a position away from a base of the first sealing portion, The fold is formed by a cut that does not penetrate the exterior film, The lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, The first sealing portion is formed by sealing the surfaces of the exterior films facing each other with the protruding portion sandwiched therebetween, The method for manufacturing the electricity storage device includes: and folding the protruding portion starting from the crease. A method for manufacturing an electricity storage device.

11. A method for manufacturing an electricity storage device, comprising: The power storage device is An electrode body; and an exterior body that seals the electrode body, The exterior body is an exterior film that wraps the electrode body so as to form an opening; A lid body disposed on the opening; a protruding portion that protrudes outward from a portion of the exterior film that encases the electrode body; a first sealing portion in which the surfaces of the exterior film of the protruding portion facing each other are sealed together, the exterior body includes a second sealing portion in which the lid body and the exterior film are sealed together, The lid body includes a lid seal portion that is sealed to the exterior film and a protrusion that protrudes from the lid seal portion, The first sealing portion is formed by sealing the surfaces of the exterior films facing each other with the protruding portion sandwiched therebetween, The method for manufacturing the electricity storage device includes: The step of folding the protruding portion from a position away from a base of the first sealing portion as a starting point. A method for manufacturing an electricity storage device.

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