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

Abstract

To provide a power storage device that can prevent at least one of moisture and gas from entering the interior of the power storage device, a barrier film used in the power storage device, a lid unit used in the power storage device, and a manufacturing method for the lid unit.SOLUTION: A power storage device includes an electrode body, an outer casing that seals the electrode body, and a barrier film. The outer casing includes an outer casing film that wraps around the electrode body to form an opening part, and a lid body that is arranged in the opening part. The lid body has a first surface facing the electrode body, a second surface opposite the first surface, and a sealing surface connected to the first and second surfaces. The barrier film is bonded to the lid body to cover at least a part of the sealing surface.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

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

[0003] [Patent Document 1] JP 2019-153504 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above electricity storage device, there is a risk that moisture and gas may enter the inside through a gap between the lid and the exterior film. Therefore, the above electricity storage device has room for improvement in terms of preventing the intrusion of moisture and gas.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0025] Hereinafter, an electricity storage device according to one embodiment of the present invention will be described with reference to the drawings. In this specification, a numerical range indicated by "to" means "not less than" or "not more than." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

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

[0027] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes electrodes (positive and negative electrodes) constituting a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid battery, a quasi-solid battery, a polymer battery, an all-resin battery, a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator. In this embodiment, the shape of the electrode body 20 is an approximately rectangular parallelepiped. Note that the term "approximately rectangular parallelepiped" includes, in addition to a complete rectangular parallelepiped, a solid body that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0028] In this embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting electric 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 an edge of the exterior body 40, for example. Note that the electrode terminal 30 may not protrude from the exterior body 40, for example, as long as it is capable of inputting and outputting electric power to and from the electrode body 20. When the cover body 60 described later is made of, for example, a metal, the cover body 60 may also function as the electrode terminal 30. In this case, the cover body 60 having the function as an electrode terminal may or may not protrude from the exterior body 40.

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

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

[0031] From the viewpoint of suitable adhesion to the lid 60, it is preferable that the adhesive film 31 is bonded to the electrode terminal 30. The adhesive film 31 can be selected arbitrarily as long as it is a film capable of bonding the electrode terminal 30 made of metal and the lid 60 made of resin. For example, the adhesive film 31 can be a polyolefin resin such as a polyethylene resin or a polypropylene resin, a cyclic polyolefin resin, or an acid-modified polyolefin resin obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or two or more layers of these films. In this embodiment, the adhesive film 31 is bonded to almost the entire portion of the electrode terminal 30 covered by the lid 60.

[0032] For example, there is a method of forming a storage portion (recess) for storing the electrode body 20 in the exterior film 50 through cold forming. However, it is not necessarily easy to form a deep storage portion by such a method. If an attempt is made to form a deep storage portion (recess) by cold forming (for example, a forming depth of 15 mm), pinholes or cracks will occur in the exterior film 50, which is likely to cause a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode body 20 by wrapping the exterior film 50 around the electrode body 20, so that the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In addition, in order to reduce the dead space between the electrode body 20 and the exterior film 50 to improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20. In addition, in an all-solid-state battery, it is necessary to apply a high pressure uniformly from the outer surface of the battery to exhibit battery performance, so it is necessary to eliminate the space between the electrode body 20 and the exterior film 50, and therefore it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20.

[0033] The exterior film 50 is, for example, a laminate (laminate film) having a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The exterior film 50 may be laminated in the order of the heat-sealable resin layer 53, the base material layer 51, the barrier layer 52, and the heat-sealable resin layer 53. The exterior film 50 may be laminated in the order of the heat-sealable resin layer 53, the barrier layer 52, and the heat-sealable resin layer 53. Note that the exterior film 50 does not need to include all of these layers, and for example, the barrier layer 52 may not be included. That is, the exterior film 50 may be made of a material that is flexible and easily bendable, and may be made of, for example, a resin film. Note that the exterior film 50 is preferably heat-sealable.

[0034] The base layer 51 included in the exterior film 50 is a layer for imparting heat resistance to the exterior film 50 and suppressing the occurrence of pinholes that may occur during processing or distribution. The base layer 51 is configured to include at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, the base layer 51 includes at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer, so that the barrier layer 52 can be protected during processing of the exterior film 50 and breakage of the exterior film 50 can be suppressed. In addition, 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, in terms of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. The base layer 51 may be configured to include both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base layer 51 is, for example, preferably 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0035] The barrier layer 52 is a layer that at least prevents the intrusion of moisture. The barrier layer 52 is bonded to the base layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor deposition film, and resin layer having barrier properties. Examples of the vapor deposition film include metal vapor deposition film, inorganic oxide vapor deposition film, and carbon-containing inorganic oxide vapor deposition film, and 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 fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Examples of the barrier layer 52 include resin films having at least one of these vapor deposition films and resin layers. The barrier layer 52 may be provided in a plurality of layers. It is preferable that the barrier layer 52 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that the material contains at least one of an aluminum alloy foil and a stainless steel foil.

[0036] In the barrier layer 52, the layer made of the above-mentioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel plate. These recycled materials can be obtained by known methods. The recycled aluminum alloy material can be obtained by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be made of only recycled materials, or may be made of a mixed material of recycled materials and virgin materials. Note that recycled metal materials refer to metal materials that have been made reusable by collecting, isolating, and refining various products used in the city and waste from the manufacturing process. In addition, virgin metal materials refer to new metal materials refined from natural metal resources (raw materials) and are not recycled materials.

[0037] From the viewpoint of improving the formability or conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability or conformability, the aluminum alloy foil is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By making the iron content 0.1% by mass or more, an exterior film 50 having better formability can be obtained. By making the iron content 9.0% by mass or less, an exterior film 50 having better flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may be added as necessary. Softening can be performed by annealing treatment, etc. From the viewpoint of improving the mechanical strength of the exterior film 50, it is more preferable that the aluminum alloy foil is 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 a composition specified in JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14.

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

[0039] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, and SUS316L, and among these, SUS304 is particularly preferred.

[0040] In the case of a metal foil, the thickness of the barrier layer 52 is sufficient to at least function as a barrier layer that prevents moisture from penetrating, and may be, for example, about 9 to 200 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 52 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. The preferred ranges of the thickness of the barrier layer 52 include 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, and about 25 to 35 μm. When the barrier layer 52 is made of an aluminum alloy foil, the above-mentioned range is particularly preferable. From the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, and even more preferably about 55 μm or more, and is preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferable ranges are 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, and about 55 to 70 μm. The exterior film 50 has high formability, which facilitates deep drawing and can contribute to increasing the capacity of the electricity storage device. In addition, since the rigidity of the exterior film 50 is increased, when the exterior film 50 is wrapped around the electrode body 20, the exterior film 50 can be suitably wrapped around the electrode body 20. Furthermore, when the capacity of the electricity storage device is increased, the weight of the electricity storage device increases, but increasing the rigidity of the exterior film 50 can contribute to high sealing performance of the electricity storage device.In particular, when the barrier layer 52 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

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

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

[0043] The heat-sealable resin layer 53 is bonded to the barrier layer 52, for example, via an adhesive layer 55. The heat-sealable resin layer 53 included in the exterior film 50 is a layer that imparts heat-sealing sealability to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, polyolefin resins such as polyethylene resins and polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm, in terms of sealability and strength.

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

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

[0046] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, more preferably 2 mm. When the buffer layer is made of rubber, the preferred ranges of the buffer layer thickness are 1 mm to 10 mm, 1 mm to 5 mm, 1 mm to 2 mm, 0.5 mm to 10 mm, 0.5 mm to 5 mm, and 0.5 mm to 2 mm.

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

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

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

[0050] Specific examples of the resin include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. The resin material may be a mixture of these resins, a copolymer, or a modified product of the 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.

[0051] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters in which ethylene terephthalate is the main repeating unit. Specific examples of polyesters include copolymerized polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decane dicarboxylate). Of these, the resin material is preferably polybutylene terephthalate from the viewpoint of increasing heat resistance and pressure resistance.

[0052] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. Among these, polypropylene is preferred as the resin material because it has excellent heat fusion properties and electrolyte resistance.

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

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

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

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

[0057] When the lid 60 is composed of a conductive material, the lid 60 may be bonded to the exterior film 50 and the barrier film 90 described later via an adhesive film. The adhesive film can be selected arbitrarily as long as it can bond the exterior film 50 and the barrier film 90 to the lid 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant 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 the same as those 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 or different materials, and are appropriately selected according to the materials constituting the heat-sealable resin layers of the exterior film 50 and the barrier film 90, and the materials constituting the lid 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that is bonded to the lid 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealing resin layer of the adhesive film on the side to be bonded to the exterior film 50 and the barrier film 90 is preferably made of the same type of material as the material constituting the heat-sealing resin layers of the exterior film 50 and the barrier film 90 .

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

[0059] The adhesive film preferably has adhesiveness. When the adhesive film is disposed between the barrier film 90 and the lid 60 and a second sealing portion 80 is formed as described below, the adhesive film is unlikely to be displaced relative to the lid 60 and the barrier film 90. In addition, when the adhesive film is disposed between the barrier film 90 and the lid 60 and the barrier film 90 is bonded to the lid 60, the adhesive film is unlikely to be displaced relative to the lid 60 and the barrier film 90. In addition, by incorporating a tackifier resin into the heat-sealable resin layer of the adhesive film, the adhesive film can be given adhesiveness. Examples of the tackifier resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene and a copolymer of amorphous propylene and another α-olefin. The content of the tackifier resin in the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less.

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

[0061] The seal surface 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 (LR direction in this embodiment) 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 (UD direction in this embodiment) intersecting the first direction in a front view of the lid body 60. In this embodiment, the first direction and the second direction are orthogonal to each other in a front view of the lid body 60. The first direction and the second direction do not have to be orthogonal to each other 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 sealing surface 63D extends in a first direction (the LR direction in this embodiment) when the lid 60 is viewed from the front.

[0062] When the lid body 60 is plate-shaped, it is preferable that the lid body 60 has a certain degree of thickness so that deformation of the exterior body 40 is suppressed even when the power storage device 10 is arranged in a stacked manner. From another viewpoint, when the lid body 60 is plate-shaped, it is preferable that the sealing surface 63 of the lid body 60 has a certain degree of thickness so that the sealing surface 63 of the lid body 60 and the exterior film 50 can be suitably heat-sealed when forming the second sealing portion 80 described later. 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 preferred ranges of the thickness of the material constituting the lid body 60 are 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, and 4.0 mm to 10 mm. In this embodiment, when the lid body 60 is expressed as a plate-like shape, the material constituting the lid body 60 does not include a film defined by the [Packaging Terminology] standard of the JIS (Japan Industrial Standards). 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.

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

[0064] From the viewpoint of suitable heat sealing between the lid 60 and the exterior film 50, it is preferable that the material constituting the sealing surface 63 of the lid 60 and the material constituting the heat-sealable resin layer 53 of the exterior film 50 are mainly made of the same material. In this embodiment, the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 are mainly made of polypropylene. Note that the main material refers to, for example, a material that accounts for 50% or more of the materials contained in the components.

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

[0066] In this embodiment, with the exterior film 50 wrapped around the electrode body 20 so as to have an opening 40A, the facing surfaces of the exterior film 50 (heat-fusible resin layer 53) are heat-sealed to form the first sealing portion 70.

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

[0068] As shown in FIG. 5 or 6, in this embodiment, the barrier film 90 is bonded to the lid body 60 from the viewpoint of suppressing the intrusion of at least one of moisture and gas into the inside of the exterior body 40 from between the lid body 60 and the exterior film 50. In this embodiment, the barrier film 90 allows at least one of moisture and gas to intrude into the inside of the exterior body 40. The barrier film 90 only needs to cover at least a part of the sealing surface 63 of the lid body 60. In this embodiment, the barrier film 90 covers a part of the sealing surface 63, the entire second surface 62, and a part of the inside of the through hole 60X of the lid body 60. The barrier film 90 may cover the boundaries 64 to 67. Since the barrier film 90 covers the sealing surface 63 and the boundaries 64 to 67, as well as the second surface 62 and the inside of the through hole 60X, the intrusion of moisture into the inside of the exterior body 40 from between the electrode terminal 30 and the through hole 60X is suppressed. The barrier film 90 may be formed of a single film, or, for example, the portion covering the sealing surface 63 and the portion covering the second surface 62 may be formed separately. In other words, the barrier film 90 may be a film divided into a plurality of parts.

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

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

[0071] 7 to 9 are cross-sectional views showing examples of the layer structure of the barrier film 90. In FIG. 7, the barrier film 90 only needs to include at least a barrier layer 91. The specifications of the barrier layer 91 are the same as those of the barrier layer 52 of the exterior film 50. The barrier layer 91 may be thinner than the barrier layer 52 of the exterior film 50. When the barrier film 90 is a single layer consisting of only the barrier layer 91, one surface of the barrier layer 91 is bonded to the lid 60 by an adhesive or the like. When the barrier film 90 is a single layer consisting of only the barrier layer 91, the other surface of the barrier layer 91 is bonded to the heat-sealable resin layer 53 of the exterior film 50 by an adhesive or the like.

[0072] As shown in FIG. 8, the barrier film 90 may include an outer layer 92 laminated on the surface of the barrier layer 91 opposite to the surface bonded to the lid 60. The outer layer 92 plays a role as, for example, a base material layer or a heat-sealable resin layer. The role of the base material layer is to protect the barrier layer 91. The role of the heat-sealable resin layer is to be heat-sealed with the heat-sealable resin layer 53 of the exterior film 50. When the outer layer 92 plays a role as a base material layer, the specifications of the outer layer 92 as a base material layer are the same as the specifications of the base material layer 51 of the exterior film 50. When the outer layer 92 plays a role as a heat-sealable resin layer, the specifications of the outer layer 92 as a heat-sealable resin layer are the same as the specifications of the heat-sealable resin layer 53 ... it can be suitably bonded to the adhesive film 31. When the outer layer 92 serves as a heat-sealable resin layer, the outer layer 92 may be thinner than the heat-sealable resin layer 53. When the outer layer 92 serves as a heat-sealable resin layer, the thickness of the outer layer 92 may be, for example, 5 to 20 μm. When the outer layer 92 is a base layer, the barrier layer 91 is protected. When the outer layer 92 is a base layer, the outer layer 92 and the heat-sealable resin layer 53 are bonded, for example, by an adhesive or the like. When the outer layer 92 is a heat-sealable resin layer, the outer layer 92 and the heat-sealable resin layer 53 can be suitably bonded by heat fusion. The barrier layer 91 and the outer layer 92 may be bonded by an adhesive layer 54. When the outer layer 92 has adhesiveness to the barrier layer 91, the adhesive layer 54 can be omitted.

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

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

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

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

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

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

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

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

[0081] The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing device winds the exterior film 50 around the electrode body 20 and the lid body 60. In the fourth step, the manufacturing device winds the exterior film 50 around the electrode body 20 and the lid body 60 while tension is applied to the exterior film 50, while restricting the movement of the electrode body 20 and the lid body 60 by the 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 to the electrode body 20 and the lid body 60 in the opposite direction to the direction in which the exterior film 50 is pulled. The restricting means may include a roller that runs on the exterior film 50 while the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50.

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

[0083] The sixth step of step S16 is performed after the fifth step. In the sixth step, the manufacturing apparatus forms the second sealed portion 80 by heat-sealing the heat-fusible resin layer 53 of the exterior film 50 and the sealing surface 63 of the lid body 60 via the barrier film 90.

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

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

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

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

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

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

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

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

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

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

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

[0095] The ends 90A and 90B of the barrier film 90 are covered with the covering portion 330. Therefore, even if the ends 90A and 90B of the barrier film 90 come into contact with gas such as hydrogen fluoride generated from the electrolyte, the barrier layer 91 can be prevented from corroding.

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

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

[0098] When the electricity storage device 10 is a battery containing an electrolyte, such as a lithium ion battery, the end 90A of the barrier film 90 may come into contact with gas, such as hydrogen fluoride, generated from the electrolyte, causing corrosion of the barrier layer 91. In this embodiment, in order to prevent corrosion of the barrier layer 91, the position of the end 90A is designed in such a way that it is positioned appropriately.

[0099] The barrier film 90 includes a joint portion 90X joined to the sealing surface 63, and a folded portion 90Y connected to the joint portion 90X and folded back toward the second surface 62. An end portion 90A of the portion of the barrier film 90 covering the sealing surface 63 is located at the folded portion 90Y. The folded portion 90Y may extend outward beyond the lid 60 in the FB direction. In this embodiment, the barrier layer 91 or the heat-sealable resin layer 93 of the folded portion 90Y of the barrier film 90 is joined to the heat-sealable resin layer 53 of the exterior film 50.

[0100] The position of the end 90B can be selected arbitrarily. In this embodiment, the end 90B is located inside the through hole 60X. Therefore, contact between the end 90B and gas such as hydrogen fluoride is suppressed. The end 90B may be located at a position closer to the opening on the second surface 62 side than the opening on the first surface 61 side of the through hole 60X. The end 90B may be located at a position closer to the opening on the first surface 61 side than the opening on the second surface 62 side of the through hole 60X. The end 90B may be located in the vicinity of the opening on the first surface 61 side of the through hole 60X, or may extend to a position closer to the electrode body 20 than the lid body 60. The end 90B may be located outside the through hole 60X on the second surface 62 side. When the end 90B is located outside the through hole 60X on the second surface 62 side, the portion of the barrier film 90 located outside the through hole 60X may be folded.

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

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

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

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

[0105] The barrier film 90 includes an inner portion 90Z disposed in at least a part of the inside of the lid body 60. The inner portion 90Z is a portion between a part of the sealing surface 63 and a portion covering the inside of the through-hole 60X of the lid body 60. The lid unit 510 of this embodiment can be manufactured, for example, by insert molding the lid body 60 into the barrier film 90.

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

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

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

[0109] <6-1. Configuration of the power storage device> FIG. 15 is a cross-sectional view of an electricity storage device 600 of a sixth embodiment. In this embodiment, the heat-sealable resin layer 53 of the exterior film 50 and the seal surface 63 of the lid 60 are joined together. The exterior film 50 has a folded-back portion 50X that is connected to a portion joined to the seal surface 63 of the lid 60 and is folded back toward the electrode body 20. The folded-back portion 50X covers the lid 60. The barrier film 90 is joined to the exterior film 50 so as to cover the seal surface 63 on the outer side of the exterior film 50. In this embodiment, the barrier film 90 covers the seal surface 63, the boundaries 64 to 67, the second surface 62, and the electrode terminal 30. An end 90A of the portion of the barrier film 90 that covers the seal surface 63 is located on, for example, the folded-back portion 50X. The end 90A does not have to be located on the folded-back portion 50X.

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

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

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

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

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

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

[0116] <7-4> In the electricity storage device 10 of the first embodiment, the position at which the electrode terminal 30 is arranged can be selected arbitrarily. For example, the electrode terminal 30 may protrude from at least one of the first sealing portion 70 and the second sealing portion 80. This modification can be similarly applied to the electricity storage devices 200, 300, 400, 500, and 600 of the second to sixth embodiments.

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

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

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

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

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

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

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

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

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

[0126] Next, the electricity storage devices of Examples 1 and 2 and Comparative Examples 1 and 2 were removed from the thermo-hygroscopic layer and cooled at room temperature for 2 hours, and then 0.5 ml of the liquid in the device was sampled using a Karl Fischer in a dry room to measure the moisture content and calculate the moisture permeation amount. The Karl Fischer is, for example, a moisture vaporizer ADP-611 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The calculated moisture permeation amount is the amount per one lid 60.

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

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

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

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

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

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

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

[0134] <8-2-2. Check for corrosiveness> 100 g of electrolyte with salt was injected from the opening of the electricity storage device of Examples 3 and 4. Next, a lithium disk electrode was placed, and the opening was sealed with tape. Next, the cathode of the electrochemical measurement device was connected to the lithium disk electrode, and the anode of the electrochemical measurement device was connected to the other end of the conductor. The electrochemical measurement device is, for example, VMP3 (manufactured by BioLogic). After 5 minutes of OCV (Open Circuit Voltage), chronoamperometry was performed under the following setting conditions, and the current that had flowed up to 1200 minutes later was accumulated. Set voltage: 0.100V (vs. Ref) Test duration: 24 hours

[0135] The integrated value of the corrosion current after 1200 minutes for the electricity storage device of Example 3 was 13.6 C. The integrated value of the corrosion current after 1200 minutes for the electricity storage device of Example 4 was 9.6×10 -4 C. It was confirmed that the electricity storage device of Example 4 suppressed the corrosion of the barrier film more than the electricity storage device of Example 3. That is, it was confirmed that the electricity storage device 10 of Example 4 was able to suppress the corrosion of the barrier film.

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

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

[0138] Next, in the same manner as in the case of the electricity storage device of Example 3 or the electricity storage device of Example 4, the barrier layer is exposed by cutting or the like, and the exposed barrier layer is connected to one end of the conductive wire, with care taken not to make the electrode terminal 30 conductive.

[0139] The sample prepared as described above is placed in a glass container so that the second surface 62 of the lid 60 is the bottom surface, and an electrolyte is poured to a depth of about 1 cm from the first surface 61 of the lid 60. Next, a lithium disk electrode is placed on the sample. The cathode of the electrochemical measurement device is connected to the lithium disk electrode. The anode of the electrochemical measurement device is connected to the other end of the lead. Then, the corrosiveness of the barrier film can be confirmed by performing chronoamperometry. [Explanation of symbols]

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

Claims

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

2. The cover further includes an electrode terminal. A lid unit according to claim 1.

3. An electrode body; A method for manufacturing a lid unit for use in an electricity storage device comprising: The lid unit includes: A lid body disposed on the opening; A barrier film, The cover body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface, The sealing surface is a surface to be joined to the exterior film, the barrier film is bonded to the lid so as to cover at least a portion of the sealing surface, The method for manufacturing the lid unit includes the steps of: and insert-molding the lid body into the barrier film so that the barrier film covers at least a portion of the sealing surface. A method for manufacturing a lid unit.

4. An electrode body; A method for manufacturing a lid unit for use in an electricity storage device comprising: The lid unit includes: A lid body disposed on the opening; A barrier film, The cover body has a first surface facing the electrode body, a second surface opposite to the first surface, and a sealing surface connecting the first surface and the second surface, The sealing surface is a surface to be joined to the exterior film, the barrier film is bonded to the lid and to the inner surface of the exterior film so as to cover at least a part of the sealing surface; The method for manufacturing the lid unit includes the steps of: and bonding the barrier film to the lid so that the barrier film covers at least a portion of the sealing surface. A method for manufacturing a lid unit.

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