Energy storage device, lid, method for manufacturing the lid, method for manufacturing the energy storage device

Abstract

A power storage device including an exterior film and a lid body, which provides a power storage device with high sealing performance even when an electrolytic solution containing hydrofluoric acid comes into contact with the lid body. 【Solution means】 An electrode body, An exterior film that wraps the electrode body, A lid body that seals the electrode body together with the exterior film, The lid body is A lid main body composed of a conductive material, A coating body composed of a resin material and covering the lid main body, A bonding layer that bonds the lid main body and the coating body, The bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, a power storage device.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an example of a power storage device. This power storage device includes an electrode body including a current collector, an exterior body that seals the electrode body, and an electrode terminal connected to the current collector. The exterior body includes an exterior film that wraps the electrode body and a lid body joined to the exterior film. The electrode terminal is inserted into a through-hole formed in the lid body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above power storage device, for example, when the lid body is made of a metal material, since the lid body also functions as an electrode terminal, the electrode terminal can be omitted. Therefore, the configuration can be simplified. Also, from the viewpoints of improving the barrier property of the power storage device and the current extraction design, it is also conceivable to make the lid body of a metal material.

[0005] However, when the lid body is made of a metal material, it may not be suitably joined to the heat-sealing resin layer of the exterior film, and there is a risk of poor joining. Furthermore, when the electrolyte of the power storage device absorbs moisture, hydrofluoric acid is generated in the electrolyte. When such an electrolyte comes into contact with the lid body, the sealing performance of the power storage device is significantly reduced.

[0006] The present disclosure aims to provide an energy storage device comprising an outer film and a lid, which maintains high airtightness even when an electrolyte containing hydrofluoric acid comes into contact with the lid, a lid used in this energy storage device, a method for manufacturing this lid, and a method for manufacturing this energy storage device. [Means for solving the problem]

[0007] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, they have found that in an energy storage device comprising an electrode body, an outer film enclosing the electrode body, and a lid that seals the electrode body together with the outer film, the lid has a lid body made of a conductive material, a covering made of a resin material that covers the lid body, and a bonding layer that joins the lid body and the covering, and by forming the bonding layer with a cured product of a resin composition containing a resin and a curing agent, the sealing performance of the energy storage device can be improved even when an electrolyte containing hydrofluoric acid comes into contact with the lid.

[0008] This disclosure is the result of further consideration based on these novel findings. Specifically, this disclosure provides the inventions listed below.

[0009] Electrode body and The outer film enclosing the electrode body, The system comprises a lid that seals the electrode body together with the outer film, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, in an energy storage device. [Effects of the Invention]

[0010] According to the power storage device, lid body, method for manufacturing the lid body, and method for manufacturing the power storage device related to the present disclosure, it is possible to contribute to enhancing the sealing performance of the power storage device even when an electrolytic solution containing hydrofluoric acid comes into contact with the lid body.

Brief Description of the Drawings

[0011] [Figure 1A] Perspective view of the power storage device of the embodiment. [Figure 1B] Diagram related to the method for measuring the seal strength of the second sealing portion of the power storage device in FIG. 1A. [Figure 2] Cross-sectional view showing the layer structure of the exterior film included in the power storage device in FIG. 1A. [Figure 3] Diagram of the state where the exterior film included in the power storage device in FIG. 1A is expanded. [Figure 4] Perspective view of the back side of the lid body included in the power storage device in FIG. 1A. [Figure 5] Perspective view of the front side of the lid body in FIG. 4. [Figure 6] Cross-sectional view taken along line D6-D6 in FIG. 1A. [Figure 7] Cross-sectional view taken along line D7-D7 in FIG. 1A. [Figure 8] Flowchart showing an example of the method for manufacturing the power storage device in FIG. 1A. [Figure 9] Enlarged view of the flange portion of the lid body included in the power storage device of the first modification. [Figure 10] Enlarged view of the flange portion of the lid body included in the power storage device of the second modification.

Modes for Carrying Out the Invention

[0012] Hereinafter, a power storage device according to an embodiment of the present disclosure will be described with reference to the drawings. In this specification, the numerical range indicated by "~" means "or more" and "or less". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less.

[0013] [Embodiment] <1-1. Configuration of the Power Storage Device> FIG. 1A is a plan view schematically showing the power storage device 10 of the embodiment. FIG. 1B is a diagram regarding a method for measuring the seal strength of the second sealing portion 120 of the power storage device 10 in FIG. 1A. FIG. 2 is a cross-sectional view showing the layer configuration of the exterior film 50 included in the power storage device 10 in FIG. 1A. FIG. 3 is a view of the exterior film 50 included in the power storage device 10 in FIG. 1A in a spread state. FIG. 4 is a perspective view of the back side of the lid 60 included in the power storage device 10 in FIG. 1A. FIG. 5 is a perspective view of the front side of the lid 60 in FIG. 4. FIG. 6 is a cross-sectional view taken along the line D6-D6 in FIG. 1A. FIG. 7 is a cross-sectional view taken along the line D7-D7 in FIG. 1A. In FIG. 1A, the direction of the arrow UD indicates the thickness direction of the power storage device 10, the direction of the arrow LR indicates the width direction of the power storage device 10, and the direction of the arrow FB indicates the depth direction of the power storage device 10. The directions indicated by each of the arrows UDLRFB are common in the subsequent figures.

[0014] The power storage device 10 includes an electrode body 20 including a current collector 30 and an exterior body 40. The electrode body 20 includes, for example, electrodes (positive electrode and negative electrode) constituting a power storage member such as a lithium ion battery, a capacitor, a all-solid-state battery, a semi-solid-state battery, a quasi-solid-state battery, a polymer battery, a all-resin battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal-air battery, a polyvalent cation battery, or a capacitor, as well as a separator and the like. In the present embodiment, the shape of the electrode body 20 is a substantially rectangular parallelepiped. Note that the "substantially rectangular parallelepiped" includes, in addition to a perfect rectangular parallelepiped, a solid that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0015] One end portion 31 of the current collector 30 (see FIG. 7) is connected to the lid 60.

[0016] The outer casing 40 seals the electrode body 20. The outer casing 40 comprises an outer film 50 and a lid 60. The outer film 50 wraps around the electrode body 20. In this embodiment, the outer film 50 is wrapped around the electrode body 20. The lid 60 is positioned to the side of the electrode body 20 in the FB direction. In another example, the electrode body 20 may be housed inside a cylindrical outer film 50 with openings formed at both ends in the FB direction, and the openings may be closed by the lid 60. In yet another example, the electrode body 20 may be housed inside a cylindrical outer film 50 with openings formed therein, connected to the lid 60, and the openings may be closed by the lid 60.

[0017] For example, one method is to form a housing portion (recess) for housing the electrode body 20 in the outer film 50 through cold forming. However, it is not always easy to form a deep housing portion by such a method. If one attempts to form a deep housing portion (recess) (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks may occur in the outer film 50, which is likely to lead to a decrease in battery performance. On the other hand, the outer body 40 seals the electrode body 20 by wrapping the outer film 50 around the electrode body 20, so the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. Furthermore, in order to reduce the dead space between the electrode body 20 and the outer film 50 in order to improve the volumetric energy density of the energy storage device 10, it is preferable that the outer film 50 is wrapped so as to be in contact with the outer surface of the electrode body 20. In addition, in all-solid-state batteries, it is necessary to eliminate the space between the electrode body 20 and the outer film 50 from the viewpoint that it is necessary to apply high pressure uniformly from the outside surface of the battery in order to exert battery performance, so it is preferable that the outer film 50 is wrapped so as to be in contact with the outer surface of the electrode body 20.

[0018] As shown in Figure 2, the outer film 50 is a laminate (laminate film) having, for example, a base layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in that order. Note that the outer film 50 does not necessarily need to include all of these layers; for example, the barrier layer 52 may be omitted. That is, the outer film 50 only needs to be made of a flexible and easily bendable material, such as a film. Preferably, the outer film 50 is heat-sealable. The innermost and outermost layers of the outer film 50 may be the heat-sealable resin layer 53. In this case, the outer film 50 may enclose the electrode body 20 and the lid 60 by joining the outermost and innermost layers.

[0019] The outer film 50 may be composed of a laminate comprising at least a barrier layer 52 and a heat-fusible resin layer 53 in that order. In this laminate, the base layer 51 is a layer provided as needed, with the side of the barrier layer 52 opposite to the heat-fusible resin layer 53 being the outermost layer, and the heat-fusible resin layer 53 being the innermost layer.

[0020] The overall thickness of the outer film 50 can be arbitrarily selected. From the viewpoint of strength, the thickness of the outer film 50 is preferably 50 μm or more. From the viewpoint of moldability or conformability, the thickness of the outer film 50 is preferably 1200 μm or less. The thickness of the outer film 50 is preferably within the range of 50 μm to 1200 μm.

[0021] The base layer 51 included in the outer film 50 is a layer that imparts heat resistance to the outer film 50 and suppresses the occurrence of pinholes that may occur during processing or distribution. The base layer 51 is composed of, for example, at least one stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one stretched polyester resin layer and a stretched polyamide resin layer in the base layer 51, the barrier layer 52 can be protected during processing of the outer film 50, and the breakage of the outer film 50 can be suppressed. Furthermore, from the viewpoint of increasing the tensile elongation of the outer film 50, the stretched polyester resin layer is preferably a biaxially oriented polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially oriented polyamide resin layer. Moreover, from the viewpoint of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially oriented polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially oriented nylon (ONy) film. The base layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0022] The barrier layer 52 is a layer that at least prevents the penetration of moisture. The barrier layer 52 is joined to the substrate layer 51, for example, via an adhesive layer 54. Examples of barrier layers 52 include metal foil, vapor-deposited film, and resin layer. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, the barrier layer 52 may also be a film having at least one of these vapor-deposited films and resin layers. Multiple layers of barrier layer 52 may be provided. Preferably, the barrier layer 52 includes a layer made of a metal material. Examples of metal materials constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel sheets. When used as a metal foil, it is preferable to include at least one of aluminum alloy foil and stainless steel foil.

[0023] In the barrier layer 52, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and purified from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) that is not recycled material.

[0024] From the viewpoint of improving the formability or conformability of the outer film 50, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability or conformability, it is more preferably an aluminum alloy foil containing iron. In an 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 having an iron content of 0.1% by mass or more, an outer film 50 with better formability can be obtained. By having an iron content of 9.0% by mass or less, an outer film 50 with better flexibility can be obtained. In addition, silicon, magnesium, copper, manganese, etc. may be added to the aluminum alloy foil as needed. Softening can be achieved by annealing treatment, etc. From the viewpoint of improving the mechanical strength of the outer film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil composed of, for example, a work-hardened aluminum alloy. Examples of hard aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14. From the viewpoint of improving the mechanical strength of the outer film 50, it is preferable that the aluminum alloy foil is an aluminum alloy foil containing magnesium. In an aluminum alloy foil containing magnesium (100% by mass), the magnesium content is preferably 0.2 to 5.6% by mass, and more preferably 0.2 to 3.0% by mass. Examples of aluminum alloy foils containing magnesium include those having compositions specified in JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JIS H4000:2017 A5052P-O.

[0025] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an outer film 50 with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0026] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0027] In the case of metal foil, the thickness of the barrier layer 52 should at least function as a barrier layer that prevents moisture from penetrating, for example, about 5 to 1000 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 52 is preferably about 9.0 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 52 include approximately 9.0 to 1000 μm, 9.0 to 1000 μm, 9.0 to 1000 μm, 9.0 to 85 μm, 9.0 to 50 μm, 9.0 to 40 μm, 9.0 to 35 μm, 20 to 85 μm, 20 to 50 μm, 20 to 40 μm, 20 to 35 μm, 25 to 85 μm, 25 to 50 μm, 25 to 40 μm, and 25 to 35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above ranges are particularly preferred. Furthermore, from the viewpoint of providing the outer film 50 with high moldability and high rigidity, 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, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, even more preferably about 70 μm or less, and preferably The suitable ranges are approximately 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 55-200 μm, 55-85 μm, 55-75 μm, and 55-70 μm. The high moldability of the outer film 50 facilitates deep drawing, which can contribute to increasing the capacity of the energy storage device. Furthermore, while increasing the capacity of the energy storage device increases its weight, the increased rigidity of the outer film 50 contributes to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 52 is composed 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 especially preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, 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.

[0028] Furthermore, if the barrier layer 52 is aluminum foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the base layer 51 to prevent dissolution and corrosion. The barrier layer 52 may have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer 52 by performing corrosion prevention treatments on the surface of the barrier layer 52, such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or coating agent application. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer 52 (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer 52 (alkali-resistant coating), etc. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one layer. Furthermore, among these treatments, hydrothermal modification and anodic oxidation are processes that dissolve the surface of the metal foil with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Additionally, if the barrier layer 52 has a corrosion-resistant coating, the barrier layer 52 includes the corrosion-resistant coating.

[0029] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 during the molding of the outer film 50, prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride generated by the reaction of electrolyte and water, and in particular prevents the dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52 when the barrier layer 52 is aluminum alloy foil, and 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 during molding.

[0030] The heat-sealable resin layer 53 is joined to the barrier layer 52, for example, via an adhesive layer 55. The heat-sealable resin layer 53 included in the outer film 50 is a layer that imparts heat-seal sealing properties to the outer film 50. Examples of heat-sealable resin layers 53 include films made of polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polyolefin resins such as polyethylene resin and polypropylene resin, 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, from the viewpoint of sealing properties and strength.

[0031] The outer film 50 preferably has one or more layers having a buffering function (hereinafter referred to as "buffering layers") outside the heat-sealable resin layer 53, and more preferably outside the barrier layer 52. The buffering layers may be laminated on the outside of the base layer 51, or the base layer 51 may also have the function of a buffering layer. If the outer film 50 has multiple buffering layers, the multiple buffering layers may be adjacent to each other, or they may be laminated via the base layer 51 or the barrier layer 52, etc.

[0032] The materials constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Examples of cushioning materials include rubber, nonwoven fabric, or foamed sheet. Examples of rubber include natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably around 20 to 90. The materials constituting the nonwoven fabric are preferably materials with excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the buffer layer thickness is preferably 100 μm, more preferably 200 μm, and still more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the buffer layer thickness is preferably 5000 μm, and still more preferably 3000 μm. The preferred thickness ranges for the buffer layer are 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 most preferred thickness range for the buffer layer is 1000 μm to 3000 μm.

[0033] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2.0 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 0.5 mm to 2.0 mm, 0.5 mm to 5 mm, or 0.5 mm to 10 mm.

[0034] If the outer film 50 has a buffer layer, the buffer layer functions as a cushion, thus preventing damage to the outer film 50 from impact when the energy storage device 10 is dropped or from handling during the manufacturing of the energy storage device 10.

[0035] The lid 60 comprises a lid body 70, a covering 90 that covers the lid body 70, and a bonding layer 80. The lid body 70 may have a protrusion that projects in the direction opposite to the electrode body 20. This protrusion is an element for outputting current to the outside and is connected to external equipment. The protrusion may also be, for example, an element for fixing the energy storage device 10.

[0036] The lid body 70 is constructed including a conductive material. "Constructed including a conductive material" means that, when the total mass of the materials constituting the lid body 70 is considered to be 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 materials constituting the lid body 70 may contain materials other than conductive materials in addition to the conductive material. It is preferable that the lid body 70 has a corrosion-resistant coating as described in the barrier layer 52.

[0037] The conductive material constituting the lid body 70 is, for example, a metallic material. The metallic material constituting the lid body 70 is, for example, aluminum, aluminum alloy, nickel, copper, or copper alloy. For example, if the electrode body 20 is a lithium-ion battery, the lid body 70 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The lid body 70 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the lid body 70 connected to the negative electrode may be copper with nickel plating. The material constituting the lid body 70 may include recycled metallic material. The lid body 70 has a base portion 71 and a flange portion 72.

[0038] In this disclosure, the lid body 70 is made of a conductive material (for example, a metal material), but it may or may not constitute electrode terminals. If the lid body 70 constitutes electrode terminals, the lid itself functions as electrode terminals, so the electrode terminals can be omitted. On the other hand, if the lid body 70 does not constitute electrode terminals, the electrode terminals can be provided by forming through holes in the lid body 70 and inserting the electrode terminals into them.

[0039] The base portion 71 shown in Figures 4 and 5 is, for example, a rectangular plate and has a first surface 71A and a second surface 71B. The first surface 71A faces the outside. The second surface 71B is the surface opposite to the first surface 71A. The second surface 71B faces the electrode body 20. The base portion 71 may be any shape such as a cylinder, prism, rectangular parallelepiped, or cube.

[0040] The flange portion 72 is covered by the covering 90. The flange portion 72 is frame-shaped, rising from the edge of the base portion 71. The flange portion 72 has a first flange portion 72A, a second flange portion 72B, and a third flange portion 72C. The first flange portion 72A constitutes the upper surface of the lid body 70. In a front view of the lid body 70, the first flange portion 72A extends in a first direction (in this embodiment, the LR direction). The second flange portion 72B and the third flange portion 72C connect with the first flange portion 72A and constitute the side surface of the lid body 70. In a front view of the lid body 70, the second flange portion 72B and the third flange portion 72C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction. In this embodiment, in a front view of the lid body 70, the first direction and the second direction are orthogonal. The first and second directions do not have to be orthogonal in a front view of the lid body 70. The fourth flange portion 72D constitutes the lower surface of the lid body 70. The fourth flange portion 72D extends in the first direction (in this embodiment, the L-R direction) in a front view of the lid body 70.

[0041] At least a portion of the surface 72X of the flange portion 72 is covered by the coating 90. In this embodiment, the entire surface 72X of the flange portion 72 is covered by the coating 90. Any part of the lid body 70 is connected to the end 31 of the current collector 30. In the example shown in Figure 7, the second surface 71B of the base portion 71 is connected to the end 31 of the current collector 30. In another example, a connection may be formed at any part of the lid body 70 (for example, the second surface 71B). The connection may, for example, protrude toward the electrode body 20. The connection is made up of a conductive material. If the connection protrudes toward the electrode body 20, the end 31 of the current collector 30 is joined to any part of the connection. The connection may be a recess that is recessed from any part of the lid body 70 (for example, the second surface 71B).

[0042] From the viewpoint of suitably joining the bonding layer 80 described later, the flange portion 72 may have at least one of a through hole, a recess that is recessed on the side opposite to the covering 90, or a protrusion that is projected toward the covering 90.

[0043] The thickness HA (see Figure 7) of the portion constituting the lid body 70 can be arbitrarily selected. From the viewpoint of easily manufacturing the lid body 70, it is preferable that the thickness HA be 0.1 mm or more. On the other hand, if the volume of the lid body 70 is large, when forming the second sealing portion 120 described later, the heat from the heat seal may be absorbed by the lid body 70, which may cause a bonding defect in the second sealing portion 120. Also, the time required for the process of forming the second sealing portion 120 will be longer. Furthermore, if the volume of the lid body 70 is large, the gravimetric energy density of the energy storage device 10 itself will be lower. For this reason, from the viewpoint of suitably forming the second sealing portion 120 and from the viewpoint of suppressing a decrease in the gravimetric energy density of the energy storage device 10 itself, it is preferable that the thickness HA be 7.0 mm or less, more preferably 4.0 mm or less, even more preferably 3.0 mm or less, and even more preferably 2.0 mm or less. The preferred range for thickness HA is 0.1 mm to 7.0 mm, 0.1 mm to 4.0 mm, 0.1 mm to 3.0 mm, or 0.1 mm to 2.0 mm. The parts constituting the lid body 70 may have partially different thicknesses. If the parts constituting the lid body 70 have partially different thicknesses, thickness HA is the maximum thickness.

[0044] The covering 90 shown in Figures 4, 5, and 6 has a lid sealing portion 91. The lid sealing portion 91 is heat-sealed to the heat-fusible resin layer 53 of the outer film 50. The lid sealing portion 91 and the outer film 50 may be joined by any method other than heat sealing, such as welding. Specific welding methods include, for example, laser welding or ultrasonic welding, or any other method. The lid sealing portion 91 includes a first sealing surface 91A, a second sealing surface 91B, a third sealing surface 91C, and a fourth sealing surface 91D. The first sealing surface 91A constitutes the upper surface of the lid 60. The first sealing surface 91A is formed on the first flange portion 72A. In a front view of the lid 60, the first sealing surface 91A extends in a first direction (in this embodiment, the L-R direction). The second sealing surface 91B and the third sealing surface 91C connect to the first sealing surface 91A and constitute the side surface of the lid 60. The second sealing surface 91B is formed on the second flange portion 72B. The third sealing surface 91C is formed on the third flange portion 72C. The second sealing surface 91B and the third sealing surface 91C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction in a front view of the lid 60. In this embodiment, the first direction and the second direction are orthogonal in a front view of the lid 60. The first direction and the second direction do not have to be orthogonal in a front view of the lid 60. The fourth sealing surface 91D constitutes the lower surface of the lid 60. The fourth sealing surface 91D extends in a first direction (in this embodiment, the LR direction) in a front view of the lid 60. The fourth sealing surface 91D is formed on the fourth flange portion 72D.

[0045] The lid seal portion 91 further includes boundaries 92, 93, 94, and 95. Boundary 92 is the boundary between the first seal surface 91A and the second seal surface 91B. Boundary 93 is the boundary between the first seal surface 91A and the third seal surface 91C. Boundary 94 is the boundary between the fourth seal surface 91D and the second seal surface 91B. Boundary 95 is the boundary between the fourth seal surface 91D and the third seal surface 91C. The shape of boundaries 92 to 95 may be angular, or it may be rounded by R-processing. In this embodiment, boundaries 92 to 95 are angular.

[0046] The coating 90 is composed of a resin material. Here, "composed of a resin material" means that when the total mass of the materials constituting the coating 90 is considered to be 100% by mass, the resin material content is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In other words, the materials constituting the coating 90 may contain materials other than resin materials in addition to the resin material.

[0047] Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, and phenolic resin, as well as modified versions of these resins. Flame-retardant resins include polyether ether ketone resin (PEEK), polyphenylene sulfide resin (PPS), polyimide resin (PI), polytetrafluoroethylene resin (PTFE), and polyetherimide resin (PEI). Furthermore, flame-retardant resins include epoxy glass, PBT, and PMMA. The resin material may be a mixture of these resins, a copolymer, or a modified version of a copolymer. Among these, the resin material is preferably a heat-sealable resin such as polyester or polyolefin, with polyolefin being more preferred. When the resin material is a resin, the coating 90 may be molded by any molding method.

[0048] The resin material included in the material constituting the coating 90 is preferably an olefin-based random copolymer, more preferably a resin containing a polyolefin skeleton as a main component, more preferably polyolefin as a main component, and even more preferably polypropylene as a main component. Here, the main component is the resin component with the highest content among the resin components contained in the coating 90, meaning, for example, a resin component that accounts for 35% by mass or more, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. The polyolefin may be an acid-modified polyolefin. The resin material included in the material constituting the coating 90 preferably contains multiple types of amide lubricants. Furthermore, the resin material included in the material constituting the coating 90 preferably contains, in addition to saturated fatty acid amides, multiple types of amide lubricants, including unsaturated fatty acid amides. The resin material included in the material constituting the coating 90 may be a polyolefin resin to which a propylene-based elastomer with a melting point higher than 150°C has been added.

[0049] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). Among these, polybutylene terephthalate is preferred as the resin material from the viewpoint of improving heat resistance and pressure resistance.

[0050] Furthermore, specific examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. Among these, polypropylene is preferred as the resin material because it has excellent heat-sealability and electrolyte resistance.

[0051] The resin material may contain fillers as needed. Specific examples of fillers include glass beads, graphite, glass fibers, and carbon fibers. By including these fillers in the resin material, the deformation resistance of the coating 90 to temperature changes can be improved. Fire extinguishing agents and flame retardants may also be included to improve heat resistance.

[0052] The melt mass flow rate of the resin material contained in the material constituting the coating 90 is preferably in the range of 1 g / 10 min to 100 g / 10 min, and more preferably in the range of 5 g / 10 min to 80 g / 10 min. The melt mass flow rate is measured according to JIS K7210-1:2014. The measurement temperature for the melt mass flow rate is 230°C.

[0053] (Joining layer 80) The bonding layer 80 (see Figure 6) joins the lid body 70 and the covering 90. Note that in Figures 4 and 5, the bonding layer 80 is omitted from the illustration for simplification of the drawings. In this embodiment, the bonding layer 80 joins at least a portion of the flange portion 72 of the lid body 70 to the covering 90. In this embodiment, the bonding layer 80 joins the entire surface 72X of the flange portion 72 to the covering 90. If the lid body 70 does not have a flange portion 72, the bonding layer 80 may join at least a portion of the base portion 71 of the lid body 70 to the covering 90. Even if the lid body 70 has a flange portion 72, the bonding layer 80 may join at least a portion of the base portion 71 of the lid body 70 to the covering 90. When the bonding layer 80 joins at least a portion of the base 71 of the lid body 70 to the covering 90, the bonding layer 80 only needs to be joined to any location on the base 71, and does not need to be joined to the flange portion 72.

[0054] The material constituting the bonding layer 80 is a material capable of bonding the lid body 70 and the covering 90, and is formed from a cured product of a resin composition containing a resin and a curing agent.

[0055] In the resin composition that forms the bonding layer 80, the resin is the main component that reacts with the curing agent. For this reason, it is preferable that the resin has functional groups that react with the curing agent to form a cured product.

[0056] Examples of such functional groups include epoxy groups, amine groups, hydroxyl groups, carboxyl groups, aldehyde groups, acyl groups, mercapto groups, imine groups, phenol groups, ester groups, carbonyl groups, cyano groups, azo groups, diazo groups, and the like. The resin may have only one type of functional group, or two or more types. The functional groups of the resin may be included in the basic skeleton of the resin, or the functional groups may be introduced into the basic skeleton by modifying the resin. Specific examples of modification include graft modification of the resin material that forms the basic skeleton with monomers containing acidic groups (carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, etc.), graft modification with monomers containing acidic anhydrides (carboxylic acid anhydride groups, sulfonic acid anhydride groups, phosphoric acid anhydride groups, etc.), and graft modification with (meth)acrylic monomers.

[0057] The resin composition forming the bonding layer 80 is preferably a resin containing a polyolefin skeleton, such as an acid-modified polyolefin. The presence of a polyolefin skeleton in the resin of the bonding layer 80 can be analyzed by infrared spectroscopy. Furthermore, when the resin in the bonding layer 80 is analyzed by infrared spectroscopy, it is preferable to detect a peak originating from maleic anhydride. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak derived from maleic anhydride is detected in the vicinity. When the bonding layer 80 is a layer composed of a cured product of a resin composition containing maleic anhydride-modified polyolefin and a curing agent, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0058] The bonding layer 80 preferably contains a resin containing a polyolefin skeleton as its main component, more preferably contains acid-modified polyolefin as its main component, and even more preferably contains acid-modified polypropylene as its main component. Here, the main component is the resin component with the highest content among the resin components contained in the bonding layer 80, and means, for example, a resin component that accounts for 35% by mass or more, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. For example, if the bonding layer 80 contains acid-modified polypropylene as its main component, it means that among the resin components contained in the bonding layer 80, the content of acid-modified polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0059] Acid-modified polyolefins are polymers that have been modified by block polymerization or graft polymerization of polyolefins with an acid component.

[0060] Examples of polyolefins to be acid-modified include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used individually or in combination of two or more. As polyolefins to be acid-modified, copolymers obtained by copolymerizing these polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins can also be used. Examples of acid components used for acid modification include carboxylic acids or their anhydrides such as maleic acid, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0061] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin with an acid component, or by block polymerization or graft polymerization of an acid component to a cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

[0062] The acid-modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that constitute the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers that constitute the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0063] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes. When the resin composition forming the bonding layer 80 contains an acid-modified polyolefin, there may be only one type of acid-modified polyolefin or two or more types.

[0064] Furthermore, examples of resins included in the resin composition forming the bonding layer 80 include vinyl acetate resin, ethylene vinyl acetate copolymer, acrylic resin, urea resin, melamine resin, aqueous polymer-isocyanate resin, chloroprene rubber, nitrile rubber, vinyl acetate, epoxy resin, silicone resin, modified silicone resin, acrylic copolymer resin, acrylic monomer, acrylic emulsion, SBS resin, cyanoacrylate resin, urethane resin, EVA resin, synthetic rubber, polyamide, polyester resin, isobutene-maleic anhydride resin, styrene-butadiene rubber, vinyl chloride resin, chloroprene rubber, chloroprene rubber, nitrile rubber, epoxy-modified silicone resin, polymer cement mortar, and silylated urethane resin. Specifically, examples include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolymerized polyester; polyether adhesives; polyurethane adhesives; epoxy resins; phenolic resins; polyamide resins such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyvinyl acetate resins; cellulose adhesives; (meth)acrylic resins; polyimide resins; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins; and fluoroethylene propylene copolymers. When the resin composition forming the bonding layer 80 contains at least one of these resins, the resin composition may contain only one type of resin or two or more types.

[0065] Furthermore, the curing agent included in the resin composition forming the bonding layer 80 is not particularly limited as long as it cures the resin composition. Examples of curing agents include compounds having an isocyanate group, carbodiimide compounds, compounds having an oxazoline group, compounds having an epoxy group, glycidyl compounds, compounds having a carboxyl group, melamine compounds, phenol resins, acid anhydrides, thiol compounds, compounds having an amine group, and urea compounds. Other examples include dicyaminediamide, imidazole compounds, and chemitin compounds. From the viewpoint of more favorably exhibiting the effects of the present invention, it is preferable that the curing agent among these includes an epoxy resin. The curing agent used to form the bonding layer 80 may be one type or two or more types.

[0066] Compounds having an isocyanate group are not particularly limited, but polyfunctional isocyanate compounds are preferred. Polyfunctional isocyanate compounds are not particularly limited as long as they have two or more isocyanate groups. Specific examples of polyfunctional isocyanate compounds include at least one selected from the group consisting of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and derivatives thereof. Polyfunctional isocyanate compounds are selected from the group consisting of nurate, adduct, biuret, isocyanurate, and derivatives thereof. Examples include diisocyanates such as 2,4- or 2,6-tolylene diisocyanate (TDI) or its hydrogenated derivatives, crude TDI, xylylene diisocyanate (XDI) or its hydrogenated derivatives, hexamethylene diisocyanate (HDI), 4,4'-diphenylmethane diisocyanate (MDI) or its hydrogenated derivatives, crude MDI, methylene diisocyanate, isopropyl diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, and pentane diisocyanate (PDI).

[0067] The carbodiimide compound is not particularly limited as long as it has at least one carbodiimide group (-N=C=N-).

[0068] Specific examples of carbodiimide compounds include polycarbodiimide compounds having repeating units represented by the following general formula (5).

[0069] [ka] A polycarbodiimide compound having repeating units represented by the following general formula (6),

[0070] [ka] Examples include polycarbodiimide compounds having repeating units represented by the following general formula (7).

[0071] [ka]

[0072] Compounds containing an oxazoline group are not particularly limited as long as they have an oxazoline skeleton. Specific examples of compounds containing an oxazoline group include those with a polystyrene main chain and those with an acrylic main chain. Commercially available examples include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0073] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably around 50 to 2000, more preferably around 100 to 1000, and even more preferably around 200 to 800. In this disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0074] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A type epoxy resins (e.g., bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether), hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol F type epoxy resins (e.g., bisphenol F type glycidyl ether), novolac type epoxy resins (e.g., novolac glycidyl ether), bisphenol S type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclo type epoxy resins, hydantoin type epoxy resins, heterocyclic epoxy resins such as triglycidyl isocyanurate, bixylenol type epoxy resins, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0075] Examples of melamine compounds include triazine derivatives such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, 2,4-diamino-6-xylyl-S-triazine, and triaminotriazine, as well as hexa(N-methyl)melamine, hexamethoxymelamine, and hexasubtoxicated melamine.

[0076] Examples of phenolic resins include phenol novolac, cresol novolac, bisphenol A novolac, and phenol aralkyl resin.

[0077] As for acid anhydrides, Examples include docecenyl succinic anhydride (DDSA), polyazelaic anhydride (PAPA), hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), methylnadic anhydride (MNA), trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), benzophenonetetracarboxylic acid (BTDA), tetrabromophthalic anhydride (TBPA), and hetic anhydride (HET).

[0078] Compounds containing an amine group include diethylenetriamine (DETA), triethylenetetraamine (TETA), metaxylylenediamine (MXDA), isophoronediamine (IPDA), bispara-aminocyclohexylmethane (PACM), diaminidiphenylmethane (DDM), m-phenylenediamine (MPDA), diaminodiphenylsulfone (DDS), dicyandiamide (DICY), organic acid dihydrazides, and tertiary amines. These may be modified.

[0079] Examples of urea compounds include dimethylol urea and methylol group-containing urea resins.

[0080] The proportion of the curing agent in the resin composition forming the bonding layer 80 is preferably about 0.1% by mass or more, more preferably about 0.5% by mass or more, even more preferably about 1% by mass or more, and also preferably about 50% by mass or less, more preferably about 5% by mass or less, even more preferably 3% by mass or less. Preferred ranges include about 0.1 to 50% by mass, about 0.1 to 5% by mass, about 0.1 to 3% by mass, about 0.5 to 50% by mass, about 0.5 to 5% by mass, about 0.5 to 3% by mass, about 1 to 50% by mass, about 1 to 5% by mass, and about 1 to 3% by mass.

[0081] The resin composition forming the bonding layer 80 may contain various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers.

[0082] From the viewpoint of suitably bonding the coating 90 to the heat-fusible resin layer 53 of the outer film 50, the resin material forming the basic framework is preferably polyolefin. Therefore, in the resin composition forming the bonding layer 80, the resin forming the basic framework is preferably a polyolefin resin, similar to the coating 90, in that it is a material that can bond to the coating 90 which suits bonding to the heat-fusible resin layer 53 of the outer film 50.

[0083] Furthermore, from the viewpoint of suitably joining the coating 90 and the bonding layer 80, it is preferable that the basic structure of the resin material constituting the coating 90 and the basic structure of the resin contained in the resin composition forming the bonding layer 80 are common. For example, when polyolefin or acid-modified polyolefin is used as the resin material constituting the coating 90, it is preferable that the resin composition forming the bonding layer 80 contains polyolefin or acid-modified polyolefin. Specifically, if the resin of the bonding layer 80 is propylene, then if the resin material of the coating 90 is propylene, a modified product of propylene-ethylene copolymer, polypropylene-ethylene copolymer (acid modification, addition of functional groups, etc.), polypropylene with a different molecular weight, propylene-ethylene copolymer with a different molecular weight, or a modified product of polypropylene-ethylene copolymer with a different molecular weight (acid modification, addition of functional groups, etc.), then it can be said that the basic structure of the resin of the bonding layer 80 and the resin material of the coating 90 are common.

[0084] The specific structure of the bonding layer 80 is a coating or film. The coating of the bonding layer 80 can be formed by applying a coating method such as a dip coater, spray, brush, or dispenser to the resin composition. Alternatively, the film of the bonding layer 80 can be attached to the surface of the lid body 70. The bonding layer 80 may be a single-layer structure or a multi-layer structure.

[0085] The thickness of the bonding layer 80 is the thickness in the UD direction of the bonding layer 80 that extends in the LR direction and is positioned between the first flange portion 72A and the covering body 90 in Figure 6. The thickness of the bonding layer 80 can be arbitrarily selected. Preferably, the thickness of the bonding layer 80 in the UD direction is thinner than the thickness of the covering body 90 in the UD direction.

[0086] When the bonding layer 80 is a coating film, the thickness of the bonding layer 80 in the UD direction is preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 3 μm or more, even more preferably 5 μm or more, and even more preferably 10 μm or more. When the bonding layer 80 is a coating film, the thickness of the bonding layer 80 in the UD direction is preferably 20 μm or less, and more preferably 15 μm or less. When the bonding layer 80 is a coating film, preferred ranges for the thickness of the bonding layer 80 in the UD direction are 0.5 μm or more and 20 μm or less, 0.5 μm or more and 15 μm or less, 1 μm or more and 20 μm or less, 1 μm or more and 15 μm or less, 3 μm or more and 20 μm or less, 3 μm or more and 15 μm or less, 5 μm or more and 20 μm or less, 5 μm or more and 15 μm or less, 10 μm or more and 20 μm or less, 10 μm or more and 15 μm or less, etc.

[0087] When the bonding layer 80 is a coating film, the bonding layer 80 can be formed on the lid body 70 as a coating film by applying the resin composition to the lid body 70 and drying it. Examples of methods for applying the resin composition to the lid body 70 include dip coating, dispensing, inkjet printing, spraying, or screen printing. When applying the resin composition by dip coating or spraying, it is preferable that the solution or dispersion is applied while the parts of the lid body 70 that require conductivity, such as the base 71, are masked. If the parts of the lid body 70 that require conductivity, such as the base 71, are not masked, it is preferable that the coating film formed on the parts that require conductivity be removed.

[0088] If the bonding layer 80 is a film, the thickness of the bonding layer 80 in the UD direction is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 40 μm or more, and still more preferably 80 μm or more. If the bonding layer 80 is a film, the thickness of the bonding layer 80 in the UD direction is preferably 500 μm or less, more preferably 200 μm or less, and still more preferably 100 μm or less. When the bonding layer 80 is a film, the preferred ranges for the thickness of the bonding layer 80 in the UD direction are 5 μm to 500 μm, 5 μm to 200 μm, 5 μm to 100 μm, 10 μm to 500 μm, 10 μm to 200 μm, 10 μm to 100 μm, 40 μm to 500 μm, 40 μm to 200 μm, 40 μm to 100 μm, 80 μm to 500 μm, 80 μm to 200 μm, 80 μm to 100 μm, etc.

[0089] The thickness of the bonding layer 80 in the UD direction is measured as follows. First, the lid 60 is removed from the energy storage device 10. Next, the lid 60 is cut so that the surface perpendicular to the interface between the lid body 70 and the bonding layer 80 is exposed, and the surface perpendicular to the interface between the lid body 70 and the bonding layer 80 is polished with a polishing machine. Next, the polished cross section is imaged using a laser microscope (for example, a combination of a controller VK-X3000 and a head unit VK-X3050, manufactured by KEYENCE) to acquire image data of the test piece cross section. Based on the acquired image data, the bonding layer 80 is identified, and its thickness is derived using an image analysis program (for example, a multi-file analysis application VK-X3050, manufactured by KEYENCE). The thickness of the bonding layer 80 in the UD direction may vary in parts, and the preferred numerical value for the thickness of the bonding layer 80 in the UD direction as exemplified in the embodiment is the numerical value of the thickness at any point in the bonding layer 80.

[0090] When the lid 60 is plate-shaped, it is preferable that the lid 60 has a certain thickness so as to prevent deformation of the outer casing 40 even when the energy storage devices 10 are stacked on top of each other. From another viewpoint, when the lid 60 is plate-shaped, it is preferable that the lid seal portion 91 of the lid 60 has a certain width in the FB direction so as to allow for suitable heat sealing of the lid seal portion 91 of the lid 60 and the outer casing film 50 when forming the second sealing portion 120 described later. The minimum width of the lid seal portion 91 of the lid 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum width of the lid seal portion 91 of the lid 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum width of the lid seal portion 91 of the lid 60 may be 20 mm or more. The preferred width ranges for the lid seal portion 91 of the lid 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 60 is described as being plate-shaped, it does not include the form in which the lid 60 is composed solely of film as defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard. The width of the lid seal portion 91 of the lid 60 may vary depending on the part. If the width of the lid seal portion 91 of the lid 60 varies depending on the part, the width of the lid seal portion 91 of the lid 60 is the width of the widest part.

[0091] In this embodiment, with the outer film 50 wrapped around the electrode body 20, the first sealing portion 110 is formed by heat sealing the opposing surfaces (heat-fusible resin layers 53) of the outer film 50 together.

[0092] The first sealing portion 110 is formed by heat sealing the portion of the outer film 50, shown in Figure 3, that includes the first edge 50A and the portion that includes the second edge 50B. The first sealing portion 110 extends in the longitudinal direction of the outer body 40. The position in the outer body 40 where the first sealing portion 110 is formed can be arbitrarily selected. In this embodiment, it is preferable that the base 70X of the first sealing portion 110 is located on the edge 43 of the boundary between the first surface 41 and the second surface 42 of the outer body 40. The first surface 41 has a larger area than the second surface 42. The base 110X of the first sealing portion 110 may be located on any surface of the outer body 40. In this embodiment, the first sealing portion 110 protrudes outward from the electrode body 20 in a plan view. The first sealing portion 110 may be folded toward the second surface 42 of the outer body 40, or folded toward the first surface 41.

[0093] In this embodiment, the heat-sealable resin layer 53 of the outer film 50 and the lid seal portion 91 of the lid 60 are heat-sealed to form the second sealing portion 120 (lid sealing portion 100B). Hereinafter, the sealing strength between the heat-sealable resin layer 53 of the outer film 50 and the lid seal portion 91 of the lid 60 may be referred to as the sealing strength (joint strength) of the second sealing portion 120. The sealing strength of the second sealing portion 120 is the sealing strength between the heat-sealable resin layer 53 and the lid 60 in the long side portion of the lid seal portion 91, that is, the portion of the lid seal portion 91 extending in the LR (width) direction in Figure 1A.

[0094] The seal strength of the second sealing section 120 is measured as follows. First, an incision is made in the portion of the outer film 50 that constitutes the first surface 41 of the outer body 40, forming three strip-shaped members 41X, 41Y, and 41Z (see the dashed line in Figure 1B) aligned in the LR direction. The width of the three strip-shaped members 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strip-shaped members 41X, 41Y, and 41Z are joined to the lid 60 in the second sealing section 120. The length of the lid 60 in the LR direction is 45 mm or more. Next, the seal strength of the strip-shaped members 41X, 41Y, and 41Z is measured by pulling the end of each strip-shaped member 41X, 41Y, and 41Z opposite to the end joined to the lid 60 upward in the UD direction (in the direction opposite to the first surface 41B). The distance between the chucks in the UD direction is 10 mm. The sealing strength of the strip members 41X, 41Y, and 41Z is the peak value of their respective sealing strengths. In this embodiment, the sealing strength of the second sealing portion 120 is the average value of the sealing strengths of the strip members 41X, 41Y, and 41Z. If the length of the lid 60 in the LR direction is less than 45 mm, three strip members with an arbitrary width X mm of less than 15 mm are formed, and the sealing strength of the three strip members is measured in the same manner as when the length of the lid 60 in the LR direction is 45 mm or more. The obtained sealing strengths are each divided by the arbitrary width X mm and multiplied by 15 to convert them to the sealing strengths of the three strip members at a width of 15 mm. The sealing strength of the second sealing portion 120 is the average value of the sealing strengths of the three strip members converted to a width of 15 mm. Note that if the lid 60 is divided into multiple parts including the long side and short side, the sealing strength of the second sealing portion 120 is the sealing strength of the long side portion of the lid sealing portion 91 of the multiple parts.

[0095] From the viewpoint of suitably maintaining the state in which the electrode body 20 is sealed by the outer casing 40, the seal strength of the second sealing portion 120 is preferably 40 N / 15 mm or more, more preferably 50 N / 15 mm or more, more preferably 60 N / 15 mm or more, more preferably 70 N / 15 mm or more, and more preferably 85 N / 15 mm or more. When the seal strength of the second sealing portion 120 is 40 N / 15 mm or more, the state in which the electrode body 20 is sealed by the outer casing 40 is suitably maintained even if the energy storage device 10 is used for, for example, several years (less than 10 years). When the seal strength of the second sealing portion 120 is 85 N / 15 mm or more, the state in which the electrode body 20 is sealed by the outer casing 40 is suitably maintained even if the energy storage device 10 is used for, for example, 10 years or more. The seal strength of the second sealing portion 120 is preferably 300 N / 15 mm or less. The preferred range for the seal strength of the second sealing portion 120 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.

[0096] In this embodiment, it is preferable that the lid 60 has a protruding portion 96 that protrudes from the lid sealing portion 91 so that a gap is less likely to form between the outer film 50 and the lid 60. The protruding portion 96 may be formed integrally with the covering 90, or it may be formed separately from the covering 90 and joined to the covering 90. In this embodiment, the protruding portion 96 is formed integrally with the covering 90. The position in the lid sealing portion 91 where the protruding portion 96 is formed can be arbitrarily selected. A gap between the outer film 50 and the lid 60 is likely to form, for example, between the base 110X of the first sealing portion 110 and the lid 60. In particular, when the base 110X of the first sealing portion 110 is located at the boundary 92 to boundary 95 of the lid 60, the resin filling performance between the base 110X of the first sealing portion 110 and the lid 60 tends to decrease. Therefore, it is preferable that the protrusion 96 be formed in the lid sealing portion 91 at the location where the base 110X of the first sealing portion 110 is located. In this embodiment, the base 110X of the first sealing portion 110 is located at the boundary 92 of the lid 60. Therefore, it is preferable that the protrusion 96 be formed at the boundary 92 in the lid sealing portion 91. In this embodiment, the first sealing portion 110 is sealed with the protrusion 96 sandwiched between them. The protrusion 96 may be formed on at least one of the first sealing surface 91A, the second sealing surface 91B, the third sealing surface 91C, the fourth sealing surface 91D, the boundary 93, the boundary 94, and the boundary 95.

[0097] The shape of the protrusion 96 can be arbitrarily selected. In this embodiment, the shape of the protrusion 96 is plate-like. The thickness of the protrusion 96 can be arbitrarily selected. In this embodiment, the thickness of the protrusion 96 decreases as it moves away from the boundary 92. In other words, the protrusion 96 has a tapered shape as it moves away from the boundary 92. The thickness of the protrusion 96 may be constant, or it may increase as it moves away from the boundary 92.

[0098] The direction in which the protrusion 96 extends can be arbitrarily selected. In this embodiment, the protrusion 96 extends along a first direction (the LR direction in this embodiment). The protrusion 96 may also extend along a second direction (the UD direction in this embodiment). In a front view of the lid 60, the protrusion 96 may extend in a third direction that intersects the first direction (the LR direction in this embodiment) and the second direction (the UD direction in this embodiment).

[0099] The length of the protrusion 96 can be arbitrarily selected within a range less than or equal to the length of the first sealing portion 110. For example, the length of the protrusion 96 may be substantially equal to the length of the first sealing portion 110, or it may be 30% to 50% of the length of the first sealing portion 110.

[0100] <1-2. Method for manufacturing energy storage devices> Figure 8 is a flowchart showing an example of a method for manufacturing the energy storage device 10. The method for manufacturing the energy storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, a fifth step, and a sixth step. Steps 1 to 6 are carried out, for example, by a manufacturing apparatus for the energy storage device 10. At least a portion of steps 1 to 6 may be carried out by an operator. Note that steps 1 to 6 are names that are conveniently defined for each step of the method for manufacturing the energy storage device 10 and do not necessarily mean the order of the steps. The order of steps 1 to 6 can be changed arbitrarily, as long as it is not technically contradictory.

[0101] In the first step of step S11, the manufacturing apparatus manufactures the lid 60. The first step is to join the lid body 70 and the covering 90 via the bonding layer 80. The lid 60 can be manufactured, for example, by injection molding the covering 90 onto the lid body 70 with the bonding layer 80 already joined. In another example, the lid 60 may be manufactured by fitting the lid body 70 with the bonding layer 80 already joined onto the molded covering 90 and then applying heat to the lid body 70 to fuse the lid body 70, the bonding layer 80, and the covering 90 together. In yet another example, the lid 60 may be manufactured by fitting the molded covering 90 and the lid body 70 with the bonding layer 80 already joined into a mold and then applying heat while pressing them together.

[0102] In the lid 60 of this disclosure, the bonding layer 80 is formed from a cured product of a resin composition containing a resin and a curing agent. Therefore, it is preferable to include a bonding step of bonding the lid body 70 and the covering 90 via the bonding layer 80. Furthermore, it is preferable that the bonding step includes a step of curing the resin composition containing the resin and curing agent that forms the bonding layer 80. Note that the curing of the bonding layer 80 may be performed before or after bonding the lid body 70 and the covering 90.

[0103] The second step, S12, is performed after the first step. In the second step, the manufacturing apparatus places a pair of covers 60 to the side of the electrode body 20 in the FB direction.

[0104] The third step, S13, is performed after the second step. In the third step, the manufacturing apparatus joins the current collector 30 and the cover 60.

[0105] Step S14, the fourth step, is performed after the third step. In the fourth step, the manufacturing apparatus wraps the outer film 50 around the electrode body 20 and the lid 60 while tension is applied to the outer film 50, while restricting the movement of the electrode body 20 and the lid 60 with restricting means. The restricting means is, for example, a groove into which the electrode body 20 and the lid 60 are fitted. The restricting means may also be a device that applies an external force to the electrode body 20 and the lid 60 to prevent them from moving. The restricting means may also be a device that applies a force to the electrode body 20 and the lid 60 in the opposite direction to the direction in which the outer film 50 is pulled. The restricting means may also include a roller that runs on the outer film 50 while the outer film 50 is being pulled in order to remove wrinkles in the outer film 50. Alternatively, the electrode body 20 may be housed inside a cylindrical outer film 50 with openings formed at both ends in the FB direction, and after joining the current collector 30 and the cover 60, the openings may be closed with the cover 60. In yet another example, the electrode body 20, connected to the cover 60, may be housed inside a cylindrical outer film 50 with openings formed at both ends in the FB direction, and the openings may be closed with the cover 60.

[0106] Step S15, the fifth step, is performed after the fourth step. In the fifth step, the manufacturing apparatus forms the second sealing portion 120 by heat sealing the outer film 50 and the lid 60.

[0107] Step S16, the sixth step, is performed before or after step 5. In step 6, the manufacturing apparatus forms the first sealing portion 110 by heat-sealing the heat-sealable resin layer 53 of the outer film 50, including the portion including the first edge 50A, and the heat-sealable resin layer 53 of the outer film 50, including the portion including the second edge 50B, while restricting the movement of the electrode body 20 and the lid body 60, and applying tension to the outer film 50.

[0108] <1-3. Function and Effects of Energy Storage Devices> The energy storage device 10 has a lid body 70 made of a conductive material, which is covered by a coating 90 made of a resin material, allowing for suitable bonding between the coating 90 and the outer film 50. Furthermore, the lid body 70 and the coating 90 are bonded together by a bonding layer 80, allowing for suitable bonding between the lid body 70 and the coating 90. For this reason, the energy storage device 10 has high airtightness.

[0109] [2. Variant] The embodiments described above are illustrative of possible forms of the energy storage device, lid, method for manufacturing the lid, and method for manufacturing the energy storage device according to this disclosure, and are not intended to limit their forms. The energy storage device, lid, method for manufacturing the lid, and method for manufacturing the energy storage device according to this disclosure may take forms different from those illustrated in the embodiments. One example of such a form is one in which a part of the configuration of the embodiment is replaced, modified, or omitted, or a form in which a new configuration is added to the embodiment. Several examples of modifications of the embodiments are shown below. Note that the following modifications can be combined with each other as long as they do not contradict each other technically.

[0110] <2-1. First variation> Figure 9 is an enlarged view of the surface 72X of the lid 60 of the first modified energy storage device 10. In the above embodiment, from the viewpoint of more favorably joining the bonding layer 80 and the lid body 70, it is preferable that at least a portion of the surface of the part of the lid body 70 that is joined to the bonding layer 80 be a rough surface 72Y. In the first modified example, at least a portion of the surface 72X of the flange portion 72 of the lid body 70 may be a rough surface 72Y. If the base portion 71 is covered by the covering 90, at least a portion of the surface of the base portion 71 may be a rough surface 72Y. The base portion 71 and the covering 90 can be joined more firmly.

[0111] The rough surface 73 can be formed, for example, by applying a roughening treatment to the surface 72X of the flange portion 72. Specific methods for the roughening treatment include, for example, shot blasting, polishing, anodizing, wet etching, plasma treatment, laser treatment, or roughening plating. To strengthen the bond between the lid body 70 and the bonding layer 80, it is preferable that the entire surface 72X of the flange portion 72 of the lid body 70 is roughened. In other words, it is preferable that the entire surface 72X of the flange portion 72 is a rough surface 72Y. As shown in Figure 9, minute irregularities are formed on the rough surface 72Y. When the bonding layer 80 is bonded to the lid body 70, the lid body 70 and the bonding layer 80 are bonded more strongly by the anchoring effect. To obtain a higher anchoring effect, the maximum height roughness Rz of the rough surface 72Y is preferably in the range of 0.01 μm to 500 μm, and more preferably in the range of 0.5 μm to 200 μm. The maximum height roughness Rz of the rough surface 72Y is measured according to JIS B 0601-2001. The measurement of the maximum height roughness Rz of the rough surface 72Y is performed using a white light interferometer-equipped laser microscope VK-X3000 manufactured by Keyence Corporation.

[0112] <2-2. Second variation> Figure 10 is an enlarged view of the surface 72X of the lid 60 of the second modified energy storage device 10. In the above embodiment, from the viewpoint of more favorably joining the bonding layer 80 and the lid body 70, and from the viewpoint of improving the adhesion between the lid body 70 and the bonding layer 80, it is preferable that at least a portion of the surface of the lid body 70 that is joined to the bonding layer 80 has a surface treatment layer 72Z (see Figure 10). The surface treatment layer 72Z is ​​a thin film that provides corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the surface of the lid body 70 by performing treatments such as hot water modification 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 to the surface of the lid body 70. Corrosion prevention treatments by applying a coating agent include applying liquids such as chromate treatment, zirconium phosphate conversion treatment, resin-zirconium-based conversion coating treatment, and metal salt-zirconium-based conversion treatment. The surface treatment layer 72Z specifically refers to a coating that improves the acid resistance of the lid body 70 (acid-resistant coating), a coating that improves the alkali resistance of the lid body 70 (alkali-resistant coating), etc. The surface treatment layer 72Z may be formed by one type of treatment, or by a combination of two or more types. Furthermore, it can be multilayered rather than a single layer. Among these treatments, the hydrothermal modification treatment and the anodic oxidation treatment are processes that dissolve the surface of the metal foil with a treatment agent, forming a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Additionally, if the surface treatment layer 72Z is ​​formed on the surface of the lid body 70, the lid body 70 is considered to include the surface treatment layer 72Z.

[0113] Preferably, at least a portion of the surface of the lid body 70 that is joined to the bonding layer 80 shows a peak PCr originating from the chromium compound Cr2p3 / 2 in the range of 576 eV to 581 eV when analyzed by X-ray photoelectron spectroscopy. Such characteristics can be obtained, for example, by forming a surface treatment layer 72Z on at least a portion of the surface of the lid body 70 that is joined to the bonding layer 80. In this embodiment, the surface treatment layer 72Z is ​​formed on at least a portion of the surface 72X of the flange portion 72 of the lid body 70. Therefore, the adhesion between the surface treatment layer 72Z formed on the surface 72X and the bonding layer 80 can be further improved.

[0114] The detection of peak PCr confirms the presence of a chromium compound in the composition used to form the surface treatment layer 72Z by chemical conversion treatment. The Cr atom plays a central role in the film, being coordinated by -COOH groups, -NH2 groups, -CN groups, etc. Therefore, it forms cross-linked structures with functional groups that have structures that can act as other ligands, such as polycarboxylic acids and their ammonium salts, resulting in durability such as corrosion resistance and chemical resistance.

[0115] The analysis of the 72Z surface treatment layer using X-ray photoelectron spectroscopy is performed using an X-ray photoelectron spectrometer under the following measurement conditions, with reference to JIS K0162:2010.

[0116] Incident X-ray: Mg Kα (non-monochromatic X-ray, hν=1253.6eV) X-ray output: 10kV 20mA (200W) Photoelectron acquisition angle: 90 degrees (input lens positioned on the sample normal) Measurement area: 6mmφ Peak shift correction: Corrects the binding energy at which the peak intensity is maximum in the C1s peak to 285 eV.

[0117] When analyzing the peak position (binding energy) of the surface treatment layer 72Z using X-ray photoelectron spectroscopy, the bonding layer 80 and the coating 90 are physically delaminated. This delamination is performed physically without using water, organic solvents, or aqueous solutions of acids or alkalis.

[0118] When the lid body 70 and the coating 90 are separated, the bonding layer 80 and coating 90 remaining on the surface 72X of the lid body 70 are removed by etching with Ar-GCIB. The surface treatment layer 72Z of the surface 72X of the lid body 70 obtained in this way is analyzed using X-ray photoelectron spectroscopy.

[0119] The presence or absence of peak PCr can be easily confirmed by displaying it as a detected peak on the monitor screen of the X-ray photoelectron spectroscopy analyzer if the peak PCr is clear. If the peak is small and ambiguous, the determination is made based on the area, full width at half maximum, and the presence or absence of related peaks for the same atom.

[0120] Specifically, the determination is made by performing the following steps. First, (1) after subtracting the background using the Shirley method and performing curve fitting, if it can be determined from the peak area that the component is present at a concentration of 0.1% or more, then the peak is considered to be present.

[0121] Furthermore, as supplementary measures, the following criteria are used to make a judgment: (2) the full width at half maximum (FWHM) of the peaks that appear after fitting is larger than the energy resolution of the instrument, and (3) in addition to the main peak, peaks originating from photoelectrons in outer shell orbits than the main peak are also observed. Typically, X-ray photoelectron spectroscopy analyzers come with analysis software, and "Vision Processing" from the instrument manufacturer Kratos is used.

[0122] <2-3. Third Variation> In the above embodiment, the outer film 50 of the energy storage device 10 may extend outward in the FB direction beyond at least one of the two lids 60. The electrode body 20 is sealed by closing the portion of the outer film 50 that extends outward beyond the lids 60. The portion of the outer film 50 that extends outward beyond the lids 60 may be folded into a Goebeltop type pouch or a brick type pouch. In the third modification, if a protrusion is formed on the lid body 70, the length of the protrusion is preferably such that it is exposed from the portion of the outer film 50 that extends outward beyond the lids 60.

[0123] <2-4. Fourth variation> In the above embodiment, the outer casing 40 may not have one of the two lids 60. In this modification, in the FB direction, in the portion of the outer casing 40 where the lid 60 is omitted, the electrode body 20 is sealed by closing the portion of the outer film 50 that extends outward from the electrode body 20. The portion of the outer film 50 that extends outward from the electrode body 20 may be folded to form a Goebeltop type pouch or a brick type pouch.

[0124] <2-5. Fifth variation> In the above embodiment, the outer shape of the exterior body 40 can be arbitrarily changed. The outer shape of the exterior body 40 may be a cylinder, a prism, or a cube. [Examples]

[0125] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0126] <Preparation of resin composition for forming the bonding layer> (Example 1: Resin composition A-1 (with curing agent)) Resin composition A-1, which forms a bonding layer, was prepared by mixing maleic anhydride-modified polypropylene (melting peak temperature 80°C) as the main component, epoxy resin as the curing agent, and a solvent (chloroform:methyl ethyl ketone in a volume ratio of 65:35) in a mass ratio of 10:1:89.

[0127] (Comparative Example 1: Resin Composition A-2 (without curing agent)) Resin composition A-2 was prepared by mixing maleic anhydride-modified polypropylene (melting peak temperature 80°C) and a solvent (chloroform:methyl ethyl ketone volume ratio 65:35) in a mass ratio of 11:89, in the same manner as in resin composition A-1, except that a curing agent was not included, to form a bonding layer.

[0128] (Example 2: Resin composition B-1 (with curing agent)) Resin composition B-1, which forms a bonding layer, was prepared by mixing maleic anhydride-modified polypropylene (melting peak temperature 95°C) as the main component, epoxy resin as the curing agent, and a solvent (chloroform:methyl ethyl ketone in a volume ratio of 65:35) in a mass ratio of 10:1:89.

[0129] (Comparative Example 2: Resin Composition B-2 (without curing agent)) Resin composition B-2 was prepared by mixing maleic anhydride-modified polypropylene (melting peak temperature 95°C) and a solvent (chloroform:methyl ethyl ketone volume ratio 65:35) in a mass ratio of 11:89, in the same manner as in resin composition B-1, except that a curing agent was not included, to form a bonding layer.

[0130] (Example 3: Resin composition C (with curing agent)) A resin composition C for forming a bonding layer was prepared by mixing a maleic anhydride-modified olefin resin (peak melting temperature 85°C) as the main component, an epoxy resin (methylenebisphenol-type epoxy resin intermediate) as a curing agent, and a solvent (chloroform:methyl ethyl ketone in a volume ratio of 65:35) in a mass ratio of 10:0.3:89.7.

[0131] [Evaluation of shear strength before and after contact between the electrolyte containing hydrofluoric acid and the joint layer of the lid] Using resin compositions A-1, A-2, B-1, B-2, and C-1, which form the bonding layer, the shear strength before and after contact between the hydrofluoric acid-containing electrolyte and the bonding layer of the lid was measured using the following method. The results are shown in Table 1.

[0132] (Preparation of test samples) A metal plate (JIS A1050 material, 45mm long x 10mm wide x 1.5mm thick (ISO 19095)) was prepared to resemble the lid body. The metal plate was immersed in HDM1, a cleaning agent, at 50°C for 30 minutes. A chemical conversion treatment was performed on the surface of the metal plate to form a corrosion-resistant film consisting of phenolic resin, chromium fluoride compound, and phosphoric acid. Next, a bonding layer was formed on the surface of the metal plate. Specifically, each resin composition was applied to the surface of the metal plate by dip coating. For coating, the metal plate was immersed in each resin composition, pulled out at a speed of 5mm / sec, and then heated in an oven at 110°C for 10 minutes. When forming a bonding layer using a resin composition containing a curing agent, an aging treatment was further performed in an 80°C environment for one day to form the bonding layer, while the aging treatment was omitted when forming a bonding layer using a resin composition without a curing agent.

[0133] Next, a test sample was prepared by joining a bonding layer formed on a metal plate (45 mm long x 10 mm wide) with polypropylene (random polypropylene, 45 mm long x 10 mm wide x 3 mm thick) that mimicked the lid's covering. Specifically, the bonding layer on the metal plate and the polypropylene component were laminated in an area of ​​5 mm in length and 10 mm in width, and the polypropylene component was formed by injection molding on top of the bonding layer. The bonding layer and the polypropylene component were then partially joined (heat-fused) to create the test sample.

[0134] (Measurement of shear strength before the electrolyte containing hydrofluoric acid comes into contact with the bonding layer of the lid) In a 25°C environment, a tensile testing machine (Shimadzu AGX-plus) was used to pull the metal plate and polypropylene component of the test sample in a 180° direction under the conditions of a chuck distance of 10 mm and a tensile speed of 10 mm / s. The strength at which the adhesive layer of the metal plate and the polypropylene component separated was defined as the shear strength (N / 10 mm) before the electrolyte containing hydrofluoric acid came into contact with the bonding layer of the lid. The results are shown in Table 1.

[0135] (Measurement of shear strength after the electrolyte containing hydrofluoric acid comes into contact with the bonding layer of the lid) The test sample was completely immersed in an electrolyte containing hydrofluoric acid in a screw-top bottle. The electrolyte containing hydrofluoric acid was prepared by adding 1000 ppm of water to a 1 mol / liter lithium hexafluoride phosphate solution, with the solvent being ethylene carbonate:diethyl carbonate:dimethyl carbonate = 1:1:1 (volume ratio). The screw-top bottle was sealed and stored in an 85°C oven for 24 hours. The test sample was removed from the electrolyte, immersed in pure water to remove the electrolyte, and wiped dry. Next, in a 25°C environment, a tensile testing machine (Shimadzu AGX-plus) was used to pull the metal plate and polypropylene component of the test sample in a 180° direction under conditions of a chuck distance of 10 mm and a tensile speed of 10 mm / s. The strength at which the adhesive layer of the metal plate and the polypropylene component peeled off was defined as the shear strength (N / 10 mm) after the hydrofluoric acid-containing electrolyte came into contact with the bonding layer of the lid. The results are shown in Table 1.

[0136] [Table 1]

[0137] The bonding layer in Examples 1-3 is a bonding layer that joins a lid body, which is made of a conductive material, to a covering body, which is made of a resin material and covers the lid body, in an energy storage device comprising an electrode body, an outer film that encloses the electrode body, and a lid body that seals the electrode body together with the outer film. The bonding layer in Examples 1-3 is formed from a cured product of a resin composition containing a resin and a curing agent. The bonding layer in Examples 1-3 has high shear strength after the electrolyte containing hydrofluoric acid comes into contact with the bonding layer of the lid, and it can be seen that an energy storage device with high sealing performance can be provided even when the electrolyte comes into contact with the lid.

[0138] As described above, this disclosure provides inventions in the following embodiments. Item 1. Electrode body and, The outer film enclosing the electrode body, The system comprises a lid that seals the electrode body together with the outer film, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, in an energy storage device. Item 2. The energy storage device according to Item 1, wherein the resin of the bonding layer has functional groups that can react with the curing agent. Item 3. The energy storage device according to Item 1, wherein the resin of the bonding layer comprises at least one of an acid-modified polyolefin and a polyolefin. Item 4. An energy storage device according to any one of items 1 to 3, wherein the basic framework of the resin material constituting the coating and the basic framework of the resin constituting the bonding layer are common. Item 5. The energy storage device according to any one of items 1 to 4, wherein the thickness of the bonding layer is thinner than the thickness of the coating. Item 6. The energy storage device according to any one of items 1 to 5, wherein the bonding layer is a coating or a film. Item 7. The energy storage device according to any one of items 1 to 6, wherein the thickness of the bonding layer is in the range of 0.5 μm or more and 20 μm or less. Item 8. The energy storage device according to any one of items 1 to 7, wherein the thickness of the bonding layer is in the range of 5 μm or more and 500 μm or less. Item 9. The energy storage device according to any one of items 1 to 8, wherein the lid body further comprises a surface treatment layer on at least a portion of the surface to be joined with the bonding layer. Item 10. The energy storage device according to any one of items 1 to 9, wherein at least a portion of the surface of the lid body that is bonded to the bonding layer shows a peak originating from the chromium compound Cr2p3 / 2 in the range of 576 eV to 581 eV as detected by X-ray photoelectron spectroscopy. Item 11. The energy storage device according to any one of items 1 to 10, wherein at least a portion of the surface of the lid body that is joined to the bonding layer is a rough surface. Item 12. The energy storage device according to any one of items 1 to 11, wherein the curing agent comprises at least one selected from the group consisting of compounds having an isocyanate group, carbodiimide compounds, compounds having an oxazoline group, compounds having an epoxy group, glycidyl compounds, compounds having a carboxyl group, melamine compounds, phenolic resins, acid anhydrides, thiol compounds, compounds having an amine group, and urea compounds. Item 13. A cover used as an outer casing for an energy storage device, A lid body made of a conductive material, A covering body comprising a resin material and covering a part of the lid body, It has a bonding layer that joins the lid body and the covering, The aforementioned bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, and is a lid. Item 14. The lid according to item 13, wherein the resin of the bonding layer has functional groups that can react with the curing agent. Item 15. The lid according to item 13 or 14, wherein the resin comprises at least one of an acid-modified polyolefin and a polyolefin. Item 16. The lid according to any one of items 13 to 15, wherein the resin of the bonding layer has functional groups that can react with the curing agent. Item 17. The lid according to any one of items 13 to 16, wherein the thickness of the bonding layer is thinner than the thickness of the covering. Item 18. The lid according to any one of items 13 to 17, wherein the bonding layer is a coating or film. Item 19. The lid according to any one of items 13 to 18, wherein the thickness of the bonding layer is in the range of 0.5 μm or more and 20 μm or less. Item 20. The lid according to any one of items 13 to 19, wherein the thickness of the bonding layer is in the range of 5 μm or more and 500 μm or less. Item 21. The lid body according to any one of items 13 to 20, wherein the lid body further comprises a surface treatment layer on at least a portion of the surface to be joined with the bonding layer. Item 22. The lid according to any one of items 13 to 21, wherein at least a portion of the surface of the lid body that is joined to the bonding layer shows a peak originating from the chromium compound Cr2p3 / 2 in the range of 576 eV to 581 eV as detected by X-ray photoelectron spectroscopy. Item 23. The lid according to any one of items 13 to 22, wherein at least a portion of the surface of the lid body that is joined to the joining layer is a rough surface. Item 24. The lid according to any one of items 13 to 23, wherein the curing agent comprises at least one selected from the group consisting of compounds having an isocyanate group, carbodiimide compounds, compounds having an oxazoline group, compounds having an epoxy group, glycidyl compounds, compounds having a carboxyl group, melamine compounds, phenolic resins, acid anhydrides, thiol compounds, compounds having an amine group, and urea compounds. Item 25. A lid body with a bonding layer, used as an outer casing for an energy storage device, A lid body made of a conductive material, The lid body and the covering body that covers a part of the lid body are joined together by a joining layer, The lid body with a bonding layer is formed by a cured product of a resin composition containing a resin and a curing agent. Item 26. A method for manufacturing a lid used as an outer casing for an energy storage device, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed from a cured product of a resin composition containing a resin and a curing agent. A method for manufacturing a lid, comprising a joining step of joining the lid body and the covering via the joining layer. Item 27. The method for manufacturing a lid according to Item 26, wherein the bonding step includes a step of curing a resin composition comprising a resin and a curing agent that forms the bonding layer. Item 28. A method for manufacturing an energy storage device, The aforementioned energy storage device is Electrode body and The outer film enclosing the electrode body, The system comprises a lid that seals the electrode body together with the outer film, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering a part of the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed from a cured product of a resin composition containing a resin and a curing agent. A method for manufacturing an energy storage device, comprising the step of placing the cover on the electrode body. [Explanation of Symbols]

[0139] 10: Energy storage devices 20: Electrode body 30: Current collector 40: Exterior 50: Exterior film 60: Lid 70: Lid body 72X: Surface 80: Bonding layer 90: Covering body

Claims

1. Electrode body and The outer film enclosing the electrode body, The system comprises a lid that seals the electrode body together with the outer film, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, in an energy storage device.

2. The energy storage device according to claim 1, wherein the resin of the bonding layer has functional groups that can react with the curing agent.

3. The energy storage device according to claim 1, wherein the resin of the bonding layer comprises at least one of an acid-modified polyolefin and a polyolefin.

4. The energy storage device according to claim 1 or 2, wherein the basic framework of the resin material constituting the covering and the basic framework of the resin constituting the bonding layer are common.

5. The energy storage device according to claim 1 or 2, wherein the thickness of the bonding layer is thinner than the thickness of the coating.

6. The energy storage device according to claim 1 or 2, wherein the bonding layer is a coating or film.

7. The energy storage device according to claim 1 or 2, wherein the thickness of the bonding layer is in the range of 0.5 μm or more and 20 μm or less.

8. The energy storage device according to claim 1 or 2, wherein the thickness of the bonding layer is in the range of 5 μm or more and 500 μm or less.

9. The energy storage device according to claim 1 or 2, wherein the lid body further comprises a surface treatment layer on at least a portion of the surface to be joined with the bonding layer.

10. The energy storage device according to claim 1 or 2, wherein at least a portion of the surface of the lid body that is joined to the bonding layer shows a peak originating from the chromium compound Cr2p3 / 2 in the range of 576 eV to 581 eV, as detected by X-ray photoelectron spectroscopy.

11. The energy storage device according to claim 1 or 2, wherein at least a portion of the surface of the lid body that is joined to the joining layer is a rough surface.

12. The energy storage device according to claim 1 or 2, wherein the curing agent comprises at least one selected from the group consisting of compounds having an isocyanate group, carbodiimide compounds, compounds having an oxazoline group, compounds having an epoxy group, glycidyl compounds, compounds having a carboxyl group, melamine compounds, phenolic resins, acid anhydrides, thiol compounds, compounds having an amine group, and urea compounds.

13. A lid used as an outer casing for an energy storage device, A lid body made of a conductive material, A covering body comprising a resin material and covering a part of the lid body, It has a bonding layer that joins the lid body and the covering, The aforementioned bonding layer is formed of a cured product of a resin composition containing a resin and a curing agent, and is a lid.

14. The lid according to claim 13, wherein the resin of the bonding layer has functional groups that can react with the curing agent.

15. The lid according to claim 13 or 14, wherein the resin comprises at least one of an acid-modified polyolefin and a polyolefin.

16. The lid according to claim 13 or 14, wherein the resin of the bonding layer has functional groups that can react with the curing agent.

17. The lid according to claim 13 or 14, wherein the thickness of the bonding layer is thinner than the thickness of the covering.

18. The lid according to claim 13 or 14, wherein the bonding layer is a coating or film.

19. The lid according to claim 13 or 14, wherein the thickness of the bonding layer is in the range of 0.5 μm or more and 20 μm or less.

20. The lid according to claim 13 or 14, wherein the thickness of the bonding layer is in the range of 5 μm or more and 500 μm or less.

21. The lid body according to claim 13 or 14, wherein the lid body further comprises a surface treatment layer on at least a portion of the surface to be joined with the bonding layer.

22. The lid according to claim 13 or 14, wherein at least a portion of the surface of the lid body that is joined to the bonding layer shows a peak originating from the chromium compound Cr2p3 / 2 in the range of 576 eV to 581 eV when analyzed by X-ray photoelectron spectroscopy.

23. The lid according to claim 13 or 14, wherein at least a portion of the surface of the lid body that is joined to the joining layer is a rough surface.

24. The lid according to claim 13 or 14, wherein the curing agent comprises at least one selected from the group consisting of compounds having an isocyanate group, carbodiimide compounds, compounds having an oxazoline group, compounds having an epoxy group, glycidyl compounds, compounds having a carboxyl group, melamine compounds, phenolic resins, acid anhydrides, thiol compounds, compounds having an amine group, and urea compounds.

25. A lid body with a bonding layer, used as an outer casing for an energy storage device, A lid body made of a conductive material, The lid body and the covering body that covers a part of the lid body are joined together by a joining layer, The lid body with a bonding layer is formed by a cured product of a resin composition containing a resin and a curing agent.

26. A method for manufacturing a lid used as an outer casing for an energy storage device, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed from a cured product of a resin composition containing a resin and a curing agent. A method for manufacturing a lid, comprising a joining step of joining the lid body and the covering via the joining layer.

27. The method for manufacturing a lid according to claim 26, wherein the bonding step includes a step of curing a resin composition that includes a resin and a curing agent for forming the bonding layer.

28. A method for manufacturing an energy storage device, The aforementioned energy storage device is Electrode body and The outer film enclosing the electrode body, The system comprises a lid that seals the electrode body together with the outer film, The aforementioned cover is A lid body made of a conductive material, A covering body comprising a resin material and covering a part of the lid body, It has a bonding layer that joins the lid body and the covering, The bonding layer is formed from a cured product of a resin composition containing a resin and a curing agent. A method for manufacturing an energy storage device, comprising the step of placing the cover on the electrode body.

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