Energy storage device, lid, lid unit

Abstract

A power storage device according to the present invention comprises an electrode body and an exterior body that seals the electrode body. The exterior body includes: an exterior film that wraps around the electrode body such that an opening is formed; and a lid body that is placed on the opening. The electrode body includes a corner section at which an R surface is formed, the lid body includes a corner section at which an R surface is formed, and the absolute value of the difference between the radius of curvature of the corner section of the electrode body and the radius of curvature of the corner section of the lid body is 10 mm or less.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an example of a power storage device. This power storage device includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body such that an opening is formed, and a lid body disposed at the opening. The exterior film and the lid body are joined.

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, there may be cases where corner portions having an R surface are formed on the electrode body and the lid body. In such a case, if the shapes of the corner portions of the electrode body and the lid body are significantly different, the exterior film may not follow the electrode body, and there is a risk that the adhesion between the exterior film and the electrode body may decrease.

[0005] An object of the present invention is to provide a power storage device that can suitably hold an electrode body with an exterior film, a lid body used for this power storage device, and a lid unit including this lid body.

Means for Solving the Problems

[0006] A first aspect of the present invention relates to an energy storage device comprising an electrode body and an outer casing that seals the electrode body, wherein the outer casing includes an outer film that encloses the electrode body such that an opening is formed, and a lid that is disposed in the opening, wherein the electrode body has corners with R surfaces, the lid has corners with R surfaces, and the absolute difference between the radius of curvature of the corners of the electrode body and the radius of curvature of the corners of the lid is 10 mm or less.

[0007] A second aspect of the present invention relates to a first aspect of the present invention, wherein the radius of curvature of the corner of the cover is smaller than the radius of curvature of the corner of the electrode body.

[0008] A third aspect of the present invention relates to a power storage device according to the first or second aspect, wherein the radius of curvature of the corner of the cover is 0.05 mm or more.

[0009] A fourth aspect of the present invention is an energy storage device relating to any one of the first to third aspects, wherein the corner of the cover and the corner of the electrode body face each other.

[0010] A lid according to a fifth aspect of the present invention is a lid used as an exterior body for an energy storage device, having at least one corner on which an R-surface is formed, wherein the radius of curvature of the corner is 20 mm or less.

[0011] A lid unit according to the sixth aspect of the present invention comprises a lid according to the fifth aspect and an electrode terminal joined to the lid. [Effects of the Invention]

[0012] According to the present invention, the energy storage device, the lid used in this energy storage device, and the lid unit equipped with this lid, the electrode body can be suitably held by the outer film. [Brief explanation of the drawing]

[0013] [Figure 1A] A perspective view of the energy storage device according to the embodiment. [Figure 1B] A diagram related to a method for measuring the sealing strength of the second sealing portion of the power storage device in FIG. 1A. [Figure 2] A perspective view showing the outer shape of the electrode body included in the power storage device of FIG. 1A. [Figure 3] A diagram showing the outer shape of the front surface of the electrode body in FIG. 2. [Figure 4] A cross-sectional view showing the layer structure of the exterior film included in the power storage device of FIG. 1A. [Figure 5] A diagram of the state where the exterior film included in the power storage device of FIG. 1A is spread out. [Figure 6] A cross-sectional view along the D6-D6 line in FIG. 1A. [Figure 7] A side view of the lid body with the exterior film in FIG. 6 omitted. [Figure 8] A plan view of the lid body with the exterior film in FIG. 6 omitted. [Figure 9] A flowchart showing an example of the manufacturing process of the power storage device of FIG. 1A. [Figure 10] A cross-sectional view of the lid body included in the power storage device of the modified example. [Figure 11] A cross-sectional view of the lid body included in the power storage device of another modified example.

Mode for Carrying Out the Invention

[0014] Hereinafter, a power storage device according to an embodiment of the present invention will be described while referring 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.

[0015] [1. Embodiment] <1-1. Configuration of Power Storage Device> FIG. 1A is a plan view schematically showing a power storage device 10 according to the first embodiment. FIG. 1B is a diagram regarding a method of measuring the seal strength of a second sealing portion 80 of the power storage device 10. FIG. 2 is a perspective view showing an outer shape of an electrode body 20 included in the power storage device 10 of FIG. 1A. FIG. 3 is a diagram showing an outer shape of a front surface of the electrode body 20 of FIG. 2. FIG. 4 is a cross-sectional view showing a layer configuration of an exterior film 50 included in the power storage device 10 of FIG. 1A. FIG. 5 is a view of the exterior film 50 included in the power storage device 10 of FIG. 1A in a spread state. FIG. 6 is a cross-sectional view taken along line D6-D6 of FIG. 1A. FIG. 7 is a side view of a lid body 60 included in the power storage device 10 of FIG. 1A. FIG. 8 is a plan view of the lid body 60 of FIG. 7. In FIG. 1A, the direction of arrow UD indicates the thickness direction of the power storage device 10, the direction of arrow LR indicates the width direction of the power storage device 10, and the direction of arrow FB indicates the depth direction of the power storage device 10. The directions indicated by each of arrows UDLRFB are common in each of the subsequent figures.

[0016] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes, for example, electrodes (a positive electrode and a negative electrode) constituting a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid-state battery, a quasi-solid-state battery, a polymer battery, an all-resin battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator or the like. In the present embodiment, the shape of the electrode body 20 is substantially a rectangular parallelepiped. Note that the "substantially rectangular parallelepiped" includes a solid that can be regarded as a rectangular parallelepiped by modifying a part of the shape of the outer surface in addition to a perfect rectangular parallelepiped. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0017] As shown in Figure 2, in this embodiment, the electrode body 20 has a front surface 21, a back surface 22, an upper surface 23, a lower surface 24, a first side surface 25, and a second side surface 26. The front surface 21 faces one of the lids 60. The back surface 22 faces the other lid 60. The upper surface 23 constitutes one of a pair of first surfaces 41 of the outer casing 40, which will be described later. The lower surface 24 constitutes the other of a pair of first surfaces 41 of the outer casing 40, which will be described later. The first side surface 25 constitutes one of a pair of second surfaces 42 of the outer casing 40, which will be described later. The second side surface 26 constitutes the other of a pair of second surfaces 42 of the outer casing 40, which will be described later.

[0018] As shown in Figure 3, the electrode body 20 has corners 20A, 20B, 20C, and 20D. Corners 20A, 20B, 20C, and 20D have rounded edges (R-shaped). Corner 20A is formed at the boundary between the upper surface 23 and the first side surface 25. Corner 20B is formed at the boundary between the upper surface 23 and the second side surface 26. Corner 20C is formed at the boundary between the first side surface 25 and the lower surface 24. Corner 20D is formed at the boundary between the second side surface 26 and the lower surface 24. Note that in Figure 2, the shape of the rounded edges of corners 20A to 20D is omitted for the sake of simplicity.

[0019] In this embodiment, the energy storage device 10 is equipped with two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting power to the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from, for example, the edge of the outer casing 40. Note that the electrode terminals 30 only need to be able to input and output power to the electrode body 20, and do not need to protrude from, for example, the outer casing 40. If the cover 60, which will be described later, is made of metal, for example, the cover 60 may also function as an electrode terminal 30, and in this case, the cover 60 that functions as an electrode terminal may or may not protrude from the outer casing 40.

[0020] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, or copper. For example, if the electrode body 20 is a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum, and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, or the like. The outermost layer of the electrode body 20 does not necessarily have to be an electrode; for example, it may be a protective tape or a separator.

[0021] 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 so as to have an opening 40A. In this embodiment, the outer film 50 is wrapped around the electrode body 20 so as to have an opening 40A. The lid 60 is positioned to the side of the electrode body 20 so as to close the opening 40A. Alternatively, the electrode body 20 may be housed inside the outer film 50, which is configured in a cylindrical shape so as to form the opening 40A, and the opening 40A may be closed by the lid 60.

[0022] From the viewpoint of suitably adhering to the lid 60, it is preferable that an adhesive film 31 is bonded to the electrode terminal 30. The adhesive film 31 can be arbitrarily selected as long as it is a film that can bond the electrode terminal 30, which is made of metal, to the lid 60, which is made of resin. For example, the adhesive film 31 can be made of polyethylene resin, polyolefin resin such as polypropylene resin, cyclic polyolefin resin, or acid-modified polyolefin resin obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or a film of two or more layers. In this embodiment, the adhesive film 31 is bonded to approximately the entire portion of the electrode terminal 30 that is covered by the lid 60.

[0023] 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.

[0024] As shown in Figure 4, 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. The outer film 50 may also be laminated in the order of heat-sealable resin layer 53, base layer 51, barrier layer 52, and heat-sealable resin layer 53. The outer film 50 may also be laminated in the order of heat-sealable resin layer 53, barrier layer 52, and heat-sealable resin layer 53. The outermost layer and the innermost layer of the outer film 50 may be joined to form the first sealing portion 70, which will be described later. Note that the outer film 50 does not need to include all of these layers; for example, the barrier layer 52 may not be included. That is, the outer film 50 only needs to be made of a flexible and easily bendable material, for example, it may be made of a resin film. It is preferable that the outer film 50 is heat-sealable.

[0025] 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 or a biaxially oriented polybutylene terephthalate (PBT) film, and the stretched polyamide resin layer is more preferably a biaxially oriented nylon (ONy) film. The base layer 51 may also 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 20 to 150 μm, from the viewpoint of film strength.

[0026] 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, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as the barrier layer 52. Multiple layers of the 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.

[0027] 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) and is not recycled material.

[0028] 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. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments. From the viewpoint of improving the mechanical strength of the outer film 50, it is more preferable that the aluminum alloy foil be 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.

[0029] 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 or conformability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0030] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0031] 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 9 to 200 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 52 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Furthermore, preferred ranges for the thickness of the barrier layer 52 include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above range is particularly preferred. Furthermore, from the viewpoint of providing the outer film 50 with high formability 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 is preferred 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, the increased rigidity of the outer film 50 allows for suitable wrapping of the outer film 50 around the electrode body 20. Furthermore, while increasing the capacity of the energy storage device increases its weight, improving the rigidity of the outer film 50 contributes to the high airtightness 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.

[0032] 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.

[0033] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 during the molding or winding of the outer film 50, prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride produced by the reaction of electrolytes and moisture, 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.

[0034] 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 the heat-sealable resin layer 53 include 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.

[0035] 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.

[0036] 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.

[0037] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and still more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 1 mm to 10 mm, 1 mm to 5 mm, 1 mm to 2 mm, 0.5 mm to 10 mm, 0.5 mm to 5 mm, and 0.5 mm to 2 mm.

[0038] 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.

[0039] The lid 60 is, for example, rectangular in shape and is made of, for example, a resin material. The lid 60 may also be a metal molded product. The material constituting the lid 60 may include at least two of the following materials: metal oxides, carbon materials, and rubber materials.

[0040] The lid 60 is preferably made up of a resin material. Here, "made up of a resin material" means that when the total mass of the materials constituting the lid 60 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 lid 60 may contain materials other than resin materials in addition to resin materials.

[0041] 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. The resin material may also 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, and more preferably polyolefin. When the resin material is a resin, the lid 60 may be molded by any molding method.

[0042] 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.

[0043] 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.

[0044] The resin material may contain fillers as needed. Specific examples of fillers include glass beads, graphite, glass fibers, and carbon fibers. By including the above-mentioned fillers in the resin material, the deformation resistance of the lid 60 to temperature changes can be improved.

[0045] The melt mass flow rate of the resin material contained in the material constituting the lid 60 is preferably in the range of 1 g / 10 min to 80 g / 10 min, and more preferably in the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured according to JIS K7210-1:2014.

[0046] The lid 60 may be made up of a conductive material. "Made up of a conductive material" means that when the total mass of the materials constituting the lid 60 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 60 may contain materials other than conductive materials in addition to conductive materials.

[0047] The conductive material constituting the cover 60 is, for example, a metallic material. The metallic material constituting the cover 60 is, for example, aluminum, aluminum alloy, nickel, copper, or copper alloy. For example, if the electrode body 20 is a lithium-ion battery, the cover 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The cover 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the cover 60 connected to the negative electrode may be copper with nickel plating. The material constituting the cover 60 may also include recycled metallic material. If the cover 60 is made of a conductive material, the cover 60 also functions as an electrode terminal 30. Since the electrode terminal 30 can be omitted from the energy storage device 10, the configuration of the energy storage device 10 can be simplified.

[0048] If the lid 60 is made of a conductive material, the lid 60 may be joined to the outer film 50 via an adhesive film. The adhesive film can be arbitrarily selected as long as it is a film that can adhere the outer film 50 and the lid 60. Preferably, the adhesive film is a laminated film having at least a heat-fusible resin layer, a heat-resistant substrate layer, and a heat-fusible resin layer in this order. The specifications for the heat-fusible resin layer of the adhesive film can be the same as those for the heat-fusible resin layer 53. The materials constituting the heat-fusible resin layers on both sides of the adhesive film may be the same material or different materials, and are appropriately selected in accordance with the materials constituting the heat-fusible resin layer 53 of the outer film 50 and the materials constituting the lid 60. Preferably, the material constituting the heat-fusible resin layer on the side of the adhesive film that is adhered to the lid 60 is an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. It is preferable that the heat-sealable resin layer of the adhesive film that is bonded to the outer film 50 is made of the same material as the material that constitutes the heat-sealable resin layer 53 of the outer film 50.

[0049] The heat-resistant base layer can be any film made of a heat-resistant resin. For example, unstretched or stretched films of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, etc. can be used. Polyethylene terephthalate is particularly preferred because it is inexpensive and strong.

[0050] The adhesive film preferably has adhesive properties. When the second sealing portion 80, described later, is formed with the adhesive film positioned between the outer film 50 and the lid 60, the position of the adhesive film relative to the lid 60 and the outer film 50 is less likely to shift. Adhesion can be imparted to the adhesive film by incorporating an adhesive-imparting resin into the heat-fusible resin layer of the adhesive film. Examples of adhesive-imparting resins include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene, or copolymers of amorphous propylene and other α-olefins. The content of the adhesive-imparting resin relative to the base material constituting the heat-fusible resin is preferably 10 to 20% by weight or less.

[0051] The lid 60 has a lid body 60A. The lid body 60A has a first surface 61, a second surface 62, and a lid sealing portion 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface opposite to the first surface 61. The lid sealing portion 63 is connected to the first surface 61 and the second surface 62 and is heat-sealed to the heat-sealable resin layer 53 of the outer film 50. The lid sealing portion 63 includes a first sealing surface 63A, a second sealing surface 63B, a third sealing surface 63C, and a fourth sealing surface 63D. The first sealing surface 63A constitutes the upper surface of the lid 60. In a front view of the lid 60, the first sealing surface 63A extends in a first direction (in this embodiment, the L-R direction). The second sealing surface 63B and the third sealing surface 63C are connected to the first sealing surface 63A and constitute the side surface of the lid 60. The second sealing surface 63B and the third sealing surface 63C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction in a front view of the lid 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 63D constitutes the lower surface of the lid 60. The fourth sealing surface 63D extends in a first direction (in this embodiment, the LR direction) in a front view of the lid 60.

[0052] The lid seal portion 63 further includes corners 64, 65, 66, and 67. Corner 64 is formed including the boundary between the first seal surface 63A and the second seal surface 63B. Corner 65 is formed including the boundary between the first seal surface 63A and the third seal surface 63C. Corner 66 is formed including the boundary between the fourth seal surface 63D and the second seal surface 63B. Corner 67 is formed including the boundary between the fourth seal surface 63D and the third seal surface 63C. Corners 65 to 67 have rounded edges. Therefore, deformation of the outer casing 40, such as the formation of wrinkles in the outer film 50, is suppressed during the manufacturing process of the energy storage device 10 or when the finished energy storage device 10 is vacuumed. Also, compared to the case where corners 65 to 67 are right angles, external impacts are less likely to act on corners 65 to 67. Therefore, damage to the outer casing 40 is suppressed. Note that in Figure 1, the shape of the rounded corners 65-67 has been omitted for the sake of simplifying the drawing.

[0053] Corner 64 faces corner 20A of the electrode body 20. Corner 65 faces corner 20B of the electrode body 20. Corner 66 faces corner 20C of the electrode body 20. Corner 67 faces corner 20D of the electrode body 20.

[0054] If 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, if the lid 60 is plate-shaped, it is preferable that the sealing surfaces 63A, 63B, 63C, 63D of the lid 60 have a certain thickness so as to allow for suitable heat sealing of the sealing surfaces 63A, 63B, 63C, 63D of the lid 60 with the outer casing film 50 when forming the second sealing portion 80 described later. The minimum thickness of the lid 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum thickness of the lid 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum thickness of the lid 60 may be 20 mm or more. The preferred thickness ranges for the material constituting 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-like, the lid 60 does not include the form in which it is composed solely of film as defined by the JIS (Japanese Industrial Standards) [Packaging Terminology] standard. The thickness of the lid 60 may vary depending on the part of the lid 60. If the thickness of the lid 60 varies depending on the part, the thickness of the lid 60 is the thickness of the thickest part.

[0055] From the viewpoint of suitably heat-sealing the lid 60 and the outer film 50, it is preferable that the main material of the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 of the outer film 50 are the same. In this embodiment, examples of materials constituting the lid 60 include polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polyolefin resins such as polyethylene resin, fluororesin and polypropylene resin, cyclic polyolefin resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. From the viewpoint of suitably heat-sealing the lid 60 and the outer film 50, it is preferable that the main material of the material constituting the lid 60 and the material constituting the heat-sealable resin layer 53 of the outer film 50 are the same. In this embodiment, the main materials for the lid 60 and the heat-sealable resin layer 53 are, for example, polyethylene resins, polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The main material refers to, for example, a material that accounts for 50% or more of the materials included in the constituent elements.

[0056] In this embodiment, the cover 60 has a through hole 60X into which the electrode terminal 30 is inserted. The through hole 60X penetrates the first surface 61 and the second surface 62. When the electrode body 20 is encased in the outer film 50, the electrode terminal 30 protrudes to the outside of the outer casing 40 through the through hole 60X formed in the cover 60. The small gap between the through hole 60X in the cover 60 and the electrode terminal 30 is filled with, for example, resin. In the energy storage device 10, the position in which the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude to the outside through a hole formed in any of the six surfaces of the outer casing 40. In this case, the small gap between the outer casing 40 and the electrode terminal 30 is filled with, for example, resin. In another example, the electrode terminals 30 may protrude from the outside of the outer casing 40 through the gap between the sealing surfaces 63A, 63B, 63C, 63D of the cover 60 and the outer film 50. In this case, the cover 60 does not need to have through holes 60X. In the energy storage device 10, the cover 60 and the electrode terminals 30 are provided as separate parts, but the cover 60 and the electrode terminals 30 may be formed integrally. Furthermore, even if the electrode terminals 30 do not protrude from the edge of the outer casing 40, the cover 60 does not need to have through holes 60X.

[0057] In this embodiment, the first sealing portion 70 is formed when the outer film 50 is wrapped around the electrode body 20 so as to have an opening 40A, and the opposing surfaces of the outer film 50 (heat-fusible resin layers 53) are heat-sealed together.

[0058] The first sealing portion 70 is formed by heat sealing the portion of the outer film 50 shown in Figure 5 that includes the first edge 50A and the portion that includes the second edge 50B. The first sealing portion 70 extends in the longitudinal direction (FB direction) of the outer body 40. The position in the outer body 40 where the first sealing portion 70 is formed can be arbitrarily selected. In this embodiment, it is preferable that the base 70X of the first sealing portion 70 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 70X of the first sealing portion 70 may be located on any surface of the outer body 40. In this embodiment, the first sealing portion 70 protrudes outward from the electrode body 20 in a plan view. The first sealing portion 70 may be folded toward the second surface 42 of the outer body 40, or it may be folded toward the first surface 41.

[0059] In this embodiment, the second sealing portion 80 is formed by heat sealing the heat-fusible resin layer 53 of the outer film 50 and the lid sealing portion 63 of the lid 60. Hereinafter, the sealing strength between the heat-fusible resin layer 53 of the outer film 50 and the lid sealing portion 63 of the lid 60 may be referred to as the sealing strength of the second sealing portion 80. The sealing strength of the second sealing portion 80 is the sealing strength between the heat-fusible resin layer 53 and the lid 60 in the long side portion of the lid sealing portion 63, that is, the portion of the lid sealing portion 63 extending in the LR (width) direction in Figure 1A.

[0060] The seal strength of the second sealing section 80 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 80. 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). In this embodiment, the seal strength of the second sealing portion 80 is the average value of the seal strengths of the strip members 41X, 41Y, and 41Z. 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 less than 15 mm are formed, and the seal 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 seal strengths are each divided by the arbitrary width X mm and multiplied by 15 to convert them to the seal strengths of the three strip members at a width of 15 mm. The seal strength of the second sealing portion 80 is the average value of the seal strengths of the three strip members converted to a width of 15 mm. Note that if the lid 60 is divided into multiple parts including the long side and the short side, the seal strength of the second sealing portion 80 is the seal strength of the long side portion of the lid sealing portion 63 of the multiple parts.

[0061] 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 80 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 80 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 several years (less than 10 years). When the seal strength of the second sealing portion 80 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 more than 10 years. The seal strength of the second sealing portion 80 is preferably 300 N / 15 mm or less. The preferred range for the seal strength of the second sealing portion 80 is 40N / 15mm to 300N / 15mm, 50N / 15mm to 300N / 15mm, 60N / 15mm to 300N / 15mm, 70N / 15mm to 300N / 15mm, or 85N / 15mm to 300N / 15mm.

[0062] In this embodiment, the lid 60 has a protruding portion 68 that extends from the lid sealing portion 63 so that a gap is less likely to form between the outer film 50 and the lid 60. The protruding portion 68 may be formed integrally with the lid body 60A, or it may be formed separately from the lid body 60A and joined to the lid body 60A. In this embodiment, the protruding portion 68 is formed integrally with the lid body 60A. The position in the lid sealing portion 63 where the protruding portion 68 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 70X of the first sealing portion 70 and the lid 60. In particular, when the base 70X of the first sealing portion 70 is located at the corners 64 to 67 of the lid 60, the resin filling between the base 70X of the first sealing portion 70 and the lid 60 tends to decrease. For this reason, it is preferable that the protruding portion 68 is formed in the lid sealing portion 63 at the location where the base 70X of the first sealing portion 70 is located. In this embodiment, the base 70X of the first sealing portion 70 is located at the corner 64 of the lid 60. Therefore, it is preferable that the protrusion 68 is formed at the corner 64 in the lid sealing portion 63. In this embodiment, the first sealing portion 70 is sealed with the protrusion 68 sandwiched between them. The protrusion 68 may be formed at least one of the first sealing surface 63A, the second sealing surface 63B, the third sealing surface 63C, the fourth sealing surface 63D, the corner 65, the corner 66, and the corner 67.

[0063] The shape of the protrusion 68 can be arbitrarily selected. In this embodiment, the shape of the protrusion 68 is plate-like. The thickness of the protrusion 68 can be arbitrarily selected. In this embodiment, the thickness of the protrusion 68 decreases as it moves away from the corner 64. In other words, the protrusion 68 has a tapered shape as it moves away from the corner 64. The thickness of the protrusion 68 may be constant, or it may increase as it moves away from the corner 64.

[0064] The direction in which the projection 68 extends can be arbitrarily selected. In this embodiment, the projection 68 extends along a first direction (the LR direction in this embodiment). The projection 68 may also extend along a second direction (the UD direction in this embodiment).

[0065] The length of the protrusion 68 can be arbitrarily selected within a range of less than or equal to the length of the first sealing portion 70. For example, the length of the protrusion 68 may be substantially equal to the length of the first sealing portion 70, or it may be 30% to 50% of the length of the first sealing portion 70.

[0066] If the shapes of the corners 20A to 20D of the electrode body 20 and the corners 65 to 67 of the cover body 60 differ significantly, more specifically, if the radius of curvature of the corners 20A to 20D and the radius of curvature of the corners 65 to 67 differ significantly, the outer film 50 may not conform to the electrode body 20, potentially reducing the adhesion between the outer film 50 and the electrode body 20. As a result, the electrode body 20 cannot be adequately held by the outer film 50.

[0067] In this embodiment, from the viewpoint of suitably holding the electrode body 20 with the outer film 50, the absolute value of the difference between the radius of curvature of any corner 20A to 20D of the electrode body 20 and the radius of curvature of any corner 65 to 67 of the lid 60 is 10 mm or less. More preferably, the absolute value of the difference between the radius of curvature of any corner 20A to 20D of the electrode body 20 and the radius of curvature of any corner 65 to 67 of the lid 60 is 5 mm or less, and even more preferably 3 mm or less. In this embodiment, the radius of curvature of the corners 20A to 20D of the electrode body 20 includes the radius of curvature of the corners 20A to 20D that appear on the exterior of the outer film 40 when the electrode body 20 is wrapped in the outer film 50.

[0068] In this embodiment, the radius of curvature of the corners 20A to 20D is measured at a position close to the cover 60 of the electrode body 20. The radius of curvature of the corners 20A to 20D is a measured value obtained by wrapping the outer film 50 around the outer surface of the electrode body 20 so that it is in contact with the outer surface of the electrode body 20 while tension is applied to the outer film 50, and measuring it with an R gauge.

[0069] From the viewpoint of more effectively holding the electrode body 20 with the outer film 50, it is preferable that the absolute value of the difference in the radius of curvature of opposing corners among the corners 20A to 20D of the electrode body 20 and the corners 65 to 67 of the cover body 60 be 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. That is, it is preferable that the absolute value of the difference between the radius of curvature of corner 20B of the electrode body 20 and the radius of curvature of corner 65 of the cover body 60 be 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. It is preferable that the absolute value of the difference between the radius of curvature of corner 20C of the electrode body 20 and the radius of curvature of corner 66 of the cover body 60 be 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. The absolute value of the difference between the radius of curvature of the corner 20D of the electrode body 20 and the radius of curvature of the corner 67 of the cover body 60 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0070] Furthermore, if the radius of curvature of any corner 65-67 of the lid 60 is greater than the radius of curvature of any corner 20A-20D of the electrode body 20, the circumference of the outer film 50 joined to the lid 60 will be longer than the circumference of the electrode body 20, which may reduce the adhesion between the outer film 50 and the electrode body 20. For this reason, the outer film 50 may not be able to adequately hold the electrode body 20.

[0071] Therefore, it is preferable that the radius of curvature of any corner 65 to 67 of the lid 60 is smaller than the radius of curvature of any corner 20A to 20D of the electrode body 20. From the viewpoint of more favorably holding the electrode body 20 with the outer film 50, it is preferable that the radius of curvature of the corners 65 to 67 of the lid 60 is smaller than the radius of curvature of the opposing corners 20A to 20D of the electrode body 20. That is, it is preferable that the radius of curvature of corner 65 of the lid 60 is smaller than the radius of curvature of corner 20B of the electrode body 20. It is preferable that the radius of curvature of corner 66 of the lid 60 is smaller than the radius of curvature of corner 20C of the electrode body 20. It is preferable that the radius of curvature of corner 67 of the lid 60 is smaller than the radius of curvature of corner 20D of the electrode body 20.

[0072] The radius of curvature of at least one corner 65-67 of the lid 60 can be arbitrarily selected as long as the absolute value of the difference between it and the radius of curvature of any corner 20A-20D of the electrode body 20 is 10 mm or less. From the viewpoint of suppressing an increase in the circumference of the outer film 50, it is preferable that the radius of curvature of at least one corner 65-67 of the lid 60 is 10 mm or less. From the viewpoint of suitably forming corners 65-67 having R surfaces on the lid 60, and from the viewpoint of improving the adhesion between the outer film 50 and the lid 60, it is preferable that the radius of curvature of at least one corner 65-67 of the lid 60 is 0.05 mm or more. From the viewpoint of suppressing a large difference in shape from the corners 20A-20D of the electrode body 20, it is preferable that the radius of curvature of at least one corner 65-67 is 20 mm or less. The preferred range for the radius of curvature of at least one corner 65-67 of the lid 60 is 0.05 mm to 20 mm.

[0073] In the LR direction, the ratio of the portion of the cover 60 with the largest outer diameter to the portion of the electrode body 20 with the largest outer diameter is preferably ±10% or less. In the UD direction, the ratio of the portion of the cover 60 with the largest outer diameter to the portion of the electrode body 20 with the largest outer diameter is preferably ±10% or less.

[0074] <1-2. Method for manufacturing energy storage devices> Figure 9 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, a sixth step, and a seventh step. Steps 1 through 7 are carried out, for example, by a manufacturing apparatus for the energy storage device 10. Note that steps 1 through 7 are names that are conveniently defined for each step of the method for manufacturing the energy storage device 10, and do not necessarily indicate the order of the steps.

[0075] In the first step of step S11, the manufacturing apparatus joins the lid 60 and the electrode terminals 30. Upon completion of the second step, a pair of lid units 60Z are completed, with the electrode terminals 30 joined to the lid 60.

[0076] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus places a pair of lid units 60Z to the side of the electrode body 20 and joins the electrode terminals 30 to the electrode body 20. Alternatively, the manufacturing method of the energy storage device 10 may include a step in which the electrode body 20 and the electrode terminals 30 are joined first, and the lid 60 is joined to the electrode terminals 30 joined to the electrode body 20, instead of the first and second steps.

[0077] Step S13, the third step, is performed after the second step. In the third step, the manufacturing apparatus wraps the outer film 50 around the electrode body 20 and the lid 60. In the third 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.

[0078] Step S14, the fourth step, is performed after the third step. In the fourth step, the manufacturing apparatus forms a first sealing portion (hereinafter referred to as the "provisional first sealing portion") in which an unsealed portion for injecting electrolyte is formed. In the provisional first sealing portion, the heat-sealable resin layers 53 of the outer film 50 are joined together with the protruding portion 68 of the lid 60 sandwiched between the outer film 50. If the energy storage device 10 is, for example, an all-solid-state battery, the step of injecting electrolyte is not necessary, so in the fourth step, the manufacturing apparatus forms a first sealing portion 70.

[0079] Step S15, the fifth step, is performed after the fourth step. In the fifth step, the manufacturing apparatus forms the second sealing portion 80 by, for example, heat sealing the heat-fusible resin layer 53 of the outer film 50 and the lid sealing portion 63 of the lid 60. Preferably, the fifth step includes a first sealing step and a second sealing step. In the first sealing step, the manufacturing apparatus heat seals the first sealing surface 63A, the second sealing surface 63B, the third sealing surface 63C, the fourth sealing surface 63D of the lid sealing portion 63, and the protruding portion 68 including the corner portion 64, with the outer film 50. The second sealing step is performed after the first sealing step. In the second sealing step, the manufacturing apparatus heat seals the corner portions 65-67 with the outer film 50. Preferably, in the second sealing step, a heat sealing bar having the same radius of curvature as the R surface of the corner portions 65-67 is used.

[0080] Step S16, the sixth step, is performed after step 5. In step 6, the manufacturing apparatus injects the electrolyte through the unsealed portion formed in the temporary first sealing portion.

[0081] Step S17, the seventh step, is performed after step 6. In step 7, the manufacturing apparatus forms the first sealing portion 70 by heat sealing the portion of the temporary first sealing portion that includes the unsealed portion. Note that if the energy storage device 10 is, for example, an all-solid-state battery, steps 6 and 7 are omitted.

[0082] <1-3. Effects of Energy Storage Devices> In the energy storage device 10, the absolute difference between the radius of curvature of any corner 20A to 20D of the electrode body 20 and the radius of curvature of any corner 65 to 67 of the cover body 60 is 10 mm or less, so the outer film 50 can easily follow the electrode body 20. For this reason, the electrode body 20 can be suitably held by the outer film 50.

[0083] [2. Variant] The embodiments described above are illustrative of possible forms of the energy storage device and cover according to the present invention, and are not intended to limit their forms. The energy storage device and cover according to the present invention may take forms different from those illustrated in the embodiments. One example is a form in which some of the configurations of the embodiments are replaced, modified, or omitted, or a form in which new configurations are added to the embodiments. 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.

[0084] <2-1> In the above embodiment, the lid 60 may omit the protruding portion 68. In this modified example, from the viewpoint of suitably forming the first sealing portion 70, it is preferable that the corner portion 64 is substantially right-angled.

[0085] In another example, if the protrusion 68 is omitted from the lid 60, a rounded surface may be formed on the corner 64. From the viewpoint of suitably holding the electrode body 20 with the outer film 50, the absolute value of the difference between the radius of curvature of any corner 20A to 20D of the electrode body 20 and the radius of curvature of the corner 64 of the lid 60 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0086] From the viewpoint of more favorably holding the electrode body 20 with the outer film 50, the absolute value of the difference between the radius of curvature of the corner portion 20A of the electrode body 20 and the radius of curvature of the corner portion 64 of the lid 60 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0087] Furthermore, if the radius of curvature of the corner 64 of the lid 60 is greater than the radius of curvature of any corner 20A to 20D of the electrode body 20, the circumference of the outer film 50 joined to the lid 60 will be longer than the circumference of the electrode body 20, which may reduce the adhesion between the outer film 50 and the electrode body 20. For this reason, the electrode body 20 cannot be properly held in the outer film 50.

[0088] Therefore, it is preferable that the radius of curvature of the corner 64 of the lid 60 is smaller than the radius of curvature of any corner 20A to 20D of the electrode body 20. From the viewpoint of more favorably holding the electrode body 20 with the outer film 50, it is preferable that the radius of curvature of the corner 64 of the lid 60 is smaller than the radius of curvature of corner 20A of the electrode body 20. However, the radius of curvature of the corner 64 of the lid 60 may be greater than or equal to the radius of curvature of any corner 20A to 20D of the electrode body 20.

[0089] The radius of curvature of the corners 64 of the lid 60 can be arbitrarily selected. From the viewpoint of suppressing an increase in the circumference of the outer film 50, it is preferable that the radius of curvature of the corners 64 of the lid 60 be 20 mm or less. From the viewpoint of suitably forming corners 64 with R surfaces on the lid 60, it is preferable that the radius of curvature of the corners 64 of the lid 60 be 0.05 mm or more. From the viewpoint of suppressing a large difference in shape from the corners 20A to 20D of the electrode body 20, it is preferable that the radius of curvature of the corners 64 be 20 mm or less. The preferred range for the radius of curvature of the corners 64 of the lid 60 is 0.05 mm or more and 20 mm or less.

[0090] <2-2> In the above embodiment, the relationship between the radius of curvature of any corner 65-67 of the lid 60 and the radius of curvature of any corner 20A-20D of the electrode body 20 can be arbitrarily changed. The radius of curvature of any corner 65-67 of the lid 60 may be greater than or equal to the radius of curvature of any corner 20A-20D of the electrode body 20.

[0091] <2-3> In the energy storage device 10 of the above embodiment, the direction in which the protrusion 68 extends can be arbitrarily changed. For example, as shown in Figure 10, the protrusion 68 may extend in a third direction that intersects the first direction (LR direction in the embodiment) and the second direction (UD direction in the embodiment) in a front view of the lid 60.

[0092] <2-4> In the energy storage device 10 of the above embodiment, the configuration of the lid 60 can be arbitrarily changed. As shown in Figure 11, the lid 60 may include a frame 60B that covers the lid body 60A. In this modified example, for example, the material constituting the lid body 60A can be any material such as metal, resin, or a composite material of metal and resin. The material constituting the frame 60B is, for example, a resin that can suitably seal with the heat-sealable resin layer 53 of the exterior film 50. In this modified example, the lid seal portion 63 and the protruding portion 68 of the lid 60 are formed on the frame 60B.

[0093] <2-5> In the energy storage device 10 of the above embodiment, the specific method for forming the protrusion 68 of the lid 60 can be arbitrarily changed. For example, the protrusion 68 may be formed by an adhesive film that is joined to the lid seal portion 63 of the lid body 60A. In this modified example, for example, the protrusion 68 may be formed by joining multiple adhesive films to the lid seal portion 63 in an overlapping manner, or the protrusion 68 may be formed by joining an adhesive film to the lid seal portion 63 in a flap-like manner.

[0094] <2-6> The energy storage device 10 of the above embodiment may have an adhesive film placed between the outer film 50 and the lid 60 in order to suitably bond the outer film 50 and the lid 60. In this modified example, for example, the lid 60 with the adhesive film attached is attached to the openings 40A at both ends of the outer body 40, after which the second sealing portion 80 is formed. The adhesive film is wrapped around the lid 60 so as to cover the entire surface of the lid sealing portion 63 of the lid 60. It is preferable that the adhesive film as a whole is wider than the lid sealing portion 63 of the lid 60. In this case, the adhesive film can be easily bonded to the lid 60. Furthermore, since the corners 64-67 of the lid sealing portion 63 are covered by the adhesive film, the adhesion between the lid 60 and the adhesive film is enhanced.

[0095] The adhesive film can be arbitrarily selected as long as it is a film that can adhere the outer film 50 and the lid 60. Preferably, the adhesive film is a laminated film having at least a heat-fusible resin layer, a heat-resistant substrate layer, and a heat-fusible resin layer in this order. The specifications for the heat-fusible resin layer of the adhesive film can be the same as the specifications for the heat-fusible resin layer 53. The materials constituting the heat-fusible resin layers on both sides of the adhesive film may be the same type of material or different materials, and are appropriately selected in accordance with the materials constituting the heat-fusible resin layer 53 of the outer film 50 and the materials constituting the lid 60. Preferably, the material constituting the heat-fusible resin layer on the side of the adhesive film that is adhered to the lid 60 is an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. Preferably, the heat-fusible resin layer on the side of the adhesive film that is adhered to the outer film 50 is the same type of material as the material constituting the heat-fusible resin layer 53 of the outer film 50.

[0096] The heat-resistant base layer can be any film made of a heat-resistant resin. For example, unstretched or stretched films of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, polypropylene, etc. can be used. Polyethylene terephthalate is particularly preferred because it is inexpensive and strong.

[0097] The adhesive film preferably has adhesive properties. When forming the second sealing portion 80 with the adhesive film positioned between the outer film 50 and the lid 60, the position of the adhesive film relative to the lid 60 and the outer film 50 is less likely to shift. Adhesion can be imparted to the adhesive film by incorporating an adhesive-imparting resin into the heat-fusible resin layer of the adhesive film. Examples of adhesive-imparting resins include amorphous polyolefins. Examples of amorphous polyolefins include amorphous polypropylene or copolymers of amorphous propylene and other α-olefins. The content of the adhesive-imparting resin relative to the base material constituting the heat-fusible resin is preferably 10 to 20% by weight or less.

[0098] <2-7> In the above embodiment, the position where the electrode terminals 30 are arranged can be arbitrarily selected. For example, the electrode terminals 30 may protrude from the first sealing portion 70. [Explanation of Symbols]

[0099] 10: Energy storage devices 20: Electrode body 20A, 20B, 20C, 20D: Corner 40: Exterior 40A: Opening 50: Exterior film 60: Lid 60Z: Lid Unit 64, 65, 66, 67: Corner

Claims

1. Electrode body and The electrode body is enclosed by an outer casing, The exterior body is, An outer film that encloses the electrode body so that an opening is formed, The lid is positioned in the opening, The electrode body is substantially a rectangular parallelepiped and has corners on which rounded surfaces are formed. The lid has corners with rounded surfaces, The absolute value of the difference between the radius of curvature of the corner of the electrode body and the radius of curvature of the corner of the cover is 5 mm or less. The radius of curvature of the corner of the electrode body is the radius of curvature of the corner that appears on the exterior of the outer film when the electrode body is wrapped in the outer film, and is measured with an R gauge at a position on the electrode body close to the lid, with tension applied to the outer film and the outer film wrapped around the outer surface of the electrode body in contact with it. Energy storage device.

2. The radius of curvature of the corner of the cover is smaller than the radius of curvature of the corner of the electrode body. The energy storage device according to claim 1.

3. The radius of curvature of the corner of the lid is 0.05 mm or more. The energy storage device according to claim 1 or 2.

4. The corner of the cover and the corner of the electrode body are opposite each other. The energy storage device according to claim 1 or 2.

5. The circumference of the cover is shorter than the circumference of the electrode body. The energy storage device according to claim 1 or 2.

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