Power storage device, lid body and lid unit

Abstract

To provide a power storage device, a lid body, and a lid unit in which an electrode body can be suitably held by an exterior film.SOLUTION: A power storage device includes an electrode body and an exterior body for sealing the electrode body, and the exterior body includes an exterior film for wrapping the electrode body such that an opening portion is formed, and a lid body to be placed on the opening portion. The electrode body has a corner portion having an R surface formed thereon, and the lid body has a corner portion having an R surface formed thereon. The absolute value of the difference between the radius of curvature of the corner portion of the electrode body and the radius of curvature of the corner portion of the lid body is 10 mm or less.SELECTED DRAWING: Figure 6

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 together.

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 a case where a corner portion having an R surface is formed on the electrode body and the lid body. In this 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 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 preferably 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] The power storage device according to the first aspect of the present invention includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body such that an opening is formed, and a lid body disposed at the opening. The electrode body has a corner portion where an R surface is formed, the lid body has a corner portion where an R surface is formed, and the absolute value of the difference between the radius of curvature of the corner portion of the electrode body and the radius of curvature of the corner portion of the lid body is 10 mm or less.

[0007] The power storage device according to the second aspect of the present invention is the power storage device according to the first aspect, wherein the radius of curvature of the corner portion of the lid body is smaller than the radius of curvature of the corner portion of the electrode body.

[0008] The power storage device according to the third aspect of the present invention is the power storage device according to the first aspect or the second aspect, wherein the radius of curvature of the corner portion of the lid body is 0.05 mm or more.

[0009] The power storage device according to the fourth aspect of the present invention is the power storage device according to any one of the first aspect to the third aspect, wherein the corner portion of the lid body and the corner portion of the electrode body face each other.

[0010] The lid body according to the fifth aspect of the present invention is a lid body used as an exterior body of a power storage device, and has at least one corner portion where an R surface is formed, and the radius of curvature of the corner portion is 20 mm or less.

[0011] The lid unit according to the sixth aspect of the present invention includes the lid body according to the fifth aspect and an electrode terminal joined to the lid body.

Advantages of the Invention

[0012] According to the power storage device, the lid body used in this power storage device, and the lid unit including this lid body of the present invention, the electrode body can be preferably held by the exterior film.

Brief Description of the Drawings

[0013]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a power storage device according to an embodiment of the present invention will be described with reference to the drawings. In this specification, the numerical range indicated by "~" means "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 the Power Storage Device> FIG. 1A is a plan view schematically showing the power storage device 10 of the first embodiment. FIG. 1B is a diagram regarding a method for measuring the seal strength of the second sealing portion 80 of the power storage device 10. FIG. 2 is a perspective view showing the outer shape of the electrode body 20 included in the power storage device 10 of FIG. 1A. FIG. 3 is a view showing the outer shape of the front surface of the electrode body 20 of FIG. 2. FIG. 4 is a cross-sectional view showing the layer configuration of the 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 an unfolded state. FIG. 6 is a cross-sectional view taken along line D6-D6 of FIG. 1A. FIG. 7 is a side view of the 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 the 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, as well as a separator and 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, 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, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0017] As shown in FIG. 2, in the present 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 lid bodies 60. The back surface 22 faces the other lid body 60. The upper surface 23 constitutes one of a pair of first surfaces 41 of the exterior body 40 described later. The lower surface 24 constitutes the other of the pair of first surfaces 41 of the exterior body 40 described later. The first side surface 25 constitutes one of a pair of second surfaces 42 of the exterior body 40 described later. The second side surface 26 constitutes the other of the pair of second surfaces 42 of the exterior body 40 described later.

[0018] As shown in FIG. 3, the electrode body 20 has a corner 20A, a corner 20B, a corner 20C, and a corner 20D. An R surface is formed at the corners 20A, 20B, 20C, and 20D. The corner 20A is formed at the boundary between the upper surface 23 and the first side surface 25. The corner 20B is formed at the boundary between the upper surface 23 and the second side surface 26. The corner 20C is formed at the boundary between the first side surface 25 and the lower surface 24. The corner 20D is formed at the boundary between the second side surface 26 and the lower surface 24. In FIG. 2, for the sake of simplifying the drawing, the shape of the R surfaces of the corners 20A to 20D is omitted.

[0019] In the present embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminal 30 is a metal terminal used for power input and output in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from the edge of the exterior body 40, for example. Note that the electrode terminal 30 only needs to be capable of power input and output of the electrode body 20, and for example, it does not need to protrude from the exterior body 40. When the lid body 60 described later is made of, for example, metal, the lid body 60 may also serve as the function of the electrode terminal 30. In this case, the lid body 60 having the function as an electrode terminal may or may not protrude from the exterior body 40.

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

[0021] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a lid body 60. The exterior film 50 wraps the electrode body 20 so as to have an opening 40A. In the present embodiment, the exterior film 50 is wound around the electrode body 20 so as to have an opening 40A. The lid body 60 is disposed on the side of the electrode body 20 so as to close the opening 40A. Note that the electrode body 20 may be accommodated inside the exterior film 50 configured in a cylindrical shape so that the opening 40A is formed, and the opening 40A may be closed by the lid body 60.

[0022] From the viewpoint of favorably adhering to the lid body 60, an adhesive film 31 is preferably joined to the electrode terminal 30. The adhesive film 31 can be arbitrarily selected as long as it is a film capable of adhering the electrode terminal 30 made of metal and the lid body 60 made of resin. The adhesive film 31 can use, for example, polyolefin resins such as polyethylene-based resins and polypropylene-based resins, cyclic polyolefin resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or two or more layers of these films. In the present embodiment, the adhesive film 31 is joined to substantially the entire portion of the electrode terminal 30 covered by the lid body 60.

[0023] For example, there is a method of forming a housing portion (depression) for housing the electrode body 20 in the exterior film 50 through cold forming. However, it is not always easy to form a deep housing portion by such a method. When attempting to deeply form the housing portion (depression) by cold forming (for example, a forming depth of 15 mm), pinholes or cracks are likely to occur in the exterior film 50, increasing the possibility of deterioration of battery performance. On the other hand, since the exterior body 40 seals the electrode body 20 by winding the exterior film 50 around the electrode body 20, the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In order to reduce the dead space between the electrode body 20 and the exterior film 50 to improve the volumetric energy density of the power storage device 10, a state where the exterior film 50 is wound so as to contact the outer surface of the electrode body 20 is preferable. Also, in the all-solid-state battery, from the viewpoint that it is necessary to uniformly apply a high pressure from the outer surface of the battery to exhibit battery performance, it is necessary to eliminate the space between the electrode body 20 and the exterior film 50, so a state where the exterior film 50 is wound so as to contact the outer surface of the electrode body 20 is preferable.

[0024] As shown in FIG. 4, the exterior film 50 is, for example, a laminate (laminate film) having a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The exterior film 50 may be laminated in the order of the heat-sealable resin layer 53, the base material layer 51, the barrier layer 52, and the heat-sealable resin layer 53. The exterior film 50 may be laminated in the order of the heat-sealable resin layer 53, the barrier layer 52, and the heat-sealable resin layer 53. By joining the outermost layer and the innermost layer of the exterior film 50, a first sealing portion 70 described later may be formed. Note that the exterior film 50 does not necessarily include all of these layers, and for example, the barrier layer 52 may not be included. That is, the exterior film 50 may be made of a material having flexibility and being easy to bend, and may be made of, for example, a resin film. Note that the exterior film 50 is preferably heat-sealable.

[0025] The base material layer 51 contained in the exterior film 50 is a layer that imparts heat resistance to the exterior film 50 and suppresses the occurrence of pinholes that may occur during processing or distribution. The base material layer 51 is composed of, for example, at least one of a stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one of a stretched polyester resin layer and a stretched polyamide resin layer in the base material layer 51, the barrier layer 52 can be protected during processing of the exterior film 50, and breakage of the exterior film 50 can be suppressed. Also, from the viewpoint of increasing the tensile elongation of the exterior film 50, the stretched polyester resin layer is preferably a biaxially stretched polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially stretched polyamide resin layer. Further, from the viewpoint of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film or a biaxially stretched polybutylene terephthalate (PBT) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. Note that the base material layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base material layer 51 is preferably, for example, 5 to 300 μm, and more preferably 20 to 150 μm, from the viewpoint of film strength.

[0026] The barrier layer 52 is a layer that suppresses at least the intrusion of moisture. The barrier layer 52 is joined to the base material layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include a metal foil having barrier properties, a vapor deposition film, and a resin layer. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, and a carbon-containing inorganic oxide vapor deposition film. Examples of the resin layer include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, and fluorine-containing resins such as polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Further, examples of the barrier layer 52 include a resin film provided with at least one of these vapor deposition films and resin layers. A plurality of barrier layers 52 may be provided. The barrier layer 52 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it preferably includes at least one of an aluminum alloy foil and a stainless steel foil.

[0027] In the barrier layer 52, the layer made of the above-described metal material may contain a recycled material of the metal material. Examples of the recycled material of the metal material include recycled materials of aluminum alloys, stainless steel, titanium steel, or steel plates. These recycled materials can be obtained by known methods respectively. The recycled material of the aluminum alloy can be obtained, for example, by the production method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed only of recycled materials, or may be composed of a mixed material of recycled materials and virgin materials. Note that the recycled material of the metal material refers to a metal material that has been recycled to a reusable state by collecting, separating, purifying, etc. various products used in the market and waste generated from the manufacturing process. Also, the virgin material of the metal material refers to a new metal material refined from natural resources (raw materials) of the metal and not a recycled material.

[0028] From the perspective of improving the formability or followability of the exterior film 50, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the perspective of further improving the formability or followability, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the content of iron is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the content of iron is 0.1% by mass or more, an exterior film 50 having better formability can be obtained. When the content of iron is 9.0% by mass or less, an exterior film 50 having better flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having a composition defined by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Also, silicon, magnesium, copper, manganese, etc. may be added as necessary. The softening can be performed by annealing treatment or the like. From the perspective of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil composed of, for example, a work-hardened aluminum alloy. Examples of the hard aluminum alloy foil include aluminum alloy foils having a composition defined by JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14.

[0029] Also, examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Further, from the perspective of providing an exterior film 50 having excellent formability or followability, the stainless steel foil is preferably composed of austenitic stainless steel.

[0030] Specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

[0031] In the case of a metal foil, the thickness of the barrier layer 52 only needs to function as a barrier layer that at least suppresses the intrusion of moisture. For example, it can be 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, still more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 52 is preferably about 10 μm or more, still more preferably about 20 μm or more, and more preferably about 25 μm or more. Further, the preferable range of the thickness of the barrier layer 52 includes 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 composed of an aluminum alloy foil, the above-described range is particularly preferable. Also, from the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, still more preferably about 50 μm or more, and still more preferably about 55 μm or more. Also, it is preferably about 200 μm or less, more preferably about 85 μm or less, still more preferably about 75 μm or less, and still more preferably about 70 μm or less. The preferable range includes about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, and about 55 to 70 μm. When the exterior film 50 has high formability, deep drawing forming becomes easy, which can contribute to increasing the capacity of the power storage device. Also, since the rigidity of the exterior film 50 is increased, when the exterior film 50 is wound around the electrode body 20, the exterior film 50 can be suitably wound around the electrode body 20. Further, when the capacity of the power storage device is increased, the weight of the power storage device increases. However, by increasing the rigidity of the exterior film 50, it can contribute to the high sealing performance of the power storage device.In particular, when the barrier layer 52 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, still more preferably about 30 μm or less, and particularly preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Further, preferable ranges of 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] In addition, when the barrier layer 52 is an aluminum foil, in order to prevent dissolution and corrosion, etc., it is preferable to provide a corrosion-resistant film on at least the surface opposite to the base material layer 51. The barrier layer 52 may be provided with corrosion-resistant films on both sides. Here, the corrosion-resistant film refers to, for example, a hot water conversion treatment such as a boehmite treatment, a chemical conversion treatment, an anodizing treatment, a plating treatment such as nickel or chromium, or a corrosion prevention treatment of applying a coating agent to the surface of the barrier layer 52 to provide the barrier layer 52 with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant film means a film that improves the acid resistance of the barrier layer 52 (acid-resistant film), a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film), etc. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be combined. Also, it can be made into multiple layers instead of just one layer. Further, among these treatments, the hot water conversion treatment and the anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent and form a metal compound excellent in corrosion resistance. Note that these treatments may be included in the definition of the chemical conversion treatment. Also, when the barrier layer 52 is provided with a corrosion-resistant film, the barrier layer 52 including the corrosion-resistant film is regarded as the barrier layer 52.

[0033] The corrosion-resistant film prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base material layer 51 during the molding or winding of the exterior film 50, and prevents dissolution and corrosion of the surface of the barrier layer 52 by hydrogen fluoride generated by the reaction of the electrolyte and moisture, particularly dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52 when the barrier layer 52 is an aluminum alloy foil. Further, it improves the adhesiveness (wettability) of the surface of the barrier layer 52, and shows the effect of preventing delamination between the base material layer 51 and the barrier layer 52 during heat sealing and preventing delamination between the base material layer 51 and the barrier layer 52 during molding.

[0034] The heat-sealable resin layer 53 is joined to the barrier layer 52 via, for example, the adhesive layer 55. The heat-sealable resin layer 53 contained in the exterior film 50 is a layer that imparts heat-sealing properties to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate-based resins and polybutylene terephthalate-based resins, polyolefin resins such as polyethylene-based resins and polypropylene-based resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. From the viewpoints of sealing properties and strength, the thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm.

[0035] The exterior film 50 preferably has one or more layers having a buffering function (hereinafter referred to as "buffer layer") outside the heat-sealable resin layer 53, and more preferably outside the barrier layer 52. The buffer layer may be laminated outside the base material layer 51, or the base material layer 51 may also serve as the buffer layer. When the exterior film 50 has a plurality of buffer layers, the plurality of buffer layers may be adjacent to each other, or may be laminated via the base material layer 51 or the barrier layer 52 or the like.

[0036] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. Materials having cushioning properties are, for example, rubber, non-woven fabric, or foamed sheet. Rubber is, for example, natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the non-woven fabric is preferably a material having excellent heat resistance. When the buffer layer is constituted by a non-woven fabric, the lower limit value of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, still more preferably 1000 μm. When the buffer layer is constituted by a non-woven fabric, the upper limit value of the thickness of the buffer layer is preferably 5000 μm, more preferably 3000 μm. The preferable range of the thickness of the buffer layer is 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm. Among these, the range of the thickness of the buffer layer is most preferably 1000 μm to 3000 μm.

[0037] When the buffer layer is constituted by rubber, the lower limit value of the thickness of the buffer layer is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is constituted by rubber, the upper limit value of the thickness of the buffer layer is preferably 10 mm, more preferably 5 mm, still more preferably 2 mm. When the buffer layer is constituted by rubber, the preferable range of the thickness of the buffer layer 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, 0.5 mm to 2 mm.

[0038] When the exterior film 50 has a buffer layer, since the buffer layer functions as a cushion, it is possible to suppress the exterior film 50 from being damaged due to the impact when the power storage device 10 falls or due to the handling during the manufacture of the power storage device 10.

[0039] The lid body 60 is, for example, in the shape of a rectangular parallelepiped and is made of, for example, a resin material. Note that the lid body 60 may be a metal formed product. The material constituting the lid body 60 may contain at least two or more materials among metal oxides, carbon materials, and rubber materials. It may contain metal oxides, carbon materials, and rubber materials.

[0040] The lid body 60 is preferably configured to contain a resin material. Here, "configured to contain a resin material" means that when the total amount of the material constituting the lid body 60 is 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. That is, the material constituting the lid body 60 can contain, in addition to the resin material, materials other than the resin material.

[0041] Specific examples of the resin include resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, and thermoplastic resins such as modified products of these resins. Further, the resin material may be a mixture of these resins, a copolymer, or a modified product of a copolymer. Among these, the resin material is preferably a heat-fusible resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the lid body 60 may be formed by any forming method.

[0042] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include copolyesters having ethylene terephthalate as the main repeating unit. Specifically, copolyester polyethylenes (hereinafter abbreviated following polyethylene(terephthalate / isophthalate)) obtained by polymerizing ethylene terephthalate with ethylene isophthalate with ethylene terephthalate as the main repeating unit, polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), polyethylene(terephthalate / decanedicarboxylate), etc. are included. Among these, the resin material is preferably polybutylene terephthalate from the viewpoint of enhancing heat resistance and pressure resistance.

[0043] Examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and terpolymers of ethylene-butene-propylene. The polyolefin resin in the case of being a copolymer may be a block copolymer or a random copolymer. Among these, the resin material is preferably polypropylene because of its excellent heat sealability and electrolytic solution resistance.

[0044] The resin as the resin material may contain a filler as necessary. Specific examples of the filler include glass beads, graphite, glass fiber, carbon fiber, and the like. By the resin as the resin material containing the filler, the deformation resistance of the lid body 60 against temperature changes can be improved.

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

[0046] The lid body 60 may be configured to include a conductive material. "Configured to include a conductive material" means that when the total amount of the material constituting the lid body 60 is 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 still more preferably 95% by mass or more. That is, the material constituting the lid body 60 can contain, in addition to the conductive material, materials other than the conductive material.

[0047] The conductive material constituting the lid body 60 is, for example, a metal material. The metal material constituting the lid body 60 is, for example, aluminum, an aluminum alloy, nickel, copper, or a copper alloy. For example, when the electrode body 20 is a lithium ion battery, the lid body 60 connected to the positive electrode is preferably constituted by aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably constituted by nickel, copper, or a copper alloy. The material constituting the lid body 60 connected to the negative electrode may be nickel-plated copper. The material constituting the lid body 60 may include a recycled material of the metal material. When the lid body 60 is configured to include a conductive material, the lid body 60 also serves as the electrode terminal 30. Since the electrode terminal 30 can be omitted from the power storage device 10, the configuration of the power storage device 10 can be simplified.

[0048] When the lid body 60 is made of a conductive material, the lid body 60 may be joined to the outer film 50 via an adhesive film. The adhesive film can be arbitrarily selected as long as it can adhere the outer film 50 and the lid body 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant base material layer, and a heat-sealable resin layer in this order. The specifications regarding the heat-sealable resin layer of the adhesive film can be applied to the specifications regarding the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same kind of material or different kinds of materials, and are appropriately selected according to the material constituting the heat-sealable resin layer 53 of the outer film 50 and the material constituting the lid body 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that adheres to the lid body 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer on the side of the adhesive film that adheres to the outer film 50 preferably uses the same kind of material as the material constituting the heat-sealable resin layer 53 of the outer film 50.

[0049] The heat-resistant base material layer may be a film made of a heat-resistant resin. For example, unstretched or stretched films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, and polypropylene can be used. Note that polyethylene terephthalate is inexpensive and has high strength, and is particularly preferable.

[0050] The adhesive film preferably has adhesiveness. When forming the second sealing portion 80 described later with the adhesive film disposed between the exterior film 50 and the lid body 60, the position of the adhesive film with respect to the lid body 60 and the exterior film 50 is less likely to shift. By including an adhesion-imparting resin in the heat-fusible resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the adhesion-imparting resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene, or a copolymer of amorphous propylene and other α-olefins. The content of the adhesion-imparting resin with respect to the base material constituting the heat-fusible resin is preferably 10 to 20% by weight or less.

[0051] The lid body 60 has a lid main body 60A. The lid main body 60A has a first surface 61, a second surface 62, and a lid seal portion 63. The first surface 61 faces the electrode body 20. The second surface 62 is the surface on the side opposite to the first surface 61. The lid seal portion 63 is connected to the first surface 61 and the second surface 62 and is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50. The lid seal portion 63 includes a first seal surface 63A, a second seal surface 63B, a third seal surface 63C, and a fourth seal surface 63D. The first seal surface 63A constitutes the upper surface of the lid body 60. The first seal surface 63A extends in a first direction (in this embodiment, the LR direction) in a front view of the lid body 60. The second seal surface 63B and the third seal surface 63C are connected to the first seal surface 63A and constitute the side surface of the lid body 60. The second seal surface 63B and the third seal surface 63C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction in a front view of the lid body 60. In this embodiment, in a front view of the lid body 60, the first direction and the second direction are orthogonal. The first direction and the second direction do not have to be orthogonal in a front view of the lid body 60. The fourth seal surface 63D constitutes the lower surface of the lid body 60. The fourth seal surface 63D extends in a first direction (in this embodiment, the LR direction) in a front view of the lid body 60.

[0052] The lid seal portion 63 further includes corner portions 64, 65, 66, and 67. The corner portion 64 is formed including the boundary between the first seal surface 63A and the second seal surface 63B. The corner portion 65 is formed including the boundary between the first seal surface 63A and the third seal surface 63C. The corner portion 66 is formed including the boundary between the fourth seal surface 63D and the second seal surface 63B. The corner portion 67 is formed including the boundary between the fourth seal surface 63D and the third seal surface 63C. R surfaces are formed on the corner portions 65 to 67. For this reason, when the power storage device 10 is in the manufacturing process or the completed power storage device 10 is evacuated, deformation of the exterior body 40 such as the formation of wrinkles in the exterior film 50 is suppressed. Also, compared with the case where the corner portions 65 to 67 are right angles, it is difficult for an external impact to act on the corner portions 65 to 67. For this reason, breakage of the exterior body 40 is suppressed. In FIG. 1, for simplification of the drawing, the shape of the R surfaces of the corner portions 65 to 67 is omitted.

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

[0054] When the lid body 60 is plate-shaped, even when the power storage devices 10 are stacked, it is preferable that the lid body 60 has a certain thickness so that the exterior body 40 is suppressed from deforming. From another perspective, when the lid body 60 is plate-shaped, in order to preferably heat-seal the seal surfaces 63A, 63B, 63C, 63D of the lid body 60 and the exterior film 50 when forming the second sealing portion 80 described later, it is preferable that the seal surfaces 63A, 63B, 63C, 63D of the lid body 60 have a certain thickness. The minimum value of the thickness of the lid body 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum value of the thickness of the lid body 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum value of the thickness of the lid body 60 may be 20 mm or more. The preferable range of the thickness of the material constituting the lid body 60 is 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, 4.0 mm to 10 mm. In the present embodiment, when the lid body 60 is described as plate-shaped, the aspect in which the lid body 60 is constituted only by the film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. Note that the thickness of the lid body 60 may vary depending on the part of the lid body 60. When the thickness of the lid body 60 varies depending on the part, the thickness of the lid body 60 is the thickness of the thickest part.

[0055] From the perspective of suitably heat-sealing the lid body 60 and the exterior film 50, it is preferable that the main materials of the material constituting the lid body 60 and the material constituting the heat-sealing resin layer 53 of the exterior film 50 are the same. In the present embodiment, examples of the material constituting the lid body 60 include polyester resins such as polyethylene terephthalate-based resins and polybutylene terephthalate-based resins, polyethylene-based resins, fluorine-based resins, polyolefin-based resins such as polypropylene-based resins, cyclic polyolefin-based resins, or acid-modified polyolefin-based resins obtained by graft-modifying these polyolefin-based resins with an acid such as maleic anhydride. From the perspective of suitably heat-sealing the lid body 60 and the exterior film 50, it is preferable that the main materials of the material constituting the lid body 60 and the material constituting the heat-sealing resin layer 53 of the exterior film 50 are the same. In the present embodiment, examples of the material constituting the lid body 60 and the material constituting the heat-sealing resin layer 53 include, for example, polyolefin-based resins such as polyethylene-based resins and polypropylene-based resins, or acid-modified polyolefin-based resins obtained by graft-modifying these polyolefin-based resins with an acid such as maleic anhydride as the main material. Here, the main material refers to, for example, a material that occupies 50% or more of the materials included in the component.

[0056] In this embodiment, a through-hole 60X into which the electrode terminal 30 is inserted is formed in the lid body 60. The through-hole 60X penetrates the first surface 61 and the second surface 62. In a state where the electrode body 20 is wrapped by the exterior film 50, the electrode terminal 30 protrudes to the outside of the exterior body 40 through the through-hole 60X formed in the lid body 60. A slight gap between the through-hole 60X of the lid body 60 and the electrode terminal 30 is filled with, for example, resin. In the power storage device 10, the position where the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude to the outside through a hole formed in any one of the six surfaces of the exterior body 40. In this case, a slight gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. In another example, the electrode terminal 30 may protrude to the outside of the exterior body 40 from between the seal surfaces 63A, 63B, 63C, 63D of the lid body 60 and the exterior film 50. In this case, the through-hole 60X may not be formed in the lid body 60. In the power storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies, but the lid body 60 and the electrode terminal 30 may be integrally formed. Note that even when the electrode terminal 30 does not protrude from the edge of the exterior body 40, the through-hole 60X may not be formed in the lid body 60.

[0057] In this embodiment, with the exterior film 50 wound around the periphery of the electrode body 20 so as to have the opening 40A, the heat-sealing resin layers 53 on the opposing surfaces of the exterior film 50 are heat-sealed to form the first sealing portion 70.

[0058] The first sealing portion 70 is formed by heat-sealing a portion including the first edge 50A of the exterior film 50 shown in FIG. 5 and a portion including the second edge 50B. The first sealing portion 70 extends in the longitudinal direction (FB direction) of the exterior body 40. In the exterior body 40, the position where the first sealing portion 70 is formed can be arbitrarily selected. In the present embodiment, it is preferable that the base 70X of the first sealing portion 70 is located on the side 43 at the boundary between the first surface 41 and the second surface 42 of the exterior body 40. The area of the first surface 41 is larger than that of the second surface 42. The base 70X of the first sealing portion 70 may be located on any surface of the exterior body 40. In the present embodiment, the first sealing portion 70 protrudes outward beyond the electrode body 20 in a plan view. The first sealing portion 70 may be folded, for example, toward the second surface 42 of the exterior body 40 or toward the first surface 41.

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

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

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

[0062] In this embodiment, the lid body 60 has a protruding portion 68 that protrudes from the lid seal portion 63 so that a gap is less likely to be formed between the exterior film 50 and the lid body 60. The protruding portion 68 may be integrally formed with the lid main body 60A, or may be formed separately from the lid main body 60A and joined to the lid main body 60A. In this embodiment, the protruding portion 68 is integrally formed with the lid main body 60A. At the lid seal portion 63, the position where the protruding portion 68 is formed can be arbitrarily selected. The gap between the exterior film 50 and the lid body 60 is likely to be formed, for example, between the base 70X of the first sealing portion 70 and the lid body 60. In particular, when the base 70X of the first sealing portion 70 is located at the corner portions 64 to 67 of the lid body 60, the resin filling property between the base 70X of the first sealing portion 70 and the lid body 60 is likely to decrease. For this reason, the protruding portion 68 is preferably formed at the position where the base 70X of the first sealing portion 70 is located in the lid seal portion 63. In this embodiment, the base 70X of the first sealing portion 70 is located at the corner portion 64 of the lid body 60. For this reason, the protruding portion 68 is preferably formed at the corner portion 64 in the lid seal portion 63. In this embodiment, the first sealing portion 70 is sealed in a state sandwiching the protruding portion 68. Note that the protruding portion 68 may be formed on at least one of the first seal surface 63A, the second seal surface 63B, the third seal surface 63C, the fourth seal surface 63D, the corner portion 65, the corner portion 66, and the corner portion 67.

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

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

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

[0066] If the shapes of the corner portions 20A to 20D of the electrode body 20 and the corner portions 65 to 67 of the lid body 60, more specifically, the radii of curvature of the corner portions 20A to 20D and the radii of curvature of the corner portions 65 to 67 are significantly different, the exterior film 50 may not follow the electrode body 20, and the adhesion between the exterior film 50 and the electrode body 20 may decrease. For this reason, the electrode body 20 may not be suitably held by the exterior film 50.

[0067] In the present embodiment, from the viewpoint of suitably holding the electrode body 20 by the exterior film 50, the absolute value of the difference between the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20 and the radius of curvature of any of the corner portions 65 to 67 of the lid body 60 is 10 mm or less. The absolute value of the difference between the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20 and the radius of curvature of any of the corner portions 65 to 67 of the lid body 60 is more preferably 5 mm or less, and even more preferably 3 mm or less. In the present embodiment, the radius of curvature of the corner portions 20A to 20D includes the radius of curvature of the corner portions corresponding to the corner portions 20A to 20D that appear on the exterior of the exterior body 40 in a state where the electrode body 20 is wrapped by the exterior film 50.

[0068] In the present embodiment, the radius of curvature of the corner portions 20A to 20D is measured at a position close to the lid body 60 in the electrode body 20. The radius of curvature of the corner portions 20A to 20D is a measured value obtained by winding the exterior film 50 in contact with the outer surface of the electrode body 20 in a state where tension is applied to the exterior film 50 and measuring with an R gauge.

[0069] From the perspective of more suitably holding the electrode body 20 by the outer film 50, among the corner portions 20A to 20D of the electrode body 20 and the corner portions 65 to 67 of the lid body 60, the absolute value of the difference in the radius of curvature of the opposing corner portions is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. That is, the absolute value of the difference between the radius of curvature of the corner portion 20B of the electrode body 20 and the radius of curvature of the corner portion 65 of the lid body 60 is preferably 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 portion 20C of the electrode body 20 and the radius of curvature of the corner portion 66 of the lid body 60 is preferably 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 portion 20D of the electrode body 20 and the radius of curvature of the corner portion 67 of the lid body 60 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0070] Further, when the radius of curvature of any of the corner portions 65 to 67 of the lid body 60 is larger than the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20, the perimeter of the outer film 50 joined to the lid body 60 becomes longer than the perimeter of the electrode body 20, so there is a possibility that the adhesion between the outer film 50 and the electrode body 20 may decrease. For this reason, there are cases where the electrode body 20 cannot be suitably held by the outer film 50.

[0071] Therefore, the radius of curvature of any of the corner portions 65 to 67 of the lid body 60 is preferably smaller than the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20. From the perspective of more suitably holding the electrode body 20 by the outer film 50, the radius of curvature of the corner portions 65 to 67 of the lid body 60 is preferably smaller than the radius of curvature of the opposing corner portions 20A to 20D of the electrode body 20. That is, the radius of curvature of the corner portion 65 of the lid body 60 is preferably smaller than the radius of curvature of the corner portion 20B of the electrode body 20. The radius of curvature of the corner portion 66 of the lid body 60 is preferably smaller than the radius of curvature of the corner portion 20C of the electrode body 20. The radius of curvature of the corner portion 67 of the lid body 60 is preferably smaller than the radius of curvature of the corner portion 20D of the electrode body 20.

[0072] The radius of curvature of at least one of the corners 65 to 67 of the lid body 60 can be arbitrarily selected as long as the absolute value of the difference from the radius of curvature of any of the corners 20A to 20D of the electrode body 20 is 10 mm or less. From the viewpoint of suppressing an increase in the perimeter of the exterior film 50, the radius of curvature of at least one of the corners 65 to 67 of the lid body 60 is preferably 10 mm or less. From the viewpoints of suitably forming the corners 65 to 67 having an R surface on the lid body 60 and enhancing the adhesion between the exterior film 50 and the lid body 60, the radius of curvature of at least one of the corners 65 to 67 of the lid body 60 is preferably 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, the radius of curvature of at least one of the corners 65 to 67 is preferably 20 mm or less. The preferable range of the radius of curvature of at least one of the corners 65 to 67 of the lid body 60 is 0.05 mm or more and 20 mm or less.

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

[0074] <1-2. Method for manufacturing a power storage device> FIG. 9 is a flowchart showing an example of a method for manufacturing the power storage device 10. The method for manufacturing the power storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, a fifth step, a sixth step, and a seventh step. The first to seventh steps are performed, for example, by a manufacturing apparatus for the power storage device 10. Note that the first to seventh steps are for the sake of convenience in defining the names of the respective steps of the method for manufacturing the power storage device 10 and do not necessarily mean the order of the respective steps.

[0075] In the first step of step S11, the manufacturing apparatus joins the lid body 60 and the electrode terminal 30. When the second step is completed, a pair of lid units 60Z in which the electrode terminal 30 is joined to the lid body 60 is completed.

[0076] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus arranges a pair of lid units 60Z on the sides of the electrode body 20 and joins the electrode terminals 30 and the electrode body 20. Note that, instead of the first step and the second step, the method for manufacturing the power storage device 10 may have a step of joining the electrode body 20 and the electrode terminals 30 first and then joining the lid body 60 to the electrode terminals 30 joined to the electrode body 20.

[0077] The third step of step S13 is performed after the second step. In the third step, the manufacturing apparatus wraps the exterior film 50 around the electrode body 20 and the lid body 60. In the third step, the manufacturing apparatus wraps the exterior film 50 around the electrode body 20 and the lid body 60 while tension is applied to the exterior film 50 while restricting the movement of the electrode body 20 and the lid body 60 by a restricting means. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force in a direction opposite to the direction in which the exterior film 50 is pulled to the electrode body 20 and the lid body 60. Note that the restricting means may include a roller that travels on the exterior film 50 in a state where the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50.

[0078] The fourth step of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus forms a first sealing portion (hereinafter referred to as a "temporary first sealing portion") in which an unsealed portion for injecting an electrolytic solution is formed in part. In the temporary first sealing portion, the heat-sealable resin layers 53 of the exterior film 50 facing each other are joined in a state where the protruding portion 68 of the lid body 60 is sandwiched by the exterior film 50. Note that, when the power storage device 10 is, for example, an all-solid-state battery, since the step of injecting an electrolytic solution is not necessary, in the fourth step, the manufacturing apparatus forms the first sealing portion 70.

[0079] The fifth step of step S15 is carried out after the fourth step. In the fifth step, the manufacturing apparatus forms the second sealing portion 80 by, for example, heat-sealing the heat-sealable resin layer 53 of the exterior film 50 and the lid-sealing portion 63 of the lid body 60. Note that the fifth step preferably 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, and the protruding portion 68 including the corner portion 64 of the lid-sealing portion 63 and the exterior film 50. The second sealing step is carried out after the first sealing step. In the second sealing step, the manufacturing apparatus heat-seals the corner portions 65 to 67 and the exterior film 50. In the second sealing step, it is preferable to use a heat-sealing bar having the same radius of curvature as the R surface of the corner portions 65 to 67.

[0080] The sixth step of step S16 is carried out after the fifth step. In the sixth step, the manufacturing apparatus injects an electrolytic solution from an unsealed portion formed in the temporary first sealing portion.

[0081] The seventh step of step S17 is carried out after the sixth step. In the seventh step, the manufacturing apparatus forms the first sealing portion 70 by heat-sealing a portion including the unsealed portion of the temporary first sealing portion. Note that when the power storage device 10 is, for example, an all-solid-state battery, the sixth step and the seventh step are omitted.

[0082] <1-3. Effects of the power storage device> Since the absolute value of the difference between the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20 and the radius of curvature of any of the corner portions 65 to 67 of the lid body 60 of the power storage device 10 is 10 mm or less, the exterior film 50 easily follows the electrode body 20. For this reason, the electrode body 20 can be suitably held by the exterior film 50.

[0083] [2. Modification example] The above embodiments are examples of forms that the power storage device and the lid body according to the present invention can take, and are not intended to limit the form. The power storage device and the lid body according to the present invention can take forms different from those exemplified in the embodiments. An example thereof is a form in which a part of the configuration of the embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to the embodiment. Some examples of modifications of the embodiment are shown below. Note that the following modifications can be combined with each other as long as there is no technical contradiction.

[0084] <2-1> In the above embodiment, the protruding portion 68 of the lid body 60 may be omitted. In this modification, from the viewpoint of preferably forming the first sealing portion 70, the corner portion 64 is preferably substantially at a right angle.

[0085] In another example, when the protruding portion 68 is omitted from the lid body 60, an R surface may be formed at the corner portion 64. From the viewpoint of preferably holding the electrode body 20 by the exterior film 50, the absolute value of the difference between the radius of curvature of any corner portion 20A to 20D of the electrode body 20 and the radius of curvature of the corner portion 64 of the lid body 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 preferably holding the electrode body 20 by the exterior 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 body 60 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0087] Further, when the radius of curvature of the corner portion 64 of the lid body 60 is larger than the radius of curvature of any corner portion 20A to 20D of the electrode body 20, the perimeter of the exterior film 50 joined to the lid body 60 becomes longer than the perimeter of the electrode body 20, so that the adhesion between the exterior film 50 and the electrode body 20 may decrease. For this reason, the electrode body 20 cannot be preferably held by the exterior film 50.

[0088] Therefore, the radius of curvature of the corner portion 64 of the lid body 60 is preferably smaller than the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20. From the viewpoint of more suitably holding the electrode body 20 by the exterior film 50, the radius of curvature of the corner portion 64 of the lid body 60 is preferably smaller than the radius of curvature of the corner portion 20A of the electrode body 20. Note that the radius of curvature of the corner portion 64 of the lid body 60 may be equal to or greater than the radius of curvature of any of the corner portions 20A to 20D of the electrode body 20.

[0089] The radius of curvature of the corner portion 64 of the lid body 60 can be arbitrarily selected. From the viewpoint of suppressing an increase in the perimeter of the exterior film 50, the radius of curvature of the corner portion 64 of the lid body 60 is preferably 20 mm or less. From the viewpoint of suitably forming the corner portion 64 having an R surface on the lid body 60, the radius of curvature of the corner portion 64 of the lid body 60 is preferably 0.05 mm or more. From the viewpoint of suppressing a large difference in shape from the corner portions 20A to 20D of the electrode body 20, the radius of curvature of the corner portion 64 is preferably 20 mm or less. The preferable range of the radius of curvature of the corner portion 64 of the lid body 60 is 0.05 mm or more and 20 mm or less.

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

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

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

[0093] <2-5> In the power storage device 10 of the above-described embodiment, the specific method of forming the protruding portion 68 of the lid body 60 can be arbitrarily changed. For example, the protruding portion 68 may be formed by an adhesive film or the like joined to the lid seal portion 63 of the lid main body 60A. In this modification, for example, a plurality of adhesive films may be joined to the lid seal portion 63 so as to overlap each other to form the protruding portion 68, or the adhesive film may be joined to the lid seal portion 63 in a flap shape to form the protruding portion 68.

[0094] <2-6> The power storage device 10 of the above-described embodiment may have an adhesive film disposed between the exterior film 50 and the lid body 60 in order to suitably bond the exterior film 50 and the lid body 60. In this modification, for example, after the lid body 60 with the adhesive film adhered thereto is attached to the openings 40A at both ends of the exterior body 40, the second sealing portion 80 is formed. The adhesive film is wound around the lid body 60 so as to cover the entire surface of the lid seal portion 63 of the lid body 60, for example. The adhesive film is preferably configured to be wider than the lid seal portion 63 of the lid body 60 as a whole. In this case, the adhesive film can be easily adhered to the lid body 60. Furthermore, since the corner portions 64 to 67 of the lid seal portion 63 are covered with the adhesive film, the adhesiveness between the lid body 60 and the adhesive film is enhanced.

[0095] The adhesive film can be arbitrarily selected as long as it can adhere the exterior film 50 and the lid body 60. The adhesive film is preferably a laminated film having at least a heat-sealable resin layer, a heat-resistant base material layer, and a heat-sealable resin layer in this order. The specifications regarding the heat-sealable resin layer of the adhesive film can be applied to the specifications regarding the heat-sealable resin layer 53. The materials constituting the heat-sealable resin layers on both sides of the adhesive film may be the same kind of material or different kinds of materials, and are appropriately selected according to the material constituting the heat-sealable resin layer 53 of the exterior film 50 and the material constituting the lid body 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that is adhered to the lid body 60 is preferably an acid-modified polyolefin resin graft-modified with an acid such as maleic anhydride. The heat-sealable resin layer on the side of the adhesive film that is adhered to the exterior film 50 preferably uses the same kind of material as the material constituting the heat-sealable resin layer 53 of the exterior film 50.

[0096] The heat-resistant base material layer may be a film made of a heat-resistant resin. For example, unstretched or stretched films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polymethylpentene (registered trademark), polyacetal cyclic polyolefin, polyethylene, and polypropylene can be used. Note that polyethylene terephthalate is inexpensive and has high strength, and is particularly preferred.

[0097] The adhesive film preferably has adhesiveness. When the second sealing portion 80 is formed with the adhesive film disposed between the exterior film 50 and the lid body 60, the position of the adhesive film with respect to the lid body 60 and the exterior film 50 is less likely to shift. By including an adhesion-imparting resin in the heat-sealable resin layer of the adhesive film, adhesiveness can be imparted to the adhesive film. Examples of the adhesion-imparting resin include amorphous polyolefin. Examples of the amorphous polyolefin include amorphous polypropylene, or a copolymer of amorphous propylene and other α-olefins. The content of the adhesion-imparting resin with respect to the base material constituting the heat-sealable resin is preferably 10 to 20% by weight or less.

[0098] <2-7> In the above embodiment, the position where the electrode terminal 30 is disposed can be arbitrarily selected. For example, the electrode terminal 30 may protrude from the first sealing portion 70.

Explanation of Reference Numerals

[0099] 10: Power storage device 20: Electrode body 20A, 20B, 20C, 20D: Corner portions 40: Exterior body 40A: Opening 50: Exterior film 60: Lid body 60Z: Lid unit 64, 65, 66, 67: Corner portions

Claims

1. An electrode body, and an exterior body that seals the electrode body, comprising: The exterior body includes: an exterior film that wraps the electrode body such that an opening is formed; and a lid body disposed in the opening. The electrode body is substantially rectangular parallelepiped and has corners with R surfaces formed thereon. The lid body has corners with R surfaces formed thereon. 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 lid body is 10 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 exterior body when the electrode body is wrapped by the exterior film, and is a value measured with an R gauge at a position close to the lid body of the electrode body, with the exterior film wound around the outer surface of the electrode body in contact therewith while tension is applied to the exterior film. A power storage device.

2. The radius of curvature of the corner of the lid body is smaller than the radius of curvature of the corner of the electrode body. The power storage device according to Claim 1.

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

4. The corner of the lid body and the corner of the electrode body face each other. The power storage device according to Claim 1 or 2.

5. The perimeter of the lid body is shorter than the perimeter of the electrode body. The power storage device according to Claim 1 or 2.

6. A lid body used as an exterior body of a power storage device, wherein the exterior body includes the lid body and an exterior film joined to the lid body, the lid body has at least one corner with an R surface formed thereon for joining to the exterior film, and the radius of curvature of the corner is 20 mm or less. A lid body.

7. The lid body according to Claim 6, and an electrode terminal joined to the lid body. A lid unit.

Images