Power storage device, lid body, and method for manufacturing power storage device

Abstract

To provide a power storage device which is broken only in a limited part of an external body by increase of internal pressure, a lid body used for the power storage device, and a method for manufacturing the power storage device.SOLUTION: The power storage device includes an electrode body and an external body sealing the electrode body. The external body includes: an external film surrounding the electrode body; a lid body sealing the electrode body with the external body; and a discharge unit for discharging at least one of gas and an electrolyte by being partially broken in a case where the inner pressure of the external body is increased.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an example of a power storage device. This power storage device includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body and a lid body that is joined to the exterior film.

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, when the internal pressure rises, the exterior body may be damaged and at least one of the gas and the electrolyte may be released. In the above power storage device, the location where the exterior body breaks when the internal pressure rises cannot be specified in advance. Therefore, depending on the usage environment of the power storage device, an undesirable position of the exterior body may be damaged and at least one of the gas and the electrolyte may be released.

[0005] An object of the present invention is to provide a power storage device in which the location where the exterior body breaks when the internal pressure rises can be a limited part, a lid body used for this power storage device, and a method for manufacturing this power storage device.

Means for Solving the Problems

[0006] The power storage device according to the first aspect of the present invention includes an electrode body and an exterior body that seals the electrode body. The exterior body includes an exterior film that wraps the electrode body, a lid body that seals the electrode body together with the exterior film, and a release portion configured to be partially broken to release at least one of gas and electrolyte when the internal pressure of the exterior body rises.

[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 lid body has a lid main body including a portion joined to the exterior film, and the release portion includes a portion of the lid main body that is partially thinned.

[0008] The power storage device according to the third aspect of the present invention is the power storage device according to the first aspect, wherein the lid body has a lid main body including a portion joined to the exterior film, and the release portion includes a portion of the lid main body in which a recess is formed.

[0009] The power storage device according to the fourth aspect of the present invention is the power storage device according to the first aspect, wherein the exterior body includes at least two lid bodies, the breaking strength of one of the lid bodies is lower than that of the other lid body, and the release portion is formed in the one lid body.

[0010] The power storage device according to the fifth aspect of the present invention is the power storage device according to the first aspect, wherein the exterior body includes at least two lid bodies, the exterior body has a lid sealing portion where the lid body and the exterior film are joined, the joining strength of the lid sealing portion of one of the lid bodies is lower than that of the lid sealing portion of the other lid body, and the release portion is formed in the lid sealing portion of one of the lid bodies.

[0011] The power storage device according to the sixth aspect of the present invention is the power storage device according to the first aspect, wherein the exterior body has a lid sealing portion where the lid body and the exterior film are joined, and the release portion includes a portion of the lid sealing portion where the joining strength is partially reduced.

[0012] The power storage device according to the seventh aspect of the present invention is the power storage device according to the first aspect, wherein the lid body has a lid main body and a covering body that joins the lid main body and the exterior film, and the discharge portion is a portion where the joining strength between the lid main body and the covering body is lower than the joining strength between the covering body and the exterior film.

[0013] The power storage device according to the eighth aspect of the present invention is the power storage device according to the first aspect, wherein the lid body has a lid main body joined to the exterior film, at least a part of the portion of the lid main body joined to the exterior film includes a shape memory alloy, the discharge portion includes the portion of the lid main body configured to include the shape memory alloy, and when the temperature of the exterior body rises as the internal pressure of the exterior body increases, the portion of the lid main body configured to include the shape memory alloy returns to its original shape, whereby the exterior body is configured to be partially destroyed.

[0014] The power storage device according to the ninth aspect of the present invention is the power storage device according to the first aspect, wherein the discharge portion has a through hole formed in the lid body and a barrier film that closes the through hole.

[0015] The lid body according to the tenth aspect of the present invention is a lid body used as an exterior body of a power storage device, and has a lid main body, and the lid main body is a portion that can be broken when the internal pressure of the exterior body increases, and includes a portion that is partially configured to be thin.

[0016] The lid body according to the eleventh aspect of the present invention is a lid body used as an exterior body of a power storage device, and has a lid main body, and the lid main body is a portion that breaks when the internal pressure of the exterior body increases, or a portion that can break an element constituting the exterior body, and includes a portion where a recess is formed.

[0017] The lid according to the 12th aspect of the present invention is a lid used as an exterior body of a power storage device, and the lid has a lid body joined to an exterior film constituting the exterior body, and at least a part of a portion of the lid body joined to the exterior film is configured to include a shape memory alloy.

[0018] A method for manufacturing a power storage device according to the 13th aspect of the present invention includes an electrode body and an exterior body for sealing the electrode body. The exterior body includes an exterior film that wraps the electrode body, a lid that seals the electrode body together with the exterior film, and a discharge portion configured to be able to discharge at least one of gas and electrolyte by being broken when the internal pressure of the exterior body rises. The method for manufacturing the power storage device includes a step of forming the discharge portion.

Effect of the Invention

[0019] According to the power storage device, lid, and method for manufacturing a power storage device of the present invention, the location where the exterior body breaks when the internal pressure rises can be made a limited portion.

Brief Description of the Drawings

[0020]

Figure 1A

Figure 1B

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Figure 17

Mode for Carrying Out the Invention

[0021] 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.

[0022] [Embodiment] <1-1. Configuration of the power storage device> FIG. 1A is a plan view schematically showing the power storage device 10 of the embodiment. FIG. 1B is a diagram related to a method for measuring the seal strength of the second sealing portion 100B of the power storage device 10 in FIG. 1A. FIG. 2 is a cross-sectional view showing the layer structure of the exterior film 50 included in the power storage device 10 in FIG. 1A. FIG. 3 is a view of the exterior film 50 included in the power storage device 10 in FIG. 1A in an expanded state. FIG. 4 is a perspective view of the lid body 60 included in the power storage device 10 in FIG. 1A. FIG. 5 is a cross-sectional view taken along the line D5-D5 in FIG. 1A. FIG. 6 is a cross-sectional view taken along the line D6-D6 in FIG. 1A. In FIG. 1A, the direction of the arrow UD indicates the thickness direction of the power storage device 10, the direction of the arrow LR indicates the width direction of the power storage device 10, and the direction of the arrow FB indicates the depth direction of the power storage device 10. The directions indicated by each of the arrows UDLRFB are common in each of the subsequent figures.

[0023] The power storage device 10 includes an electrode body 20 including a current collector 30 and an exterior body 40. The electrode body 20 includes, for example, electrodes (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 a substantially rectangular parallelepiped. Note that the “substantially rectangular parallelepiped” includes, in addition to a perfect rectangular parallelepiped, a solid that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0024] One end portion 31 of the current collector 30 (see FIG. 6) is connected to the lid body 60.

[0025] 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. In the present embodiment, the exterior film 50 is wound around the electrode body 20. The lid body 60 is disposed on the side of the electrode body 20 in the FB direction. In another example, the electrode body 20 may be housed inside the exterior film 50 configured in a cylindrical shape such that openings are formed at both ends in the FB direction, and the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the lid body 60 may be housed inside the exterior film 50 configured in a cylindrical shape such that an opening is formed, and the opening may be closed by the lid body 60.

[0026] For example, there is a method of forming a housing portion (depression) for housing the electrode body 20 in the exterior film 50 through cold forming. However, it is not always easy to form a deep housing portion by such a method. If an attempt is made to deeply form the housing portion (depression) (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks are likely to occur in the exterior film 50, increasing the possibility of deterioration of battery performance. On the other hand, 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 all-solid-state batteries, from the viewpoint that it is necessary to uniformly apply a high pressure from the outside 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.

[0027] As shown in FIG. 2, the exterior film 50 is a laminate (laminated film) having, for example, a base material layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. Note that not all of these layers need to be included in the exterior film 50. 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. The innermost layer and the outermost layer of the exterior film 50 may be the heat-sealable resin layer 53. In this case, the exterior film 50 may wrap the electrode body 20 and the lid body 60 by joining the outermost layer and the innermost layer.

[0028] The exterior film 50 may be composed of at least a laminate including a barrier layer 52 and a heat-sealable resin layer 53 in this order. In this laminate, the base material layer 51 is a layer provided as needed, the side opposite to the heat-sealable resin layer 53 side of the barrier layer 52 becomes the outermost layer side, and the heat-sealable resin layer 53 becomes the innermost layer.

[0029] The total thickness of the exterior film 50 can be arbitrarily selected. From the viewpoint of strength, the thickness of the exterior film 50 is preferably 50 μm or more. From the viewpoint of formability or followability, the thickness of the exterior film 50 is preferably 1200 μm or less. The thickness of the exterior film 50 is preferably included in the range of 50 μm or more and 1200 μm or less.

[0030] The base material layer 51 included in the exterior film 50 is a layer for imparting heat resistance to the exterior film 50 and suppressing the generation of pinholes that may occur during processing or distribution. The base material layer 51 is composed of, for example, at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer in the base material layer 51, the barrier layer 52 can be protected during the processing of the exterior film 50, and the 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, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. Note that the base material layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base material layer 51 is preferably, for example, 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0031] The barrier layer 52 is a layer that at least suppresses the intrusion of moisture. The barrier layer 52 is joined to the base material layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include a metal foil having barrier properties, a vapor deposition film, and a resin layer. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, and a carbon-containing inorganic oxide vapor deposition film. Examples of the resin layer include 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 steels, titanium steels, 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.

[0032] 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 steels, titanium steels, or steel plates. These recycled materials can be obtained by known methods respectively. The recycled material of the aluminum alloy can be obtained, for example, by the production method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed only of the recycled material, or may be composed of a mixed material of the recycled material and a virgin material. Note that the recycled material of the metal material refers to a metal material that has been recycled, separated, purified, etc. from various products used in the market, waste from the manufacturing process, etc. into a reusable state. 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.

[0033] From the viewpoint of improving the formability or followability of the exterior film 50, the aluminum alloy foil is more preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint 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 iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, an exterior film 50 having better formability can be obtained. When the iron content is 9.0% by mass or less, an exterior film 50 having better flexibility can be obtained. Further, silicon, magnesium, copper, manganese, etc. may be added to the aluminum alloy foil as necessary. Softening can be performed by annealing or the like. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil made of, for example, a strain-hardened aluminum alloy. Examples of the hard aluminum alloy foil include aluminum alloy foils having compositions defined by JIS H4160:1994 A8021H-H18, JIS H4160:1994 A8079H-H18, JIS H4000:2014 A8021P-H14, or JIS H4000:2014 A8079P-H14. From the viewpoint of improving the mechanical strength of the exterior film 50, the aluminum alloy foil is preferably an aluminum alloy foil containing magnesium. In the aluminum alloy foil containing magnesium (100% by mass), the magnesium content is preferably 0.2 to 5.6% by mass, and more preferably 0.2 to 3.0% by mass. Examples of the aluminum alloy foil containing magnesium include aluminum alloy foils having compositions defined by JIS H4000:2017 A5005P-O, JIS H4000:2017 A5050P-O, and JISH4000:2017 A5052P-O.

[0034] Examples of the stainless steel foil include austenitic, ferritic, austenite-ferritic, martensitic, and precipitation hardening stainless steel foils. Further, from the viewpoint of providing the exterior film 50 with excellent formability, the stainless steel foil is preferably composed of austenitic stainless steel.

[0035] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferable.

[0036] 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, and for example, it can be about 5 to 1000 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, 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 9.0 μm or more, still more preferably about 20 μm or more, and more preferably about 25 μm or more. Also, the preferable range of the thickness of the barrier layer 52 is about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 1000 μm, about 9.0 to 85 μm, about 9.0 to 50 μm, about 9.0 to 40 μm, about 9.0 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, about 25 to 35 μm. When the barrier layer 52 is composed of an aluminum alloy foil, the above-mentioned range is particularly preferable. Also, from the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, still more preferably about 50 μm or more, and still more preferably about 55 μm or more. 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 is about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, about 55 to 70 μm. 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, when the capacity of the power storage device is increased, the weight of the power storage device increases, but by increasing the rigidity of the exterior film 50, it can contribute to the high sealing performance of the power storage device.Further, particularly when the barrier layer 52 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Also, 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.

[0037] Further, when the barrier layer 52 is an aluminum foil, it is preferable to provide a corrosion-resistant film on at least the surface opposite to the base material layer 51 in order to prevent dissolution and corrosion. The barrier layer 52 may be provided with corrosion-resistant films on both sides. Here, the corrosion-resistant film means, for example, a thin film that is formed by performing 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 on 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), and the like. 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 surface of the metal foil with a treatment agent and form a metal compound having excellent corrosion resistance. Note that these treatments may be included in the definition of the chemical conversion treatment. Also, when the barrier layer 52 is provided with a corrosion-resistant film, the barrier layer 52 including the corrosion-resistant film is used.

[0038] The corrosion-resistant film prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base material layer 51 during the molding of the outer packaging film 50, and prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride generated by the reaction of electrolytes and moisture. In particular, when the barrier layer 52 is an aluminum alloy foil, it prevents dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52. In addition, it improves the adhesiveness (wettability) of the surface of the barrier layer 52, and shows the effect of preventing delamination between the base material layer 51 and the barrier layer 52 during heat sealing and preventing delamination between the base material layer 51 and the barrier layer 52 during molding.

[0039] The heat-sealable resin layer 53 is joined to the barrier layer 52 via, for example, an adhesive layer 55. The heat-sealable resin layer 53 contained in the outer packaging film 50 is a layer that imparts sealing properties to the outer packaging film 50 by heat sealing. Examples of the heat-sealable resin layer 53 include polyester resins such as polyethylene terephthalate-based resins and polybutylene terephthalate-based resins, polyolefin resins such as polyethylene-based resins and polypropylene-based resins, or resin films made of acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with 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.

[0040] The outer packaging film 50 preferably has one or more layers having a buffering function (hereinafter referred to as "buffer layer") outside the heat-sealable resin layer 53, more preferably outside the barrier layer 52. The buffer layer may be laminated outside the base material layer 51, or the base material layer 51 may also serve as a buffer layer. When the outer packaging film 50 has a plurality of buffer layers, the plurality of buffer layers may be adjacent to each other, or may be laminated via the base material layer 51 or the barrier layer 52 or the like.

[0041] 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. The rubber is, for example, natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the non-woven fabric is preferably a material having excellent heat resistance. When the buffer layer is constituted by a non-woven fabric, the lower limit value of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and 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.

[0042] When the buffer layer is constituted by rubber, the lower limit value of the thickness of the buffer layer is preferably 0.5 mm. When the buffer layer is constituted by rubber, the upper limit value of the thickness of the buffer layer is preferably 10 mm, more preferably 5 mm, and still more preferably 2 mm. When the buffer layer is constituted by rubber, the preferable range of the thickness of the buffer layer is 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0043] 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 by the impact when the power storage device 10 falls or by the handling during the manufacture of the power storage device 10.

[0044] The lid body 60 includes a lid main body 70, a joint portion 80, and a covering body 90 that covers a part of the lid main body 70. The lid body 60 can be manufactured, for example, by injection molding the covering body 90 onto the lid main body 70.

[0045] The lid body 70 and the joint portion 80 are configured to include a conductive material. "Configured to include a conductive material" means that when the total amount of the materials constituting the lid body 70 and the joint portion 80 is 100% by mass, the content rate 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 materials constituting the lid body 70 and the joint portion 80 can contain materials other than the conductive material in addition to the conductive material. The lid body 70 and the joint portion 80 preferably have the corrosion-resistant film described for the barrier layer 52.

[0046] The conductive material constituting the lid body 70 and the joint portion 80 is, for example, a metal material. The metal materials constituting the lid body 70 and the joint portion 80 are, 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 70 and the joint portion 80 connected to the positive electrode are preferably made of aluminum or an aluminum alloy. The lid body 70 and the joint portion 80 connected to the negative electrode are preferably made of nickel, copper, or a copper alloy. The material constituting the lid body 70 and the joint portion 80 connected to the negative electrode may be copper with nickel plating. The materials constituting the lid body 70 and the joint portion 80 may include recycled materials of metal materials. The lid body 70 has a base portion 71 and a covering portion 72.

[0047] The base portion 71 shown in FIGS. 4 and 5 is, for example, in the shape of a rectangular plate and has a first surface 71A and a second surface 71B. The first surface 71A faces the outside. The second surface 71B is the surface on the side opposite to the first surface 71A. The second surface 71B faces the electrode body 20.

[0048] The covering portion 72 is covered by a covering body 90. The covering portion 72 is in a frame shape rising from the first surface 71A of the base portion 71. The covering portion 72 has a first covering portion 72A, a second covering portion 72B, and a third covering portion 72C. The first covering portion 72A constitutes the upper surface of the lid body 70. The first covering portion 72A extends in a first direction (in this embodiment, the LR direction) when viewed from the front of the lid body 70. The second covering portion 72B and the third covering portion 72C are connected to the first covering portion 72A and constitute the side surface of the lid body 70. The second covering portion 72B and the third covering portion 72C extend in a second direction (in this embodiment, the UD direction) intersecting the first direction when viewed from the front of the lid body 70. In this embodiment, the first direction and the second direction are orthogonal when viewed from the front of the lid body 70. The first direction and the second direction do not have to be orthogonal when viewed from the front of the lid body 70.

[0049] At least a part of the surface 72X of the covering portion 72 is covered by the covering body 90. In this embodiment, the entire surface 72X of the covering portion 72 is covered by the covering body 90.

[0050] The joint portion 80 is formed so that the current collector 30 of the electrode body 20 and the lid body 60 can be easily joined. The shape of the joint portion 80 can be arbitrarily selected as long as it protrudes from the lid body 70 toward the electrode body 20. In this embodiment, the joint portion 80 is plate-shaped and protrudes in a first direction, which is the direction from the second surface 71B of the base portion 71 toward the electrode body 20.

[0051] The lid body 70 and the joint portion 80 may be made of the same conductive material or different conductive materials. At least one of the lid body 70 and the joint portion 80 may be partially made of different conductive materials. The lid body 70 and the joint portion 80 may be integrally formed or separately formed and joined. When the lid body 70 and the joint portion 80 are integrally formed, the lid body 70 and the joint portion 80 can be manufactured, for example, by cutting, polishing, electrical discharge machining, cutting, pressing, casting, plastic working, sintering, 3D printers, or forging. When the lid body 70 and the joint portion 80 are separately formed, the lid body 70 and the joint portion 80 may be joined by welding, fitting of unevenness, or caulking. The lid body 70 and the joint portion 80 are not limited thereto and can be manufactured by any method.

[0052] The joint portion 80 has a first end portion 81 and a second end portion 82. The first end portion 81 is one end portion in the FB direction. The first end portion 81 is connected to the lower surface of the base portion 71. The second end portion 82 is the other end portion in the FB direction. The portion of the joint portion 80 including the first end portion 81 is sandwiched between the second covering portion 72B and the third covering portion 72C.

[0053] The joint portion 80 is joined to the current collector 30, for example, by ultrasonic bonding. From the viewpoint of ensuring a wide space for arranging the device 110 (see FIG. 8) in the manufacturing process of the power storage device 10, the second end portion 82 of the joint portion 80 is preferably formed at a position that does not overlap the lid body 70 in a plan view. The second end portion 82 may be formed at a position spaced apart from the exterior film 50. When the second end portion 82 is formed at a position spaced apart from the exterior film 50, it is difficult for the second end portion 82 and the exterior film 50 to come into contact with each other. Therefore, breakage of the exterior film 50 due to contact between the joint portion 80 and the exterior film 50 is suppressed.

[0054] It has an upper surface 83 and a lower surface 84 of the joint portion 80. The upper surface 83 is joined to the current collector 30. The current collector 30 may be joined to the lower surface 84. At least a portion of the upper surface 83 and the lower surface 84 that is joined to the current collector 30 is preferably surface-treated for suitable joining to the current collector 30.

[0055] In this embodiment, at least a part of the lower surface 84 is covered by a covering body 90. The lower surface 84 is preferably joined to the exterior film 50 via the covering body 90. The region of the lower surface 84 that is joined to the exterior film 50 can be arbitrarily selected. In this embodiment, a part of the lower surface 84 and the exterior film 50 are joined. Almost the entire lower surface 84 and the exterior film 50 may be joined. When the lid body 60 does not have the covering body 90, the lid main body 70 and the joint portion 80 may be joined to the exterior film 50 with an adhesive.

[0056] The thickness HA of the joint portion 80 can be arbitrarily selected. In the exterior body 40, the joint portion 80 preferably has a thickness that can be easily bent so that the position of the second end portion 82 can be adjusted. Even when an external force acts on the exterior body 40, the joint portion 80 preferably has a certain thickness so that the joint portion 80 does not break. From such a viewpoint, the minimum value of the thickness HA of the joint portion 80 is preferably, for example, 0.05 mm. The maximum value of the thickness HA of the joint portion 80 is preferably, for example, 16 mm. The preferable range of the thickness HA of the joint portion 80 is 0.6 mm to 0.05 mm. Note that the thickness HA of the joint portion 80 may vary depending on the part. When the thickness HA of the joint portion 80 varies depending on the part, the thickness HA of the joint portion 80 is the thickness of the thickest part.

[0057] The covering body 90 shown in FIGS. 4 and 5 has a lid sealing portion 91. The lid sealing portion 91 is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50. The lid sealing portion 91 and the exterior film 50 may be joined by any method other than heat-sealing, for example, welding or the like. Specific methods of welding are, for example, laser welding or ultrasonic welding, as well as any other method. The lid sealing portion 91 includes a first sealing surface 91A, a second sealing surface 91B, a third sealing surface 91C, and a fourth sealing surface 91D. The first sealing surface 91A constitutes the upper surface of the lid body 60. The first sealing surface 91A is formed on the first covering portion 72A. The first sealing surface 91A extends in the first direction (in this embodiment, the LR direction) when viewed from the front of the lid body 60. The second sealing surface 91B and the third sealing surface 91C are connected to the first sealing surface 91A and constitute the side surface of the lid body 60. The second sealing surface 91B is formed on the second covering portion 72B. The third sealing surface 91C is formed on the third covering portion 73C. The second sealing surface 91B and the third sealing surface 91C extend in the second direction (in this embodiment, the UD direction) that intersects the first direction when viewed from the front of the lid body 60. In this embodiment, when viewed from the front of the lid body 60, the first direction and the second direction are orthogonal. The first direction and the second direction may not be orthogonal when viewed from the front of the lid body 60. The fourth sealing surface 91D constitutes the lower surface of the lid body 60. The fourth sealing surface 91D extends in the first direction (in this embodiment, the LR direction) when viewed from the front of the lid body 60. The fourth sealing surface 91D is formed on the lower surface 84 of the joint portion 80.

[0058] The lid sealing portion 91 further includes boundaries 92, 93, 94, and 95. The boundary 92 is the boundary between the first sealing surface 91A and the second sealing surface 91B. The boundary 93 is the boundary between the first sealing surface 91A and the third sealing surface 91C. The boundary 94 is the boundary between the fourth sealing surface 91D and the second sealing surface 91B. The boundary 95 is the boundary between the fourth sealing surface 91D and the third sealing surface 91C. The shapes of the boundaries 92 to 95 may be corners, or may be rounded by R processing. In this embodiment, the boundaries 92 to 95 are corners.

[0059] The covering 90 is composed of a resin material. Here, "composed of a resin material" means that when the total amount of the materials constituting the covering 90 is 100% by mass, the content rate 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 materials constituting the covering 90 can contain, in addition to the resin material, materials other than the resin material.

[0060] 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-sealable resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the covering 90 may be formed by any molding method.

[0061] The resin material contained in the materials constituting the covering 90 is preferably an olefin-based random copolymer, more preferably contains a resin containing a polyolefin skeleton as a main component, still more preferably contains polyolefin as a main component, and still more preferably contains polypropylene as a main component. The polyolefin may be an acid-modified polyolefin. It is preferable that the resin material contained in the materials constituting the covering 90 has a plurality of types of amide-based lubricants. Further, it is preferable that the resin material contained in the materials constituting the covering 90 further contains an unsaturated fatty acid amide in addition to the saturated fatty acid amide and has a plurality of types of amide-based lubricants. The resin material contained in the materials constituting the covering 90 may be a polyolefin resin added with a propylene-based elastomer having a melting point higher than 150°C.

[0062] 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 obtained by polymerizing ethylene terephthalate with ethylene isophthalate (hereinafter abbreviated following polyethyleneterephthalate / isophthalate), polyethyleneterephthalate / adipate, polyethyleneterephthalate / sodium sulfoisophthalate, polyethyleneterephthalate / sodium isophthalate, polyethyleneterephthalate / phenyl-dicarboxylate, polyethyleneterephthalate / decanedicarboxylate, etc. can be mentioned. Among these, the resin material is preferably polybutylene terephthalate from the viewpoint of enhancing heat resistance and pressure resistance.

[0063] Examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), 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 sealing property and electrolyte resistance.

[0064] The resin as the resin material may contain a filler as required. Specific examples of the filler include glass beads, graphite, glass fibers, carbon fibers, and the like. By the resin as the resin material containing the filler, the deformation resistance of the covering 90 against temperature changes can be improved.

[0065] The melt mass flow rate of the resin material contained in the material constituting the covering 90 is preferably in the range of 1 g / 10 min to 100 g / 10 min, and more preferably in the range of 5 g / 10 min to 80 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014. The measurement temperature of the melt mass flow rate is 230°C.

[0066] In the lid body 60, the lid main body 70 may be configured to include a resin material. When the lid main body 70 is configured to include a resin material, the covering 90 may be omitted. When the lid main body 70 is configured to include a resin material, it is preferable that an electrode terminal is joined to the lid main body 70. The electrode terminal is joined to the current collector 30.

[0067] The cover body 60 may be joined to the exterior film 50 via an adhesive film instead of the covering body 90. The adhesive film can be arbitrarily selected as long as it is a film capable of adhering the exterior film 50 and the cover 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 cover body 60. The material constituting the heat-sealable resin layer on the side of the adhesive film that is adhered to the cover 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.

[0068] 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. Polyethylene terephthalate is particularly preferred because it is inexpensive and has high strength.

[0069] The adhesive film preferably has adhesiveness. When forming the second sealing portion 100B 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.

[0070] 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, when forming the second sealing portion 100B described later, it is preferable that the lid seal portion 91 of the lid body 60 has a certain thickness in the FB direction so that the lid seal portion 91 of the lid body 60 and the exterior film 50 can be suitably heat-sealed. The minimum value of the thickness of the lid seal portion 91 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 seal portion 91 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 seal portion 91 of the lid body 60 may be 20 mm or more. The preferable range of the thickness of the lid seal portion 91 of 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, an aspect in which the lid body 60 is composed only of a film defined by the [Packaging Terms] standard of JIS (Japanese Industrial Standards) is not included. Note that the thickness of the lid seal portion 91 of the lid body 60 may vary depending on the part of the lid body 60. When the thickness of the lid seal portion 91 of the lid body 60 varies depending on the part, the thickness of the lid seal portion 91 of the lid body 60 is the thickness of the thickest part.

[0071] In the present embodiment, with the exterior film 50 wound around the electrode body 20, the first sealing portion 100A is formed by heat-sealing the mutually facing surfaces (heat-fusible resin layers 53) of the exterior film 50.

[0072] The first sealing portion 100A is formed by heat-sealing the portion including the first edge 50A of the exterior film 50 shown in FIG. 3 and the portion including the second edge 50B. The first sealing portion 100A extends in the longitudinal direction of the exterior body 40. In the exterior body 40, the position where the first sealing portion 100A is formed can be arbitrarily selected. In the present embodiment, it is preferable that the base 70X of the first sealing portion 100A 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 100AX of the first sealing portion 100A may be located on any surface of the exterior body 40. In the present embodiment, the first sealing portion 100A protrudes outward beyond the electrode body 20 in plan view. The first sealing portion 100A may be folded, for example, toward the second surface 42 of the exterior body 40 or toward the first surface 41.

[0073] In the present embodiment, the second sealing portion 100B (lid sealing portion 100B) is formed by heat-sealing the heat-fusible resin layer 53 of the exterior film 50 and the lid sealing portion 91 of the lid body 60. Hereinafter, the sealing strength between the heat-fusible resin layer 53 of the exterior film 50 and the lid sealing portion 91 of the lid body 60 may be referred to as the sealing strength (bonding strength) of the second sealing portion 100B. Note that the sealing strength of the second sealing portion 100B is the sealing strength between the heat-fusible resin layer 53 and the lid body 60 in the long-side portion of the lid sealing portion 91, that is, the lid sealing portion 91 extending in the LR (width) direction in FIG. 1A.

[0074] The seal strength of the second sealing portion 100B is measured as follows. First, a cut is formed in a portion of the outer packaging film 50 that constitutes the first surface 41 of the outer package 40, and three strip members 41X, 41Y, and 41Z arranged in the LR direction (see the two-dot chain line in FIG. 1B) are formed. Note that the strip members 41X, 41Y, and 41Z are formed so as to avoid the release portion 100X described later. 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 100B. The length of the lid body 60 in the LR direction is 45 mm or more. Next, the seal strengths of the strip members 41X, 41Y, and 41Z are measured respectively by pulling the ends of the strip members 41X, 41Y, and 41Z on the side opposite to the ends joined to the lid body 60 upward in the UD direction (the direction opposite to the first surface 41B). The distance between the chucks in the UD direction is 10 mm. The seal strength of the strip members 41X, 41Y, and 41Z is the peak value of their respective seal strengths. In the present embodiment, the seal strength of the second sealing portion 100B 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 strengths of the three strip members are measured in the same manner as when the length of the lid body 60 in the LR direction is 45 mm or more. By dividing the obtained seal strengths by the arbitrary width X mm and multiplying by 15 respectively, they are converted into the seal strengths of the three strip members at a width of 15 mm. The seal strength of the second sealing portion 100B 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 long sides and short sides, the seal strength of the second sealing portion 100B is the seal strength at the long side portion of the lid seal portion 91 of the plurality of parts.

[0075] 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 100B 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 100B 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 100B 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 100B is preferably 300 N / 15 mm or less. The preferable range of the sealing strength of the second sealing portion 100B 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.

[0076] In this embodiment, it is preferable that the lid body 60 has a protruding portion 96 protruding from the lid seal portion 91 so that a gap is less likely to be formed between the exterior film 50 and the lid body 60. The protruding portion 96 may be integrally formed with the covering body 90, or may be formed separately from the covering body 90 and joined to the covering body 90. In this embodiment, the protruding portion 96 is integrally formed with the covering body 90. In the lid seal portion 91, the position where the protruding portion 96 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 100AX of the first sealing portion 100A and the lid body 60. In particular, when the base 100AX of the first sealing portion 100A is located at the boundaries 92 to 95 of the lid body 60, the resin filling property between the base 100AX of the first sealing portion 100A and the lid body 60 is likely to decrease. For this reason, it is preferable that the protruding portion 96 is formed at a position where the base 100AX of the first sealing portion 100A is located in the lid seal portion 91. In this embodiment, the base 100AX of the first sealing portion 100A is located at the boundary 92 of the lid body 60. For this reason, it is preferable that the protruding portion 96 is formed at the boundary 92 in the lid seal portion 91. In this embodiment, the first sealing portion 100A is sealed with the protruding portion 96 sandwiched therebetween. Note that the protruding portion 96 may be formed on at least one of the first sealing surface 100AA, the second sealing surface 100AB, the third sealing surface 100AC, the fourth sealing surface 100AD, the boundary 93, the boundary 94, and the boundary 95.

[0077] The shape of the protruding portion 96 can be arbitrarily selected. In this embodiment, the shape of the protruding portion 96 is plate-like. The thickness of the protruding portion 96 can be arbitrarily selected. In this embodiment, the protruding portion 96 becomes thinner as it moves away from the boundary 92. In other words, the protruding portion 96 has a tapered shape as it moves away from the boundary 92. The thickness of the protruding portion 96 may be constant, or may become thicker as it moves away from the boundary 92.

[0078] The direction in which the protrusion 96 extends can be arbitrarily selected. In the present embodiment, the protrusion 96 extends along the first direction (in the present embodiment, the LR direction). The protrusion 96 may extend along the second direction (in the present embodiment, the UD direction). The protrusion 96 may extend in a third direction that intersects the first direction (in the embodiment, the LR direction) and the second direction (in the embodiment, the UD direction) in a front view of the lid body 60.

[0079] The length of the protrusion 96 can be arbitrarily selected within the range that is equal to or less than the length of the first sealing portion 100A. For example, the length of the protrusion 96 may be substantially equal to the length of the first sealing portion 100A, or may be 30% - 50% of the length of the first sealing portion 100A.

[0080] When the power storage device 10 is in use, the internal pressure of the outer package 40 increases due to at least one of the expansion of the electrode body 20 and the gas generated inside the outer package 40. When the internal pressure of the outer package 40 increases, a part of the outer package 40 is broken, and at least one of the gas and the electrolyte is released. The power storage device 10 of the present embodiment includes a release portion 100X configured to be able to limit to a certain extent the location where the outer package 40 breaks when the internal pressure of the outer package 40 increases. The number of release portions 100X provided in the power storage device 10 can be arbitrarily selected. In the present embodiment, the number of release portions 100X provided in the power storage device 10 is one. The power storage device 10 may include two or more release portions 100X.

[0081] The release portion 100X is an element in which the strength of the outer package 40 is partially reduced. The position where the release portion 100X is formed in the outer package 40 is, for example, a position where the influence on surrounding devices is small even when gas or the like is released. For this reason, in the outer package 40, the position where the release portion 100X is formed is arbitrary, and it is preferably determined based on the usage environment of the power storage device 10.

[0082] In this embodiment, the release portion 100X is a portion where the bonding strength has partially decreased in the second sealing portion 100B. For example, the release portion 100X is formed in a portion including the center of the first sealing surface 91A in the LR direction.

[0083] The material (hereinafter referred to as "first material") that constitutes the location where the release portion 100X is formed in the covering 90 is made of a resin material different from the material (hereinafter referred to as "second material") that constitutes other locations. In the first example, the first material is a material with a lower melting point than the second material. The first material in the first example is polyethylene or polypropylene with a higher amount of polyethylene added than the second material. In the second example, the first material is a material that contains more filler than the second material. The filler is, for example, glass fiber or carbon fiber. Note that the first material and the second material can be arbitrarily selected as long as they are materials that can adjust the bonding strength of the second sealing portion 100B, not limited to resin materials.

[0084] The entire covering 90 may be made of the same resin material. In this case, by making at least one of the width in the FB direction and the thickness in the UD direction of the location corresponding to the release portion 100X in the covering 90 smaller than other locations, the release portion 100X where the bonding strength of the second sealing portion 100B has partially decreased can be formed. Note that the material that constitutes the covering 90 can be arbitrarily selected as long as it is a material that can bond the lid body 70 and the exterior film 50.

[0085] <1-2. Manufacturing method of the power storage device> FIG. 7 is a flowchart showing an example of a method for manufacturing the power storage device 10. The method for manufacturing the power storage device 10 includes, for example, a first step, a second step, a third step, a fourth step, and a fifth step. The first to fifth steps are, for example, performed by a manufacturing apparatus for the power storage device 10. At least a part of the first to fifth steps may be performed by an operator. Note that the first to fifth steps are for the convenience of 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. The order of the first to fifth steps can be arbitrarily changed as long as there is no technical contradiction.

[0086] In the first step of step S11, the manufacturing apparatus arranges a pair of lid bodies 60 on the side of the electrode body 20 in the FB direction.

[0087] The second step of step S12 is performed after the first step. In the second step, the manufacturing apparatus joins the current collector 30 and the joint portion 80 of the lid body 60. When the lid main body 70 and the joint portion 80 are configured as separate bodies, the joint portion 80 and the lid main body 70 may be joined after the current collector 30 and the joint portion 80 are joined.

[0088] FIG. 8 is a diagram related to the second step. In the present embodiment, in the second step, the current collector 30 and the joint portion 80 are joined by ultrasonic welding. The current collector 30 and the joint portion 80 may be joined by resistance welding or laser welding. The ultrasonic welding is performed using an apparatus 110. The apparatus 110 is a known ultrasonic apparatus and includes a chip 111, an anvil 112, a horn 113, and an oscillator 114. In the second step, the current collector 30 and the joint portion 80 are ultrasonically welded in a state where a portion including the upper surface 83, the lower surface 84 of the joint portion 80, and the end portion 31 of the current collector 30 is sandwiched between the chip 111 and the anvil 112.

[0089] The third step of step S13 is carried out after the second step. In the third step, while restricting the movement of the electrode body 20 and the lid body 60 by the restricting means, the manufacturing apparatus winds the exterior film 50 around the electrode body 20 and the lid body 60 with tension acting on the exterior film 50. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force in a direction opposite to the direction in which the exterior film 50 is pulled to the electrode body 20 and the lid body 60. Note that the restricting means may include a roller that travels on the exterior film 50 in a state where the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50. Note that the electrode body 20 may be accommodated inside the exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and after joining the current collector 30 and the joint portion 80, the openings may be closed by the lid body 60. In yet another example, the electrode body 20 connected to the joint portion 80 of the lid body 60 may be accommodated inside the exterior film 50 configured in a cylindrical shape so that openings are formed at both ends in the FB direction, and the openings may be closed by the lid body 60.

[0090] The fourth step of step S14 is carried out after the third step. In the fourth step, the manufacturing apparatus forms the second sealing portion 110B by heat-sealing the exterior film 50 and the lid body 60. By completing the fourth step, the release portion 100X in which the joining strength of the second sealing portion 110B is partially reduced is formed.

[0091] The fifth step of step S15 is carried out before or after the fourth step. In the fifth step, the manufacturing apparatus forms the first sealing portion 100A by heat-sealing the heat-fusible resin layer 53 of the portion including the first edge 50A of the exterior film 50 and the heat-fusible resin layer 53 of the portion including the second edge 50B while restricting the movement of the electrode body 20 and the lid body 60 and with tension acting on the exterior film 50.

[0092] <1-3. Action and Effect of the Power Storage Device> The power storage device 10 includes a discharge portion 100X. Since the discharge portion 100X is an element where the strength of the exterior body 40 is partially reduced, when the internal pressure of the exterior body 40 rises, the discharge portion 100X is more likely to break (peel off) earlier than other locations, and there is a high possibility that gas or the like will be discharged. For this reason, when the internal pressure of the exterior body 40 rises, the location where the exterior body 40 breaks can be made a limited portion.

[0093] [2. Modification Example] The above embodiment is an example of a form that the power storage device, lid body, and manufacturing method of the power storage device according to the present invention can take, and is not intended to limit that form. The power storage device, lid body, and manufacturing method of the power storage device according to the present invention can take a form different from the form exemplified in the embodiment. An example thereof is a form in which a part of the configuration of the embodiment is replaced, changed, or omitted, or a new configuration is added to the embodiment. Some examples of modification examples of the embodiment are shown below. Note that the following modification examples can be combined with each other as long as there is no technical contradiction.

[0094] <2-1. First Modification Example> In the above embodiment, the position where the joint portion 80 of the lid body 60 is formed can be arbitrarily changed. FIG. 9 is a perspective view of the lid body 160 included in the power storage device 10 of the first modified example. The lid body 160 has a joint portion 180. The first end portion 81 of the joint portion 180 only needs to be connected to at least the lid main body 70. In the example shown in FIG. 9, the covering portion 72 preferably has a fourth covering portion 72D. The fourth covering portion 72D constitutes the lower surface of the lid main body 70. The fourth covering portion 72D is connected to the second covering portion 72B and the third covering portion 72C. The fourth covering portion 72D extends in the first direction (in this embodiment, the LR direction) in the front view of the lid body 160. When the covering portion 72 has the fourth covering portion 72D, the lower surface 84 of the joint portion 180 does not need to be covered by the covering body 90, so the second end portion 82 may be formed at a position separated from the exterior film 50. When the second end portion 82 is formed at a position separated from the exterior film 50, it is difficult for the second end portion 82 to contact the exterior film 50. Therefore, damage to the exterior film 50 caused by the contact between the joint portion 80 and the exterior film 50 is suppressed.

[0095] <2-2. Second Modified Example> In the above embodiment, the shape of the joint portion 80 can be arbitrarily changed. FIG. 10 is a cross-sectional view of the power storage device 10 of the second modified example. The power storage device 10 of the second modified example includes a lid body 260. The lid body 260 has a joint portion 280. The joint portion 280 has a first portion 281 and a second portion 282. The first portion 281 is connected to the lid main body 70 and extends in the first direction toward the electrode body 20. In the example shown in FIG. 10, the first direction is the FB direction. The second portion 282 is connected to the first portion 281 and extends in a second direction intersecting the first direction in the side view of the lid body 60. In the example shown in FIG. 10, the second direction is the UD direction. The angle formed by the first direction and the second direction is included in the range greater than 0° and less than 180°. In the example shown in FIG. 10, the angle formed by the first direction and the second direction is 90°. In the second modified example, the second portion 282 of the joint portion 280 is joined to the current collector 30.

[0096] The first part 281 and the second part 282 may be integrally formed, or may be separately formed and joined. In the second modification, the first part 281 and the second part 282 are integrally formed. More specifically, in the second modification, the first part 281 and the second part 282 are formed by bending one joint 280. In the second modification, the joint 280 has a thickness that can be bent, so it has flexibility. Therefore, even when an external force such as vibration acts on the power storage device 10, the joint 280 is less likely to be damaged. In other words, the joint 280 has high durability. Also, since the joint 280 extends in the second direction, the size of the power storage device 10 in the FB direction can be made smaller compared to a configuration in which the joint extends in the first direction as a whole. Further, since the second end 82 is formed at a position separated from the outer film 50, the second end 82 and the outer film 50 are less likely to come into contact. Therefore, damage to the outer film 50 due to contact between the joint 280 and the outer film 50 is suppressed.

[0097] <2-3. Third Modification> FIG. 11 is a cross-sectional view of a power storage device 10 according to a third modification, which is a further modification of the second modification. The power storage device 10 according to the third modification includes a lid 360. The lid 360 has a joint 380. The joint 380 has a third part 383 in addition to the first part 281 and the second part 282 of the second modification. The third part 383 is connected to the second part 282 and extends in the first direction toward the electrode body 20. In the example shown in FIG. 11, the first direction is the FB direction. The first part 281, the second part 282, and the third part 383 may be integrally formed, or at least two of them may be separately formed and joined. In the third modification, the first part 281, the second part 282, and the third part 383 are integrally formed. More specifically, in the third modification, the first part 281, the second part 282, and the third part 383 are formed by bending one joint 380. Also in the power storage device 10 according to the third modification, the same effects as those of the power storage device 10 according to the second modification can be obtained.

[0098] <2-4. Fourth Modification> In the above embodiment, the covering portion 72 may be omitted from the lid body 70. In the fourth modification, the side surface (edge) of the base portion 71 may be covered by a covering body 90. In the fourth modification, the first end portion 81 of the joint portion 80 may be connected to the second surface 71B of the base portion 71 or may be connected to the side surface of the base portion 71.

[0099] <2-5. Fifth Modification> In the above embodiment, the specific configuration of the release portion 100X can be arbitrarily changed. FIG. 12 is a cross-sectional view of the lid body 570 of the lid 60 provided in the power storage device 10 of the fifth modification. In FIG. 5, the illustration of the covering body 90 is omitted.

[0100] The lid body 570 includes a release portion 500X. The release portion 500X is an element that is partially configured to be thin in the lid body 570. In the example shown in FIG. 12, the release portion 500X is formed in the base portion 571. The release portion 500X may be formed in the covering portion 72 or may be formed at the boundary between the base portion 71 and the covering portion 72. In the power storage device 10 of the fifth modification, when the internal pressure of the exterior body 40 rises, the release portion 500X is more likely to break (rupture) earlier than other locations, and there is a high possibility that gas or the like is released. Therefore, the power storage device 10 of the fifth modification can obtain the same effects as the power storage device 10 of the embodiment.

[0101] <2-6. Sixth Modification> FIG. 13 is a cross-sectional view of the lid body 670 of the lid 60 provided in the power storage device 10 of the sixth modification. In FIG. 6, the illustration of the covering body 90 is omitted.

[0102] The lid body 670 includes a release portion 600X. The release portion 600X is an element where the strength of the lid body 670 is partially reduced due to the formation of the recess 610 in the lid body 670. The recess 610 does not penetrate the lid body 670. The recess 610 is, for example, a depression or a notch. In the example shown in FIG. 12, the recess 610 is formed in the covering portion 72. The recess 610 may be formed in the base portion 71. In the power storage device 10 of the sixth modification, when the internal pressure of the exterior body 40 rises, the release portion 600X is more likely to break (rupture) earlier than other locations, and there is a high possibility that gas or the like is released. Therefore, the power storage device 10 of the sixth modification can obtain the same effects as the power storage device 10 of the embodiment.

[0103] <2-7. Seventh Modification> In the above-described embodiment, at least a part of the covering portion 72 of the lid body 70 may be configured to include a shape memory alloy having a curved shape at a predetermined temperature. In the seventh modification, the discharge portion 700X includes a portion of the lid body 70 configured to include a shape memory alloy. FIGS. 14 and 15 are cross-sectional views of the power storage device 10 according to the seventh modification in a state where the internal pressure has increased and the discharge portion 700X has been destroyed. The covering portion 72 of the power storage device 10 according to the seventh modification has a linear shape as shown in FIG. 6 or the like before the temperature rises, but deforms as shown in FIG. 14 or FIG. 15 when the temperature rises with an increase in the internal pressure. In the examples shown in FIGS. 14 and 15, the covering portion 72 deforms so as to curve. The covering portion 72 may also deform so as to bend. That is, in the power storage device 10 according to the seventh modification, when the temperature of the exterior body 40 rises as the internal pressure of the exterior body 40 increases, the portion of the lid body 70 configured to include a shape memory alloy returns to its original shape, whereby the exterior body 40 is configured to be partially destroyed. The partial destruction of the exterior body 40 includes at least one of the destruction of the portion of the lid body 70 configured to include a shape memory alloy and the destruction of elements in the vicinity of the portion of the lid body 70 such as the exterior film 50 and the covering body 90 that are configured to include a shape memory alloy. In the power storage device 10 according to the seventh modification, when the internal pressure of the exterior body 40 increases, the discharge portion 700X is more likely to be destroyed (broken) earlier than other locations, and there is a high possibility that gas or the like is discharged. For this reason, the power storage device 10 according to the seventh modification can obtain the same effects as the power storage device 10 of the embodiment.

[0104] <2-8. Eighth Modification> In the above-described embodiment, the power storage device 10 may have a discharge portion 800X instead of, or in addition to, the discharge portion 100X. The discharge portion 800X is a portion where the bonding strength between the lid body 70 and the covering body 90 is lower than the bonding strength between the covering body 90 and the exterior film 50. FIG. 16 is a cross-sectional view of the power storage device 10 according to the eighth modification example in a state where the internal pressure has risen and the discharge portion 800X has been destroyed. In the power storage device 10 according to the eighth modification example, when the internal pressure of the exterior body 40 rises, the lid body 70 is peeled off from the covering body 90 while the bonding between the exterior film 50 and the covering body 90 is maintained, and there is a high possibility that gas or the like is discharged. Therefore, the power storage device 10 according to the eighth modification example can obtain the same effects as the power storage device 10 of the embodiment. In FIG. 16, a state where the entire lid body 70 is peeled off from the covering body 90 is shown, but depending on the range where the discharge portion 800X is formed, the lid body 70 may be partially peeled off from the covering body 90.

[0105] <2-9. Ninth Modification Example> FIG. 17 is a cross-sectional view of the power storage device 10 of the ninth modification. The power storage device 10 of the ninth modification includes a discharge portion 900X. The discharge portion 900X has a through-hole 971X formed in the base portion 71 of the lid body 70 and a barrier film 910. The through-hole 971X penetrates the first surface 71A and the second surface 71B of the base portion 71. The barrier film 910 is joined to the first surface 71A of the base portion 71 so as to close the through-hole 971X. The barrier film 910 may be joined to the second surface 71B of the base portion 71 so as to close the through-hole 971X. The barrier film 910 may be disposed inside the lid body 70 in the FB direction so as to close the through-hole 971X. The barrier film 910 is a film including the barrier layer 52 of the exterior film 50 exemplified in the embodiment. In the ninth modification, the through-hole 971X may be closed by the covering body 90, and the barrier film 910 may be joined to the portion of the covering body 90 that closes the through-hole 971X. In the power storage device 10 of the ninth modification, when the internal pressure of the exterior body 40 rises, the barrier film 910 of the discharge portion 700X is more likely to be broken (ruptured) earlier than other portions, and there is a high possibility that gas or the like is discharged. Therefore, the power storage device 10 of the ninth modification can obtain the same effects as the power storage device 10 of the embodiment.

[0106] <2-10. Tenth Modification> When the power storage device 10 includes at least two lid bodies 60 as in the power storage device 10 of the embodiment, the breaking strength of one lid body 60 may be configured to be lower than that of the other lid body 60. The breaking strength of the lid body 60 is defined by the pressure when the lid body 60 is clamped by a jig and pneumatic pressure is applied from the first surface 71A or the second surface 71B by a leak tester and the lid body 60 is broken. In the tenth modification, the release portion 100X is formed in one lid body 60. The difference between the breaking strength of one lid body 60 and the breaking strength of the other lid body 60 can be arbitrarily selected, but from the viewpoint of preferably forming the release portion 100X, it is preferably 0.05 MPa or more, and more preferably 0.1 MPa or more. In the power storage device 10 of the tenth modification, when the internal pressure of the exterior body 40 rises, there is a high possibility that one lid body 60 breaks (ruptures) before the other lid body 60 and gas or the like is released. Therefore, the power storage device 10 of the tenth modification can obtain the same effects as the power storage device 10 of the embodiment.

[0107] <2-11. Tenth Modification> When the power storage device 10 includes at least two lid bodies 60 as in the power storage device 10 of the embodiment, the bonding strength of the second sealing portion 100B of one lid body 60 may be configured to be lower than that of the second sealing portion 100B of the other lid body 60. In this case, the release portion 100X is formed in the second sealing portion 100B corresponding to one lid body 60. In the power storage device 10 of the eleventh modification, when the internal pressure of the exterior body 40 rises, there is a high possibility that the second sealing portion 100B corresponding to one lid body 60 breaks (peels off) before the other lid body 60 and gas or the like is released. Therefore, the power storage device 10 of the eleventh modification can obtain the same effects as the power storage device 10 of the embodiment.

[0108] <2-12. Eleventh Modification> In the above embodiment, the exterior film 50 of the power storage device 10 may project outward beyond at least one of the two lid bodies 60 in the FB direction. By closing the portion of the exterior film 50 that projects outward beyond the lid body 60, the electrode body 20 is sealed. The portion of the exterior film 50 that projects beyond the lid body 60 may be folded like a gable-top type pouch or a brick type pouch. In the twelfth modification, it is preferable that the electrode terminal is joined to the second surface 71B of the lid body 60. The length of the electrode terminal in the FB direction is preferably such that it is exposed from the portion of the exterior film 50 that projects outward beyond the lid body 60.

[0109] <2-13. Twelfth Modification> In the above embodiment, the exterior body 40 may not have one of the two lid bodies 60. In this modification, in the FB direction, in the portion where the lid body 60 of the exterior body 40 is omitted, by closing the portion of the exterior film 50 that projects outward beyond the electrode body 20, the electrode body 20 is sealed. The portion of the exterior film 50 that projects outward beyond the electrode body 20 may be folded like a gable-top type pouch or a brick type pouch.

[0110] <2-14. Thirteenth Modification> In the above embodiment, the outer shape of the exterior body 40 can be arbitrarily changed. The outer shape of the exterior body 40 may be a cylinder, a prism, or a cube.

Description of Reference Numerals

[0111] 10: Power storage device 20: Electrode body 40: Exterior body 50: Exterior film 60, 260, 360: Lid body 70, 570, 670: Lid main body 100B: Second sealing portion (lid sealing portion) 100X: Discharging portion 200X: Discharging portion 300X: Discharge section 400X: Discharge section 500X: Discharge section 600X: Discharge section 700X: Discharge section 800X: Discharge section 900X: Discharge section 910: Barrier film 971X: Through-hole

Claims

1. An electrode body, and an exterior body that seals the electrode body, and includes: The exterior body includes: an exterior film that wraps the electrode body, a lid body that seals the electrode body together with the exterior film, and a discharge portion configured to be partially destroyed to release at least one of gas and electrolyte when the internal pressure of the exterior body rises. A power storage device.

2. The lid body has a lid main body including a portion joined to the exterior film, and the discharge portion includes a portion of the lid main body that is partially formed thinner. The power storage device according to claim 1.

3. The lid body has a lid main body including a portion joined to the exterior film, and the discharge portion includes a portion of the lid main body in which a recess is formed. The power storage device according to claim 1.

4. The exterior body includes at least two of the lid bodies, the breaking strength of one of the lid bodies is lower than that of the other lid body, and the discharge portion is formed in the one lid body. The power storage device according to claim 1.

5. The exterior body includes at least two of the lid bodies, the exterior body has a lid sealing portion where the lid body and the exterior film are joined, the joining strength of the lid sealing portion of one of the lid bodies is lower than that of the lid sealing portion of the other lid body, and the discharge portion is formed in the lid sealing portion of one of the lid bodies. The power storage device according to claim 1.

6. The exterior body has a lid sealing portion where the lid body and the exterior film are joined, and the discharge portion includes a portion where the joining strength is partially reduced in the lid sealing portion. The power storage device according to claim 1.

7. The lid body has a lid main body and a covering body that joins the lid main body and the exterior film, and the discharge portion is a portion where the joining strength between the lid main body and the covering body is lower than the joining strength between the covering body and the exterior film. The power storage device according to claim 1.

8. The lid body has a lid main body joined to the exterior film, at least a part of a portion of the lid main body joined to the exterior film is configured to include a shape memory alloy, the discharge portion includes a portion of the lid main body configured to include the shape memory alloy, and when the temperature of the exterior body rises as the internal pressure of the exterior body rises, the portion of the lid main body configured to include the shape memory alloy returns to its original shape, thereby configuring the exterior body to be partially destroyed. The power storage device according to claim 1.

9. The discharging part has a through hole formed in the lid body, and a barrier film closing the through hole. The power storage device according to claim 1.

10. A lid body used as an exterior body of a power storage device, having a lid main body, wherein the lid main body is a part that can be broken when the internal pressure of the exterior body rises, and includes a part that is partially thin. The lid body.

11. A lid body used as an exterior body of a power storage device, having a lid main body, wherein the lid main body is a part that breaks when the internal pressure of the exterior body rises, or a part that can break an element constituting the exterior body, and includes a part where a recess is formed. The lid body.

12. A lid body used as an exterior body of a power storage device, wherein the lid body has a lid main body joined to an exterior film constituting the exterior body, and at least a part of a part of the lid main body joined to the exterior film is configured to include a shape memory alloy. The lid body.

13. A method for manufacturing a power storage device, wherein the power storage device includes an electrode body, and an exterior body for sealing the electrode body, wherein the exterior body includes an exterior film wrapping the electrode body, a lid body for sealing the electrode body together with the exterior film, and a discharging part configured to be able to discharge at least one of gas and electrolyte by being broken when the internal pressure of the exterior body rises, wherein the method for manufacturing the power storage device includes a step of forming the discharging part. The method for manufacturing a power storage device.

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