Electricity storage device, deformation suppression member, lid unit

Abstract

To provide an electricity storage device capable of suppressing deformation of an exterior body when the internal pressure of an electricity storage device changes, a deformation suppressing member used in the electricity storage device, and a lid unit including the deformation suppressing member.SOLUTION: An electricity storage device includes an electrode body and an exterior body that seals an electrode body. The exterior body includes an exterior film that wraps the electrode body and a deformation suppression member that suppresses deformation of the exterior body when a temperature rises in the electricity storage device.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] The present invention relates to an electricity storage device, a deformation suppression member, and a lid unit. [Background technology]

[0002] Patent Document 1 discloses an example of an electricity storage device. This electricity storage device includes an electrode assembly and an exterior body that seals the electrode assembly. The exterior body includes an exterior film that encases the electrode assembly and a lid that is joined to the exterior film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-123686 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electricity storage device, the internal pressure of the electricity storage device may increase due to volumetric changes in the positive electrode active material and the negative electrode active material accompanying charging and discharging, gas generation, etc. When the internal pressure of the electricity storage device increases, the exterior body expands, causing the exterior film to stretch, which may reduce the mechanical strength of the exterior film.

[0005] The present invention aims to provide an electricity storage device that can suppress deformation of an exterior body when the internal pressure of the electricity storage device changes, a deformation suppression member used in this electricity storage device, and a lid unit equipped with this deformation suppression member. [Means for solving the problem]

[0006] The energy storage device according to a first aspect of the present invention comprises an electrode body and an exterior body that seals the electrode body, the exterior body including an exterior film that wraps the electrode body, and a deformation suppression member that suppresses deformation of the exterior body when the internal pressure of the energy storage device changes.

[0007] An electricity storage device according to a second aspect of the present invention is the electricity storage device according to the first aspect, wherein the deformation suppression member is configured to suppress expansion of the exterior body when internal pressure of the electricity storage device increases.

[0008] An electricity accumulation device according to a third aspect of the present invention is the electricity accumulation device according to the first or second aspect, wherein the deformation suppression member is sealed by the exterior body.

[0009] An electricity accumulation device according to a fourth aspect of the present invention is the electricity accumulation device according to the first or second aspect, wherein the deformation suppression member is joined to an inner surface of the exterior film.

[0010] An electricity storage device according to a fifth aspect of the present invention is the electricity storage device according to the fourth aspect, wherein the deformation suppression member includes a first surface facing the electrode body, a second surface opposite the first surface, and a side surface connecting the first surface and the second surface, and at least a portion of the side surface is joined to the inner surface of the exterior film.

[0011] An electricity storage device according to a sixth aspect of the present invention is the electricity storage device according to the fourth aspect, wherein the deformation suppression member has a first surface facing the electrode body and a second surface opposite to the first surface, and at least a portion of the second surface is joined to the exterior film.

[0012] An electricity storage device according to a seventh aspect of the present invention is the electricity storage device according to the sixth aspect, wherein the entire second surface and the exterior film are joined together.

[0013] An electricity storage device according to an eighth aspect of the present invention is the electricity storage device according to the sixth aspect, wherein an edge of the second surface and the exterior film are joined together.

[0014] An energy storage device according to a ninth aspect of the present invention is an energy storage device according to any one of the first to eighth aspects, wherein the exterior body has a first sealing portion in which facing surfaces of the exterior film are sealed together, and the deformation suppression member is positioned so as to suppress expansion of a portion of the exterior body that is continuous with the first sealing portion.

[0015] An energy storage device according to a tenth aspect of the present invention is an energy storage device according to any one of the first to ninth aspects, wherein the exterior body has a lid body that seals the electrode body together with the exterior film, and the deformation suppression member is joined to at least one of the lid body and the exterior film.

[0016] An electricity accumulation device according to an eleventh aspect of the present invention is the electricity accumulation device according to any one of the first to tenth aspects, wherein the deformation suppression member has a passage portion through which an electrolyte can pass.

[0017] An electricity accumulation device according to a twelfth aspect of the present invention is the electricity accumulation device according to the first aspect, wherein the deformation suppression member is disposed outside the exterior body.

[0018] An electricity storage device according to a thirteenth aspect of the present invention is the electricity storage device according to the twelfth aspect, wherein the exterior body has a lid body that seals the electrode body together with the exterior film, and the deformation suppression member is connected to the lid body.

[0019] The electricity storage device according to a fourteenth aspect of the present invention comprises an electrode body and an outer casing that seals the electrode body, the outer casing including an outer casing film that wraps the electrode body, and the outer casing film partially has a deformation suppression structure that suppresses deformation of the outer casing when the internal pressure of the electricity storage device changes.

[0020] A lid unit according to a fifteenth aspect of the present invention comprises a lid body used as an outer casing for an electricity storage device, and a deformation suppression member joined to the lid body and suppressing deformation of the outer casing when the internal pressure of the electricity storage device changes.

[0021] A deformation suppressing member according to a sixteenth aspect of the present invention is a deformation suppressing member for use in an electricity storage device, which is configured to suppress deformation of an exterior body of the electricity storage device when an internal pressure of the electricity storage device changes. Effect of the Invention

[0022] The electricity storage device, deformation suppression member, and lid unit according to the present invention can suppress deformation of the exterior body when the internal pressure of the electricity storage device changes. [Brief description of the drawings]

[0023] [Figure 1A] FIG. 1 is a perspective view of an electricity storage device according to an embodiment. [Figure 1B] FIG. 2 is a diagram showing a method for measuring the seal strength of the second sealing portion of the power storage device of FIG. 1A. [Diagram 2] 1B is a cross-sectional view showing an example of a layer structure of an exterior film included in the electricity storage device of FIG. 1A. [Diagram 3] FIG. 1B is a diagram showing the state in which the exterior film of the power storage device of FIG. 1A is unfolded. [Figure 4] 1B is a perspective view of a lid provided in the electricity storage device of FIG. 1A. [Figure 5A] 1B is a cross-sectional view taken along line D5-D5 in FIG. 1A. [Figure 5B] FIG. 2 is a diagram showing an example of a usage state of the electricity storage device in FIG. 1. [Figure 6] 1B is a perspective view of a deformation suppressing member included in the electricity accumulation device in FIG. 1A. [Figure 7] FIG. 1B is a perspective view of a lid unit included in the electricity storage device of FIG. 1A. [Figure 8] 4 is a flowchart showing an example of a method for manufacturing the electricity storage device in FIG. 1A. [Figure 9] 9 is a diagram showing a third step of the method for producing the electricity storage device in FIG. 8. [Figure 10] 9 is a diagram showing a fourth step of the method for producing the electricity storage device in FIG. 8. [Figure 11] 9 is a diagram showing a fifth step of the method for producing the electricity storage device in FIG. 8. [Figure 12]9 is a diagram showing a sixth step of the method for manufacturing the electricity storage device in FIG. 8. [Figure 13] 9 is a diagram showing an eighth step of the method for manufacturing the electricity storage device in FIG. 8. [Figure 14] 13 is a diagram showing an example of a sealed region on a second surface of a deformation suppressing member included in an electricity accumulation device of a first modified example. FIG. [Figure 15] 13 is a diagram showing another example of a sealed region on a second surface of the deformation suppressing member included in the electricity accumulation device of the first modified example. FIG. [Figure 16] FIG. 11 is a perspective view of a deformation suppressing member included in an electricity accumulation device according to a second modified example. [Figure 17] FIG. 13 is a perspective view of a deformation suppressing member included in an electricity accumulation device according to another modified example of the second modified example. [Figure 18] FIG. 13 is a perspective view of a deformation suppressing member included in an electricity accumulation device according to still another modified example of the second modified example. [Figure 19] FIG. 13 is a front view of an electricity accumulation device according to a third modified example. [Figure 20] FIG. 13 is a diagram showing a state in which an exterior film provided on an electricity storage device according to a fourth modified example is unfolded. [Figure 21] FIG. 13 is a diagram showing the relationship between the size of a second surface of a deformation suppressing member included in an electricity accumulation device of a sixth modified example and the size of an inner surface of an exterior film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an electricity storage device according to an embodiment of the present invention will be described with reference to the drawings. In this specification, a numerical range indicated by "to" means "not less than" or "not more than." For example, the expression "2 to 15 mm" means 2 mm or more and 15 mm or less.

[0025] [Embodiment] <1-1. Configuration of the power storage device> FIG. 1A is a perspective view that shows a schematic diagram of an electricity storage device 10 according to an embodiment. FIG. 1B is a diagram that shows a method for measuring the seal strength of the second sealing portion 80 of the electricity storage device 10 in FIG. 1. FIG. 2 is a cross-sectional view that shows an example of a layer structure of an exterior film 50 that is included in the electricity storage device 10 in FIG. 1A. FIG. 3 is a diagram that shows the exterior film 50 that is included in the electricity storage device 10 in FIG. 1A in an unfolded state. FIG. 4 is a perspective view of a lid body 60 that is included in the electricity storage device 10 in FIG. 1A. In FIG. 1A, the direction of the arrow UD indicates the thickness direction of the electricity storage device 10, the direction of the arrow LR indicates the width direction of the electricity storage device 10, and the direction of the arrow FB indicates the depth direction of the electricity storage device 10. The directions shown by the arrows UDLRFB are common to the subsequent figures.

[0026] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an exterior body 40. The electrode body 20 includes electrodes (positive and negative electrodes) constituting a power storage member such as a lithium ion battery, a capacitor, an all-solid-state battery, a semi-solid battery, a quasi-solid battery, a polymer battery, an all-resin battery, a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, or a capacitor, and a separator. In this embodiment, the shape of the electrode body 20 is an approximately rectangular parallelepiped. Note that the term "approximately rectangular parallelepiped" includes, in addition to a complete rectangular parallelepiped, a solid body that can be regarded as a rectangular parallelepiped by modifying the shape of a part of the outer surface, for example. The shape of the electrode body 20 may be, for example, a cylinder or a polygonal prism.

[0027] In this embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminals 30 are metal terminals used for inputting and outputting electric power in the electrode body 20. One end of the electrode terminal 30 is electrically connected to an electrode (positive electrode or negative electrode) included in the electrode body 20. The other end of the electrode terminal 30 protrudes outward from an edge of the exterior body 40, for example. Note that the electrode terminal 30 may not protrude from the exterior body 40, for example, as long as it is capable of inputting and outputting electric power to and from the electrode body 20. When the cover body 60 described later is made of, for example, a metal, the cover body 60 may also function as the electrode terminal 30. In this case, the cover body 60 having the function as an electrode terminal may or may not protrude from the exterior body 40.

[0028] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, copper, etc. For example, when the electrode body 20 is a lithium ion battery, the electrode terminal 30 connected to the positive electrode is usually made of aluminum, etc., and the electrode terminal 30 connected to the negative electrode is usually made of copper, nickel, etc. The outermost layer of the electrode body 20 does not necessarily have to be an electrode, and may be, for example, a protective tape or a separator.

[0029] The exterior body 40 seals the electrode body 20. The exterior body 40 includes an exterior film 50 and a lid 60. The exterior film 50 wraps the electrode body 20 so as to form a pair of openings 40A. In this embodiment, the exterior film 50 is wrapped around the electrode body 20 so as to form a pair of openings 40A. The electrode body 20 may be accommodated inside the exterior film 50 configured in a cylindrical shape so as to form a pair of openings 40A, and the openings 40A may be closed by the lid 60. The exterior body 40 has a pair of first surfaces 41A, 41B and a pair of second surfaces 42A, 42B. In this embodiment, the pair of first surfaces 41A, 41B are substantially the same size. In this embodiment, the pair of second surfaces 42A, 42B are substantially the same size. The pair of first surfaces 41A, 41B have a larger area than the pair of second surfaces 42A, 42B. The pair of lid bodies 60 are disposed on the sides of the electrode body 20 so as to close the pair of openings 40A, respectively.

[0030] For example, there is a method of forming a recess in the exterior film 50 through cold forming to accommodate the electrode body 20. However, it is not necessarily easy to form a deep recess by such a method. If an attempt is made to form a deep recess (for example, a forming depth of 15 mm) by cold forming, pinholes or cracks will occur in the exterior film 50, which is likely to cause a decrease in battery performance. On the other hand, the exterior body 40 seals the electrode body 20 by wrapping the exterior film 50 around the electrode body 20, so that the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In addition, in order to reduce the dead space between the electrode body 20 and the exterior film 50 to improve the volumetric energy density of the power storage device 10, it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20. In addition, in an all-solid-state battery, it is necessary to apply a high pressure uniformly from the outer surface of the battery to exhibit battery performance, so it is necessary to eliminate the space between the electrode body 20 and the exterior film 50, and therefore it is preferable that the exterior film 50 is wrapped so as to contact the outer surface of the electrode body 20.

[0031] As shown in FIG. 2, the exterior film 50 is a laminate (laminate film) having, for example, a base layer 51, a barrier layer 52, and a heat-sealable resin layer 53 in this order. The exterior film 50 does not need to include all of these layers, and may not include, for example, the barrier layer 52. That is, the exterior film 50 may be made of a material that is flexible and easy to bend, and may be made of, for example, a resin film. 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.

[0032] The base layer 51 included in the exterior film 50 is a layer for imparting heat resistance to the exterior film 50 and suppressing the occurrence of pinholes that may occur during processing or distribution. The base layer 51 is configured to include at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer. For example, the base layer 51 includes at least one layer of a stretched polyester resin layer and a stretched polyamide resin layer, so that the barrier layer 52 can be protected during processing of the exterior film 50 and breakage of the exterior film 50 can be suppressed. In addition, from the viewpoint of increasing the tensile elongation of the exterior film 50, the stretched polyester resin layer is preferably a biaxially stretched polyester resin layer, and the stretched polyamide resin layer is preferably a biaxially stretched polyamide resin layer. Furthermore, in terms of excellent puncture strength or impact strength, the stretched polyester resin layer is more preferably a biaxially stretched polyethylene terephthalate (PET) film, and the stretched polyamide resin layer is more preferably a biaxially stretched nylon (ONy) film. The base layer 51 may be configured to include both a stretched polyester resin layer and a stretched polyamide resin layer. The thickness of the base layer 51 is, for example, preferably 5 to 300 μm, and more preferably 5 to 150 μm, from the viewpoint of film strength.

[0033] The barrier layer 52 is a layer that at least prevents the intrusion of moisture. The barrier layer 52 is bonded to the base layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor deposition film, and resin layer having barrier properties. Examples of the vapor deposition film include metal vapor deposition film, inorganic oxide vapor deposition film, and carbon-containing inorganic oxide vapor deposition film, and examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, and ethylene-vinyl alcohol copolymers. Examples of the barrier layer 52 include resin films having at least one of these vapor deposition films and resin layers. The barrier layer 52 may be provided in a plurality of layers. It is preferable that the barrier layer 52 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that the material contains at least one of an aluminum alloy foil and a stainless steel foil.

[0034] In the barrier layer 52, the layer made of the above-mentioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel plate. These recycled materials can be obtained by known methods. The recycled aluminum alloy material can be obtained by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be made of only recycled materials, or may be made of a mixed material of recycled materials and virgin materials. Note that recycled metal materials refer to metal materials that have been made reusable by collecting, isolating, and refining various products used in the city and waste from the manufacturing process. In addition, virgin metal materials refer to new metal materials refined from natural metal resources (raw materials) and are not recycled materials.

[0035] From the viewpoint of improving the formability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving the formability, the aluminum alloy foil containing iron is preferable. In the aluminum alloy foil containing iron (100 mass%), the content of iron is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%. By having an iron content of 0.1 mass% or more, an exterior film 50 having better formability can be obtained. By having an iron content of 9.0 mass% or less, an exterior film 50 having better flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. If necessary, silicon, magnesium, copper, manganese, etc. may be added. Softening can be achieved by annealing or the like.

[0036] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. From the viewpoint of providing an exterior film 50 with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

[0037] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, and SUS316L, and among these, SUS304 is particularly preferred.

[0038] In the case of a metal foil, the thickness of the barrier layer 52 is sufficient to at least function as a barrier layer that prevents moisture from penetrating, and may be, for example, about 9 to 200 μm. The thickness of the barrier layer 52 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. The thickness of the barrier layer 52 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. The preferred ranges of the thickness of the barrier layer 52 include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 52 is made of an aluminum alloy foil, the above-mentioned range is particularly preferable. From the viewpoint of imparting high formability and high rigidity to the exterior film 50, the thickness of the barrier layer 52 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, and even more preferably about 55 μm or more, and is preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. Preferable ranges are about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, and about 55 to 70 μm. When the exterior film 50 has high formability, deep drawing becomes easy, which can contribute to increasing the capacity of the electricity storage device. Furthermore, when the capacity of the electricity storage device is increased, the weight of the electricity storage device increases, but the rigidity of the exterior film 50 is increased, which can contribute to high sealing performance of the electricity storage device.In particular, when the barrier layer 52 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0039] In addition, when the barrier layer 52 is an aluminum foil, it is preferable that at least the surface opposite to the base layer 51 is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 52 may be provided with a corrosion-resistant film on both sides. Here, the corrosion-resistant film refers to a thin film that is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) on the barrier layer 52 by performing, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, or corrosion prevention treatment by applying a coating agent on the surface of the barrier layer 52. Specifically, the corrosion-resistant film refers to a film that improves the acid resistance of the barrier layer 52 (acid-resistant film), a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film), etc. The treatment for forming the corrosion-resistant film may be one type, or two or more types may be combined. In addition, not only one layer but also multiple layers may be formed. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments in which the metal foil surface is dissolved by a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. In addition, when the barrier layer 52 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 52.

[0040] The corrosion-resistant coating prevents delamination between the barrier layer 52 (e.g., aluminum alloy foil) and the base layer 51 during molding of the exterior film 50, prevents dissolution and corrosion of the surface of the barrier layer 52 due to hydrogen fluoride produced by a reaction between an electrolyte and moisture, and in particular prevents dissolution and corrosion of aluminum oxide present on the surface of the barrier layer 52 when the barrier layer 52 is an aluminum alloy foil, and also improves the adhesion (wettability) of the surface of the barrier layer 52, thereby preventing delamination between the base layer 51 and the barrier layer 52 during heat sealing and between the base layer 51 and the barrier layer 52 during molding.

[0041] The heat-sealable resin layer 53 is bonded to the barrier layer 52, for example, via an adhesive layer 55. The heat-sealable resin layer 53 included in the exterior film 50 is a layer that imparts heat-sealing sealability to the exterior film 50. Examples of the heat-sealable resin layer 53 include resin films made of polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, polyolefin resins such as polyethylene resins and polypropylene resins, or acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an acid such as maleic anhydride. The thickness of the heat-sealable resin layer 53 is preferably, for example, 20 to 300 μm, and more preferably 40 to 150 μm, in terms of sealability and strength.

[0042] The exterior film 50 preferably has one or more layers having a buffer function (hereinafter referred to as "buffer layer") outside the heat-sealable resin layer 53, more preferably outside the barrier layer 52. The buffer layer may be laminated on the outside of the base material layer 51, or the base material layer 51 may also function as a buffer layer. When the exterior film 50 has multiple buffer layers, the multiple buffer layers may be adjacent to each other, or may be laminated via the base material layer 51, the barrier layer 52, etc.

[0043] The material constituting the buffer layer can be arbitrarily selected from materials having cushioning properties. The material having cushioning properties is, for example, rubber, nonwoven fabric, or foam sheet. The rubber is, for example, natural rubber, fluororubber, or silicone rubber. The rubber hardness is preferably about 20 to 90. The material constituting the nonwoven fabric is preferably a material having excellent heat resistance. When the buffer layer is made of nonwoven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and more preferably 1000 μm. When the buffer layer is made of nonwoven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and more preferably 3000 μm. The thickness of the buffer layer is preferably in the range of 100 μm to 5000 μm, 100 μm to 3000 μm, 200 μm to 5000 μm, 200 μm to 3000 μm, 1000 μm to 5000 μm, or 1000 μm to 3000 μm. Among these, the thickness of the buffer layer is most preferably in the range of 1000 μm to 3000 μm.

[0044] When the buffer layer is made of rubber, the lower limit of the thickness of the buffer layer is preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the thickness of the buffer layer is preferably 10 mm, more preferably 5 mm, and more preferably 2 mm. When the buffer layer is made of rubber, the preferred 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.

[0045] When the exterior film 50 has a buffer layer, the buffer layer functions as a cushion, thereby preventing the exterior film 50 from being damaged by impact when the electricity storage device 10 is dropped or by handling during production of the electricity storage device 10.

[0046] The lid body 60 is, for example, plate-shaped and made of, for example, a resin material. The lid body 60 may be formed by, for example, cold forming the exterior film 50, or may be a metal molded product. The material constituting the lid body 60 may contain at least two or more types of materials selected from a metal oxide, a carbon material, and a rubber material, or may contain each of a metal oxide, a carbon material, and a rubber material.

[0047] As shown in FIG. 4, the lid body 60 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 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) when the lid body 60 is viewed from the front. The second seal surface 63B and the third seal surface 63C are connected to the first seal surface 63A, and constitute the side surfaces of the lid body 60. The second seal surface 63B and the third seal surface 63C extend in a second direction (UD direction in this embodiment) intersecting the first direction in a front view of the lid body 60. In this embodiment, the first direction and the second direction are perpendicular to each other in a front view of the lid body 60. The first direction and the second direction do not have to be perpendicular to each other in a front view of the lid body 60. The fourth seal surface 63D forms the lower surface of the lid body 60. The fourth seal surface 63D extends in the first direction (LR direction in this embodiment) in a front view of the lid body 60.

[0048] When the lid body 60 is plate-shaped, it is preferable that the lid body 60 has a certain degree of thickness so that deformation of the exterior body 40 is suppressed even when the power storage device 10 is arranged in a stacked manner. From another viewpoint, when the lid body 60 is plate-shaped, it is preferable that the lid seal portion 63 of the lid body 60 has a certain degree of thickness so that the lid seal portion 63 of the lid body 60 and the exterior film 50 can be suitably heat-sealed when the second sealing portion 80 is formed. The minimum value of the thickness of the lid body 60 is, for example, 1.0 mm, more preferably 3 mm, and further preferably 4 mm. The maximum value of the thickness of the lid body 60 is, for example, 10 mm, more preferably 8.0 mm, and further preferably 7.0 mm. The maximum value of the thickness of the lid body 60 may be 10 mm or more. The preferred ranges of the thickness of the material constituting the lid body 60 are 1.0 mm to 10 mm, 1.0 mm to 8.0 mm, 1.0 mm to 7.0 mm, 3.0 mm to 10 mm, 3.0 mm to 8.0 mm, 3.0 mm to 7.0 mm, 4.0 mm to 10 mm, 4.0 mm to 8.0 mm, and 4.0 mm to 7.0 mm. In this embodiment, when the lid body 60 is expressed as a plate-like body, the embodiment in which the lid body 60 is composed only of a film defined by the [packaging terminology] standard of JIS (Japan Industrial Standards) is not included. The thickness of the lid body 60 may differ depending on the part of the lid body 60. When the thickness of the lid body 60 differs depending on the part, the thickness of the lid body 60 is the thickness of the thickest part.

[0049] The lid seal portion 63 further includes boundaries 64, 65, 66, and 67. The boundary 64 is a boundary between the first seal surface 63A and the second seal surface 63B. The boundary 65 is a boundary between the first seal surface 63A and the third seal surface 63C. The boundary 66 is a boundary between the fourth seal surface 63D and the second seal surface 63B. The boundary 67 is a boundary between the fourth seal surface 63D and the third seal surface 63C. The shapes of the boundaries 64 to 67 may be angular, or may be rounded by performing R processing. In this embodiment, the boundaries 64 to 67 are angular.

[0050] In this embodiment, the lid body 60 is made of a resin material. Here, "made of a resin material" means that, when the entire material constituting the lid body 60 is taken as 100% by mass, the content of the resin material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. In other words, the material constituting the lid body 60 can contain materials other than the resin material in addition to the resin material.

[0051] Specific examples of the resin include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. The resin material may be a mixture of these resins, a copolymer, or a modified product of the copolymer. Among these, the resin material is preferably a heat-sealable resin such as polyester or polyolefin, and more preferably polyolefin. When the resin material is a resin, the lid 60 may be molded by any molding method.

[0052] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters in which ethylene terephthalate is the main repeating unit. Specific examples of polyesters include copolymerized polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decane dicarboxylate). Of these, the resin material is preferably polybutylene terephthalate from the viewpoint of increasing heat resistance and pressure resistance.

[0053] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. Among these, polypropylene is preferred as the resin material because it has excellent heat fusion properties and electrolyte resistance.

[0054] The resin as the resin material may contain a filler as necessary. Specific examples of the filler include glass beads, graphite, glass fiber, and carbon fiber. When the resin as the resin material contains the filler, the deformation resistance of the lid body 60 against temperature changes can be improved.

[0055] The melt mass flow rate of the resin material contained in the material constituting the lid body 60 is preferably within the range of 1 g / 10 min to 80 g / 10 min, and more preferably within the range of 5 g / 10 min to 60 g / 10 min. The melt mass flow rate is measured based on JIS K7210-1:2014.

[0056] In another example, the lid body 60 may be made of a metal material. Here, "made of a metal material" means that the content of the metal material is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, when the entire material constituting the lid body 60 is taken as 100% by mass. That is, the material constituting the lid body 60 may contain materials other than the metal material in addition to the metal material. The metal material constituting the lid body 60 can be selected arbitrarily. The metal material constituting the lid body 60 is, for example, aluminum, aluminum alloy, nickel, copper, or copper alloy. For example, when the electrode body 20 is a lithium ion battery, the lid body 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The lid body 60 connected to the negative electrode is preferably made of nickel, copper, or a copper alloy. The material constituting the lid body 60 connected to the negative electrode may be copper plated with nickel. The material constituting the lid body 60 may include recycled metal materials.

[0057] In this embodiment, the lid body 60 is formed with a through hole 60X into which the electrode terminal 30 is inserted. The through hole 60X penetrates the first surface 61 and the second surface 62. When the electrode body 20 is stored, 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 small gap between the through hole 60X of the lid body 60 and the electrode terminal 30 is filled with, for example, resin. In the electricity storage device 10, the position from which the electrode terminal 30 protrudes to the outside can be arbitrarily selected. For example, the electrode terminal 30 may protrude to the outside from a hole formed on any one of the six surfaces of the exterior body 40. In this case, a small gap between the exterior body 40 and the electrode terminal 30 is filled with, for example, resin. The electrode terminal 30 may protrude from between the lid body 60 and the exterior film 50, or may protrude from a first sealing portion 70 described later. In the electricity storage device 10, the lid body 60 and the electrode terminal 30 are provided as separate bodies, but the lid body 60 and the electrode terminal 30 may be formed integrally. When the electrode terminal 30 does not protrude from the edge of the exterior body 40, the lid body 60 does not need to have a through hole 60X formed therein.

[0058] In this embodiment, with the exterior film 50 wrapped around the electrode body 20 so as to have an opening 40A, the facing surfaces of the exterior film 50 (heat-fusible resin layer 53) are heat-sealed to form the first sealing portion 70.

[0059] The first sealed portion 70 is formed by heat-sealing a portion including the first edge 50A and a portion including the second edge 50B of the exterior film 50 shown in FIG. 3. The first sealed portion 70 extends in the longitudinal direction (FB direction) of the exterior body 40. The position at which the first sealed portion 70 is formed in the exterior body 40 can be selected arbitrarily. In this embodiment, the root 70X of the first sealed portion 70 is preferably located on the side 43 at the boundary between the first surface 41A and the second surface 42A of the exterior body 40. The first surface 41A has a larger area than the second surface 42A. The root 70X of the first sealed portion 70 may be located on any surface of the exterior body 40. In this embodiment, the first sealed portion 70 protrudes outward from the electrode body 20 in a plan view. The first sealed portion 70 may be folded, for example, toward the second surface 42A of the exterior body 40, or toward the first surface 41A.

[0060] In this 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 seal 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 seal strength of the second sealing portion 80. The seal strength of the second sealing portion 80 is the seal strength between the heat-fusible resin layer 53 and the lid body 60 at the long side portion of the lid seal portion 63, i.e., the lid seal portion 63 extending in the LR (width) direction in FIG. 1A.

[0061] The seal strength of the second sealing portion 80 is measured as follows. First, a cut is made in a portion of the exterior film 50 that constitutes the first surface 41A of the exterior body 40, and three strip-shaped members 41X, 41Y, and 41Z (see the two-dot chain line in FIG. 1B) arranged in the LR direction are formed. The width of the three strip-shaped members 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strip-shaped members 41X, 41Y, and 41Z are joined to the lid body 60 at the second sealing portion 80. The length of the lid body 60 in the LR direction is 45 mm or more. Next, the end of the strip-shaped members 41X, 41Y, and 41Z opposite to the end joined to the lid body 60 is pulled upward in the UD direction (the direction opposite to the first surface 41B) to measure the seal strength of each of the strip-shaped members 41X, 41Y, and 41Z. In this embodiment, the seal strength of the second sealing portion 80 is the average value of the seal strengths of the strip members 41X, 41Y, and 41Z. When the length of the lid body 60 in the LR direction is less than 45 mm, three strip members of an arbitrary width X mm less than 15 mm are formed, and the seal strengths of the three strip members are measured in the same manner as when the length of the lid body 60 in the LR direction is 45 mm or more. The obtained seal strengths are divided by the arbitrary width X mm and multiplied by 15 to convert them into the seal strengths of the three strip members in a width of 15 mm. The seal strength of the second sealing portion 80 is the average value of the seal strengths of the three strip members converted into a width of 15 mm. In addition, when the lid body 60 is divided into multiple parts including long sides and short sides, the seal strength of the second sealing portion 80 is the seal strength of the long side portion of the lid seal portion 63 of the multiple parts.

[0062] From the viewpoint of suitably maintaining the state in which the electrode body 20 is sealed by the exterior body 40, the seal strength of the second sealing portion 80 is preferably 40N / 15mm or more, more preferably 50N / 15mm or more, more preferably 60N / 15mm or more, more preferably 70N / 15mm or more, and more preferably 85N / 15mm or more. When the seal strength of the second sealing portion 80 is 40N / 15mm or more, the state in which the electrode body 20 is sealed by the exterior body 40 is suitably maintained even if the power storage device 10 is used for, for example, several years (less than 10 years). When the seal strength of the second sealing portion 80 is 85N / 15mm or more, the state in which the electrode body 20 is sealed by the exterior body 40 is suitably maintained even if the power storage device 10 is used for, for example, 10 years or more. The seal strength of the second sealing portion 80 is preferably 200N / 15mm or less. A preferred range of the seal strength of the second sealing portion 80 is 40N / 15mm to 150N / 15mm, 50N / 15mm to 150N / 15mm, 60N / 15mm to 150N / 15mm, 70N / 15mm to 150N / 15mm, or 85N / 15mm to 150N / 15mm.

[0063] In the electricity storage device 10, the internal pressure of the electricity storage device 10 may increase due to volume changes in the positive and negative active materials of the electrode body 20 accompanying charging and discharging, and due to gas generation, etc. When the internal pressure of the electricity storage device 10 increases, the exterior body 40 expands, causing the exterior film 50 to stretch, which may reduce the mechanical strength of the exterior film 50. In this embodiment, the electricity storage device 10 includes a deformation suppressing member 90 that suppresses the expansion of the exterior film 50. Note that the deformation suppressing member 90 also has the additional effect of suppressing deformation of the exterior body 40 caused by contraction of the exterior film 50 when vacuum drawing is performed to increase the degree of adhesion between the exterior film 50 and the electrode body 20 during the manufacturing process of the electricity storage device 10.

[0064] In this embodiment, the deformation suppressing member 90 is a component specialized for the function of suppressing deformation of the exterior body 40, and is an independent component from the lid body 60. The deformation suppressing member 90 being an independent component from the lid body 60 means that the deformation suppressing member 90 is a component functionally independent from the lid body 60. Therefore, the deformation suppressing member 90 may be structurally configured integrally with the lid body 60 or may be configured separately. In this embodiment, the deformation suppressing member 90 is disposed on at least a part of the surfaces of the exterior body 40 other than the surface configured by the lid body 60, that is, between at least a part of the surface configured by the exterior film 50 and the electrode body 20. The surfaces configured by the exterior film 50 are the first surface 41A, the first surface 41B, the second surface 42A, and the second surface 42B.

[0065] Fig. 5A is a cross-sectional view taken along line D5-D5 in Fig. 1A. Fig. 5B is a diagram showing an example of a state in which the electricity storage device 10 in Fig. 1 is used. Fig. 6 is a perspective view of a deformation suppressing member 90 in Fig. 5. Fig. 7 is a perspective view of a lid unit 60Z included in the electricity storage device 10 in Fig. 1A.

[0066] The position where the deformation suppressing member 90 is arranged can be arbitrarily selected as long as it is a position of the exterior body 40 that can be deformed. The power storage devices 10 of the present embodiment are used, for example, arranged so that the second surfaces 42B of the power storage devices 10 contact the cooling mechanism 200 (see FIG. 5B). In the power storage devices 10 arranged as shown in FIG. 5B, the second surfaces 42B contact the cooling mechanism 200, and the first surfaces 41A contact the first surfaces 41B of the adjacent power storage devices 10 directly or indirectly via a plate-like member, a buffer material, or the like. For this reason, for example, when considering expansion as one mode of deformation of the exterior body 40, in the power storage devices 10 arranged as shown in FIG. 5B, the first surfaces 41A, 41B, and the second surfaces 42B of the exterior body 40 are relatively unlikely to expand even when the internal pressure of the power storage device 10 increases.

[0067] On the other hand, the second surface 42A of the exterior body 40 is not in contact with other elements such as the power storage device 10, and is therefore likely to expand when the internal pressure of the power storage device 10 increases. For this reason, in this embodiment, the deformation suppressing member 90 is disposed inside the exterior body 40 so as to suppress expansion of the second surface 42A of the exterior body 40. In other words, the deformation suppressing member 90 is sealed by the exterior body 40. Note that, taking into consideration contraction as one form of deformation of the exterior body 40, the deformation suppressing member 90 may be disposed inside the exterior body 40 so as to suppress deformation of at least one of the first surface 41A, the first surface 41B, and the second surface 42B of the exterior body 40.

[0068] The shape of the deformation suppression member 90 can be selected arbitrarily. In this embodiment, the deformation suppression member 90 is a plate extending in the FB direction. The specifications of the material of the deformation suppression member 90 are the same as the specifications of the material of the cover body 60. The deformation suppression member 90 has a first surface 91, a second surface 92, and a side surface 93. The first surface 91 faces the electrode body 20. From the viewpoint of reducing the dead space between the electrode body 20 and the exterior film 50 to improve the volumetric energy density of the power storage device 10, it is preferable that the gap between the first surface 91 of the deformation suppression member 90 and the electrode body 20 is as small as possible. When the deformation suppression member 90 is made of a metal material, it is preferable that at least a part of the first surface 91 is coated with a corrosion-resistant coating from the viewpoint of suppressing corrosion by the electrolyte. When the deformation suppression member 90 is made of a metal material, it is preferable that an insulating sheet or the like is bonded to at least a part of the first surface 91 from the viewpoint of suppressing short-circuiting of the electrode body 20. The second surface 92 is the surface opposite to the first surface 91, and faces the inner surface of the exterior film 50 (in this embodiment, the heat-sealable resin layer 53). In this embodiment, the second surface 92 is not joined to the inner surface of the exterior film 50. At least a portion of the second surface 92 may be joined to the inner surface of the exterior film 50. The shapes of the first surface 91 and the second surface 92 are preferably the same as the shape of the second surface 42A of the exterior body 40.

[0069] The side surface 93 is connected to the first surface 91 and the second surface 92, and is heat-sealed to the lid body 60 and the heat-fusible resin layer 53 of the exterior film 50. The side surface 93 includes a first side surface 93A, a second side surface 93B, a third side surface 93C, and a fourth side surface 93D.

[0070] The first side surface 93A constitutes the upper surface of the deformation suppressing member 90. The first side surface 93A extends in the FB direction in a front view seen from the first surface 91 of the deformation suppressing member 90. The first side surface 93A is heat-sealed to the heat-fusible resin layer 53 of the exterior film 50 in a portion that constitutes the first surface 41A.

[0071] The second side surface 93B and the third side surface 93C are connected to the first side surface 93A and form the side surfaces of the deformation suppressing member 90. The second side surface 93B and the third side surface 93C extend in the UD direction in a front view seen from the first surface 91 of the deformation suppressing member 90. The second side surface 93B is heat sealed to the first surface 61 of one of the lid bodies 60. The third side surface 93C is heat sealed to the first surface 61 of the other lid body 60. In manufacturing the lid unit 60Z, the deformation suppressing member 90 and the lid body 60 can be joined together by, for example, heat sealing, welding, or hot plate welding.

[0072] The fourth side surface 93D constitutes the lower surface of the deformation suppressing member 90. The fourth side surface 93D extends in the FB direction in a front view seen from the first surface 91 of the deformation suppressing member 90. The fourth side surface 93D is heat-sealed to the heat-fusible resin layer 53 of the portion constituting the first surface 41B of the exterior film 50. The electricity storage device 10 may be manufactured using a lid unit 60Z in which a pair of lid bodies 60 and a pair of deformation suppressing members 90 are joined in advance, or may be manufactured using a device in which the pair of lid bodies 60 and the pair of deformation suppressing members 90 are in a separated state.

[0073] The side surface 93 further includes boundaries 94, 95, 96, and 97. The boundary 94 is the boundary between the first side surface 93A and the second side surface 93B. The boundary 95 is the boundary between the first side surface 93A and the third side surface 93C. The boundary 96 is the boundary between the fourth side surface 93D and the second side surface 93B. The boundary 97 is the boundary between the fourth side surface 93D and the third side surface 93C. The shapes of the boundaries 94 to 97 may be corners, or may be rounded by applying R processing. In this embodiment, the boundaries 94 to 97 are corners.

[0074] Since the side surface 93 of the deformation suppressing member 90 is sealed to the lid 60 and the exterior film 50, a small gap between the second surface 92 of the deformation suppressing member 90 and the inner surface of the exterior film 50 is sealed. Therefore, even if gas is generated inside the electricity storage device 10, the gas does not enter the small gap between the second surface 92 of the deformation suppressing member 90 and the inner surface of the exterior film 50. Therefore, the second surface 42A of the exterior body 40 is suppressed from expanding.

[0075] Furthermore, in this embodiment, the deformation suppressing member 90 is disposed so as to suppress expansion of the portion of the exterior body 40 that is continuous with the first sealing portion 70, i.e., the second surface 42A. Therefore, even if the internal pressure of the electricity storage device 10 increases, peeling of the first sealing portion 70 due to expansion of the portion of the exterior body 40 that constitutes the second surface 42A is suppressed.

[0076] <1-2. Method for manufacturing electricity storage device> FIG. 8 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, a seventh step, an eighth step, and a ninth step. The first step to the ninth step are performed, for example, by a manufacturing device for the power storage device 10. At least a part of the first step to the ninth step may be performed by an operator. Note that the first step to the ninth step are merely names of the steps in the method for manufacturing the power storage device 10 for the sake of convenience, and do not necessarily refer to the order of the steps. The order of the following steps can be changed as desired.

[0077] In the first step of step S11, the manufacturing apparatus places the lid unit 60Z to which the electrode terminal 30 is joined relative to the electrode body 20, and electrically connects the electrode terminal 30 and the electrode body 20. Note that in the first step, the lid body 60 may be joined to the electrode terminal 30 electrically connected to the electrode body 20, and then the deformation suppressing member 90 may be joined to the lid body 60 by, for example, heat sealing or welding. Also, in the first step, the lid body 60 to which the electrode terminal 30 is joined may be electrically connected to the electrode body 20, and then the lid body 60 and the deformation suppressing member 90 may be joined to each other by, for example, heat sealing or welding.

[0078] The second step of step S12 is performed after the first step. In the second step, the manufacturing device wraps the electrode body 20 and the lid unit 60Z with the exterior film 50. In the second step, in order to form a gas pocket 300 described later, an exterior film 50 having a larger area than the exterior film 50 of the completed power storage device 10 is used. In the second step, the manufacturing device winds the exterior film 50 around the electrode body 20 and the lid body 60 while tension is applied to the exterior film 50, while restricting the movement of the electrode body 20 and the lid body 60 by the restricting means. The restricting means is, for example, a groove into which the electrode body 20 and the lid body 60 are fitted. The restricting means may be a device that applies an external force to the electrode body 20 and the lid body 60 so that the electrode body 20 and the lid body 60 do not move. The restricting means may be a device that applies a force to the electrode body 20 and the lid body 60 in the opposite direction to the direction in which the exterior film 50 is pulled. The restricting means may include a roller that runs over the exterior film 50 while the exterior film 50 is being pulled in order to remove wrinkles in the exterior film 50 .

[0079] The third step of step S13 is performed after the second step. As shown in Fig. 9, in the third step, the manufacturing device forms the first FB direction seal portion 71 having an unsealed portion 71Z in the center. Note that the hatched portion in Fig. 9 shows an example of the region where the first FB direction seal portion 71 is formed.

[0080] The fourth step of step S14 is performed after the third step. As shown in Fig. 10, in the fourth step, the manufacturing equipment forms the second short side seal portion 82. The second short side seal portion 82 is a portion where the second seal surface 63B and the third seal surface 63C of the lid body 60 are heat sealed to the exterior film 50. The hatched portion in Fig. 10 shows an example of an area where the second short side seal portion 82 is formed.

[0081] The fifth step of step S15 is performed after the fourth step. As shown in Fig. 11, in the fifth step, the manufacturing equipment forms a second long side seal portion 81. The second long side seal portion 81 is a portion where the first seal surface 63A and the fourth seal surface 63D of the lid body 60 are heat-sealed to the exterior film 50. The hatched portion in Fig. 11 shows an example of an area where the second long side seal portion 81 is formed.

[0082] The sixth step of step S16 is performed after the fifth step. As shown in Fig. 12, in the sixth step, the manufacturing apparatus forms the first LR direction seal portion 72. In the sixth step, the first LR direction seal portion 72 is formed so as to overlap partially with the first FB direction seal portion 71 in a portion including the side 43. Note that the hatched portion in Fig. 12 shows an example of an area where the first LR direction seal portion 72 is formed. Completion of the sixth step results in the completion of a gas pocket 300 having a larger area in a plan view than the first sealing portion 70 of the completed electricity storage device 10.

[0083] The seventh step of step S17 is performed after the sixth step. In the seventh step, the manufacturing apparatus heat-seals the side surface 93 of the deformation suppressing member 90 and the exterior film 50. In the seventh step, since an electrolytic solution is injected in the eighth step described below, in the seventh step, a part of the first side surface 93A and the exterior film 50 are not heat-sealed in the seventh step. Note that, when the deformation suppressing member 90 is arranged so as to suppress the expansion of the second surface 42B, in the seventh step, the entire side surface 93 of the deformation suppressing member 90 arranged so as to suppress the expansion of the second surface 42B may be heat-sealed to the inner surface of the exterior film 50.

[0084] The eighth step of step S18 is performed after the seventh step. In the eighth step, the manufacturing device injects an electrolyte through the opening of the gas pocket 300. As shown in FIG. 13, after the electrolyte is injected, the gas pocket 300 is bonded at the edge including the opening to form a pocket sealing portion 310. After the eighth step, an aging step is performed. Gas generated by the aging step is stored in the gas pocket 300. The gas stored in the gas pocket 300 is discharged through an opening formed by cutting a part of the gas pocket 300. The gas pocket 300 is cut, for example, along the dashed line XA shown in FIG. 13 to form an opening for discharging the gas.

[0085] The ninth step of step S19 is performed after the eighth step and after the aging step is completed. In the ninth step, the manufacturing device heat-seals the unsealed portion of the first side surface 93A and the exterior film 50, and further forms the first sealed portion 70. In the ninth step, the first FB direction sealed portion 71 may or may not be resealed.

[0086] <1-3. Actions and Effects of Electricity Storage Devices> According to the electricity storage device 10, since the deformation suppression member 90 is provided, even if the internal pressure of the electricity storage device 10 changes, deformation of the exterior body 40 can be suppressed.

[0087] [2. Modifications] The above-mentioned embodiments are examples of forms that the electric storage device, the deformation suppression member, and the lid unit according to the present invention may take, and are not intended to limit the forms. The electric storage device, the deformation suppression member, and the lid unit according to the present invention may take forms different from those exemplified in the embodiments. One example of such a form 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. Below are some examples of modified embodiments. The following modified forms can be combined with each other as long as there is no technical contradiction.

[0088] <2-1. First modified example> In the above-described power storage device 10, the side surface 93 of the deformation suppressing member 90 is sealed to the lid 60 and the exterior film 50, but instead of or in addition to the side surface 93, the second surface 92 may be bonded to the inner surface of the exterior film 50. Figures 14 and 15 are diagrams showing an example of an area of ​​the second surface 92 of the deformation suppressing member 90 that is bonded to the inner surface of the exterior film 50. The dots in Figures 14 and 15 indicate the area of ​​the second surface 92 that is bonded to the inner surface of the exterior film 50.

[0089] 14, substantially the entire second surface 92 is joined to the inner surface of the exterior film 50. In the example shown in Fig. 14, substantially no gap is formed between the second surface 92 and the inner surface of the exterior film 50. Therefore, even if gas is generated inside the electricity storage device 10, the gas does not penetrate between the second surface 92 and the inner surface of the exterior film 50. Therefore, expansion of the second surface 42A of the exterior body 40 is suitably suppressed.

[0090] 15, a portion of the second surface 92 including the edge is joined to the inner surface of the exterior film 50. In the example shown in Fig. 15, a small gap between the second surface 92 of the deformation suppressing member 90 and the inner surface of the exterior film 50 is sealed. Therefore, even if gas is generated inside the electricity storage device 10, the gas does not enter the small gap between the second surface 92 of the deformation suppressing member 90 and the inner surface of the exterior film 50. Therefore, expansion of the second surface 42A of the exterior body 40 is suppressed.

[0091] <2-2. Second modified example> In the above-mentioned power storage device 10, the configuration of the deformation suppression member 90 can be changed as desired within a range in which the expansion of the exterior film 50 can be suppressed. FIG. 16 is a perspective view of the deformation suppression member 90 included in the power storage device 10 of the second modification. The deformation suppression member 90 may have a passage portion 90X through which the electrolytic solution passes in the eighth step. In the example shown in FIG. 16, the passage portion 90X is a through hole penetrating the first surface 91 and the second surface 92 of the deformation suppression member 90. The shape and number of the passage portions 90X formed in the deformation suppression member 90 can be selected as desired. In the example shown in FIG. 16, a part of the electrolytic solution injected through the opening of the gas pocket 300 in the eighth step penetrates into a small gap between the second surface 92 and the inner surface of the exterior film 50 and passes through the passage portion 90X. For this reason, the eighth step can be efficiently performed. In the second modification, at least a part of the second surface 92 of the deformation suppression member 90 and the inner surface of the exterior film 50 are joined in the seventh step. The first modified example can be applied to the area of ​​the second surface 92 that is sealed with the inner surface of the exterior film 50. In the second modified example, when the eighth step is performed after the seventh step, it is preferable that the portion of the second surface 92 that corresponds to the portion where the electrolyte is injected is not sealed in the seventh step, but is sealed after the eighth step. In the second modified example, the seventh step may be performed after the eighth step.

[0092] FIG. 17 is a perspective view of a deformation suppressing member 90 of another modified example of the second modified example. In the example shown in FIG. 17, the deformation suppressing member 90 has a passing portion 90Y. The passing portion 90Y is a recess recessed from the first side surface 93A toward the fourth side surface 93D. The depth and number of the passing portions 90Y formed in the deformation suppressing member 90 can be selected arbitrarily. In the eighth step, from the viewpoint of suitably injecting the electrolyte, it is preferable that the passing portion 90Y is formed at a position corresponding to the unsealed portion 71Z in the LR direction. In the example shown in FIG. 17, the passing portion 90Y is formed approximately in the center in the LR direction.

[0093] FIG. 18 is a perspective view of a deformation suppressing member 90 according to yet another modification of the second modification. In the example shown in FIG. 18, the deformation suppressing member 90 has a passing portion 90Z. In the example shown in FIG. 18, the passing portion 90Z is a mesh member attached to the passing portion 90Y shown in FIG. 17. The passing portion 90Z may be a member having punched holes. In the example shown in FIG. 18, it is preferable to bond the passing portion 90Z to the inner surface of the exterior film 50 after the eighth step. This makes it possible to suppress expansion of a portion of the second surface 42A of the exterior body 40 that comes into contact with the passing portion 90Z.

[0094] <2-3.Third modified example> In the above embodiment, the deformation suppressing member 90 is disposed inside the exterior body 40, but the deformation suppressing member 90 may be disposed outside the exterior body 40. FIG. 19 is a front view of the electricity storage device 10 of the third modified example. In the example shown in FIG. 19, the deformation suppressing member 90 is disposed outside the exterior body 40 so as to suppress the expansion of the second surfaces 42A and 42B of the exterior body 40. The deformation suppressing member 90 may be disposed so as to suppress the expansion of either one of the second surfaces 42A and 42B of the exterior body 40. When the deformation suppressing member 90 is disposed outside the exterior body 40, it is preferable that the deformation suppressing member 90 is connected to the lid body 60. In the example shown in FIG. 19, it is preferable that the deformation suppressing member 90 is connected to the lid body 60 by the connection member 100. The connection member 100, the deformation suppressing member 90, and the lid body 60 are connected, for example, by fitting of recesses and protrusions. For example, when one of a recess and a protrusion is formed in the connecting member 100, the other of a recess and a protrusion is formed in the deformation suppressing member 90 and the lid body 60. The deformation suppressing member 90, the lid body 60, and the connecting member 100 may each be separate bodies, or at least two of them may be integrally configured.

[0095] <2-4. Fourth modified example> In the above embodiment, the exterior film 50 may have a deformation suppression structure 50X. Fig. 20 is a diagram showing an exterior film 50 having a deformation suppression structure 50X in an unfolded state. In Fig. 20, in order to easily understand the regions of the exterior film 50 corresponding to the first surfaces 41A, 41B and the second surfaces 42A, 42B of the exterior body 40, dashed two-dot lines are drawn on the boundaries between these regions.

[0096] 20, the deformation suppression structure 50X is formed in a portion of the exterior film 50 that constitutes the second surfaces 42A, 42B of the exterior body 40. The deformation suppression structure 50X is, for example, a portion of the exterior film 50 where the barrier layer 52 is partially thickened. In another example, the deformation suppression structure 50X is a portion where a metal having higher rigidity is used as a metal material constituting the barrier layer 52 compared to a portion not having the deformation suppression structure 50X. In the fourth modified example, the deformation suppression member 90 can also be omitted.

[0097] <2-5. Fifth Modification> In the above embodiment, in the first step, the electrode terminal 30 and the lid body 60 may be placed on the electrode body 20, and in the second step, the electrode body 20 and the lid body 60 may be wrapped in the exterior film 50 to which the deformation suppression member 90 is joined.

[0098] <2-6. Sixth Modification> In the above embodiment, the size of the second surface 92 of the deformation suppressing member 90 was the same as the size of the portion of the second surface 42A of the exterior body 40 that is not joined to the lid body 60, but as shown in Fig. 21, the size of the second surface 92 may be smaller than the portion of the second surface 42A that is not joined to the lid body 60. In the sixth modified example, it is preferable that at least a part of the second surface 92 and the inner surface of the exterior film 50 are joined.

[0099] <2-7. Seventh Variation> In the above embodiment, the exterior film 50 of the electricity storage device 10 may protrude outward from at least one of the two lid bodies 60 in the FB direction. The electrode body 20 is sealed by closing the portion of the exterior film 50 that protrudes outward from the lid body 60. The portion of the exterior film 50 that protrudes outward from the lid body 60 may be folded inward so that the outer surfaces of the exterior films 50 come into contact with each other, as in a Goebel-top container, or may be folded toward any surface of the exterior body 40, as in a brick container.

[0100] <2-8. Eighth 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 a portion of the exterior body 40 where the lid body 60 is omitted, the electrode body 20 is sealed by closing a portion of the exterior film 50 that protrudes outward beyond the electrode body 20. The portion of the exterior film 50 that protrudes outward beyond the electrode body 20 may be folded like a Goebel-top container or a brick container, as in the seventh modification.

[0101] <2-9. 9th Variation> In the above embodiment, the outer shape of the exterior body 40 can be changed as desired. The outer shape of the exterior body 40 may be a cylinder, a prism, or a cube.

[0102] <2-10. 10th Variation> In the above embodiment, the electrode body 20 is wrapped in one exterior film 50, but it may be wrapped in two or more exterior films 50. [Explanation of symbols]

[0103] 10: Energy storage device 20: Electrode body 40: Exterior body 50: Exterior film 50X: Deformation suppression structure 60: Lid 60Z: Lid unit 70: First sealing part 90: Deformation suppression member 90X, 90Y, 90Z: Passage section 91: 1st page 92: 2nd side 93: Side

Claims

1. An electrode body; and an exterior body that seals the electrode body, The exterior body includes an exterior film that wraps the electrode body, The device further includes a deformation suppressing member that suppresses deformation of the exterior body when the internal pressure of the power storage device changes. Energy storage device.

2. The deformation suppression member is configured to suppress expansion of the exterior body when an internal pressure of the power storage device increases. The power storage device according to claim 1 .

3. The deformation suppression member is sealed by the exterior body. The electricity storage device according to claim 1 or 2.

4. The deformation suppressing member is joined to the inner surface of the exterior film. The electricity storage device according to claim 1 or 2.

5. the deformation suppression member includes a first surface facing the electrode body, a second surface opposite to the first surface, and a side surface connecting the first surface and the second surface, At least a part of the side surface is joined to the inner surface of the exterior film. The electricity storage device according to claim 4 .

6. the deformation suppression member has a first surface facing the electrode body and a second surface opposite to the first surface, At least a portion of the second surface is joined to the exterior film. The electricity storage device according to claim 4 .

7. The entire second surface is joined to the exterior film. The electricity storage device according to claim 6 .

8. The edge of the second surface and the exterior film are joined together. The electricity storage device according to claim 6 .

9. The exterior body has a first sealing portion in which opposing surfaces of the exterior film are sealed to each other, The deformation suppressing member is disposed so as to suppress expansion of a portion of the exterior body that is continuous with the first sealing portion. The electricity storage device according to claim 1 or 2.

10. the exterior body has a lid body that seals the electrode body together with the exterior film, The deformation suppressing member is joined to at least one of the lid body and the exterior film. The electricity storage device according to claim 1 or 2.

11. The deformation suppressing member has a passage portion through which an electrolyte can pass. The electricity storage device according to claim 1 or 2.

12. The deformation suppressing member is disposed outside the exterior body. The power storage device according to claim 1 .

13. the exterior body has a lid body that seals the electrode body together with the exterior film, The deformation suppressing member is connected to the lid. The power storage device according to claim 12.

14. An electrode body; and an exterior body that seals the electrode body, The exterior body is An exterior film that wraps the electrode body, The exterior film partially has a deformation suppression structure that suppresses deformation of the exterior body when the internal pressure of the electricity storage device changes. Energy storage device.

15. A lid body used as an exterior body of the electricity storage device; a deformation suppressing member that is joined to the lid and suppresses deformation of the exterior body when the internal pressure of the power storage device changes. Lid unit.

16. A deformation suppression member for use in an electricity storage device, The power storage device is configured to suppress deformation of an exterior body of the power storage device when the internal pressure of the power storage device changes. Deformation suppression member.

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