Electricity storage device, exterior film, and method for manufacturing electricity storage device

Abstract

The present invention provides a power storage device comprising an electrode body and an exterior body for sealing the electrode body, the exterior body comprising: an exterior film covering the electrode body so as to form an opening; and a cover body disposed in the opening portion. The exterior film has a first mark formed so as to correspond to at least a portion of a corner portion of the cover body.

Description

Technical Field

[0001] The present invention relates to an electricity storage device, an exterior film, and a method for manufacturing the electricity storage device. Background Art

[0002] Patent Document 1 discloses an example of an electrical storage device. The electrical storage device includes an electrode assembly and an exterior body that seals the electrode assembly. The exterior body includes an exterior film that covers the electrode assembly to form an opening, and a cover disposed over the opening. The exterior film and the cover are bonded to each other.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-123686. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the above-described energy storage device, after the electrode assembly is covered with an exterior film, a cover is placed over the opening of the exterior film. Consequently, the cover may deviate from its intended position relative to the exterior film. This deviation can lead to various problems, such as a reduction in the bonding area between the exterior film and the cover.

[0008] An object of the present invention is to provide an electricity storage device having a lid with high positional accuracy relative to an exterior film, an exterior film used for the electricity storage device, and a method for manufacturing the electricity storage device.

[0009] Technical means to solve the problem

[0010] A first aspect of the present invention provides an electrical storage device comprising: an electrode body; and an outer casing for sealing the electrode body, the outer casing comprising: an outer casing film covering the electrode body in a manner forming an opening; and a cover body arranged at the opening, the outer casing film having a first mark formed in a manner corresponding to at least a portion of a corner of the cover body.

[0011] According to a second aspect of the present invention, in the power storage device according to the first aspect, the first mark is at least one of a fold, a line, and a cut that does not penetrate the exterior film.

[0012] In a power storage device according to a third aspect of the present invention, in the power storage device according to the first aspect or the second aspect, the first mark is formed at least in a range including an end portion of the corner portion of the cover.

[0013] According to a fourth aspect of the present invention, in the electricity storage device according to any one of the first to third aspects, the exterior film has a second mark formed to correspond to at least a portion of a corner portion of the electrode body.

[0014] A power storage device according to a fifth aspect of the present invention is the power storage device according to the fourth aspect, wherein the first marker and the second marker are connected.

[0015] An exterior film according to a sixth aspect of the present invention can be used as an exterior body of an electricity storage device including an electrode assembly and a cover, the exterior film having a first mark formed to correspond to at least a portion of a corner of the cover.

[0016] According to a seventh aspect of the present invention, in the exterior film according to the sixth aspect, the first mark is at least one of a fold, a line, and a slit that does not penetrate the exterior film.

[0017] According to an eighth aspect of the present invention, in the exterior film according to the sixth aspect or the seventh aspect, the first mark is formed at least in a range including an end portion of the corner portion of the cover.

[0018] A ninth aspect of the present invention provides the exterior film according to any one of the sixth to eighth aspects, further comprising a second mark formed to correspond to at least a portion of a corner portion of the electrode assembly.

[0019] According to a tenth aspect of the present invention, in the exterior film according to the ninth aspect, the first mark and the second mark are connected.

[0020] According to an eleventh aspect of the present invention, a method for manufacturing an electrical storage device is a method for manufacturing an electrical storage device including an electrode body and an outer casing that seals the electrode body, the outer casing including: an outer casing film that covers the electrode body in a manner forming an opening; and a cover body that is arranged at the opening, the outer casing having a first mark formed in a manner corresponding to at least a portion of a corner of the cover body, the method for manufacturing the electrical storage device including a mark forming step of forming the first mark on the outer casing.

[0021] The method for manufacturing a storage battery device according to the twelfth aspect of the present invention, in the method for manufacturing a storage battery device according to the eleventh aspect, includes: a configuration step, performed after the mark forming step, of configuring the cover body on the exterior film in such a manner that a corner of the cover body is aligned with the first mark; and a packaging step, performed after the configuration step, of covering the electrode body and the cover body with the exterior film while bending the exterior film along the first mark.

[0022] Effects of the Invention

[0023] According to the power storage device, the exterior film used for the power storage device, and the method for manufacturing the power storage device of the present invention, it is possible to contribute to improving the accuracy of the position of the cover relative to the exterior film. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1A It is a perspective view of the power storage device according to the embodiment.

[0025] Figure 1B It's about Figure 1A A diagram illustrating a method for measuring the sealing strength of a second sealing portion of a power storage device.

[0026] Figure 2 yes Figure 1A A three-dimensional diagram of an electrode body included in the power storage device.

[0027] Figure 3 Yes Figure 1A A cross-sectional view of the layer structure of an exterior film included in a power storage device.

[0028] Figure 4 yes Figure 1A A three-dimensional view of a cover body included in the power storage device.

[0029] Figure 5 yes Figure 1A FIG. 1 is a diagram showing an expanded state of an exterior film included in a power storage device.

[0030] Figure 6 is Figure 5 Schematic diagram of a crease forming device for forming creases on an exterior film.

[0031] Figure 7 Yes Figure 1A A flowchart of an example of a method for manufacturing a power storage device.

[0032] Figure 8 It's about Figure 7 Figure 3 shows the third process.

[0033] Figure 9 It's about Figure 7 Figure 4 shows the fourth process.

[0034] Figure 10 It is a diagram showing a state in which an exterior film included in a power storage device according to a modified example is unfolded.

[0035] Figure 11 This is a diagram showing a state in which an exterior film included in a power storage device according to another modified example is unfolded.

[0036] Figure 12 It is a schematic diagram showing another example of the fold forming device.

[0037] Figure 13 TABLE 1 is a table showing the results of the first test, the second test, and the third test. DETAILED DESCRIPTION

[0038] The following describes an electric storage device according to one embodiment of the present invention with reference to the accompanying drawings. In this specification, numerical ranges indicated by "to" refer to "above" or "below." For example, the expression "2 to 15 mm" means "above 2 mm and below 15 mm." Furthermore, in this specification, corners include not only right-angled corners but also corners with rounded surfaces.

[0039] [1. First embodiment]

[0040] <1-1. Structure of Power Storage Device>

[0041] Figure 1A It is a plan view schematically showing the power storage device 10 according to the first embodiment. Figure 1B This is a diagram illustrating a method for measuring the sealing strength of the second sealing portion 80 of the power storage device 10 . Figure 2 yes Figure 1A A perspective view of an electrode body 20 included in the power storage device. Figure 3 Yes Figure 1A 1 is a cross-sectional view showing a layer structure of an exterior film 50 included in the power storage device 10 . Figure 4 yes Figure 1A 1 is a perspective view of a cover 60 included in the power storage device 10. Figure 5 yes Figure 1A FIG. 1 is a diagram showing an expanded state of the outer film 50 included in the power storage device 10. Figure 1A , arrow UD indicates the thickness direction of the power storage device 10, arrow LR indicates the width direction of the power storage device 10, and arrow FB indicates the depth direction of the power storage device 10. The directions indicated by arrows UD, LR, and FB are common to the following figures.

[0042] The power storage device 10 includes an electrode body 20, an electrode terminal 30, and an outer body 40. The electrode body 20 includes, for example, electrodes (positive and negative electrodes) and a separator that constitute a power storage component such as a lithium-ion battery, a capacitor, an all-solid battery, a semi-solid battery, a pseudo-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-zinc oxide battery, a metal-air battery, a multivalent cation battery, or a capacitor. In this embodiment, the shape of the electrode body 20 is roughly rectangular. Here, "roughly rectangular" includes not only a complete rectangular parallelepiped but also a three-dimensional shape that can be regarded as a rectangular parallelepiped by modifying the shape of a portion of the outer surface. The shape of the electrode body 20 can be, for example, a cylinder or a polygonal prism.

[0043] In this embodiment, the power storage device 10 includes two electrode terminals 30. The electrode terminal 30 is a metal terminal 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 the end edge of the outer casing 40, for example. In addition, the electrode terminal 30 only needs to be able to input and output electric power to and from the electrode body 20, and, for example, it does not need to protrude from the outer casing 40. In the case where the cover body 60 described later is made of metal, for example, the cover body 60 sometimes also serves as the function of the electrode terminal 30. In this case, the cover body 60 having the function of an electrode terminal may or may not protrude from the outer casing 40.

[0044] like Figure 2 As shown, in this embodiment, the electrode body 20 has a front surface 21, a back surface 22, an upper surface 23, a lower surface 24, a first side surface 25, and a second side surface 26. The front surface 21 faces one cover 60. The back surface 22 faces the other cover 60. The upper surface 23 constitutes one of a pair of first surfaces 41 of the outer casing 40 described later. The lower surface 24 constitutes the other of the pair of first surfaces 41 of the outer casing 40 described later. The first side surface 25 constitutes one of a pair of second surfaces 42 of the outer casing 40 described later. The second side surface 26 constitutes the other of the pair of second surfaces 42 of the outer casing 40 described later.

[0045] The electrode body 20 has a corner 20A, a corner 20B, a corner 20C, and a corner 20D. Corners 20A to 20D are formed with R surfaces. At least one of the corners 20A to 20D may also form an R surface. Corner 20A is formed at the boundary between the upper surface 23 and the first side surface 25. Corner 20B is formed at the boundary between the upper surface 23 and the second side surface 26. Corner 20C is formed at the boundary between the first side surface 25 and the lower surface 24. Corner 20D is formed at the boundary between the second side surface 26 and the lower surface 24. In addition, Figure 2 In order to simplify the drawings, the shapes of the R surfaces of the corner portions 20A to 20D are omitted.

[0046] The metal material constituting the electrode terminal 30 is, for example, aluminum, nickel, or copper. For example, in the case of a lithium-ion battery, the electrode terminal 30 connected to the positive electrode is typically made of aluminum, while the electrode terminal 30 connected to the negative electrode is typically made of copper, nickel, or the like. Furthermore, the outermost layer of the electrode body 20 does not necessarily have to be an electrode; for example, it may also be a protective tape or a separator.

[0047] The outer casing 40 seals the electrode body 20. The outer casing 40 includes an outer film 50 and a pair of lids 60. The outer film 50 surrounds the electrode body 20, forming a pair of openings 40A. In this embodiment, the outer film 50 is wound around the electrode body 20, forming a pair of openings 40A. Alternatively, the electrode body 20 may be housed within the outer film 50, which is cylindrical and formed with a pair of openings 40A, and the openings 40A may be closed by the lids 60. The pair of lids 60 are respectively arranged on the sides of the electrode body 20, so as to close the pair of openings 40A.

[0048] From the perspective of good bonding with the cover 60, it is preferred that an adhesive film 31 be bonded to the electrode terminal 30. The adhesive film 31 can be arbitrarily selected as long as it is a film that can bond the electrode terminal 30 made of metal to the cover 60 made of resin. The adhesive film 31 can be made of, for example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, a cyclic polyolefin resin, or an acid-modified polyolefin resin obtained by grafting these polyolefin resins with an acid such as maleic anhydride. The adhesive film 31 can be a single layer or a film of two or more layers of these materials. In the present embodiment, the adhesive film 31 is bonded to substantially the entire portion of the electrode terminal 30 covered by the cover 60.

[0049] For example, there is a method of forming a housing portion (recess) for housing the electrode body 20 in the outer film 50 by cold forming. However, it is not necessarily easy to form a deep housing portion by such a method. If you want to form the housing portion (recess) deeply by cold forming (for example, a forming depth of 15 mm), there is a possibility of pinholes or cracks in the outer film 50, which increases the possibility of reduced battery performance. On the other hand, the outer body 40 seals the electrode body 20 by winding the outer film 50 around the electrode body 20, so the electrode body 20 can be easily sealed regardless of the thickness of the electrode body 20. In addition, in order to reduce the ineffective area between the electrode body 20 and the outer film 50 to increase the volume energy density of the power storage device 10, it is preferred that the outer film 50 is wound in a manner in contact with the outer surface of the electrode body 20. In addition, in an all-solid-state battery, from the perspective of applying high pressure uniformly to the outer surface of the battery in order to exert battery performance, it is also necessary to eliminate the space between the electrode body 20 and the outer film 50. Therefore, it is preferred that the outer film 50 is wound in a manner that contacts the outer surface of the electrode body 20.

[0050] like Figure 3As shown, the exterior film 50 is, for example, a laminate (laminated film) comprising a base layer 51, a barrier layer 52, and a heat-weldable resin layer 53 in this order. Furthermore, the exterior film 50 need not include all of these layers; for example, the barrier layer 52 may not be included. Specifically, the exterior film 50 may be made of a flexible and easily bendable material, such as a resin film. Furthermore, the exterior film 50 is preferably heat-sealable.

[0051] The base layer 51 included in the exterior film 50 is used to impart heat resistance to the exterior film 50 and to suppress the formation of pinholes that may occur during processing or distribution. The base layer 51 is composed, for example, of at least one of a stretched polyester resin layer and a stretched polyamide resin layer. For example, by including at least one of the stretched polyester resin layer and the stretched polyamide resin layer in the base layer 51, the barrier layer 52 can be protected during processing of the exterior film 50, thereby suppressing breakage of the exterior film 50. Furthermore, to increase 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, to provide excellent puncture strength and 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. Alternatively, the base layer 51 may be composed of both a stretched polyester resin layer and a stretched polyamide resin layer. From the viewpoint of film strength, the thickness of the base material layer 51 is, for example, preferably 5 to 300 μm, and more preferably 5 to 150 μm.

[0052] The barrier layer 52 is a layer that at least inhibits moisture intrusion. The barrier layer 52 is bonded to the substrate layer 51 via, for example, an adhesive layer 54. Examples of the barrier layer 52 include metal foil, vapor-deposited films, and resin layers having barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers based on fluoroalkyl units, such as fluororesins and ethylene-vinyl alcohol copolymers. Furthermore, examples of the barrier layer 52 include resin films having at least one of these vapor-deposited films and resin layers. The barrier layer 52 may also be a multi-layered layer. The barrier layer 52 preferably includes a layer composed of a metal material. Specific examples of the metal material constituting the barrier layer 52 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, it preferably contains at least one of aluminum alloy foil and stainless steel foil.

[0053] In the barrier layer 52, the layer composed of the above-mentioned metal material may also contain recycled materials of the metal material. As recycled materials of the metal material, for example, recycled materials of aluminum alloy, stainless steel, titanium steel, or steel plate can be cited. These recycled materials can be obtained by known methods respectively. Recycled materials of aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 52 may be composed only of recycled materials, or may be composed of a mixture of recycled materials and virgin materials (virgin materials). Among them, recycled materials of metal materials refer to metal materials that are recycled, separated, refined, etc. from various products used in the so-called market and waste from the manufacturing process to become reusable. In addition, virgin materials of metal materials refer to new metal materials refined from natural resources (raw materials) of metals, and are not recycled materials.

[0054] To improve the formability and conformability of the exterior film 50, the aluminum alloy foil is preferably a soft aluminum alloy foil, such as one made from an annealed aluminum alloy. To further improve formability and conformability, an aluminum alloy foil containing iron is preferred. In an aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. An iron content of 0.1% or greater can provide an exterior film 50 with even better formability. An iron content of 9.0% or less can provide an exterior film 50 with even greater flexibility. Examples of soft aluminum alloy foil include aluminum alloy foil having the composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may also be added as needed. Softening can be achieved through annealing or other treatments. To enhance the mechanical strength of the exterior film 50, the aluminum alloy foil is more preferably a hard aluminum alloy foil, such as one made of a work-hardened aluminum alloy. Examples of the hard aluminum alloy foil include aluminum alloy foil having a composition specified in JIS H4160: 1994 A8021H-H18, JIS H4160: 1994 A8079H-H18, JIS H4000: 2014 A8021P-H14, or JIS H4000: 2014 A8079P-H14.

[0055] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. Furthermore, the stainless steel foil is preferably made of austenitic stainless steel in order to provide an exterior film 50 with improved formability.

[0056] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS 304, SUS 301, and SUS 316 L. Among them, SUS 304 is particularly preferred.

[0057] In the case of a metal foil, the thickness of the barrier layer 52 is sufficient as long as it at least functions as a barrier layer to inhibit moisture intrusion, and can be, for example, approximately 5 to 200 μm. The thickness of the barrier layer 52 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. Furthermore, the thickness of the barrier layer 52 is preferably approximately 10 μm or greater, more preferably approximately 20 μm or greater, and even more preferably approximately 25 μm or greater. Preferred ranges for the thickness of the barrier layer 52 include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the barrier layer 52 is made of aluminum alloy foil, the above range is particularly preferred. In addition, 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. In addition, it 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. The preferred range is 35 to 200 μm. The thickness of the outer film 50 is 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. The outer film 50 has high formability, which makes deep drawing easier and can contribute to increasing the capacity of the power storage device. In addition, 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 outer film 50, it can contribute to high sealing performance of the power storage device. Furthermore, particularly when the barrier layer 52 is formed of stainless steel foil, the thickness of the stainless steel foil is preferably approximately 60 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, even more preferably approximately 30 μm or less, and particularly preferably approximately 25 μm or less. Furthermore, the thickness of the stainless steel foil is preferably approximately 10 μm or greater, more preferably approximately 15 μm or greater. Preferred ranges for the thickness of the stainless steel foil include approximately 10 to 60 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 30 μm, approximately 10 to 25 μm, approximately 15 to 60 μm, approximately 15 to 50 μm, approximately 15 to 40 μm, approximately 15 to 30 μm, and approximately 15 to 25 μm.

[0058] Furthermore, when the barrier layer 52 is aluminum foil, it is preferably coated with a corrosion-resistant film on at least the surface opposite the base layer 51 to prevent dissolution and corrosion. The barrier layer 52 may have a corrosion-resistant film on both surfaces. Here, a corrosion-resistant film refers to a thin film imparting corrosion resistance (e.g., acid resistance, alkali resistance, etc.) to the barrier layer 52 by undergoing an anti-corrosion treatment such as a hot water conversion treatment such as boehmite treatment, a chemical conversion treatment, anodizing, plating with nickel or chromium, or coating with a coating agent. Specifically, a corrosion-resistant film includes a film that improves the acid resistance of the barrier layer 52 (acid-resistant film) or a film that improves the alkali resistance of the barrier layer 52 (alkali-resistant film). The corrosion-resistant film can be formed using a single treatment or a combination of two or more. Furthermore, the film may be formed using not only a single layer but also multiple layers. Furthermore, hot water conversion and anodizing are treatments in which a treatment agent dissolves the surface of the metal foil to form a metal compound with excellent corrosion resistance. In addition, these treatments may also be included in the definition of chemical conversion treatment. In addition, when the barrier layer 52 has a corrosion-resistant film, it is regarded as the barrier layer 52 including the corrosion-resistant film.

[0059] The corrosion-resistant coating has the following effects: during the molding of the exterior film 50, it prevents delamination between the barrier layer 52 (for example, aluminum alloy foil) and the substrate layer 51, prevents hydrogen fluoride generated by the reaction between the electrolyte and moisture from dissolving and corroding the surface of the barrier layer 52, and particularly, when the barrier layer 52 is an aluminum alloy foil, prevents aluminum oxide present on the surface of the barrier layer 52 from dissolving and corroding, improves the adhesion (wettability) of the surface of the barrier layer 52, prevents delamination between the substrate layer 51 and the barrier layer 52 during heat sealing, and prevents delamination between the substrate layer 51 and the barrier layer 52 during molding.

[0060] The heat-fusible resin layer 53 is bonded to the barrier layer 52 via, for example, an adhesive layer 55. The heat-fusible 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-fusible resin layer 53 include resin films composed 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. From the perspective of sealability and strength, the thickness of the heat-fusible resin layer 53 is preferably 20 to 300 μm, and more preferably 40 to 150 μm.

[0061] The exterior film 50 preferably includes one or more layers having a buffering function (hereinafter referred to as "buffer layers") located outside the thermally fusible resin layer 53, and more preferably located outside the barrier layer 52. The buffer layer may be laminated outside the base layer 51, or the base layer 51 may also function as a buffer layer. If the exterior film 50 includes multiple buffer layers, the multiple buffer layers may be adjacent to each other or laminated with the base layer 51 or the barrier layer 52 interposed therebetween.

[0062] The material constituting the buffer layer can be arbitrarily selected from materials having buffering properties. Examples of materials having buffering properties are rubber, non-woven fabric, or foam sheet. Examples of rubber are 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. In the case where the buffer layer is composed of a non-woven fabric, the lower limit of the thickness of the buffer layer is preferably 100 μm, more preferably 200 μm, and more preferably 1000 μm. In the case where the buffer layer is composed of a non-woven fabric, the upper limit of the thickness of the buffer layer is preferably 5000 μm, and more preferably 3000 μm. The preferred 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. The most preferred thickness range of the buffer layer is 1000 μm to 3000 μm.

[0063] When the buffer layer is made of rubber, the lower limit of the buffer layer thickness is preferably 1 mm, more preferably 0.5 mm. When the buffer layer is made of rubber, the upper limit of the buffer layer thickness is preferably 10 mm, more preferably 5 mm, and even more preferably 2 mm. When the buffer layer is made of rubber, the preferred range of the buffer layer thickness is 1 mm to 10 mm, 1 mm to 5 mm, 1 mm to 2 mm, 0.5 mm to 10 mm, 0.5 mm to 5 mm, or 0.5 mm to 2 mm.

[0064] When the exterior film 50 includes a buffer layer, the buffer layer functions as a shock absorber, thereby preventing the exterior film 50 from being damaged by an impact when the power storage device 10 is dropped or by handling during the manufacture of the power storage device 10 .

[0065] Figure 4The cover body 60 shown is, for example, a rectangular parallelepiped shape, and is, for example, a resin molded product made of a resin material. In addition, the cover body 60 can be formed by, for example, cold forming the exterior film 50, or can be a metal molded product. The material constituting the cover body 60 can also include at least two or more materials selected from metal oxides, carbon materials, and rubber materials. In addition, when distinguishing a pair of cover bodies 60, the cover body 60 arranged on one side relative to the electrode body 20 in the FB direction is sometimes referred to as the cover body 60A, and the cover body 60B arranged on the other side is sometimes referred to as the cover body 60B. In this embodiment, the cover body 60A and the cover body 60B have the same structure, so when they are not particularly distinguished, they are simply referred to as the cover body 60.

[0066] The lid 60 has a first surface 61, a second surface 62, and a sealing surface 63. The first surface 61 faces the electrode assembly 20. The second surface 62 is the surface opposite the first surface 61. The sealing surface 63 is continuous with the first surface 61 and the second surface 62 and is bonded to the heat-fusible resin layer 53 of the exterior film 50.

[0067] The sealing surface 63 includes a first sealing surface 63A, a second sealing surface 63B, a third sealing surface 63C, and a fourth sealing surface 63D. The first sealing surface 63A constitutes the upper surface of the cover 60. The first sealing surface 63A extends in a first direction (in this embodiment, the LR direction) in a front view of the cover 60. The second sealing surface 63B and the third sealing surface 63C are connected to the first sealing surface 63A and constitute the side surface of the cover 60. In a front view of the cover 60, the second sealing surface 63B and the third sealing surface 63C extend in a second direction (in this embodiment, the UD direction) that intersects the first direction. In this embodiment, when the cover 60 is viewed from the front, the first direction and the second direction are orthogonal. The first and second directions do not necessarily need to be orthogonal in a front view of the cover 60. The fourth sealing surface 63D constitutes the lower surface of the cover 60. The fourth sealing surface 63D extends in the first direction (in this embodiment, the LR direction) in a front view of the cover 60.

[0068] When the cover 60 is plate-shaped, even when the power storage device 10 is arranged in an overlapping manner, the cover 60 preferably has a certain degree of thickness to suppress deformation of the outer body 40. From another perspective, when the cover 60 is plate-shaped, the sealing surface 63 of the cover 60 preferably has a certain degree of thickness in order to properly heat-seal the sealing surface 63 of the cover 60 with the outer film 50 when forming the second sealing portion 80 described later. The minimum thickness of the cover 60 is, for example, 1.0 mm, more preferably 3.0 mm, and even more preferably 4.0 mm. The maximum thickness of the cover 60 is, for example, 20 mm, more preferably 15 mm, and even more preferably 10 mm. The maximum thickness of the cover 60 may also be 20 mm or more. The preferred thickness ranges for the material constituting the cover 60 are 1.0 mm to 20 mm, 1.0 mm to 15 mm, 1.0 mm to 10 mm, 3.0 mm to 20 mm, 3.0 mm to 15 mm, 3.0 mm to 10 mm, 4.0 mm to 20 mm, 4.0 mm to 15 mm, and 4.0 mm to 10 mm. In this embodiment, while the cover 60 is described as being plate-shaped, this does not include a configuration where the cover 60 is constructed solely of a film defined in the JIS (Japanese Industrial Standards) "Packaging Terms" standard. Furthermore, the thickness of the cover 60 may vary depending on the location of the cover 60. If the thickness of the cover 60 varies depending on the location, the thickness of the cover 60 is the thickness of the thickest portion.

[0069] The cover body 60 also includes corners 64, 65, 66, and 67. Corner 64 is the boundary between the first sealing surface 63A and the second sealing surface 63B. Corner 65 is the boundary between the first sealing surface 63A and the third sealing surface 63C. Corner 66 is the boundary between the fourth sealing surface 63D and the second sealing surface 63B. Corner 67 is the boundary between the fourth sealing surface 63D and the third sealing surface 63C. The shape of corners 64 to 67 can be a corner, or it can be rounded by performing R processing, in other words, by forming an R surface. In this embodiment, corners 64 to 67 are corners.

[0070] In this embodiment, the cover 60 is made of a resin material. Here, "made of a resin material" means that, with the total mass of the material constituting the cover 60 being 100%, the resin material content is 50% by mass or greater, preferably 80% by mass or greater, more preferably 90% by mass or greater, and even more preferably 95% by mass or greater. In other words, the material constituting the cover 60 may contain materials other than resin.

[0071] Specific examples of resins include thermoplastic resins such as polyester, polyolefin, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified forms of these resins. Furthermore, the resin material may be a mixture of these resins, a copolymer, or a modified form of a copolymer. The resin material is preferably a heat-fusible resin such as polyester or polyolefin, with polyolefin being more preferred. When the resin material is a resin, the cover 60 may be formed using any molding method.

[0072] Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyesters. Copolyesters include those having ethylene terephthalate as a main repeating unit. Specific examples include polyester copolymers composed mainly of ethylene terephthalate and ethylene isophthalate (hereinafter referred to as poly(ethylene terephthalate / isophthalate)), poly(ethylene terephthalate / adipate), poly(ethylene terephthalate / sodium sulfoisophthalate), poly(ethylene terephthalate / sodium isophthalate), poly(ethylene terephthalate / phenyl dicarboxylate), and poly(ethylene terephthalate / sebacyl carboxylate). Among these, polybutylene terephthalate is a preferred resin material from the perspective of improving heat resistance and pressure resistance.

[0073] 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 terpolymers of ethylene, butene, and propylene. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. Among these, polypropylene is preferred due to its excellent thermal sealability and electrolyte resistance.

[0074] The resin material may contain fillers as needed. Specific examples of fillers include glass beads, graphite, glass fibers, and carbon fibers. By including such fillers in the resin material, the deformation resistance of the cover 60 to temperature changes can be improved.

[0075] The melt flow rate of the resin material included in the material constituting the cover 60 is preferably within the range of 1 g / 10 min to 80 g / 10 min, more preferably within the range of 5 g / 10 min to 60 g / 10 min. The melt flow rate is measured in accordance with JIS K7210-1:2014.

[0076] In another example, the cover 60 may also be made of a metal material. Here, "made of a metal material" means that, when the total amount of the material constituting the cover 60 is 100% by mass, 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. That is, the material constituting the cover 60 may contain materials other than metal materials in addition to metal materials. The metal material constituting the cover 60 may be selected arbitrarily. The metal material constituting the cover 60 is, for example, aluminum, an aluminum alloy, nickel, copper or a copper alloy. For example, in the case where the electrode body 20 is a lithium-ion battery, the cover 60 connected to the positive electrode is preferably made of aluminum or an aluminum alloy. The cover 60 connected to the negative electrode is preferably made of nickel, copper or a copper alloy. The material constituting the cover 60 connected to the negative electrode may also be made by nickel-plating the copper. The material constituting the cover 60 may also include recycled materials of metal materials.

[0077] In this embodiment, the cover 60 is formed with a through-hole 60X for inserting the electrode terminal 30. The through-hole 60X extends through the first surface 61 and the second surface 62. When the electrode body 20 is covered by the exterior film 50, the electrode terminal 30 protrudes from the exterior of the exterior body 40 through the through-hole 60X formed in the cover 60. The small gap between the through-hole 60X in the cover 60 and the electrode terminal 30 is filled, for example, with resin. Furthermore, in the power storage device 10, the position where the electrode terminal 30 protrudes can be arbitrarily selected. For example, the electrode terminal 30 may protrude from a hole formed on any of the six surfaces of the exterior body 40. In this case, the small gap between the exterior body 40 and the electrode terminal 30 is filled, for example, with resin. In another example, the electrode terminal 30 may protrude from between the sealing surface 63 of the cover 60 and the exterior film 50 to the exterior of the exterior body 40. In this case, the through-hole 60X may not be formed in the cover 60. In the power storage device 10 , the cover 60 and the electrode terminal 30 are provided separately, but the cover 60 and the electrode terminal 30 may be formed integrally. Furthermore, when the electrode terminal 30 does not protrude from the edge of the exterior body 40 , the through hole 60X may not be formed in the cover 60 .

[0078] In this embodiment, with the exterior film 50 wound around the electrode assembly 20 with the opening 40A, the facing surfaces (thermo-fusible resin layers 53 ) of the exterior film 50 are heat-sealed to form the first sealing portion 70 .

[0079] The first sealing portion 70 is formed by Figure 5 The portion including the first edge 50A and the portion including the second edge 50B of the outer film 50 shown are heat-sealed. The first sealing portion 70 extends in the longitudinal direction (FB direction) of the outer body 40. In the outer body 40, the position where the first sealing portion 70 is formed can be selected arbitrarily. In the present embodiment, the root 70X of the first sealing portion 70 is preferably located on the edge 43 of the boundary between the first surface 41 and the second surface 42 of the outer body 40. The area of ​​the first surface 41 is larger than the area of ​​the second surface 42. The root 70X of the first sealing portion 70 may also be located on any surface of the outer body 40. In the present embodiment, the first sealing portion 70 extends outward compared to the electrode body 20 when viewed from above. The first sealing portion 70 may be folded toward the second surface 42 of the outer body 40, or may be folded toward the first surface 41.

[0080] 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 sealing surface 63 of the cover 60. Hereinafter, the sealing strength between the heat-fusible resin layer 53 of the exterior film 50 and the sealing surface 63 of the cover 60 may be referred to as the sealing strength of the second sealing portion 80. In addition, the sealing strength of the second sealing portion 80 is the sealing strength of the long side portion of the sealing surface 63, i.e., Figure 1A The sealing strength between the heat-fusible resin layer 53 and the lid 60 on the sealing surface 63 extending in the LR (width) direction is measured.

[0081] The sealing strength of the second sealing portion 80 is measured as follows. First, a cut is made in the portion of the first surface 41 of the outer body 40 in the outer film 50 to form three strip-shaped parts 41X, 41Y, and 41Z arranged in the LR direction (see FIG. Figure 1B(Double-dashed line). The width of the three strips 41X, 41Y, and 41Z in the LR direction is 15 mm. The ends of the strips 41X, 41Y, and 41Z are joined to the cover 60 in the second sealing portion 80. The length of the cover 60 in the LR direction is 45 mm or longer. Next, the sealing strength of each strip 41X, 41Y, and 41Z is measured by pulling the ends of the strips 41X, 41Y, and 41Z opposite to the ends joined to the cover 60 upward in the UD direction (in the direction opposite to the first surface 41B). In this embodiment, the sealing strength of the second sealing portion 80 is the average of the sealing strengths of the strips 41X, 41Y, and 41Z. If the length of the cover 60 in the LR direction is less than 45 mm, three strips of any width X mm less than 15 mm are formed and the sealing strength of the three strips is measured using the same method as when the length of the cover 60 in the LR direction is 45 mm or longer. The obtained seal strengths are divided by an arbitrary width X mm, and then multiplied by 15 to convert the seal strengths of the three strip-shaped components to a width of 15 mm. The seal strength of the second sealing portion 80 is the average of the seal strengths of the three strip-shaped components converted to a width of 15 mm. Furthermore, when the cover 60 is divided into multiple sections containing long and short sides, the seal strength of the second sealing portion 80 is the seal strength of the long side of the multiple sealing surfaces 63.

[0082] From the perspective of properly maintaining the state in which the electrode body 20 is sealed by the outer casing 40, the sealing strength of the second sealing portion 80 is preferably 40 N / 15 mm or greater, more preferably 50 N / 15 mm or greater, further preferably 60 N / 15 mm or greater, further preferably 70 N / 15 mm or greater, and even further preferably 85 N / 15 mm or greater. When the sealing strength of the second sealing portion 80 is 40 N / 15 mm or greater, the state in which the electrode body 20 is sealed by the outer casing 40 can be properly maintained even if the power storage device 10 is used for, for example, several years (less than 10 years). When the sealing strength of the second sealing portion 80 is 85 N / 15 mm or greater, the state in which the electrode body 20 is sealed by the outer casing 40 can be properly maintained even if the power storage device 10 is used for, for example, more than 10 years. The sealing strength of the second sealing portion 80 is preferably 300 N / 15 mm or less. The sealing strength of the second sealing portion 80 preferably ranges from 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.

[0083] The power storage device 10 of this embodiment is manufactured by winding the exterior film 50 around the electrode body 20 and the lid 60, with the electrode body 20 and the lid 60 arranged on the exterior film 50. If the position of the lid 60 relative to the exterior film 50 deviates from a predetermined position, at least one of the first and second problems may occur.

[0084] The first problem is that the bonding area between the exterior film 50 and the lid 60 is reduced. Therefore, the sealing strength of the second sealing portion 80 may be reduced.

[0085] The second problem is that the adhesion of the exterior film 50 to the lid 60 is reduced, resulting in a gap between the sealing surface 63 of the lid 60 and the exterior film 50. Consequently, for example, when forming the second seal 80, holes may be formed in the corners 64 to 67 of the lid 60. Furthermore, wrinkles may form in the exterior film 50.

[0086] In this embodiment, in order to improve the accuracy of the position of the cover 60 relative to the exterior film 50, the exterior film 50 has a first mark 91 formed so as to correspond to at least a part of the corners 64 to 67 of the cover 60 (see Figure 5 In this embodiment, in order to improve the accuracy of the position of the electrode body 20 relative to the outer film 50, it is preferable to have a second mark 92 formed in a manner corresponding to at least a part of the corners 20A to 20D of the electrode body 20 (see Figure 5 ). In addition, Figure 5 In the figure, in order to easily understand the ranges where the first mark 91 and the second mark 92 are formed, the first mark 91 is indicated by a solid line and the second mark 92 is indicated by a dotted line.

[0087] The specific structure of the first mark 91 can be arbitrarily selected as long as it is a structure that can grasp the position of the cover body 60 relative to the outer film 50. In the present embodiment, the first mark 91 is a fold formed on the outer film 50. The first mark 91 can also be a line. In the case where the first mark 91 is a line, the line serving as the first mark 91 can also be formed by ink. In the case where the first mark 91 is a line, the line serving as the first mark 91 can also be formed by applying color to the surface of the outer film 50 using a laser. The type of line can be arbitrarily selected. The line can be, for example, a solid line, a dotted line, a dashed line, or a double-dotted line. The first mark 91 can also be a slit that does not penetrate the outer film 50. The first mark 91 can also include at least two of a fold, a line, and a slit. The slit can be continuous in the FB direction or can be formed intermittently. The surface of the outer film 50 on which the first mark 91 is formed can also be at least one of the outer surface and the inner surface of the outer film 50.

[0088] The specific structure of the second mark 92 can be arbitrarily selected as long as it is a structure that can grasp the position of the electrode body 20 relative to the outer film 50. In the present embodiment, the second mark 92 is a fold formed on the outer film 50. The second mark 92 may also be a line. In the case where the second mark 92 is a line, the line serving as the second mark 92 may be formed by giving color to the surface of the outer film 50 using a laser. The type of line can be arbitrarily selected. The line may be, for example, a solid line, a dotted line, a dashed line, or a double-dotted line. The second mark 92 may also be a slit that does not penetrate the outer film 50. The second mark 92 may also include at least two of a fold, a line, and a slit. The slit may be continuous in the FB direction or may be formed intermittently. The surface of the outer film 50 on which the second mark 92 is formed may also be at least one of the outer surface and the inner surface of the outer film 50.

[0089] like Figure 5 As shown, the first marker 91 includes markers 91A to 91E corresponding to the cover 60A and markers 91F to 91J corresponding to the cover 60B.

[0090] Mark 91A corresponds to corner 67 of cover 60A. Mark 91B corresponds to corner 66 of cover 60A. Mark 91C corresponds to corner 65 of cover 60A. Marks 91D and 91E correspond to corner 64 of cover 60A.

[0091] Markings 91A to 91E extend from the third edge 50C of the exterior film 50 toward the fourth edge 50D. The length of the markings 91A to 91E in the FB direction can be arbitrarily selected. In this embodiment, the length of the markings 91A to 91E in the FB direction is equal to the length of the corresponding corners 64 to 67 of the cover body 60A. The length of the markings 91A to 91E in the FB direction may be longer or shorter than the length of the corresponding corners 64 to 67 of the cover body 60A. Preferably, the markings 91A to 91E are formed at least at the ends of the corresponding corners 64 to 67 in the FB direction.

[0092] Mark 91F corresponds to corner 66 of cover 60B. Mark 91G corresponds to corner 67 of cover 60B. Mark 91H corresponds to corner 64 of cover 60B. Marks 91I and 91J correspond to corner 65 of cover 60B.

[0093] Markings 91F to 91J extend from the fourth edge 50D of the exterior film 50 toward the third edge 50C. The length of the markings 91F to 91J in the FB direction can be arbitrarily selected. In this embodiment, the length of the markings 91F to 91J in the FB direction is equal to the length of the corresponding corners 64 to 67 of the cover body 60B. The length of the markings 91F to 91J in the FB direction may be longer or shorter than the length of the corresponding corners 64 to 67 of the cover body 60B. Preferably, the markings 91F to 91J are formed at least at the ends of the corresponding corners 64 to 67 in the FB direction.

[0094] The second mark 92 includes marks 92A to 92E. Mark 92A corresponds to corner 20D of electrode body 20. Mark 92A is connected to mark 91A and mark 91F. Mark 92A may not be connected to at least one of mark 91A and mark 91F.

[0095] Mark 92B corresponds to corner 20C of electrode body 20. Mark 92B is connected to mark 91B and mark 91G. Mark 92B may not be connected to at least one of mark 91B and mark 91G.

[0096] Mark 92C corresponds to corner 20B of electrode body 20. Mark 92C is connected to mark 91C and mark 91H. Mark 92C may not be connected to at least one of mark 91C and mark 91H.

[0097] Mark 92D and mark 92E correspond to corner 20A of electrode body 20. Mark 92D is connected to mark 91D and mark 91I. Mark 92D may not be connected to at least one of mark 91D and mark 91I.

[0098] The mark 92E is connected to the mark 91E and the mark 91J. The mark 92E may not be connected to at least one of the mark 91E and the mark 91J.

[0099] The marks 92A to 92E extend in the FB direction. The length of the marks 92A to 92E in the FB direction can be arbitrarily selected. In the present embodiment, the length of the marks 92A to 92E in the FB direction is longer than the length of the corresponding corners 20A to 20D of the electrode body 20. The length of the marks 92A to 92E in the FB direction may be equal to or shorter than the length of the corners 20A to 20D of the electrode body 20. It is preferred that the marks 92A to 92E are formed at least at the ends of the corresponding corners 20A to 20D in the FB direction.

[0100] In this embodiment, Figure 1AIn the embodiment, when the first seal portion 70 is folded from the side 43 toward the second surface 42 of the exterior body 40, while the marks 92D, 91D, 91I, the marks 92C, 91C, 91H, the marks 92A, 91A, 91F, and the marks 92B, 91B, 91G indicate a valley-shaped fold, the marks 92E, 91E, 91J indicate a mountain-shaped fold. When the first seal portion 70 is not folded, at least one of the marks 92D, 91D, 91I and the marks 92E, 91E, 91J on the side 43 may be omitted.

[0101] <1-2. Structure of Crease Forming Device>

[0102] Figure 6 This is a schematic diagram showing an example of a fold forming device 100 (hereinafter referred to as “device 100 ”) for forming first and second fold marks 91 and 92 as folds on an exterior film 50 . The device 100 includes a female mold 110 , a male mold 120 , and an air cylinder 130 .

[0103] The female mold 110 is placed on a stage 150. The female mold 110 is preferably placed on the stage 150 via, for example, a silicone rubber sheet 140. To properly form folds in the exterior film 50, the exterior film 50 is preferably heated while the folds are formed. Therefore, a rubber heater 160, for example, is preferably attached to the female mold 110 to heat the exterior film 50.

[0104] The male mold 120 presses the exterior film 50 against the female mold 110. A heating device, such as a rubber heater (not shown), is preferably attached to the male mold 120 to heat the exterior film 50. By sandwiching the exterior film 50 between the female mold 110 and the male mold 120, a fold of strength corresponding to the rounded shape and angle of the tip of the male mold 120, the pressure and temperature during the pressing of the male mold 120, and other factors are formed on the exterior film 50.

[0105] The air cylinder 130 is connected to the male mold 120. By driving the air cylinder 130, the male mold 120 presses the exterior film 50 against the female mold 110. Alternatively, the exterior film 50 may be bent to form at least one of a fold serving as the first mark 91 and a fold serving as the second mark 92.

[0106] <1-3. Method for Manufacturing Power Storage Device>

[0107] Figure 7This is a flowchart illustrating 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 through ninth steps are performed, for example, by a manufacturing apparatus for the power storage device 10. The manufacturing apparatus includes a fold forming apparatus 100. The first through ninth steps are simply names for the steps in the method for manufacturing the power storage device 10 for convenience and do not necessarily indicate the order of the steps. The order of the following steps can be arbitrarily changed.

[0108] In the first process of step S11, the manufacturing apparatus joins the cover body 60 to the electrode terminal 30. Upon completion of the first process, a pair of cover units 60Z in which the electrode terminal 30 is joined to the cover body 60 is completed.

[0109] The second step (mark forming step) of step S12 is performed before or after the first step. In the second step, the manufacturing apparatus forms the first mark 91 and the second mark 92 on the exterior film 50 .

[0110] The third process of step S13 is performed after the first and second processes. In the third process, the manufacturing apparatus arranges the electrode body 20 on the outer film 50. Figure 8 As shown, in the third step, the electrode body 20 is placed on the exterior film 50 so that the corner 20D of the electrode body 20 is aligned with the mark 92A and the corner 20C of the electrode body 20 is aligned with the mark 92B.

[0111] The fourth step (cover placement step) of step S14 is performed after the third step. In the fourth step, the manufacturing apparatus places a pair of cover units 60Z on the sides of the electrode body 20 and joins the electrode terminal 30 to the electrode body 20. Figure 9 As shown, in the third step, the cover unit 60Z including the cover body 60A is placed on the exterior film 50 so that the corner 67 of the cover body 60A is aligned with the mark 91A and the corner 66 is aligned with the mark 91B. In the fourth step, the cover unit 60Z including the cover body 60B is placed on the exterior film 50 so that the corner 66 of the cover body 60B is aligned with the mark 91F and the corner 67 is aligned with the mark 91G. Alternatively, the method for manufacturing the power storage device 10 may include a step in which, instead of the first and fourth steps, the electrode body 20 and the electrode terminal 30 are first joined together, and then the cover body 60 is joined to the electrode terminal 30 joined to the electrode body 20.

[0112] The fifth step (packaging step) of step S15 is performed after the fourth step. In the fifth step, the manufacturing device winds the outer film 50 around the electrode body 20 and the cover 60. In the fifth step, the manufacturing device bends the outer film 50 along the first mark 91 and the second mark 92 while covering the electrode body 20 and the cover 60 with the outer film 50. In the fifth step, the manufacturing device winds the outer film 50 around the electrode body 20 and the cover 60 while limiting the movement of the electrode body 20 and the cover 60 using a limiting unit, while applying tension to the outer film 50. The limiting unit is, for example, a groove into which the electrode body 20 and the cover 60 are inserted. The limiting unit may also be a device that applies an external force to the electrode body 20 and the cover 60 so that the electrode body 20 and the cover 60 do not move. The limiting unit may also be a device that applies a force to the electrode body 20 and the cover 60 in a direction opposite to the direction in which the outer film 50 is stretched. Furthermore, in order to remove wrinkles from the exterior film 50 , the restricting means may include a roller that runs on the exterior film 50 while the exterior film 50 is stretched.

[0113] The sixth step, step S16, is performed after the fifth step. In the sixth step, the manufacturing apparatus forms a first sealed portion (hereinafter referred to as a "temporary first sealed portion"), which has an unsealed portion formed in a portion for injecting electrolyte. In this temporary first sealed portion, the facing thermally fusible resin layers 53 of the exterior film 50 are bonded to each other. If the power storage device 10 is, for example, an all-solid-state battery, the electrolyte injection step is unnecessary, so the manufacturing apparatus forms the first sealed portion 70 in the sixth step.

[0114] The seventh step of step S17 is performed after the sixth step. In the seventh step, the manufacturing apparatus heat-seals the heat-fusible resin layer 53 of the exterior film 50 and the sealing surface 63 of the lid 60 to form the second seal portion 80 .

[0115] The eighth step of step S18 is performed after the seventh step. In the eighth step, the manufacturing apparatus injects the electrolyte solution from the unsealed portion formed in the temporary first sealed portion.

[0116] The ninth step of step S19 is performed after the eighth step. In the ninth step, the manufacturing apparatus heat-seals the temporary first sealed portion, including the unsealed portion, to form the first sealed portion 70. If the power storage device 10 is, for example, an all-solid-state battery, the eighth and ninth steps are omitted.

[0117] <1-4. Effects of the Power Storage Device>

[0118] External film 50 of power storage device 10 has first marks 91 formed to correspond to at least a portion of corners 64 to 67 of lid 60. First marks 91 enable lid 60 to be positioned relative to external film 50, resulting in high positional accuracy of lid 60 relative to external film 50.

[0119] [2. Modifications]

[0120] The above-described embodiments are examples of possible embodiments of the power storage device and the method for manufacturing the power storage device according to the present invention and are not intended to limit the embodiments. The power storage device and the method for manufacturing the power storage device according to the present invention may adopt a different embodiment than the embodiment exemplified. One example is a method in which a portion of the structure of the embodiment is replaced, changed, or omitted, or a method in which a new structure is added to the embodiment. Several examples of variations of the embodiment are shown below. In addition, the following variations can be combined with each other as long as they are not technically inconsistent.

[0121] <2-1>

[0122] In the above embodiment, the exterior film 50 only needs to have at least one of the marks 91A to 91J. Figure 10 As shown, the outer film 50 may also have only the first mark 91. In another example, as Figure 11 As shown, the marks 92D, 91D, and 91I which are not necessary for forming the second sealing portion 80 may be omitted.

[0123] <2-2>

[0124] In the above embodiment, at least one of the marks 91A to 91J and 92A to 92D may differ from the other marks in at least one of the length, type, and fold strength. Furthermore, the fold strength may be determined, for example, by the angle at which the exterior film 50 with the fold is raised when the exterior film 50 is placed on a flat surface, or by the degree of depression of the heat-fusible resin layer 53 in the portion with the fold.

[0125] <2-3>

[0126] The structure of the device 100 can be changed arbitrarily. Figure 12 As shown, the male mold 120 can also be configured to approach and separate from the female mold 110 in a direction intersecting the gravity direction XA. Figure 12 In the illustrated example, it is preferred that the exterior film 50 be fixed in position relative to the stage 150 by being pressed against the stage 150 by the fixing tool 200 .

[0127] <2-4>

[0128] In the above embodiment, the exterior film 50 of the power storage device 10 may extend further outward than at least one of the two lids 60 in the FB direction. By sealing the portion of the exterior film 50 that extends further outward than the lids 60, the electrode assembly 20 is sealed. The portion of the exterior film 50 that extends further than the lids 60 may be folded inward so that the outer surfaces of the exterior film 50 contact each other, as in a gable-top container, or folded toward any surface of the exterior body 40, as in a brick-pack container.

[0129] <2-5>

[0130] In the above embodiment, the exterior body 40 does not need to include one of the two lids 60. In this variation, the portion of the exterior film 50 that extends outward from the electrode body 20 in the FB direction is sealed in the portion of the exterior body 40 where the lid 60 is omitted, thereby sealing the electrode body 20. The portion of the exterior film 50 that extends outward from the electrode body 20 can also be folded, similar to a gable roof container or a brick-shaped container.

[0131] <2-6>

[0132] In the above embodiment, the outer shape of the outer casing 40 can be arbitrarily changed. The outer shape of the outer casing 40 may be a cylinder, a prism, or a cube.

[0133] [3. Example]

[0134] The inventors of the present application conducted a first test, a second test, and a third test on the power storage devices of Example 1, Example 2, and Comparative Example 1. For ease of description, the elements constituting the power storage devices of the Examples and Comparative Examples that are identical to those in the embodiment are denoted by the same reference numerals as in the embodiment.

[0135] The power storage devices of Examples 1 and 2 are power storage devices according to the embodiment. The specifications of the power storage devices of Examples 1 and 2 are as follows.

[0136] The exterior film 50 is a laminate (laminated film) comprising a base layer 51, a barrier layer 52, and a heat-fusible resin layer 53 in this order. In Examples 1 and 2, the base layer 51 is composed of a polyethylene terephthalate film, an adhesive layer, a stretched nylon film, and an adhesive layer laminated in this order. The polyethylene terephthalate film is 15 μm thick. The stretched nylon film is 15 μm thick. The adhesive layer is made of a two-component polyurethane adhesive. The cured adhesive layer has a thickness of 3 μm. The barrier layer 52 in Examples 1 and 2 is made of aluminum foil. The barrier layer 52 in Examples 1 and 2 is 40 μm thick. The heat-fusible resin layer 53 in Examples 1 and 2 is composed of maleic anhydride-modified polypropylene and random polypropylene laminated in this order. The maleic anhydride-modified polypropylene is 40 μm thick. The random polypropylene is 40 μm thick.

[0137] The lid 60 is made of polypropylene and manufactured by injection molding. Its length (height) in the UD direction is 30 mm, its length (width) in the LR direction is 100 mm, and its length (thickness) in the FB direction is 5 mm. In other words, the length of the sealing surface 63 of the lid 60, or in other words, the circumference of the lid 60, is 260 mm.

[0138] Method for manufacturing the power storage device of embodiment 1 and embodiment 2 Figure 7 The method is the same as that shown in FIG. However, the power storage devices of Examples 1 and 2 used in the first test are Figure 7 The state in which the sixth step is completed is shown. The power storage devices of Examples 1 and 2 used in the second and third tests are Figure 7 The seventh step is shown as completed. The exterior film 50 of Example 1 and Example 2 has the marks 91A, 91B, 91E, 91F, 91G, and 91J. The marks 91A, 91B, 91E, 91F, 91G, and 91J are used Figure 12 The device 100 shown is formed. Markings 91A, 91B, 91E, 91F, 91G, and 91J represent folds. In Example 1, the pressing conditions for the male mold 120 against the female mold 110 in the second step were a linear pressure of 0.4 N / mm and a pressing time of 1 second. In Example 2, the pressing conditions were a set temperature of 60°C, a pressing time of 10 seconds, and a linear pressure of 1.2 N / mm. Furthermore, in Example 1, markings 91A, 91B, 91E, 91F, 91G, and 91J were formed without heating the exterior film 50.

[0139] The sealing conditions for forming the temporary first sealing portion 70 in the sixth step were a set temperature of 226°C, a pressing time of 10 seconds, and a surface pressure of 0.25 MPa. The sealing conditions for forming the second sealing portion 80 in the seventh step were a set temperature of 180°C, a pressing time of 3 seconds, and a surface pressure of 0.78 MPa.

[0140] The elements of the comparative example power storage device are the same as those of the power storage devices of Examples 1 and 2, except that no mark is formed on the outer film 50. The comparative example power storage device used in the first test is Figure 7 The state in which the sixth step is completed is shown. The comparative example power storage device used in the second and third tests is Figure 7 The seventh process is shown as completed.

[0141] The first test measured the circumference of the exterior body 40. In the first test, the length (circumference) of the portion of the exterior body 40 corresponding to the sealing surface 63 was measured for the power storage devices of Example 1, Example 2, and Comparative Example 1.

[0142] The second test was to confirm the sealing properties of the outer casing 40. In the second test, for the power storage devices of Example 1, Example 2, and Comparative Example 1, a portion of the outer casing 40 was cut open, and Ageless Sealcheck spray (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was sprayed onto the inside of the outer casing 40. After approximately 5 minutes, the presence of the sealant leaking from the second seal portion 80 was visually confirmed.

[0143] The third test was a test for confirming the presence of wrinkles on the outer casing 40. In the third test, the presence of wrinkles on the outer casing 40 was visually confirmed for the power storage devices of Example 1, Example 2, and Comparative Example 1.

[0144] Figure 13 are the results of the first, second, and third tests.

[0145] In the first test, it was confirmed that there was no significant difference between the circumference of the exterior body 40 and the circumference of the cover 60 in the power storage devices of Examples 1 and 2. In the power storage devices of Examples 1 and 2, it was confirmed that the exterior film 50 was in close contact with the sealing surface 63 of the cover 60. On the other hand, in the power storage device of Comparative Example 1, it was confirmed that the circumference of the exterior body 40 was significantly longer than that of the cover 60. This suggests that a gap exists between the exterior film 50 and the sealing surface 63 of the cover 60.

[0146] In the second test, no leakage of the test fluid was observed in the power storage devices of Examples 1 and 2. In other words, no gap was observed between the exterior body 40 and the cover 60 in the power storage devices of Examples 1 and 2. However, leakage of the test fluid was observed in the power storage device of Comparative Example 1. In other words, a gap was observed between the exterior body 40 and the cover 60 in the power storage device of Comparative Example 1.

[0147] In the third test, no wrinkles were observed in the exterior body 40 of the power storage devices of Examples 1 and 2. In other words, the exterior film 50 was confirmed to be in close contact (tightly adhered) to the cover 60 in the power storage devices of Examples 1 and 2. In the power storage device of Comparative Example 1, wrinkles were observed in the exterior body 40. In other words, the exterior film 50 was confirmed to have low adhesion to the cover 60 in the power storage device of Comparative Example 1.

[0148] Description of Reference Numerals

[0149] 10: Power storage device

[0150] 20: Electrode body

[0151] 20A, 20B, 20C, 20D: Corners

[0152] 40: Exterior body

[0153] 40A: Opening

[0154] 50: Exterior film

[0155] 60: Cover

[0156] 64~67: Corner

[0157] 91: First Mark

[0158] 92: Second mark.

Claims

1. A power storage device, characterized in that: include: Electrode body; and An outer body for sealing the electrode body, The outer body comprises: an outer film covering the electrode body so as to form an opening; and a cover body disposed at the opening, The exterior film has a first mark formed to correspond to at least a portion of a corner portion of the cover.

2. The power storage device according to claim 1, wherein: The first mark is at least one of a fold, a line, and a slit that does not penetrate the exterior film.

3. The power storage device according to claim 1 or 2, wherein: The first mark is formed at least in a range including an end portion of the corner portion of the cover.

4. The power storage device according to claim 1 or 2, wherein: The exterior film has a second mark formed to correspond to at least a portion of a corner portion of the electrode body.

5. The power storage device according to claim 4, wherein: The first mark and the second mark are connected.

6. An exterior film that can be used as an exterior body of an electricity storage device, characterized in that: The power storage device includes an electrode body and a cover body, The exterior film has a first mark formed to correspond to at least a portion of a corner portion of the cover.

7. The exterior film according to claim 6, characterized in that: The first mark is at least one of a fold, a line, and a slit that does not penetrate the exterior film.

8. The exterior film according to claim 6 or 7, characterized in that: The first mark is formed at least in a range including an end portion of the corner portion of the cover.

9. The exterior film according to claim 6 or 7, characterized in that: The electrode body includes a second mark formed to correspond to at least a portion of a corner portion of the electrode body.

10. The exterior film according to claim 9, characterized in that: The first mark and the second mark are connected.

11. A method for manufacturing an electricity storage device, characterized in that: The power storage device includes an electrode body and an outer casing that seals the electrode body. The outer body comprises: an outer film covering the electrode body in a manner having an opening; and a cover body disposed at the opening, The exterior film has a first mark formed so as to correspond to at least a portion of a corner portion of the cover. The method for manufacturing an electricity storage device includes a mark forming step of forming the first mark on the exterior film.

12. The method for manufacturing an electricity storage device according to claim 11, wherein: include: an arrangement step, performed after the mark forming step, of arranging the cover on the exterior film in such a manner that a corner of the cover is aligned with the first mark; and The packaging step is performed after the arrangement step, and covers the electrode assembly and the lid with the exterior film while folding the exterior film along the first mark.

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