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

Abstract

This power storage device comprises: a power storage module that includes a plurality of electrodes stacked along a first direction; and an exterior body that accommodates the power storage module therein. The exterior body has a pair of exterior parts that are disposed so as to sandwich the power storage module from both sides in the first direction and have peripheral edge parts joined to each other. Each of the pair of exterior parts includes: a conductive plate stacked on an electrode disposed at an outermost layer of the power storage module in the first direction; and a rectangular frame-shaped laminate member joined to a rectangular outer edge part of the conductive plate. At least a part of the laminate member has a first laminate L1 in which a first metal layer 103, a second metal layer 108, and an intervening layer 111 disposed between the first metal layer 103 and the second metal layer 108 are stacked.

Description

Energy storage device, method for manufacturing an energy storage device, and casing

[0001] This disclosure relates to an energy storage device, a method for manufacturing an energy storage device, and an exterior body.

[0002] Patent Document 1 describes a battery in which a power generation element is fitted into a housing space formed by overlapping a pair of aluminum laminate sheets with recesses formed therein. The power generation element is sealed by heat welding the peripheral edges of the pair of aluminum laminate sheets together.

[0003] Japanese Patent Publication No. 2005-174680

[0004] In the type of battery described above, wrinkles may form in the aluminum laminate sheet after the power generation module is sealed under reduced pressure. These wrinkles may cause damage to the aluminum laminate sheet.

[0005] This disclosure provides a power storage device capable of suppressing wrinkles in the exterior, a method for manufacturing the power storage device, and an exterior.

[0006] The energy storage device according to this disclosure comprises an energy storage module including a plurality of electrodes stacked along a first direction, and an outer casing that houses the energy storage module, wherein the outer casing is arranged to sandwich the energy storage module from both sides in the first direction and has a pair of outer casings whose peripheral edges are joined together, and each of the pair of outer casings includes a conductive plate stacked on the outermost electrode arranged in the first direction of the energy storage module, and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, and at least a part of the laminate member has a first laminate in which a first metal layer, a second metal layer, and an intervening layer arranged between the first metal layer and the second metal layer are stacked.

[0007] In the above-described energy storage device, at least a portion of each laminated member of the pair of exterior parts has a first metal layer and a second metal layer, thus improving rigidity compared to a laminated member having only one metal layer. Furthermore, since at least a portion of the laminated member of the above-described energy storage device has an intervening layer between the first metal layer and the second metal layer, bending rigidity can be particularly improved compared to a laminated member in which two metal layers are in contact. As a result, wrinkles in the exterior can be suppressed.

[0008] The exterior portion includes a recess for housing the energy storage module and a flange portion surrounding the recess, the recess having a rectangular bottom surface, and the four corners of the bottom surface may have a first laminate.

[0009] Viewed from a first direction, the first laminate further comprises a cover member positioned between the energy storage module and the outer casing, and viewed from a first direction, the first laminate may overlap with the gap between the energy storage module and the cover member.

[0010] The laminated member includes a pair of first portions facing each other in a second direction perpendicular to a first direction, and a pair of second portions facing each other in a third direction perpendicular to both the first and second directions, wherein the second portions have a first laminate and may be thicker than the first portions.

[0011] The laminated member may further include a joint portion formed by the overlapping and joining of a portion of the first part and a portion of the second part.

[0012] At least a portion of the intervening layer may have a second laminate in which a first resin layer provided on the surface of a first metal layer, a second resin layer provided on the surface of a second metal layer, and a third resin layer provided between the first and second resin layers are laminated.

[0013] The first resin layer and the second resin layer may be composed of different resin materials.

[0014] The first resin layer and the second resin layer may be made of the same resin material.

[0015] At least one of the first resin layer and the second resin layer may be an acid-modified resin.

[0016] At least one of the first resin layer, the second resin layer, and the third resin layer may be made of nylon.

[0017] The third resin layer may be a welded layer.

[0018] The laminated member further includes a first outermost layer provided on the opposite side of the intervening layer from the first metal layer, and a second outermost layer provided on the opposite side of the intervening layer from the second metal layer, and the first outermost layer and the second outermost layer may be made of the same resin material as the third resin layer.

[0019] The laminated member further includes a fifth resin layer provided between a first metal layer and a first outermost layer, and a sixth resin layer provided between a second metal layer and a second outermost layer, wherein the first resin layer and the sixth resin layer are made of the same resin material, and the second resin layer and the fifth resin layer are made of the same resin material, but may be made of different resin materials than the first resin layer and the sixth resin layer, respectively.

[0020] The laminated member further includes a fifth resin layer provided between a first metal layer and a first outermost layer, and a sixth resin layer provided between a second metal layer and a second outermost layer, wherein the first resin layer and the second resin layer are made of the same resin material, and the fifth resin layer and the sixth resin layer are made of the same resin material, but may be made of different resin materials than the first resin layer and the second resin layer, respectively.

[0021] A method for manufacturing an energy storage device according to the present disclosure comprises: an energy storage module including a plurality of electrodes stacked along a first direction; and an exterior body for housing the energy storage module, the exterior body having a pair of exterior parts arranged to sandwich the energy storage module from both sides in the first direction and having their peripheral edges joined together, the method for manufacturing an energy storage device comprising: a step of forming at least a part of a laminate member by bonding a pair of laminate films, each having a metal layer and a resin layer provided on the metal layer, by welding the resin layers together; and a step of joining the laminate member to the outer edge of a conductive plate to form an exterior part.

[0022] In the above-described method for manufacturing the energy storage device, since at least a portion of the laminated member is formed as described above, at least a portion of the laminated member has a pair of metal layers and an intervening layer made of resin between the pair of metal layers. The pair of metal layers can improve the rigidity of at least a portion of the laminated member. The intervening layer can improve the bending rigidity of at least a portion of the laminated member. As a result, wrinkles in the exterior can be suppressed.

[0023] The exterior body according to this disclosure is an exterior body that houses a power storage module including a plurality of electrodes stacked along a first direction, and the exterior body has a pair of exterior parts that are arranged to sandwich the power storage module from both sides in the first direction and whose peripheral edges are joined together, and each of the pair of exterior parts has a conductive plate and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, and at least a part of the laminate member may have a first laminate in which a first metal layer, a second metal layer and an intervening layer disposed between the first metal layer and the second metal layer are stacked.

[0024] In the above-described exterior body, at least a portion of each laminated member of the pair of exterior parts has a first metal layer and a second metal layer, thus improving rigidity compared to a laminated member having only one metal layer. Furthermore, since at least a portion of the laminated member of the above-described exterior body has an intervening layer between the first metal layer and the second metal layer, bending rigidity can be particularly improved compared to a laminated member in which two metal layers are in contact. As a result, wrinkles in the exterior body can be suppressed.

[0025] According to this disclosure, it is possible to provide a power storage device capable of suppressing wrinkles in the exterior, a method for manufacturing the power storage device, and an exterior.

[0026] Figure 1 is a schematic plan view of the energy storage device according to this embodiment. Figure 2 is a schematic cross-sectional view along line II-II in Figure 1. Figure 3 is a schematic plan view of the energy storage module shown in Figures 1 and 2. Figure 4 is a schematic cross-sectional view of the energy storage module shown in Figures 1 and 2. Figure 5(a) is a schematic plan view showing the first exterior part. Figure 5(b) is a schematic plan view showing the second exterior part. Figure 6 is a schematic cross-sectional view showing the second portion of the first laminate member and the second laminate member shown in Figure 1. Figure 7 is a schematic cross-sectional view for explaining the method of forming the second portion of the first laminate member and the second laminate member shown in Figure 1. Figure 8 is a schematic cross-sectional view showing the first portion of the first laminate member and the second laminate member shown in Figure 1. Figure 9 is a schematic cross-sectional view showing an enlarged portion of Figure 2. Figure 10 is a schematic cross-sectional view showing the second portion of the first laminate member and the second laminate member according to the first modified example. Figure 11 is a schematic cross-sectional view showing the first laminate member and the second portion of the second laminate member according to a second modified example.

[0027] Hereinafter, an energy storage device and a method for manufacturing an energy storage device according to one embodiment will be described with reference to the drawings. In the description of each figure, the same or corresponding elements will be denoted by the same reference numeral, and redundant explanations may be omitted. In addition, each figure may show a Cartesian coordinate system that defines a first direction D1, a second direction D2 perpendicular to the first direction D1, and a third direction D3 perpendicular to both the first direction D1 and the second direction D2.

[0028] Figure 1 is a schematic plan view of the energy storage device according to this embodiment. Figure 2 is a schematic cross-sectional view taken along line II-II in Figure 1. Figure 3 is a schematic plan view of the energy storage module shown in Figures 1 and 2. Figure 4 is a schematic cross-sectional view of the energy storage module shown in Figures 1 and 2. The energy storage device 100 shown in Figures 1 to 4 is used in the batteries of various vehicles, such as forklifts, hybrid vehicles, and electric vehicles. The energy storage device 100 is a secondary battery, such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage device 100 may be an electric double-layer capacitor or an all-solid-state battery. Here, the case in which the energy storage device 100 is a lithium-ion secondary battery is given as an example.

[0029] As shown in Figures 1 to 4, the energy storage device 100 comprises an energy storage module 1, an outer casing 40 provided on the energy storage module 1, and a pair of cover members 50. The energy storage device 100 is constructed by sealing the energy storage module 1 and the pair of cover members 50 with the outer casing 40. The energy storage module 1 and the pair of cover members 50 constitute a housing 2 housed within the outer casing 40.

[0030] The energy storage module 1 includes an electrode stack 10 formed by stacking a plurality of electrodes along a first direction D1, and a sealing body 20 provided on the outer circumference of the electrode stack 10.

[0031] The electrode stack 10 includes a plurality of electrodes stacked along a first direction D1. The plurality of electrodes include a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13. Separators 14 are interposed between adjacent electrodes.

[0032] The bipolar electrode 11 includes a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 is, for example, in the shape of a rectangular sheet. The current collector 15 includes a first surface 15a and a second surface 15b. For example, the first surface 15a is a surface that intersects the first direction D1, and the second surface 15b intersects the first direction D1 and is the surface opposite to the first surface 15a. Here, the first surface 15a of the current collector 15 is a surface facing one direction of the first direction D1 (the direction from the positive electrode terminal electrode 13 to the negative electrode terminal electrode 12 in Figure 4), and the second surface 15b of the current collector 15 is a surface facing the other direction of the first direction (the direction from the negative electrode terminal electrode 12 to the positive electrode terminal electrode 13 in Figure 4).

[0033] The positive electrode active material layer 16 is provided on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the second surface 15b of the current collector 15. The peripheral portion surrounding the positive electrode active material layer 16 on the first surface 15a of the current collector 15 and the peripheral portion surrounding the negative electrode active material layer 17 on the second surface 15b of the current collector 15 are unformed regions (uncoated regions) where no active material layer is provided. Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 and the negative electrode active material layer 17 of another bipolar electrode 11 face each other via a separator 14. Grooves may be formed in the positive electrode active material layer 16 and the negative electrode active material layer 17 of each bipolar electrode 11 to improve liquid injection and gas escape properties.

[0034] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from a first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from a first direction D1. In a plan view from a first direction D1, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17. In other words, when viewed from a first direction D1, the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16.

[0035] The negative electrode terminal electrode 12 comprises a current collector 15 and a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15. The negative electrode terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on the first surface 15a of the current collector 15. In other words, the first surface 15a of the current collector 15 of the negative electrode terminal electrode 12 does not have an active material layer and constitutes the negative electrode terminal surface of the energy storage module 1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the first direction D1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 via a separator 14 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0036] The positive terminal electrode 13 has a current collector 15 and a positive electrode active material layer 16 provided on the first surface 15a of the current collector 15. The positive terminal electrode 13 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 on the second surface 15b, which is the opposite surface of the first surface 15a of the current collector 15. That is, no active material layer is provided on the second surface 15b of the current collector 15 of the positive terminal electrode 13, and it constitutes the positive electrode terminal surface of the power storage module 1. The positive terminal electrode 13 is laminated on the bipolar electrode 11 at the other end in the first direction D1 of the electrode laminate 10. The positive terminal electrode 13 is laminated on the bipolar electrode 11 such that its positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11 through the separator 14.

[0037] In the present embodiment, the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 are denoted by the same reference numeral 15 as the current collector, but the materials constituting the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 may be the same as each other or different from each other.

[0038] The separator 14 is disposed between adjacent bipolar electrodes 11 in the first direction D1, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive terminal electrode 13 and the bipolar electrode 11, respectively. That is, the separator 14 is interposed between the positive electrode surface provided with the positive electrode active material layer 16 and the negative electrode surface provided with the negative electrode active material layer 17 of the current collector 15. The separator 14 is a member that allows charge carriers such as lithium ions to pass through, and by isolating the positive electrode surface and the negative electrode surface, it prevents short circuits due to contact between adjacent electrodes.

[0039] The current collector 15 is a chemically inert electrical conductor for continuously passing current through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charging of the lithium ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material, etc. Examples of the conductive resin material include a resin obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as necessary. The current collector 15 may include a plurality of layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material and / or conductive resin material.

[0040] A coating layer may be formed on the surface of the current collector 15. The coating layer may be formed by a known method such as plating or spray coating. The current collector 15 may have a shape such as plate-like, foil-like, film-like, or mesh-like. Examples of the metal foil include aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 15 may be an alloy foil of the above metals or a foil formed by integrating a plurality of metal foils. When the current collector 15 has a foil shape, the thickness of the current collector 15 may be, for example, 1 μm to 200 μm. The current collector 15 may be a foil formed by bonding an aluminum foil and a copper foil together through a conductive adhesive or a foil formed by vapor-depositing a copper layer on one side of an aluminum foil.

[0041] The positive electrode active material layer 16 contains a positive electrode active material capable of occluding and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, polyanion-based compounds, etc. The positive electrode active material may be any material that can be used in a lithium ion secondary battery. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In the present embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO ４ ) as a composite oxide.

[0042] The negative electrode active material layer 17 contains a negative electrode active material capable of occluding and releasing charge carriers such as lithium ions. The negative electrode active material may be any of a single substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, metal compounds, etc. Examples of the negative electrode active material include lithium and lead, artificial graphite, hard carbon (carbon with low graphitization property), or soft carbon (carbon with high graphitization property). Examples of artificial graphite include highly oriented graphite, mesocarbon microbeads, etc. Examples of elements capable of alloying with lithium include silicon or tin. In the present embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0043] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter, may be simply referred to as "active material layer") may further contain a conductive assistant, a binder, an electrolyte, an electrolyte supporting salt, etc. as required. The conductive assistant is added to enhance electrical conductivity. The conductive assistant is, for example, acetylene black, carbon black, graphite, or the like. The electrolyte supporting salt is added to enhance ion conductivity.

[0044] Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, acrylic resins such as acrylic acid or methacrylic acid, styrene-butadiene rubber, carboxymethyl cellulose, alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester cross-linked products, starch-acrylic acid graft polymers, and the like. These binders can be used alone or in combination. As the solvent for the binder, for example, water, N-methyl-2-pyrrolidone, or the like is used.

[0045] The separator 14 may be, for example, a porous sheet or non-woven fabric containing a polymer that absorbs and retains an electrolyte. Examples of the material of the separator 14 include polyolefins such as polypropylene and polyethylene, or polyester. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may have, for example, an adhesive layer or a ceramic layer as a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0046] As the electrolyte salt of the electrolyte solution, LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ )２ Known lithium salts such as the above may be used. Furthermore, known solvents such as cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers may be used as non-aqueous solvents. Two or more of these known solvent materials may be used in combination.

[0047] The sealing body 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the first direction D1. For example, the sealing body 20 is formed on the periphery of the electrode stack 10 as a rectangular cylindrical member so as to surround the four sides of the electrode stack 10, which is substantially rectangular parallelepiped in shape. The sealing body 20 can be joined (welded) to the first surface 15a and the second surface 15b of the current collector 15 at the periphery 15c of each current collector 15. The sealing body 20 insulates adjacent current collectors 15 in the first direction D1 and cooperates with these adjacent current collectors 15 to form an internal space S. The sealing body 20 is also for sealing each of these internal spaces S. An electrolyte is contained in each internal space S. The sealing body 20 can suppress the outflow of the electrolyte contained in the internal space S to the outside. Furthermore, the sealing body 20 can suppress the intrusion of air, moisture, and other elements from the outside of the electrode stack 10 into the internal space S.

[0048] The sealant 20 contains an insulating material. Examples of materials for the sealant 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile styrene resin.

[0049] The sealing body 20 includes a plurality of resin sealing materials 21 and a plurality of resin spacers 22. The sealing materials 21 are provided on each of the plurality of electrodes. More specifically, the sealing materials 21 are provided on each peripheral edge 15c of the current collector 15. Therefore, the plurality of sealing materials 21 are stacked along the first direction D1. The sealing materials 21 provided on the peripheral edge 15c of the current collector 15 are formed in a frame shape that follows the outer shape of the current collector 15 when viewed from the first direction D1. Here, since the current collector 15 is rectangular in plan view, the sealing material 21 is rectangular in plan view. The sealing material 21 includes an inner portion that overlaps the peripheral edge 15c of the current collector 15 when viewed from the first direction D1, and an outer portion that extends beyond the edge of the current collector 15. The sealing material 21 is constructed by joining together the outer portion of one resin member joined to the first surface 15a of the current collector 15 and another resin member joined to the second surface 15b of the current collector 15, thereby integrating them into one unit. In other words, the sealing material 21 covers the peripheral edge 15c of the current collector 15.

[0050] In this embodiment, the sealing material provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the negative terminal electrode 12, and the current collector 15 of the positive terminal electrode 13 are all denoted by the same reference numeral as sealing material 21. However, the sealing material provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the negative terminal electrode 12, and the sealing material provided on the current collector 15 of the positive terminal electrode 13 may be the same as or different from each other.

[0051] The spacer 22 is formed in a substantially frame shape so as to surround the positive electrode active material layer 16 when viewed from the first direction D1. The spacer 22 has an inner portion that overlaps the current collector 15 and an outer portion that extends outward beyond the edge of the current collector 15 when viewed from the first direction D1. The spacer 22 is positioned to be interposed between each of the sealing materials 21 provided on adjacent electrodes in the first direction D1. As a result, the spacer 22, together with the pair of sealing materials 21 adjacent in the first direction D1, maintains the distance between the adjacent current collectors 15 in the first direction D1. The internal space S is defined by the pair of adjacent current collectors 15 in the first direction D1, the spacer 22, and the pair of sealing materials 21 adjacent to the spacer 22.

[0052] The spacer 22 is formed in a frame shape that follows the outer shape of the current collector 15 when viewed from the first direction D1. Therefore, the sealing body 20 is constructed by stacking multiple resin frames (sealing material 21 and spacer 22) provided on the peripheral edge 15c of the current collector 15 along the first direction D1, sealing the internal space S between adjacent electrodes in the first direction D1.

[0053] Viewed from the first direction D1, the inner edge 22e of the spacer 22 is located between the outer edge 17e of the negative electrode active material layer 17 and the outer edge 16e of the positive electrode active material layer 16. That is, the inner edge 22e of the spacer 22 is located inside the outer edge 17e of the negative electrode active material layer 17. As a result, the spacer 22 includes a portion that overlaps with the negative electrode active material layer 17 when viewed from the first direction D1. Multiple spacers 22 may be configured so that they do not come into contact with the current collectors 15 of adjacent bipolar electrodes 11. In other words, a small gap may be provided between the spacer 22 and the first surface 15a of the current collector 15 of the adjacent bipolar electrode.

[0054] The outer edges of the multiple sealing materials 21 and the outer edges of the multiple spacers 22 are welded together to form a welded portion 23. That is, the sealing body 20 includes a welded portion 23 formed by the welding and integration of the multiple sealing materials 21 and the multiple spacers 22. When viewed from the first direction D1, the welded portion 23 has a frame shape (here, a rectangular frame shape) that surrounds the electrode stack 10 and constitutes the outer periphery of the sealing body 20. Therefore, the outer surface 23s of the welded portion 23 form the outer surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer surface 23s that extend along the first direction D1. The spacers 22 do not need to be welded to the sealing material 21 in at least the inner portion of the sealing material 21 adjacent to the first direction D1.

[0055] The end of the separator 14 may be held in place between the sealing material 21 and the spacer 22. The separator 14 may be fixed by welding its end to at least one of the sealing material 21 and the spacer 22.

[0056] The pair of cover members 50 are arranged so as to sandwich the energy storage module 1 when viewed from a first direction D1, and so as to face each other along a third direction D3. The cover members 50 are formed in a hollow shape, for example, from resin. The cover members 50 constitute the four (in this case) housing corners 2c of the housing 2, which consists of the energy storage module 1 and the pair of cover members 50. The housing corners 2c are chamfered, for example, into an R-shaped surface. One of the pair of cover members 50 has a pull-out section for bringing out wiring DL (for example, a flexible substrate) including voltage detection lines extending from the electrode stack 10 to the outside.

[0057] As shown in Figures 1 and 2, the outer casing 40 is provided so as to cover the housing 2. The outer casing 40 houses the housing 2 inside. The outer casing 40 is arranged so as to sandwich the housing 2 from both sides in the first direction D1 and includes a first outer casing portion 41 and a second outer casing portion 42 whose peripheral edges (first flange portion 41f and second flange portion 42f) are joined together.

[0058] Figure 5(a) is a schematic plan view showing the first exterior part. Figure 5(b) is a schematic plan view showing the second exterior part. As will be described later, in the energy storage device 100, the peripheral edges of the first exterior part 41 and the second exterior part 42 are bent, but Figures 5(a) and 5(b) show them in an unbent state. The first exterior part 41 is smaller than the second exterior part 42 in plan view, but the first exterior part 41 and the second exterior part 42 may have the same shape as each other in plan view.

[0059] The first exterior portion 41 and the second exterior portion 42 each include a conductive plate and a laminate member. Here, the first exterior portion 41 includes a first conductive plate 31 and a first laminate member 91. The second exterior portion 42 includes a second conductive plate 32 and a second laminate member 92. The first conductive plate 31 and the second conductive plate 32 are rectangular and have the same shape as each other. The first laminate member 91 and the second laminate member 92 are rectangular frame-shaped and have inner edges of the same shape and outer edges of different shapes as each other. The outer edge of the first laminate member 91 is smaller than the outer edge of the second laminate member 92. The first laminate member 91 and the second laminate member 92 may have outer edges of the same shape as each other. The first conductive plate 31 and the second conductive plate 32 are made of metal. The first laminate member 91 is joined to the rectangular outer edge portion 31c of the first conductive plate 31. The second laminate member 92 is joined to the rectangular outer edge 32c of the second conductive plate 32.

[0060] As shown in Figures 1, 5(a), and 5(b), the first laminate member 91 and the second laminate member 92 each have a pair of first portions 81, second portions 82 and 83, and a plurality (in this case, four) of joining portions 84. The pair of first portions 81 face each other in the third direction D3. The first portions 81 are formed in a rectangular shape when viewed from the first direction D1. The second portions 82 and 83 face each other in the second direction D2. The second portions 82 and 83 are formed in a U-shape that faces each other when viewed from the first direction D1. The second portions 82 and 83 are spaced apart from each other in the third direction D3 when viewed from the first direction D1. The pair of first portions 81 extend in the third direction D3 to connect the second portions 82 and 83 and are arranged parallel to each other.

[0061] The joint portion 84 is the portion where a part of the first portion 81 and parts of the second portions 82 and 83 overlap and are joined. The first joint portion 84a is the portion where one end of one first portion 81 and one end of the second portion 82 overlap and are joined. The second joint portion 84b is the portion where one end of the other first portion 81 and the other end of the second portion 82 overlap and are joined. The third joint portion 84c is the portion where the other end of one first portion 81 and one end of the second portion 83 overlap and are joined. The fourth joint portion 84d is the portion where the other end of the other first portion 81 and the other end of the second portion 83 overlap and are joined. The fourth joint portion 84d may be fixed by welding the other end of the other first portion 81 and the other end of the second portion 83 together. The first laminate member 91 and the second laminate member 92 are each formed in a rectangular frame shape when viewed from the first direction D1, by joining a pair of first portions 81 and second portions 82 and 83 together by a joining portion 84.

[0062] In the joint portion 84, for example, the first portion 81 is positioned inside the outer casing 40 so as to be in contact with the housing 2, and the second portions 82 and 83 are positioned outside the outer casing 40. That is, the first portion 81 in the joint portion 84 is positioned between the housing 2 and the second portions 82 and 83. Alternatively, in the joint portion 84, the second portions 82 and 83 may be positioned inside the outer casing 40 so as to be in contact with the housing 2, and the first portion 81 may be positioned outside the outer casing 40. That is, the second portions 82 and 83 in the joint portion 84 may be positioned between the housing 2 and the first portion 81.

[0063] Figure 6 is a schematic cross-sectional view showing the second portion of the first and second laminate members shown in Figure 1. In this embodiment, the second portions 82 and 83 have the same layer structure. The second portions 82 and 83 each have a first adhesive layer 101 (first outermost layer), a second adhesive layer 102 (fifth resin layer), a first metal layer 103, a first molding auxiliary layer 104 (first resin layer), a third adhesive layer 105 (seventh resin layer), a fourth adhesive layer 106 (eighth resin layer), a fifth adhesive layer 107 (second resin layer), a second metal layer 108, a second molding auxiliary layer 109 (sixth resin layer), and a sixth adhesive layer 110 (second outermost layer), and are laminate films formed by laminating these layers in order.

[0064] The first metal layer 103 and the second metal layer 108 are, for example, made of the same metal material. The first metal layer 103 and the second metal layer 108 are, for example, aluminum foil. The first metal layer 103 and the second metal layer 108 may be formed of, for example, A1100P, A3104P, or A3105P. The first metal layer 103 and the second metal layer 108 may be formed of an aluminum material having a high yield strength, such as A5052P. In this case, the first laminate member 91 and the second laminate member 92 are aluminum laminate films. An intervening layer 111, including a first molding auxiliary layer 104, a third adhesive layer 105, a fourth adhesive layer 106, and a fifth adhesive layer 107, is interposed between the first metal layer 103 and the second metal layer 108.

[0065] At least a portion of each of the first laminate member 91 and the second laminate member 92 has a first laminate L1 in which a first metal layer 103, a second metal layer 108, and an intervening layer 111 disposed between the first metal layer 103 and the second metal layer 108 are laminated. The first laminate L1 includes the first metal layer 103, the intervening layer 111, and the second metal layer 108 laminated in this order. In this embodiment, the second portions 82 and 83 of the first laminate member 91 and the second laminate member 92, respectively, have the first laminate L1.

[0066] The first molding auxiliary layer 104 is a resin layer that assists in the elongation of the first metal layer 103 during molding and is provided on the first metal layer 103. The fifth adhesive layer 107 is a resin layer that enhances the adhesion between the second metal layer 108 and the fourth adhesive layer 106 and is provided on the second metal layer 108. The third adhesive layer 105 and the fourth adhesive layer 106 are provided between the first molding auxiliary layer 104 and the fifth adhesive layer 107 and are welded together to form a single welded layer 112 (third resin layer).

[0067] At least a portion of the intervening layer 111 has a second laminate L2 in which a first molding auxiliary layer 104 provided on the surface of the first metal layer 103, a fifth adhesive layer 107 provided on the surface of the second metal layer 108, and a welding layer 112 provided between the first molding auxiliary layer 104 and the fifth adhesive layer 107 are laminated. The second laminate L2 includes the first molding auxiliary layer 104, the welding layer 112, and the fifth adhesive layer 107 laminated in this order. In this embodiment, the entire intervening layer 111 has the second laminate L2.

[0068] The first adhesive layer 101 is provided on the side opposite the intervening layer 111 to the first metal layer 103 and is a resin layer that constitutes the outermost layer of the laminate member. The first adhesive layer 101 has a part of the inner surface of the outer casing 40. The second adhesive layer 102 is a resin layer for improving the adhesion between the first metal layer 103 and the first adhesive layer 101 and is provided between the first adhesive layer 101 and the first metal layer 103.

[0069] The sixth adhesive layer 110 is provided on the side opposite the intervening layer 111 to the second metal layer 108 and is a resin layer that constitutes the outermost layer of the laminate member. The sixth adhesive layer 110 has a part of the outer surface of the exterior body 40. The second molding auxiliary layer 109 is a resin layer that assists in the elongation of the second metal layer 108 during molding and is provided on the second metal layer 108. The second molding auxiliary layer 109 is provided between the sixth adhesive layer 110 and the second metal layer 108.

[0070] The first adhesive layer 101, the third adhesive layer 105, the fourth adhesive layer 106, and the sixth adhesive layer 110 are made of polyolefins such as polypropylene and polyethylene. The third adhesive layer 105 and the fourth adhesive layer 106 are made of mutually compatible resin materials, for example. Here, the third adhesive layer 105 and the fourth adhesive layer 106 are made of the same resin material. The first adhesive layer 101, the third adhesive layer 105, the fourth adhesive layer 106, and the sixth adhesive layer 110 are made of mutually compatible resin materials, for example. Here, the first adhesive layer 101, the third adhesive layer 105, the fourth adhesive layer 106, and the sixth adhesive layer 110 are made of the same resin material. The first adhesive layer 101, the third adhesive layer 105, the fourth adhesive layer 106, and the sixth adhesive layer 110 are made of polypropylene.

[0071] The second adhesive layer 102 is made of a resin material compatible with the first adhesive layer 101. The fifth adhesive layer 107 is made of a resin material compatible with the fourth adhesive layer 106. The second adhesive layer 102 and the fifth adhesive layer 107 are made of, for example, an acid-modified resin. The second adhesive layer 102 and the fifth adhesive layer 107 are made of, for example, an acid-modified polyolefin such as acid-modified polypropylene or acid-modified polyethylene. The second adhesive layer 102 and the fifth adhesive layer 107 are made of, for example, the same resin material. Here, the second adhesive layer 102 and the fifth adhesive layer 107 are made of acid-modified polypropylene. It can be said that at least one of the first molding auxiliary layer 104 and the fifth adhesive layer 107 contained in the intervening layer 111 is an acid-modified resin.

[0072] The first molding auxiliary layer 104 and the second molding auxiliary layer 109 are made of the same resin material, for example. The second adhesive layer 102 and the fifth adhesive layer 107 are made of different resin materials than the first molding auxiliary layer 104 and the second molding auxiliary layer 109, respectively. Here, the first molding auxiliary layer 104 and the second molding auxiliary layer 109 are made of nylon. It can be said that at least one of the layers included in the intervening layer 111 (i.e., the first molding auxiliary layer 104, the fifth adhesive layer 107, the third adhesive layer 105, and the fourth adhesive layer 106) is nylon.

[0073] The thickness of the first metal layer 103 and the second metal layer 108 is, for example, 40 μm or more and 150 μm or less, and here it is 80 μm. The thickness of the first molding auxiliary layer 104 and the second molding auxiliary layer 109 may be, for example, 60 μm or more, 80 μm or more, or 100 μm or more. The thickness of the first adhesive layer 101, the second adhesive layer 102, the third adhesive layer 105, the fourth adhesive layer 106, the fifth adhesive layer 107, and the sixth adhesive layer 110 is, for example, 10 μm or more and 50 μm or less, and here it is 30 μm. The thickness of the first molding auxiliary layer 104 and the second molding auxiliary layer 109 is, for example, 10 μm or more and 100 μm or less, and here it is 25 μm. The thickness of the first molding auxiliary layer 104 and the second molding auxiliary layer 109 may be, for example, 25 μm or more, 50 μm or more, or 70 μm or more.

[0074] Figure 7 is a schematic cross-sectional view illustrating the method for forming the second portion of the first laminate member and the second laminate member shown in Figure 1. In this embodiment, the second portions 82 and 83 are formed by the same formation method. The second portions 82 and 83 are formed using the first laminate film 93 and the second laminate film 94 (a pair of laminate films), respectively.

[0075] The first laminate film 93 has a resin layer 121 which becomes the first adhesive layer 101, a resin layer 122 which becomes the second adhesive layer 102, a metal layer 123 which becomes the first metal layer 103 (metal layer), a resin layer 124 which becomes the first molding auxiliary layer 104, and a resin layer 125 which becomes the third adhesive layer 105 (resin layer), and these layers are laminated in order. The second laminate film 94 has a resin layer 126 which becomes the fourth adhesive layer 106 (resin layer), a resin layer 127 which becomes the fifth adhesive layer 107, a metal layer 128 which becomes the second metal layer 108 (metal layer), a resin layer 129 which becomes the second molding auxiliary layer 109, and a resin layer 130 which becomes the sixth adhesive layer 110, and these layers are laminated in order.

[0076] The first laminate film 93 has the same structure as the second laminate film 94. That is, the resin layer 121 is made of the same material and thickness as the resin layer 126. The resin layer 122 is made of the same material and thickness as the resin layer 127. The metal layer 123 is made of the same material and thickness as the metal layer 128. The resin layer 124 is made of the same material and thickness as the resin layer 129. The resin layer 125 is made of the same material and thickness as the resin layer 130.

[0077] The second portions 82 and 83 are formed by bonding (e.g., welding) a resin layer 125 provided on a metal layer 123 via a resin layer 124, and a resin layer 126 provided on a metal layer 128 via a resin layer 127, respectively, to the first laminate film 93 and the second laminate film 94. More specifically, the first laminate film 93 and the second laminate film 94 are bonded together to form the laminate members that will become the second portions 82 and 83. The resulting laminate members are then cut to form the second portions 82 and 83.

[0078] Figure 8 is a schematic cross-sectional view showing the first portion of the first laminate member and the second laminate member shown in Figure 1. The first portion 81 has a resin layer 141, a resin layer 142, a metal layer 143, a resin layer 144, and a resin layer 145, and these layers are laminated in order. The number of layers in the first portion 81 is less than the number of layers in the second portions 82 and 83. The second portions 82 and 83 are thicker than the first portion 81.

[0079] The first portion 81 has the same structure as, for example, the first laminate film 93 or the second laminate film 94. That is, the resin layer 141 is made of the same material and thickness as the resin layer 121 or the resin layer 126. The resin layer 142 is made of the same material and thickness as the resin layer 122 or the resin layer 127. The metal layer 143 is made of the same material and thickness as the metal layer 123 or the metal layer 128. The resin layer 144 is made of the same material and thickness as the resin layer 124 or the resin layer 129. The resin layer 145 is made of the same material and thickness as the resin layer 125 or the resin layer 130.

[0080] The first portion 81 may be formed by cutting the first laminate film 93 or the second laminate film 94. Each of the first laminate member 91 and the second laminate member 92 is formed by joining a pair of first portions 81 and second portions 82, 83 at a joining portion 84. The joining portion 84 has three metal layers: a first metal layer 103, a second metal layer 108, and a metal layer 143. The first metal layer 103, the second metal layer 108, and the metal layer 143 are arranged spaced apart from each other.

[0081] Figure 9 is a schematic cross-sectional view showing an enlarged portion of Figure 2. As shown in Figure 9, the first conductive plate 31 is laminated on the positive terminal electrode 13, which is located in the outermost layer in one of the first directions D1 of the energy storage module 1 (see Figure 4 for details). The first conductive plate 31 is laminated on the exposed portion of the second surface 15b of the current collector 15 of the positive terminal electrode 13 that is not covered by the sealant 20 (i.e., the portion where the sealant 21 is not provided when viewed from the first direction D1). The second conductive plate 32 is laminated on the negative terminal electrode 12, which is located in the outermost layer in the other of the first directions D1 of the energy storage module 1. The second conductive plate 32 is laminated on the exposed portion of the first surface 15a of the current collector 15 of the negative terminal electrode 12 that is not covered by the sealant 20 (i.e., the portion where the sealant 21 is not provided when viewed from the first direction D1).

[0082] The first conductive plate 31 is in contact with the second surface 15b of the positive terminal electrode 13 and is laminated on the positive terminal electrode 13 so as to be electrically connected to the positive terminal electrode 13 via the second surface 15b. The second conductive plate 32 is in contact with the first surface 15a of the negative terminal electrode 12 and is laminated on the negative terminal electrode 12 so as to be electrically connected to the negative terminal electrode 12 via the first surface 15a. The first conductive plate 31 and the second conductive plate 32 are electrically connected by direct contact with the surface of the current collector 15 where the active material layer is not formed.

[0083] The first conductive plate 31 includes a first surface 31s opposite to the positive terminal electrode 13, and the second conductive plate 32 includes a second surface 32s opposite to the negative terminal electrode 12. The first surface 31s of the first conductive plate 31 and the second surface 32s of the second conductive plate 32 can be used to extract current from the energy storage module 1, respectively. Furthermore, when a battery pack is constructed by stacking multiple energy storage devices 100 in a first direction D1 and connecting them in series, a conductive plate or conductive adhesive is placed between two adjacent energy storage devices 100 in the first direction D1 to electrically connect the multiple energy storage devices 100. That is, the first conductive plate 31 and the second conductive plate 32 can be used to electrically connect the multiple energy storage devices 100.

[0084] The first exterior portion 41 includes a first recess 41p for housing the energy storage module 1 and a first flange portion 41f surrounding the first recess 41p when viewed from a first direction D1. The first flange portion 41f is formed from a first laminate member 91 and forms the peripheral edge of the first exterior portion 41. The second exterior portion 42 includes a second recess 42p for housing the energy storage module 1 and a second flange portion 42f surrounding the second recess 42p when viewed from a first direction D1. The second flange portion 42f is formed from a second laminate member 92 and forms the peripheral edge of the second exterior portion 42.

[0085] The first exterior portion 41 and the second exterior portion 42 are bonded together by welding the first adhesive layers 101 (see Figure 6) to each other while the first flange portion 41f and the second flange portion 42f are overlapped. The peripheral edges of the first exterior portion 41 and the peripheral edges of the second exterior portion 42 are bonded together by joining the first adhesive layers 101 of the first laminate member 91 and the second laminate member 92.

[0086] As shown in Figures 5(a) and 5(b), the corners of the first recess 41p and the second recess 42p are formed in a curved shape that is convex outward from the first recess 41p and the second recess 42p (i.e., they have a radius). The width W42 of the second flange portion 42f, which is the distance from the outer edge of the second recess 42p to the outer edge of the second flange portion 42f (second outer edge 42e), is greater than the width W41 of the first flange portion 41f, which is the distance from the outer edge of the first recess 41p to the outer edge of the first flange portion 41f (first outer edge 41e). As shown in Figures 2 and 9, the cover member 50 is positioned between the energy storage module 1 and the outer casing 40 within the first recess 41p and the second recess 42p, as viewed from the first direction D1.

[0087] The first recess 41p has a rectangular bottom 41b. The second recess 42p has a rectangular bottom 42b. The bottoms 41b and 42b are the same shape as each other and have a shape corresponding to the housing 2. The four corners 41c of the bottom 41b and the four corners 42c of the bottom 42b are formed by the second parts 82 and 83. That is, each corner 41c and 42c has the first laminate L1.

[0088] The first flange portion 41f and the second flange portion 42f are rectangular in shape when viewed from the first direction D1. The first flange portion 41f has four straight sections 411, 412, 413, and 414 that extend along the rectangular energy storage module 1 when viewed from the first direction D1. The second flange portion 42f has four straight sections 421, 422, 423, and 424 that extend along the rectangular energy storage module 1 when viewed from the first direction D1.

[0089] As shown in Figure 1, the outer casing 40 includes four corners 40c that, when viewed from a first direction D1, are opposite the corners 2c of the housing 2. The corners 40c are chamfered, for example, in a C-shape. The corners 40c include the corners 41c of the bottom portions 41b and 42b shown in Figures 5(a) and 5(b). In other words, the corners 41c are part of the corners 40c.

[0090] As shown in Figures 2 and 9, when viewed from a direction intersecting the first direction D1, the first laminate member 91 is bonded to the first surface 31s of the first conductive plate 31. The second laminate member 92 is bonded to the second surface 32s of the second conductive plate 32.

[0091] The first end 91p of the first laminate member 91, which is the end opposite to the end joined to the first surface 31s, and the second end 92p of the second laminate member 92, which is the end opposite to the end joined to the second surface 32s, are hermetically joined (e.g., welded) to each other on the side surface of the energy storage module 1 along the first direction D1 to form an end joint 90p. At the end joint 90p, the first adhesive layer 101 of the first laminate member 91 and the first adhesive layer 101 of the second laminate member 92 are joined. This ensures insulation between the first laminate member 91 and the second laminate member 92 (i.e., the first exterior part 41 and the second exterior part 42).

[0092] As described above, the width W42 of the second flange portion 42f, which is made up of the second laminate member 92, is greater than the width W41 of the first flange portion 41f, which is made up of the first laminate member 91. The first end portion 91p of the first laminate member 91 is the end portion that includes the outer edge of the first flange portion 41f, and the second end portion 92p of the second laminate member 92 is the end portion that includes the outer edge of the second flange portion 42f. Therefore, due to the difference in width W41 of the first flange portion 41f and the width W42 of the second flange portion 42f, the first end surface 91s, which is the end surface of the first end portion 91p of the first laminate member 91, and the second end surface 92s, which is the end surface of the second end portion 92p of the second laminate member 92, are offset from each other. The end joint portion 90p is then bent while maintaining the offset between the first end surface 91s and the second end surface 92s.

[0093] The first laminate member 91 overlaps with the outer edge 31c of the first conductive plate 31 when viewed from the first direction D1, and is provided in a rectangular frame shape so as to surround the outer edge. The first laminate member 91 has a joint portion 96 with the first conductive plate 31. The end face 91r of the first laminate member 91 on the joint portion 96 side is covered with the first insulating material 61. The first insulating material 61 includes an outer portion A1 that is joined to the sixth adhesive layer 110 of the first laminate member 91, and an inner portion A2 that is joined to the first conductive plate 31. The first insulating material 61 is made of a resin compatible with the first adhesive layer 101 and the sixth adhesive layer 110 of the first laminate member 91. The first insulating material 61 covers the end face (part of the end face 91r) on the joint portion 96 side of the first metal layer 103 and the second metal layer 108.

[0094] A second insulating material 62 is interposed between the first adhesive layer 101 of the first laminate member 91 and the first conductive plate 31 in the first direction D1. The second insulating material 62 is made of a resin compatible with the first adhesive layer 101. The second insulating material 62 extends inward from the end face 91r of the first laminate member 91 and is also interposed between the first insulating material 61 and the first conductive plate 31. Therefore, the first laminate member 91 and the first insulating material 61 are joined to the first conductive plate 31 via the second insulating material 62. The inner portion A2 of the first insulating material 61 is welded to the second insulating material 62. The first insulating material 61 and the second insulating material 62 are made of resins compatible with each other. The first insulating material 61 and the second insulating material 62 are made of, for example, acid-modified resins. The first insulating material 61 and the second insulating material 62 are made of, for example, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene.

[0095] The same applies to the second laminate member 92. That is, the second laminate member 92 overlaps with the outer edge 32c of the second conductive plate 32 when viewed from the first direction D1, and is provided in a rectangular frame shape so as to surround the outer edge. The second laminate member 92 is joined to the second surface 32s of the second conductive plate 32 via the second insulating material 62. The second laminate member 92 has a joint portion 97 with the second conductive plate 32. The end face 92r of the second laminate member 92 on the joint portion 97 side is covered with the first insulating material 61. The first insulating material 61 includes an outer portion that is joined to the sixth adhesive layer 110 of the second laminate member 92 and an inner portion that is joined to the second conductive plate 32. The first insulating material 61 is made of a resin compatible with the first adhesive layer 101 and the sixth adhesive layer 110 of the second laminate member 92. The first insulating material 61 covers the end face (part of the end face 92r) on the joint 97 side of the first metal layer 103 and the second metal layer 108. When the first insulating material 61 is welded to the welding layer 112, the resin of the welding layer 112 may cover the end faces of the first metal layer 103 and the second metal layer 108.

[0096] A second insulating material 62 is interposed between the first adhesive layer 101 of the second laminate member 92 and the second conductive plate 32 in the first direction D1. The second insulating material 62 extends inward beyond the end face 92r of the second laminate member 92 and is also interposed between the first insulating material 61 and the second conductive plate 32. Therefore, the second laminate member 92 and the first insulating material 61 are joined to the second conductive plate 32 via the second insulating material 62. The inner portion of the first insulating material 61 is welded to the second insulating material 62.

[0097] The gap G between the energy storage module 1 and the cover member 50 is covered by the second portions 82 and 83. That is, when viewed from the first direction D1, the first laminate L1 overlaps with the gap G between the energy storage module 1 and the cover member 50.

[0098] Next, the manufacturing method of the energy storage device 100 will be described. First, the first laminate member 91 and the second laminate member 92 are formed by the method described above. Next, the first laminate member 91 is joined to the outer edge portion 31c of the first conductive plate 31 via the second insulating material 62 to form the first exterior member which will become the first exterior portion 41. Similarly, the second laminate member 92 is joined to the outer edge portion 32c of the second conductive plate 32 via the second insulating material 62 to form the second exterior member which will become the second exterior portion 42.

[0099] Next, the first exterior member is embossed by a hot press to form a first exterior portion 41 having a first recess 41p and a first flange portion 41f. At this time, the first recess 41p is formed in a range that includes a first opening 41h. That is, the first opening 41h is formed at the bottom 41b of the first recess 41p. Similarly, the second exterior member is embossed by a hot press to form a second exterior portion 42 having a second recess 42p and a second flange portion 42f. At this time, the second recess 42p is formed in a range that includes a second opening 42h. That is, the second opening 42h is formed at the bottom 42b of the second recess 42p.

[0100] Next, the energy storage module 1 is housed in the first recess 41p of the first exterior portion 41 and the second recess 42p of the second exterior portion 42, and the first flange portion 41f and the second flange portion 42f are overlapped. Next, the first flange portion 41f and the second flange portion 42f are heat-pressed and the first adhesive layer 101 is welded together to join the first flange portion 41f and the second flange portion 42f to each other, thereby sealing the energy storage module 1 and the pair of cover members 50 under reduced pressure. Next, the joined first flange portion 41f and the second flange portion 42f are bent.

[0101] As described above, an outer casing 40 is formed from the first outer casing 41 and the second outer casing 42 to cover the energy storage module 1 and the pair of cover members 50. Subsequently, by insulating with the first insulating material 61, the energy storage device 100 is obtained.

[0102] As described above, in the energy storage device 100, the second portions 82 and 83 of the first laminate member 91 of the first exterior portion 41 and the second portions 82 and 83 of the second laminate member 92 of the second exterior portion 42 each have a first laminate L1 including a first metal layer 103 and a second metal layer 108. Since the first metal layer 103 and the second metal layer 108 are made of metal, they have high rigidity against bending. For this reason, the second portions 82 and 83 of the first laminate member 91 and the second portions 82 and 83 of the second laminate member 92 can each have improved rigidity compared to laminate members having only one metal layer.

[0103] Furthermore, the second portions 82 and 83 have an intervening layer 111 between the first metal layer 103 and the second metal layer 108. For example, in the case of bending with the first metal layer 103 on the inside and the second metal layer 108 on the outside, the presence of the intervening layer 111 causes the second metal layer 108 to move away from the bending center, thus increasing its resistance to bending. As a result, the first laminate member 91 and the second laminate member 92 can each have particularly improved bending rigidity compared to a laminate member in which two metal layers are provided in contact. As a result, wrinkles in the first laminate member 91 and the second laminate member 92 of the outer casing 40 after vacuum sealing can be suppressed.

[0104] The intervening layer 111 has a second laminate L2 which includes a first molding auxiliary layer 104 provided on the first metal layer 103, a fifth adhesive layer 107 provided on the second metal layer 108, and a welding layer 112 provided between the first molding auxiliary layer 104 and the fifth adhesive layer 107. Since the intervening layer 111 includes multiple layers in this way, the distance between the first metal layer 103 and the second metal layer 108 can be increased. This makes it possible to further improve the rigidity of the first laminate member 91 and the second laminate member 92.

[0105] The first exterior portion 41 includes a first recess 41p that houses the energy storage module 1 and a pair of cover members 50. The four corners 41c of the rectangular bottom portion 41b of the first recess 41p have a first laminate L1. The second exterior portion 42 includes a second recess 42p that houses the energy storage module 1 and a pair of cover members 50. The four corners 42c of the rectangular bottom portion 42b of the second recess 42p have a first laminate L1. Because each corner 41c, 42c has a first laminate L1 in this way, the stress at each corner 41c, 42c is distributed, making it easier to emboss when forming the first recess 41p and the second recess 42p. In addition, wrinkles at each corner 41c, 42c of the exterior portion 40 after vacuum sealing can be suppressed.

[0106] Viewed from the first direction D1, the first laminate L1 overlaps with the gap G between the energy storage module 1 and the cover member 50. As described above, the first laminate L1, including the first metal layer 103 and the second metal layer 108, has high rigidity against bending. Therefore, even if a gap G is formed between the energy storage module 1 and the cover member 50 due to tolerances, it is possible to suppress the outer casing 40 from falling into the gap G when sealed under reduced pressure. This suppresses wrinkles in the outer casing 40 in the gap G. Furthermore, there is no need to fix the cover member 50.

[0107] The second parts 82 and 83 have the first laminate L1 and are thicker than the first part 81. The above effects are obtained by forming the corners 41c and 42c with the second parts 82 and 83. Compared to the second parts 82 and 83 that cover the housing corners 2c, the first part 81 is easier to emboss and less prone to wrinkles after vacuum sealing. By making the pair of first parts 81 thinner, the end joint 90p can be easily folded. Also, since the end joint 90p can be folded compactly, the energy storage device 100 can be made smaller by that amount.

[0108] The first laminate member 91 and the second laminate member 92 include a joint portion 84 formed by overlapping and joining a part of the first portion 81 and a part of the second portions 82 and 83. Since the joint portion 84 has at least three metal layers, the rigidity of the first laminate member 91 and the second laminate member 92 can be further improved in this region. The joint portion 84 of the first laminate member 91 and the joint portion 84 of the second laminate member 92 may overlap each other when viewed from a first direction D1, or they may be offset from each other in a third direction D3 so as not to overlap. With a configuration in which the joint portions 84 do not overlap each other, the size of the energy storage device 100 in the first direction D1 can be reduced compared to a configuration in which the joint portions 84 overlap each other.

[0109] The first molding auxiliary layer 104 and the fifth adhesive layer 107 are made of different resin materials. The first molding auxiliary layer 104 makes it easier to stretch the first metal layer 103 when creating the first recess 41p and the second recess 42p by embossing. Therefore, the first exterior part 41 and the second exterior part 42 can be easily formed. Since the first molding auxiliary layer 104 is made of nylon, the moldability of the first metal layer 103 can be reliably improved. The fifth adhesive layer 107 can improve the adhesion between the second metal layer 108 and the fourth adhesive layer 106. Since the fifth adhesive layer 107 is made of acid-modified resin, the adhesion between the second metal layer 108 and the fourth adhesive layer 106 can be reliably improved.

[0110] The welded layer 112 is formed by heat welding the third adhesive layer 105 and the fourth adhesive layer 106 together. Therefore, the first laminate film 93, which includes a resin layer 125 corresponding to the third adhesive layer 105, and the second laminate film 94, which includes a resin layer 126 corresponding to the fourth adhesive layer 106, can be bonded together to form the second portions 82 and 83 of the first laminate member 91 and the second laminate member 92, respectively.

[0111] The second portions 82 and 83 of the first laminate member 91 and the second laminate member 92 each include a first adhesive layer 101 and a sixth adhesive layer 110, which form the outermost layers. The first adhesive layer 101 and the sixth adhesive layer 110 are made of the same resin material as the welding layer 112. By using a common resin material in this way, the formation of the first laminate member 91 and the second laminate member 92 becomes easier.

[0112] The second portions 82 and 83 of the first laminate member 91 and the second laminate member 92 each include a second adhesive layer 102 provided between the first metal layer 103 and the first adhesive layer 101, and a second molding auxiliary layer 109 provided between the second metal layer 108 and the sixth adhesive layer 110. The first molding auxiliary layer 104 and the second molding auxiliary layer 109 are made of the same resin material. The fifth adhesive layer 107 and the second adhesive layer 102 are made of the same resin material. By using a common resin material in this way, the formation of the first laminate member 91 and the second laminate member 92 becomes easier.

[0113] A method for manufacturing the energy storage device 100 according to the embodiment includes the steps of: bonding a first laminate film 93 having a metal layer 123 and a resin layer 125 provided on the metal layer 123, and a second laminate film 94 having a metal layer 128 and a resin layer 126 provided on the metal layer 128, by welding the resin layer 125 and the resin layer 126 to form second portions 82 and 83 of the first laminate member 91 and the second laminate member 92, respectively; joining the first laminate member 91 to the outer edge portion 31c of the first conductive plate 31 to form a first exterior portion 41; and joining the second laminate member 92 to the outer edge portion 32c of the second conductive plate 32 to form a second exterior portion 42. As the second portions 82 and 83 of the first laminate member 91 and the second laminate member 92 are formed in this manner, the second portions 82 and 83 of the first laminate member 91 and the second laminate member 92 each have a first metal layer 103, a second metal layer 108, and an intervening layer 111, respectively. Therefore, the rigidity of the second portions 82 and 83 of the first laminate member 91 and the second laminate member 92 can be improved. As a result, wrinkles in the first laminate member 91 and the second laminate member 92 of the outer casing 40 after vacuum sealing can be suppressed.

[0114] Examples of each form of this disclosure have been described above with reference to the drawings, but this disclosure is not limited to the above forms.

[0115] Figure 10 is a schematic cross-sectional view showing the first laminate member and the second portion of the second laminate member according to the first modified example. The second portions 82A and 83A according to the first modified example have the same layer structure. The second portions 82A and 83A each have a first adhesive layer 101 (first outermost layer), a second adhesive layer 102 (fifth resin layer), a first metal layer 103, a first molding auxiliary layer 104 (first resin layer), a third adhesive layer 105 (seventh resin layer), a sixth adhesive layer 110 (eighth resin layer), a second molding auxiliary layer 109 (second resin layer), a second metal layer 108, a fifth adhesive layer 107 (sixth resin layer), and a fourth adhesive layer 106 (second outermost layer), and are laminate films constructed by laminating these layers in order.

[0116] The second sections 82A and 83A differ from the second sections 82 and 83 in that the stacking order of the sixth adhesive layer 110, the second molding auxiliary layer 109, the second metal layer 108, the fifth adhesive layer 107, and the fourth adhesive layer 106 is reversed, respectively. In the second sections 82A and 83A, an intervening layer 111A, including the first molding auxiliary layer 104, the third adhesive layer 105, the sixth adhesive layer 110, and the second molding auxiliary layer 109, is interposed between the first metal layer 103 and the second metal layer 108. The third adhesive layer 105 and the sixth adhesive layer 110 are provided between the first molding auxiliary layer 104 and the second molding auxiliary layer 109, and are welded together to form a single welded layer 112A (third resin layer).

[0117] In the intervening layer 111A, a first molding auxiliary layer 104 is provided on the first metal layer 103, and a second molding auxiliary layer 109 is provided on the second metal layer 108. The first molding auxiliary layer 104 and the second molding auxiliary layer 109 are made of the same resin material.

[0118] The second portions 82A and 83A are formed using the first laminate film 93 and the second laminate film 94 shown in Figure 7, respectively, in the same manner as the second portions 82 and 83. The second portions 82A and 83A are formed by inverting the second laminate film 94 from the state shown in Figure 7 and bonding the first laminate film 93 and the second laminate film 94 together so that the resin layer 125 of the first laminate film 93 and the resin layer 130 of the second laminate film 94 are joined.

[0119] Since the second parts 82A and 83A each have a first metal layer 103 and a second metal layer 108 and an intervening layer 111A, respectively, their rigidity can be improved. As a result, wrinkles in the outer casing 40 after vacuum sealing can be suppressed.

[0120] In the second sections 82A and 83A, both the first molding auxiliary layer 104 and the second molding auxiliary layer 109 are included in the intervening layer 111A.

[0121] Figure 11 is a schematic cross-sectional view showing the first laminate member and the second portion of the second laminate member according to the second modified example. The second portions 82B and 83B according to the second modified example have the same layer structure. The second portions 82B and 83B each have a third adhesive layer 105 (first outermost layer), a first molding auxiliary layer 104 (fifth resin layer), a first metal layer 103, a second adhesive layer 102 (first resin layer), a first adhesive layer 101 (seventh resin layer), a fourth adhesive layer 106 (eighth resin layer), a fifth adhesive layer 107 (second resin layer), a second metal layer 108, a second molding auxiliary layer 109 (sixth resin layer), and a sixth adhesive layer 110 (second outermost layer), and are laminate films constructed by laminating these layers in order.

[0122] The second parts 82B and 83B differ from the second parts 82 and 83 in that the stacking order of the third adhesive layer 105, the first molding auxiliary layer 104, the first metal layer 103, the second adhesive layer 102, and the first adhesive layer 101 is reversed, respectively. In the second parts 82B and 83B, an intervening layer 111B, which includes the second adhesive layer 102, the first adhesive layer 101, the fourth adhesive layer 106, and the fifth adhesive layer 107, is interposed between the first metal layer 103 and the second metal layer 108. The first adhesive layer 101 and the fourth adhesive layer 106 are provided between the second adhesive layer 102 and the fifth adhesive layer 107, and are welded together to form a single welded layer 112B (third resin layer).

[0123] In the intervening layer 111B, the second adhesive layer 102 is provided on the first metal layer 103, and the fifth adhesive layer 107 is provided on the second metal layer 108. The second adhesive layer 102 and the fifth adhesive layer 107 are made of mutually compatible resin materials.

[0124] The second parts 82B and 83B are formed using the first laminate film 93 and the second laminate film 94 shown in Figure 8, respectively, in the same manner as the second parts 82 and 83. The second parts 82B and 83B are formed by inverting the first laminate film 93 from the state shown in Figure 8 and bonding the first laminate film 93 and the second laminate film 94 together so that the resin layer 121 of the first laminate film 93 and the resin layer 126 of the second laminate film 94 are joined together.

[0125] Since the second parts 82B and 83B also have a first metal layer 103 and a second metal layer 108 and an intervening layer 111B, respectively, their rigidity can be improved. As a result, wrinkles in the outer casing 40 after vacuum sealing can be suppressed.

[0126] In the second sections 82B and 83B, neither the first molding auxiliary layer 104 nor the second molding auxiliary layer 109 is included in the intervening layer 111B.

[0127] In the above embodiment, the second portions 82 and 83 are thicker than the pair of first portions 81, but this is not limited to this. The pair of first portions 81 may also have the same structure and thickness as the second portions 82 and 83.

[0128] The above embodiments and modifications may be used in appropriate combinations.

[0129] Embodiments of the present disclosure may be shown as follows: [Clause 1] A power storage device comprising: a power storage module including a plurality of electrodes stacked along a first direction; and an outer casing housing the power storage module, wherein the outer casing has a pair of outer casings arranged to sandwich the power storage module from both sides in the first direction and having their peripheral edges joined together, and each of the pair of outer casings includes: a conductive plate stacked on the electrodes arranged on the outermost layer in the first direction of the power storage module; and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, wherein at least a portion of the laminate member has a first laminate comprising a first metal layer, a second metal layer, and an intervening layer disposed between the first metal layer and the second metal layer. [Clause 2] The power storage device according to Clause 1, wherein the outer casing includes a recess for housing the power storage module and a flange portion surrounding the recess, the recess having a rectangular bottom surface, and the four corners of the bottom surface having the first laminate. [Clause 3] The energy storage device according to Clause 1 or 2, further comprising a cover member disposed between the energy storage module and the outer casing when viewed from the first direction, wherein the first laminate overlaps with the gap between the energy storage module and the cover member when viewed from the first direction. [Clause 4] The energy storage device according to any one of Clauses 1 to 3, wherein the laminate member includes a pair of first portions facing each other in a second direction perpendicular to the first direction, and a pair of second portions facing each other in a third direction perpendicular to the first and second directions, wherein the second portions have the first laminate and are thicker than the first portions. [Clause 5] The energy storage device according to Clause 4, further comprising a joint portion formed by the overlapping and joining of a portion of the first portion and a portion of the second portion. [Clause 6] The energy storage device according to any one of Clauses 1 to 5, wherein at least a portion of the intervening layer has a second laminate in which a first resin layer provided on the surface of the first metal layer, a second resin layer provided on the surface of the second metal layer, and a third resin layer provided between the first resin layer and the second resin layer are laminated.[Clause 7] The energy storage device according to Clause 6, wherein the first resin layer and the second resin layer are made of different resin materials. [Clause 8] The energy storage device according to Clause 6, wherein the first resin layer and the second resin layer are made of the same resin material. [Clause 9] The energy storage device according to any one of Clauses 6 to 8, wherein at least one of the first resin layer and the second resin layer is an acid-modified resin. [Clause 10] The energy storage device according to any one of Clauses 6 to 9, wherein at least one of the first resin layer, the second resin layer and the third resin layer is nylon. [Clause 11] The energy storage device according to any one of Clauses 6 to 10, wherein the third resin layer is a welded layer. [Clause 12] The energy storage device according to any one of Clauses 6 to 11, wherein the laminate member further includes a first outermost layer provided on the opposite side of the intervening layer to the first metal layer, and a second outermost layer provided on the opposite side of the intervening layer to the second metal layer, and the first outermost layer and the second outermost layer are made of the same resin material as the third resin layer. [Clause 13] The energy storage device according to Clause 12, wherein the laminate member further includes a fifth resin layer provided between the first metal layer and the first outermost layer, and a sixth resin layer provided between the second metal layer and the second outermost layer, and the first resin layer and the sixth resin layer are made of the same resin material as the first resin layer and the sixth resin layer, respectively. [Clause 14] The energy storage device according to Clause 12, wherein the laminate member further includes a fifth resin layer provided between the first metal layer and the first outermost layer, and a sixth resin layer provided between the second metal layer and the second outermost layer, the first resin layer and the second resin layer being made of the same resin material, and the fifth resin layer and the sixth resin layer being made of the same resin material, but each being made of a different resin material than the first resin layer and the second resin layer.[Clause 15] A method for manufacturing an energy storage device comprising: an energy storage module including a plurality of electrodes stacked along a first direction; and an exterior body for housing the energy storage module, the exterior body having a pair of exterior parts arranged to sandwich the energy storage module from both sides in the first direction and having their peripheral edges joined together, the method comprising: a step of bonding a pair of laminate films, each having a metal layer and a resin layer provided on the metal layer, by welding the resin layers together to form a laminate member; and a step of joining the laminate member to the outer edge of a conductive plate to form the exterior part. [Clause 16] An exterior body for housing a power storage module including a plurality of electrodes stacked along a first direction, wherein the exterior body has a pair of exterior parts arranged to sandwich the power storage module from both sides in the first direction and whose peripheral edges are joined together, and each of the pair of exterior parts has a conductive plate and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, and at least a portion of the laminate member has a first laminate in which a first metal layer, a second metal layer and an intervening layer disposed between the first metal layer and the second metal layer are stacked together.

[0130] 1... Energy storage module, 11... Bipolar electrode, 12... Negative terminal electrode, 13... Positive terminal electrode, 31... First conductive plate, 31c... Outer edge, 32... Second conductive plate, 32c... Outer edge, 40... Outer casing, 41... First outer casing, 41b... Bottom, 41c... Corner, 41f... First flange (peripheral edge), 42... Second outer casing, 42b... Bottom, 42c... Corner, 42f... Second flange (peripheral edge), 81... First part, 82, 82A, 82B... Second part, 83, 83A, 83B... Second part, 84... Joint part, 91... First laminate member, 92... Second laminate member, 93... First laminate film, 94... Second laminate film, 100... Energy storage Apparatus, 101...first adhesive layer (first outermost layer, seventh resin layer), 102...second adhesive layer (fifth resin layer, first resin layer), 103...first metal layer, 104...first molding supplement Auxiliary layer (first resin layer, fifth resin layer), 105... third adhesive layer (seventh resin layer, first outermost layer), 106... fourth adhesive layer (eighth resin layer, second outermost layer), 107... fifth Adhesive layer (second resin layer, sixth resin layer), 108... second metal layer, 109... second molding auxiliary layer (sixth resin layer, second resin layer), 110... sixth adhesive layer (second outermost layer, 8th resin layer), 111, 111A, 111B... intervening layer, 112, 112A, 112B... welding layer (third resin layer), L1... first laminate, L2... second laminate.

Claims

1. An energy storage device comprising: an energy storage module including a plurality of electrodes stacked along a first direction; and an outer casing housing the energy storage module, wherein the outer casing has a pair of outer casings arranged to sandwich the energy storage module from both sides in the first direction and having their peripheral edges joined together, and each of the pair of outer casings includes a conductive plate stacked on the electrodes arranged on the outermost layer in the first direction of the energy storage module, and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, and at least a portion of the laminate member has a first laminate in which a first metal layer, a second metal layer, and an intervening layer disposed between the first metal layer and the second metal layer are stacked.

2. The energy storage device according to claim 1, wherein the exterior portion includes a recess for housing the energy storage module and a flange portion surrounding the recess, the recess having a rectangular bottom surface, and the four corners of the bottom surface having the first laminate.

3. The energy storage device according to claim 1, further comprising a cover member disposed between the energy storage module and the outer casing when viewed from the first direction, wherein the first laminate overlaps with the gap between the energy storage module and the cover member when viewed from the first direction.

4. The laminate member includes a pair of first portions facing each other in a second direction perpendicular to the first direction, and a pair of second portions facing each other in a third direction perpendicular to the first and second directions, wherein the second portions have the first laminate and are thicker than the first portions, the energy storage device according to claim 1.

5. The energy storage device according to claim 4, wherein the laminated member further includes a joint portion formed by the overlapping and joining of a part of the first portion and a part of the second portion.

6. The energy storage device according to any one of claims 1 to 5, wherein at least a portion of the intervening layer has a second laminate in which a first resin layer provided on the surface of the first metal layer, a second resin layer provided on the surface of the second metal layer, and a third resin layer provided between the first resin layer and the second resin layer are laminated.

7. The energy storage device according to claim 6, wherein the first resin layer and the second resin layer are made of different resin materials.

8. The energy storage device according to claim 6, wherein the first resin layer and the second resin layer are made of the same resin material.

9. The energy storage device according to claim 6, wherein at least one of the first resin layer and the second resin layer is an acid-modified resin.

10. The energy storage device according to claim 6, wherein at least one of the first resin layer, the second resin layer, and the third resin layer is nylon.

11. The energy storage device according to claim 6, wherein the third resin layer is a welded layer.

12. The energy storage device according to claim 6, wherein the laminate member further includes a first outermost layer provided on the opposite side of the intervening layer to the first metal layer, and a second outermost layer provided on the opposite side of the intervening layer to the second metal layer, and the first outermost layer and the second outermost layer are made of the same resin material as the third resin layer.

13. The laminate member further includes a fifth resin layer provided between the first metal layer and the first outermost layer, and a sixth resin layer provided between the second metal layer and the second outermost layer, wherein the first resin layer and the sixth resin layer are made of the same resin material, and the second resin layer and the fifth resin layer are made of the same resin material, but each is made of a different resin material than the first resin layer and the sixth resin layer, as described in claim 12.

14. The laminate member further includes a fifth resin layer provided between the first metal layer and the first outermost layer, and a sixth resin layer provided between the second metal layer and the second outermost layer, wherein the first resin layer and the second resin layer are made of the same resin material, and the fifth resin layer and the sixth resin layer are made of the same resin material, but each is made of a different resin material than the first resin layer and the second resin layer, as described in claim 12.

15. A method for manufacturing an energy storage device comprising: an energy storage module including a plurality of electrodes stacked along a first direction; and an exterior body for housing the energy storage module, the exterior body having a pair of exterior parts arranged to sandwich the energy storage module from both sides in the first direction and having their peripheral edges joined together, the method comprising: a step of bonding a pair of laminate films, each having a metal layer and a resin layer provided on the metal layer, by welding the resin layers together to form a laminate member; and a step of joining the laminate member to the outer edge of a conductive plate to form the exterior part.

16. An exterior body for housing a power storage module including a plurality of electrodes stacked along a first direction, wherein the exterior body has a pair of exterior parts arranged to sandwich the power storage module from both sides in the first direction and whose peripheral edges are joined together, and each of the pair of exterior parts has a conductive plate and a rectangular frame-shaped laminate member joined to the rectangular outer edge of the conductive plate, and at least a part of the laminate member has a first laminate in which a first metal layer, a second metal layer and an intervening layer disposed between the first metal layer and the second metal layer are stacked together.

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