Energy storage device

Abstract

This energy storage device comprises: an energy storage module configured to include a plurality of electrodes stacked along a first direction; an exterior body in which an accommodation part accommodating the energy storage module is formed; and a cover member accommodated in the accommodation part of the exterior body together with the energy storage module. The exterior body has a first exterior body and a second exterior body that are arranged side by side in the first direction and are joined to each other. The cover member has a first cover member fixed to the first exterior body, and a second cover member fixed to the second exterior body. The first cover member has a first inner surface facing the second cover member, and at least one support column protruding along the first direction from the first inner surface toward the second cover member.

Description

Energy storage device

[0001] This disclosure relates to an energy storage device.

[0002] Patent Document 1 discloses an energy storage device. This energy storage device has an electrode stack made up of multiple bipolar electrodes stacked on top of each other, and an outer casing that seals the electrode stack. The outer casing seals a structural member together with the electrode stack. The structural member sandwiches the electrode stack from the surface direction.

[0003] Japanese Patent Publication No. 2008-140633

[0004] When sealing an enclosure with recesses by housing an internal component such as an electrode laminate within the recesses, if a gap is formed between the enclosure and the internal component before depressurization, wrinkles may form in the enclosure after depressurization sealing. If wrinkles are formed in the enclosure, there is a risk that the enclosure may be damaged by thermal shock.

[0005] This disclosure provides an energy storage device that suppresses the formation of wrinkles in the exterior body.

[0006] An energy storage device according to one aspect of the present disclosure comprises an energy storage module comprising a plurality of electrodes stacked along a first direction; an outer casing having a housing portion for housing the energy storage module; and a cover member positioned along the end of the energy storage module when viewed from the first direction and housed together with the energy storage module in the housing portion of the outer casing. The outer casing has a first outer casing and a second outer casing arranged side by side in the first direction and joined to each other. The cover member has a first cover member fixed to the first outer casing and a second cover member positioned opposite the first cover member in the first direction and fixed to the second outer casing. The first cover member has a first inner surface extending in a second direction intersecting the first direction and facing toward the second cover member, and at least one support column projecting from the first inner surface toward the second cover member along the first direction.

[0007] In the above-described energy storage device, the first cover member and the second cover member, which are arranged opposite each other in the first direction, are located at the ends of the energy storage module and are housed together with the energy storage module in the housing section of the outer casing. The outer casing is composed of a first outer casing and a second outer casing arranged side by side in the first direction, and the first cover member and the second cover member are fixed to the first outer casing and the second outer casing, respectively. As a result, since the first cover member and the second cover member are fixed to the first outer casing and the second outer casing, respectively, while housed in the housing section of the outer casing, displacement of the cover members relative to the outer casing is suppressed, and the formation of wrinkles in the outer casing is suppressed. Furthermore, in the above-described energy storage device, since the first cover member has a support column that protrudes toward the second cover member, even if deformation occurs in the cover member, displacement of the relative positional relationship between the first cover member and the second cover member can be suppressed. This further suppresses displacement between the outer casing and the cover member.

[0008] At least one support column may come into contact with the second cover member.

[0009] The energy storage module may have a first surface intersecting in a first direction, a second surface continuous with the first surface and intersecting in a second direction, and a third surface continuous with the first and second surfaces and intersecting in a third direction that intersects both the first and second directions. The first cover member has a first wall intersecting in a first direction, a second wall continuous with the first wall and intersecting in a second direction, and a third wall continuous with the first and second walls and intersecting in a third direction, and may be arranged to cover one side of the second surface of the energy storage module in the first direction when viewed from the second direction. The second cover member has a fourth wall intersecting in a first direction, a fifth wall continuous with the fourth wall and intersecting in a second direction, and a sixth wall continuous with the fourth and fifth walls and intersecting in a third direction, and may be arranged to cover the other side of the second surface of the energy storage module in the first direction when viewed from the second direction.

[0010] The first exterior has a first housing section formed by a first portion intersecting in a first direction, a second portion continuous with the first portion and intersecting in a second direction, and a third portion continuous with the first and second portions and intersecting in a third direction, and can house the first cover member and one side of the energy storage module in the first direction within the first housing section. The second exterior has a second housing section formed by a fourth portion intersecting in a first direction, a fifth portion continuous with the fourth portion and intersecting in a second direction, and a sixth portion continuous with the fourth and fifth portions and intersecting in a third direction, and can house the second cover member and the other side of the energy storage module in the first direction within the second housing section. The first cover member may be joined to the inner surface of the first exterior with its first wall, second wall, and third wall in contact with the first, second, and third portions of the first exterior, respectively. The second cover member may be joined to the inner surface of the second outer casing such that the fourth wall, fifth wall, and sixth wall of the second outer casing are in contact with the fourth, fifth, and sixth portions of the second outer casing, respectively.

[0011] At least one support may be a plurality of support columns protruding from the first inner surface. The plurality of support columns may include first support columns positioned at both ends of the first cover member in the third direction, and second support columns positioned in the center of the first cover member in the third direction. The second support columns may be shorter than the first support columns in the first direction.

[0012] The second cover member may have a second inner surface facing the first inner surface. The second inner surface may have a receiving portion that accommodates the tip of at least one support column.

[0013] According to this disclosure, it is possible to provide an energy storage device that suppresses the formation of wrinkles in the exterior body.

[0014] Figure 1 is a schematic plan view showing an example of an energy storage device. Figure 2 is a schematic side view showing one side of an energy storage module constituting an example of an energy storage device. Figure 3 is a cross-sectional view along line III-III in Figure 2. Figure 4 is a cross-sectional view along line IV-IV in Figure 1. Figure 5 is a cross-sectional view along line V-V in Figure 1. Figure 6 is a cross-sectional view along line VI-VI in Figure 1. Figure 7 is a perspective view showing an example of a cover member. Figure 8 is a perspective view showing an example of a cover member. Figure 9 is a perspective view showing an example of a cover member. Figure 10 is a perspective view showing an example of a cover member. Figure 11 is a schematic diagram illustrating an example of a support column for a cover member. Figure 12 is a schematic diagram illustrating another example of a support column for a cover member. Figure 13 is a flow chart showing the manufacturing process of an example of an energy storage device. Figure 14 is a schematic cross-sectional view showing yet another example of an energy storage device. Figure 15 is a schematic perspective view showing a modified example of a cover member. Figure 16 is a schematic perspective view showing other modified examples of the cover member.

[0015] An embodiment will be described below with reference to the drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numeral, and redundant explanations may be omitted. In addition, the Cartesian coordinate system defined by the X, Y, and Z axes shown in the drawings may be referred to in the description.

[0016] Figure 1 is a schematic plan view showing an energy storage device according to this embodiment. The energy storage device 1 can be used, for example, in the batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage device 1 is a secondary battery, such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage device 1 may be an electric double-layer capacitor or an all-solid-state battery. Here, we show the case where the energy storage device 1 is a lithium-ion secondary battery.

[0017] The energy storage device 1 comprises an energy storage module 1A, a cover member 100, a connector unit 30, and an outer pack 90. ​​The energy storage module 1A has a rectangular shape when viewed from the Z-axis direction (first direction) and has four outer surfaces 20s that extend in the Z-axis direction. That is, the energy storage module 1A has a substantially rectangular parallelepiped shape and has an upper surface 10a (first surface) and a lower surface 10b (first surface) that intersect in the Z-axis direction, outer surfaces 20sA and 20sB (second surfaces) that intersect in the Y-axis direction (second direction), and outer surfaces 20sC and 20sD (third surfaces) that intersect in the X-axis direction (third direction). The upper surface 10a and the lower surface 10b face each other in the Z-axis direction, outer surfaces 20sA and 20sB face each other in the Y-axis direction, and outer surfaces 20sC and 20sD face each other in the X-axis direction. The upper surface 10a and the lower surface 10b have a positive terminal electrode 12 and a negative terminal electrode 13, respectively, as will be described later, and are used for power extraction.

[0018] One example of a cover member 100 is composed of a cover member 101, a cover member 102, and a cover member 103. Cover members 101 and 102 are arranged to cover the outer surface 20sA when viewed from the Y-axis direction. Cover member 103 is arranged to cover the outer surface 20sB when viewed from the Y-axis direction. The connector unit 30 is positioned between cover member 101 and cover member 102 in the X-axis direction.

[0019] Figure 2 is a schematic diagram showing one outer surface 20sA of the energy storage module 1A. Figure 3 is a schematic cross-sectional view of an example of the energy storage module 1A, showing a cross-section along the line III-III in Figure 2. The outer surface 20sA of the energy storage module 1A includes a region R1 on which an additional member 50, described later, is provided, and regions R2 and R3 adjacent to region R1. In the example shown in Figure 2, region R2 is located on the negative side in the X-axis direction compared to region R1, and region R3 is located on the positive side in the X-axis direction compared to region R1. The additional member includes an injection port 53A used when injecting electrolyte into the energy storage module 1A.

[0020] As shown in Figure 3, the energy storage module 1A includes an electrode stack 10 and a sealing body 29 that surrounds the electrode stack 10 when viewed from the Z-axis direction. The electrode stack 10 includes a plurality of electrodes stacked along the Z-axis direction. The Z-axis direction is the direction in which the electrodes are stacked and is the height direction of the energy storage device 1. The plurality of electrodes include a plurality of bipolar electrodes 11, a positive terminal electrode 12, and a negative terminal electrode 13. A separator 14 is interposed between adjacent electrodes. The positive terminal electrode 12 constitutes a part of the upper surface 10a of the energy storage module 1A, and the negative terminal electrode 13 constitutes a part of the lower surface 10b of the energy storage module 1A.

[0021] The bipolar electrode 11 comprises a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 is rectangular in shape when viewed from the Z-axis direction and is in the form of a sheet. The active material layers (positive electrode active material layer 16, negative electrode active material layer 17) are located in the center of the current collector 15 when viewed from the Z-axis direction and are not located on the peripheral edge 15c of the current collector 15. The positive electrode active material layer 16 is located on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is located on the second surface 15b of the current collector 15. The first surface 15a of the current collector 15 faces the other side in the Z-axis direction (the side where the negative electrode terminal electrode 13 is located in Figure 3), and the second surface 15b of the current collector 15 faces the one side in the Z-axis direction (the side where the positive electrode terminal electrode 12 is located in Figure 3). Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one adjacent bipolar electrode 11 and the negative electrode active material layer 17 of the other bipolar electrode 11 face each other in the stacking direction.

[0022] The positive terminal electrode 12 comprises a current collector 15 and a positive electrode active material layer 16 provided on the first surface 15a of the current collector 15. The second surface 15b of the current collector 15 of the positive terminal electrode 12 does not have an active material layer. The positive terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode stack 10 in the Z-axis direction. The positive terminal electrode 12 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.

[0023] The negative electrode terminal electrode 13 has a current collector 15 and a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15. The first surface 15a of the current collector 15 of the negative electrode terminal electrode 13 does not have an active material layer. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 at the end of the electrode laminate 10 in the Z-axis direction, opposite to the side on which the positive electrode terminal electrode 12 is provided. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11. In this embodiment, the current collectors of the bipolar electrode 11, positive electrode terminal electrode 12, and negative electrode terminal electrode 13 are all denoted by the same reference numeral as current collector 15, but the current collectors of the bipolar electrode 11, positive electrode terminal electrode 12, and negative electrode terminal electrode 13 may be the same as or different from each other.

[0024] The separator 14 is positioned between adjacent bipolar electrodes 11, between the positive terminal electrode 12 and the bipolar electrode 11, and between the negative terminal electrode 13 and the bipolar electrode 11. The separator 14 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, separating them. The separator 14 prevents short circuits caused by contact between adjacent electrodes while allowing charge carriers such as lithium ions to pass through.

[0025] The current collector 15 is a chemically inert electrical conductor that allows current to continue flowing through the positive electrode active material layer 16 and the negative electrode active material layer 17 during the 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. Examples of conductive resin materials include conductive polymer materials or resins to which conductive fillers are optionally added to non-conductive polymer materials. The current collector 15 may comprise multiple layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material or conductive resin material.

[0026] A coating layer may be formed on the surface of the current collector 15. This coating layer may be formed by known methods such as plating or spray coating. The current collector 15 may be in the form of a plate, foil (e.g., metal foil), film, or mesh. Examples of metal foils include aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 15 may be an alloy foil or clad foil of the above metals. If the current collector 15 is in the form of a foil, its thickness may be, for example, 1 μm to 100 μm. In this embodiment, the current collector 15 is a foil in which aluminum foil and copper foil are integrated, or aluminum foil.

[0027] The positive electrode active material layer 16 contains a positive electrode active material capable of intercalating and releasing charge carriers such as lithium ions. Examples of positive electrode active materials include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanionic compounds. The positive electrode active material can be any material suitable for use in lithium-ion secondary batteries. The positive electrode active material layer 16 may contain multiple positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO) as a composite oxide. ４ It includes ).

[0028] The negative electrode active material layer 17 contains a negative electrode active material capable of intercalating and releasing charge carriers such as lithium ions. The negative electrode active material may be an element, an alloy, or a compound. Examples of negative electrode active materials include Li, carbon, and metal compounds. The negative electrode active material may also be an element or compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (carbon that is difficult to graphitize), or soft carbon (carbon that is easily graphitized). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon or tin. In this embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0029] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter sometimes simply referred to as the "active material layer") may further contain, as necessary, conductive additives, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte solution, etc.), electrolyte-supporting salts (lithium salts) to enhance ionic conductivity, etc. Conductive additives are added to enhance the conductivity of each electrode (bipolar electrode 11, positive electrode terminal electrode 12, negative electrode terminal electrode 13). Examples of conductive additives include acetylene black, carbon black, or graphite.

[0030] Examples of binders include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; 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 (SBR); alginates such as carboxymethylcellulose, sodium alginate, and ammonium alginate; water-soluble cellulose ester crosslinked products; and starch-acrylic acid graft polymers. These binders can be used individually or in combination. Examples of solvents include water and N-methyl-2-pyrrolidone (NMP).

[0031] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains electrolytes. Examples of materials for the separator 14 include polypropylene, polyethylene, polyolefin, and polyester. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may include, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The separator 14 may be composed of an electrolyte such as a polymer electrolyte or an inorganic electrolyte. Examples of electrolytes impregnated into the separator 14 include a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, or a polymer gel electrolyte containing an electrolyte held in a polymer matrix.

[0032] When the separator 14 is impregnated with an electrolyte, the electrolyte salt is LiClO４ , 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. Further, as the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers, etc. may be used. Note that two or more of these known solvent materials may be used in combination.

[0033] The sealing body 29 includes a sealing main body portion 20 and an additional member 50. The sealing main body portion 20 is formed in a frame shape on the peripheral edge of the electrode laminate 10 so as to surround the peripheral edge of the electrode laminate 10 when viewed from the Z-axis direction. The sealing main body portion 20 can be joined to each of the first surface 15a and the second surface 15b of the current collector 15 at the peripheral edge portion 15c of each current collector 15. The sealing main body portion 20 forms an internal space S between adjacent current collectors 15 in the Z-axis direction and can seal each of the internal spaces S. An electrolytic solution (not shown) is accommodated in each internal space S in the present embodiment. That is, the sealing main body portion 20 cooperates with the current collectors 15 adjacent in the Z-axis direction to define an internal space S in which the electrolytic solution is accommodated. The sealing main body portion 20 can suppress the electrolytic solution accommodated in the internal space S from flowing out to the outside.

[0034] The sealing main body portion 20 can suppress the intrusion and discharge of air, moisture, etc. between the outside of the electrode laminate 10 and the internal space S. The sealing main body portion 20 can suppress, for example, the gas generated at each electrode due to charge and discharge reactions or the like from leaking to the outside of the power storage module 1A. The edge portion of the separator 14 is joined to the sealing main body portion 20. The sealing main body portion 20 contains an insulating material. Examples of the material of the sealing main body portion 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, acrylonitrile styrene resin, and the like.

[0035] One example of a sealing body 20 includes a plurality of sealing materials 21, a pair of end sealing materials 24, and a plurality of spacers 22. The sealing materials 21, end sealing materials 24, and spacers 22 may be frame-shaped members formed in a sheet-like manner. The sealing body 20 also has a welded end 23. The sealing material 21 is frame-shaped when viewed from the Z-axis direction and is provided along the peripheral edge 15c of the current collector 15. The sealing material 21 is provided so as to extend from the first surface 15a of the current collector 15 through the end surface to the second surface 15b, covering the peripheral edge 15c. That is, the sealing material 21 has an inner portion that overlaps the current collector 15 and an outer portion that is located outside the edge of the current collector 15 when viewed from the Z-axis direction on the first surface 15a and the second surface 15b of the current collector 15, and the outer portions of a pair of adjacent sealing materials 21 on either side of the current collector 15 are connected. The sealing material 21 can be welded to at least one of the first surface 15a and the second surface 15b of the current collector 15. In this embodiment, the sealing material 21 is welded to both the first surface 15a and the second surface 15b of the current collector 15.

[0036] The end seal material 24 has a frame shape when viewed from the Z-axis direction and is provided along the peripheral edge 15c of the current collector 15 that constitutes the positive terminal electrode 12 and the negative terminal electrode 13, respectively. Therefore, the end seal material 24 is arranged to sandwich the multiple seal materials 21 from the Z-axis direction. The end seal material 24 can be welded to at least one of the first surface 15a and the second surface 15b of the current collector 15. In this embodiment, the end seal material 24 is welded to both the first surface 15a and the second surface 15b of the current collector 15.

[0037] The spacer 22 has a frame shape when viewed from the Z-axis direction and is arranged along the peripheral edge 15c of the current collector 15. The spacer 22 is positioned to be interposed between adjacent sealing materials 21 in the Z-axis direction. Furthermore, the spacer 22 is positioned to be interposed between adjacent sealing materials 21 and end sealing materials 24 in the Z-axis direction. The spacer 22 can maintain the distance between adjacent current collectors 15 in the Z-axis direction. That is, the spacer 22, sealing materials 21 and end sealing materials 24 define an internal space S between adjacent current collectors 15.

[0038] The welded end portion 23 is formed by welding and integrating the ends on the side opposite to the internal space S in the plurality of sealing materials 21, the pair of end sealing materials 24, and the plurality of spacers 22. The welded end portion 23呈a frame shape so as to surround the electrode laminate 10 when viewed from the Z-axis direction. The side surface of the welded end portion 23 on the side opposite to the internal space S extends along the Z-axis direction and构成the outer surface 20s of the sealing main body portion 20. In other words, the sealing main body portion 20 includes the outer surface 20s on the side opposite to the internal space S. The outer surface 20s may be formed as a flat surface.

[0039] The sealing main body portion 20 has a plurality of communication holes 27 communicating with each of the plurality of internal spaces S. As an example, the communication hole 27 is a notch-shaped portion formed in the spacer 22 and is formed through the welded end portion 23. The communication hole 27 has one opening in the internal space S and the other opening in the outer surface 20s of the sealing main body portion 20. In the illustrated example, an opening is formed in the outer surface 20sA.

[0040] The additional member 50 is formed so as to overlap the region R1 where the communication hole 27 is formed in the outer surface 20sA. The additional member 50 provides a liquid injection port portion 53A having a plurality of liquid injection ports respectively communicating with the plurality of communication holes 27 by being molded into a predetermined shape. The additional member 50 is joined to the welded end portion 23. For example, the additional member 50 is integrally joined to the welded end portion 23 by injection molding. An example of the additional member 50 includes a main body portion 51, a first overhang portion 55, and a second overhang portion 57.

[0041] The main body portion 51 partially covers the outer surface 20sA. For example, the main body portion 51 covers the outer surface 20sA so as to include a region R1 where a plurality of communication holes 27 formed in the outer surface 20sA are formed. As described above, the plurality of communication holes 27 communicate with the plurality of internal spaces S respectively. In the example shown in FIG. 2, thirty communication holes 27 corresponding to the thirty internal spaces formed between the respective current collectors 15 are discretely arranged in the X-axis direction and the Z-axis direction. More specifically, the communication holes 27 corresponding to the internal spaces from the first layer to the tenth layer with the positive terminal electrode 12 side as the base end are evenly spaced along the X-axis direction, and the communication holes 27 corresponding to the internal spaces from the eleventh layer to the twentieth layer and the communication holes 27 corresponding to the internal spaces from the twenty-first layer to the thirtieth layer are respectively arranged in order in the Z-axis direction below the internal spaces from the first layer to the tenth layer. The main body portion 51 extends in a rectangular shape along the X-axis direction and the Z-axis direction in order to cover the region R1 where these thirty communication holes 27 are formed.

[0042] The main body portion 51 is formed in a rectangular plate shape having a predetermined thickness in the Y-axis direction. The main body portion 51 has an opening 52 at a position corresponding to the communication hole 27. Further, the main body portion 51 has a protruding frame portion 53 that protrudes in the Y-axis direction intersecting (orthogonal) with the outer surface 20sA from the outer surface 20sA. The protruding frame portion 53 surrounds each opening 52 when viewed from the Y-axis direction and functions as a partition wall separating each opening 52. In the example of FIG. 2, ten protruding frame portions 53 in which three spaces for separating three openings 52 arranged vertically are formed are arranged in the X-axis direction.

[0043] The protruding frame portion 53 is used, for example, when injecting electrolyte into each of the internal spaces S. For example, when injecting electrolyte, the nozzle of the injection device is brought into close contact with the top surface of the protruding frame portion 53, and the electrolyte is introduced into the space of each protruding frame portion 53 from the nozzle. This makes it possible to inject electrolyte into the internal space S from the opening 52 and the communication hole 27. After the electrolyte is injected, a laminate sheet 54 may be provided on the protruding frame portion 53 to seal it. The laminate sheet 54 may be, for example, a sheet in which a metal layer such as aluminum is covered with a resin layer. The laminate sheet 54 may be fused to, for example, the top surface of the protruding frame portion 53.

[0044] In one example, the main body 51 includes a terminal portion 58 for voltage detection (see Figure 2). The terminal portion 58 is formed on the main body 51 at a position offset to the positive side in the X-axis direction from the liquid injection port portion 53A, which is formed by a plurality of protruding frame portions 53. For example, the terminal portion 58 is provided adjacent to a protruding frame portion 53 formed at the positive end in the X-axis direction, via a flat surface 51a. In one example, the terminal portion 58 is provided at the positive end in the X-axis direction of the main body 51. The terminal portion 58 provides a plurality of terminals 58a that are electrically connected to a plurality of current collectors 15. One end of each terminal 58a is connected to the corresponding current collector 15, and the other end of each terminal 58a is exposed from the main body 51. The terminals 58a only need to be electrically connected to the current collectors 15, and may be, for example, metal pins. A connector unit 30 (see Figure 1) is fixed to the terminal portion 58. One example connector unit 30 includes a housing 31 having multiple contacts connected to a plurality of terminals 58a, and a connector 33 connected to the housing 31. A flexible circuit board may be connected to the connector 33, which is pulled out to the outside of the outer packaging pack 90.

[0045] The first overhang portion 55 and the second overhang portion 57 are formed by connecting to both ends of the main body portion 51 in the Z-axis direction. The first overhang portion 55 partially covers one end of the welded end portion 23 in the Z-axis direction (the positive Z-axis side). For example, the first overhang portion 55 partially covers the end seal material 24 joined to the positive electrode terminal 12. In the illustrated example, the end edge 55a of the first overhang portion 55 extends from the end edge of the welded end portion 23 to a position outside the inner edge 22a of the spacer 22 and the inner edge 21a of the seal material 21 when viewed from the Z-axis direction, but this is not limited to this. The first overhang portion 55 may be formed in the shape of a rectangular plate having the same length as the main body portion 51 in the X-axis direction. Similarly to the first overhang portion 55, the second overhang portion 57 partially covers the other end of the welded end portion 23 in the Z-axis direction (the negative Z-axis side).

[0046] Figure 4 is a cross-sectional view along the line IV-IV in Figure 1. Figure 5 is a cross-sectional view along the line V-V in Figure 1. Figure 6 is a cross-sectional view along the line VI-VI in Figure 1. Note that in Figures 4 to 6, the energy storage module 1A included in the energy storage device 1 is depicted in a simplified manner. An example of an outer pack 90 (outer body) includes a first outer pack 90A (first outer body) and a second outer pack 90B (second outer body) arranged to face each other in the vertical direction. The first outer pack 90A has a housing section 94A (first housing section). The housing section 94A is a recess formed by a first portion 91A that extends in the Y-axis direction (more specifically in the XY plane) and intersects in the Z-axis direction, and a second portion 92A and a third portion 93A that are continuous with the first portion 91A and extend in the Z-axis direction. The second portion 92A intersects in the Y-axis direction, and the third portion 93A intersects in the X-axis direction. The second portion 92A and the third portion 93A are continuous with each other. The second portion 92A and the third portion 93A have a flange portion 94Aa (first flange portion) that extends outward at the edge opposite to the connection portion with the first portion 91A. The housing portion 94A provides space for housing the energy storage module 1A, the cover member 100, and the connector unit 30.

[0047] The first outer packaging 90A includes a conductive member 95A and an outer film 96A (sealing member). The conductive member 95A has a rectangular shape in plan view and constitutes the center of the first portion 91A. The conductive member 95A abuts against the second surface 15b of the current collector 15 of the positive terminal electrode 12 and is electrically connected to the positive terminal electrode 12. The conductive member 95A may be, for example, a metal foil, and one example may be aluminum foil. The planar size of the conductive member 95A may be the same as or smaller than that of the current collector 15.

[0048] The outer film 96A constitutes the periphery of the first portion 91A, the second portion 92A, and the third portion 93A. The outer film 96A is configured to surround the outer periphery of the contents (in this case, the energy storage module 1A, the cover member 100, and the connector unit 30) when viewed from the Z-axis direction. The outer film 96A is connected to the periphery of the conductive member 95A. The outer film 96A has a rectangular frame shape. For example, the outer film 96A may be formed by welding together four strip-shaped sheet members along each of the four sides that make up the rectangle.

[0049] The outer film 96A is processed (e.g., by press working) so that its outer edge is located closer to the outer film 96B than its inner edge. This processing creates a housing portion 94A in the outer film 96A that opens toward the outer film 96B. The inner edge of the outer film 96A, which forms a rectangular frame shape when viewed from the Z-axis direction, is located inside the periphery of the conductive member 95A. The inner edge of the outer film 96A and the periphery of the conductive member 95A are joined together in an overlapping manner. In one example, the inner edge of the outer film 96A and the periphery of the conductive member 95A may be joined together by a resin material 97. The resin material 97 may be a rectangular frame-shaped sealing resin formed in a sheet. For example, the inner edge of the rectangular frame-shaped resin material 97 may be located inside the inner edge of the outer film 96A, and the outer edge of the resin material 97 may coincide with the periphery of the conductive member 95A. The outer edge of the outer film 96A is located outside the periphery of the contents when viewed from the Z-axis direction.

[0050] The outer film 96A may be, for example, a laminate film including a metal layer. That is, the outer film 96A may be a sheet-like member in which both sides of a metal layer 96a, such as aluminum, are covered with resin layers 96b and 96c. The resin layers 96b and 96c may be formed from the same resin as the sealant 29.

[0051] The second outer packaging 90B has the same configuration as the first outer packaging 90A. That is, the second outer packaging 90B has a conductive member 95B corresponding to the conductive member 95A and an outer film 96B corresponding to the outer film 96A. The conductive member 95B abuts against the first surface 15a of the current collector 15 of the negative terminal electrode 13 and is electrically connected to the negative terminal electrode 13. The outer film 96B has the same shape as the outer film 96A and is arranged to face the outer film 96A. That is, the outer film 96B has a housing portion 94B (second housing portion) that opens toward the outer film 96A.

[0052] The housing portion 94B is a recess formed by a fourth portion 91B intersecting in the Z-axis direction, a fifth portion 92B continuous with the fourth portion 91B and intersecting in the Y-axis direction, and a sixth portion 93B continuous with the fourth portion 91B and the fifth portion 92B and intersecting in the X-axis direction. The fifth portion 92B and the sixth portion 93B have a flange portion 94Ba (second flange portion) extending outward at the edge opposite to the connection portion with the fourth portion 91B. Similar to the housing portion 94A, the housing portion 94B provides space for housing the energy storage module 1A, the cover member 100, and the connector unit 30.

[0053] The outer edges of the outer film 96A and the outer edge of the outer film 96B are joined to each other. For example, the flange portion 94Aa formed by the outer film 96A and the flange portion 94Ba formed by the outer film 96B may be welded to each other. By sealing the outer edges of the outer film 96A and the outer edge of the outer film 96B to each other, a sealed space is formed inside the outer pack 90. ​​After the energy storage module 1A, etc., is housed in the outer pack 90, the outer pack 90 may be sealed under reduced pressure. In the following description, when conductive members 95A and 95B are not distinguished, they are collectively referred to as conductive member 95. Also, when outer film 96A and outer film 96B are not distinguished, they are collectively referred to as outer film 96.

[0054] Next, the cover member 100 will be described. The cover member 100 is housed in the outer pack 90 together with the energy storage module 1A and the connector unit 30, positioned between the outer surface 20s of the energy storage module 1A and the outer film 96. The cover member 100 is positioned to cover the outer surface 20s of the energy storage module 1A when viewed from the Y-axis direction. A gap may be formed between the cover member 100 and the outer surface 20s in the Y-axis direction.

[0055] In one example of a power storage device 1, the cover member 100 is composed of cover member 101 and cover member 102 (see Figures 1 and 5) which are positioned between the outer surface 20sA of the power storage module 1A and the outer film 96, and cover member 103 (see Figures 1 and 6) which is positioned between the outer surface 20sB of the power storage module 1A and the outer film 96. Cover member 101 is positioned on the positive side in the X-axis direction relative to the connector unit 30. Cover member 102 is positioned on the negative side in the X-axis direction relative to the connector unit 30.

[0056] The cover member 101 includes a first cover member 110 and a second cover member 120 that are adjacent to and facing each other in the Z-axis direction. The first cover member 110 is joined to the outer film 96A (first outer pack 90A), and the second cover member 120 is joined to the outer film 96B (second outer pack 90B). Figures 7 and 8 are perspective views showing the first cover member 110. Figure 9 is a perspective view showing the second cover member 120.

[0057] The first cover member 110 includes a base wall 111 (first wall) extending along the Y-axis direction (more specifically, the XY plane), and side walls 112 (second wall) and 113 projecting toward the second cover member 120 from both ends of the base wall 111 in the Y-axis direction. The outer surface 111b of the base wall 111 faces the first portion 91A of the first outer packaging 90A, and the outer surface 112b of the side wall 112 faces the second portion 92A of the first outer packaging 90A. The first cover member 110 also has side walls 114 and 115 extending toward the second cover member 120 from both ends of the base wall 111 in the X-axis direction. The base wall 111 intersects in the Z-axis direction, the side walls 112 and 113 intersect in the Y-axis direction, and the side walls 114 (third wall) and 115 intersect in the X-axis direction. The outer surface 114b of the side wall 114 faces the third portion 93 of the first outer packaging 90A.

[0058] In the illustrated example, the base wall 111 has a notched portion 111c formed at the edge where the side wall 115 is formed, for positioning the connector unit 30. As a result, the connection portion between the side wall 112 and the side wall 115 is formed in an inward corner shape. Therefore, the side wall 115 is divided into two parts in the center in the Y-axis direction. Also, the side wall 112 is divided into two parts in the X-axis direction at a position close to the side wall 115.

[0059] In one example, the connection portion 118a between the base wall 111 and the side wall 112, and the connection portion 118b between the base wall 111 and the side wall 114, are curved with a predetermined curvature. Furthermore, the connection portion 118c between the side wall 112 and the side wall 114 is curved with an even greater curvature. That is, these connection portions 118a, 118b, and 118c are formed in an R-shape with chamfered corners.

[0060] The first cover member 110 has a plurality of ribs 117. The ribs 117 are plate-shaped and extend along the YZ plane, and are connected to the base wall 111, side wall 112, and side wall 113. The height of the ribs 117 in the Z-axis direction may be the same as that of the side walls 112, side wall 113, side wall 114, and side wall 115. The plurality of ribs 117 are spaced apart from each other in the X-axis direction. The plurality of ribs 117 may be spaced equally or at different intervals in the X-axis direction.

[0061] The base wall 111 of the first cover member 110 has an inner surface 111a that extends in the Y-axis direction (more specifically, the XY plane) and faces toward the second cover member 120. The inner surface 111a is provided with support columns 119 that extend along the Z-axis direction and project toward the second cover member 120. For example, the length of the support column 119 in the Z-axis direction may be shorter than the length (thickness) of the energy storage module 1A in the Z-axis direction. The inner surface 111a in the illustrated example has a plurality of support columns 119. The positions of the plurality of support columns 119 are not particularly limited. For example, a pair of support columns 119 may be formed adjacent to each other in the Y-axis direction between a pair of adjacent ribs 117 in the X-axis direction. For example, the support columns 119 may have a hollow rectangular prism shape.

[0062] As shown in Figure 8, a welding plate 108 is fixed to the outer surface 111b of an example base wall 111. In the illustrated example, a rectangular recess 111d is formed on the outer surface 111b of the base wall 111 in plan view. The welding plate 108 is plate-shaped with the same planar shape as the recess 111d and is placed inside the recess 111d. For example, the welding plate 108 and the recess 111d may be fixed to each other by the fitting of a projection 108a provided on the welding plate 108 and a hole 111e provided on the recess 111d. When the welding plate 108 is fixed to the recess 111d, the outer surface of the base wall 111 and the surface of the welding plate 108 may be flush. The welding plate 108 is the part that is welded to the outer film 96A of the first outer packaging pack 90A and is made of the same material as the resin layer 96b of the outer packaging film 96A. Furthermore, if the first cover member 110 is formed of the same material as the resin layer 96b, the first cover member 110 does not need to have a welding plate 108.

[0063] In this embodiment, in order to suppress the stress generated in the outer pack 90 by the expansion of the seal 29 due to temperature changes in the energy storage device 1, a cover member 100 with a small coefficient of linear expansion is placed between the seal 29 and the outer pack 90. ​​In this case, for example, the cover member 100 may be a resin such as polyphenylene sulfide blended with fillers such as glass fibers. On the other hand, the resin layer 96b of the outer film 96A is formed of the same resin as the seal 29. As an example, the resin layer 96b may be made of polypropylene. In this case, the cover member has a welding plate 108 as described above, and this welding plate 108 may be made of polypropylene. In this embodiment, a gap is provided between the cover member 100 and the outer surface 20s so that the expansion of the seal 29 in the Y-axis direction does not easily affect the outer pack 90.

[0064] The welding plate 108 of the first cover member 110 is welded to the opposing outer film 96A with the outer surface 111b of the base wall 111 in contact with the outer film 96A constituting the first portion 91A of the first outer pack 90A, and the outer surface 112b of the side wall 112 in contact with the outer film 96A constituting the second portion 92A of the first outer pack 90A. In this case, the outer surface 114b of the side wall 114 may be in contact with the third portion 93A of the first outer pack 90A. When the base wall 111, side wall 112 and side wall 114 are in contact with the inner surface of the opposing housing portion 94A, the connection portion 118a between the base wall 111 and the side wall 112 may be in contact with the connection portion between the first portion 91A and the second portion 92A on the inner surface of the housing portion 94A. Similarly, the connection portion 118b between the base wall 111 and the side wall 114 may abut against the connection portion between the first portion 91A and the third portion 93A on the inner surface of the housing portion 94A. The connection portion 118c between the side wall 112 and the side wall 114 may abut against the connection portion between the second portion 92A and the third portion 93A on the inner surface of the housing portion 94A. That is, the connection portion 118a between the base wall 111 and the side wall 112 and the connection portion between the first portion 91A and the second portion 92A may have equal curvature. The connection portion 118b between the base wall 111 and the side wall 114 and the connection portion between the first portion 91A and the third portion 93A may have equal curvature. The connection portion 118c between the side wall 112 and the side wall 114 and the connection portion between the second portion 92A and the third portion 93A may have equal curvature.

[0065] The second cover member 120 has the same basic structure as the first cover member 110. The second cover member 120 has a base wall 121 (fourth wall), a side wall 122 (fifth wall), a side wall 123, a side wall 124 (sixth wall), and a side wall 125. The base wall 121 of the second cover member 120 corresponds to the base wall 111 of the first cover member 110 and extends along the Y-axis direction (more specifically, the XY plane) so as to face the base wall 111. A welding plate 108 is provided on the outer surface of the base wall 121, similar to the first cover member 110. When viewed from the Z-axis direction, the base wall 111 of the first cover member 110 and the base wall 121 of the second cover member 120 have the same shape. The side walls 122, 123, 124, and 125 of the second cover member 120 face the side walls 112, 113, 114, and 115 of the first cover member 110 in the Z-axis direction, and protrude toward the first cover member 110 from the edge of the base wall 121. A gap may be formed between the side walls of the first cover member 110 and the side walls of the second cover member 120. The second cover member 120 also has a plurality of ribs 127. The ribs 127 correspond to the ribs 117 and face the ribs 117 of the first cover member 110 in the Z-axis direction.

[0066] Unlike the first cover member 110, the second cover member 120 does not have a support column 119. The support column 119 in the first cover member 110 is formed to be higher in the Z-axis direction than the side walls 112, 113, 114, and 115 of the first cover member 110. For example, the length of the support column 119 in the Z-axis direction may be longer than the sum of the height of the side walls of the first cover member 110 and the height of the side walls of the second cover member 120. That is, when the first cover member 110 and the second cover member 120 are combined, the tip of the support column 119 provided on the first cover member 110 may come into contact with the second cover member 120. In one example, the inner surface 121a (second inner surface) of the base wall 121 of the second cover member 120 faces the inner surface 111a (first inner surface) of the first cover member 110 and may abut against the tip of the support column 119 of the first cover member 110.

[0067] Similar to the first cover member 110, the second cover member 120 is joined to the second outer pack 90B by welding a welding plate 108 provided on the base wall 121 to the outer film 96B. In this case, the outer surface 121b of the base wall 121 may abut against the outer film 96B constituting the fourth portion 91B of the second outer pack 90B, the outer surface 122b of the side wall 122 may abut against the outer film 96B constituting the fifth portion 92B of the second outer pack 90B, and the outer surface 124b of the side wall 124 may abut against the sixth portion 93B of the second outer pack 90B. When the base wall 121, side wall 122 and side wall 124 abut against the inner surface of the opposite housing portion 94B, the connection portion 128a between the base wall 121 and the side wall 122 may abut against the connection portion between the fourth portion 91B and the fifth portion 92B on the inner surface of the housing portion 94B. Similarly, the connection portion 128b between the base wall 121 and the side wall 124 may abut the connection portion between the fourth portion 91B and the sixth portion 93B on the inner surface of the housing portion 94B. The connection portion 128c between the side wall 122 and the side wall 124 may abut the connection portion between the fifth portion 92B and the sixth portion 93B on the inner surface of the housing portion 94B. That is, the connection portion 128a between the base wall 121 and the side wall 122 and the connection portion between the fourth portion 91B and the fifth portion 92B may have equal curvature. The connection portion 128b between the base wall 121 and the side wall 124 and the connection portion between the fourth portion 91B and the sixth portion 93B may have equal curvature. The connection portion 128c between the side wall 122 and the side wall 124 and the connection portion between the fifth portion 92B and the sixth portion 93B may have equal curvature.

[0068] The cover member 102 has the same configuration as the cover member 101 and includes a first cover member 130 and a second cover member 140. The first cover member 130 is joined to the first outer packaging 90A, and the second cover member 140 is joined to the second outer packaging 90B. Figure 10 is a perspective view showing the first cover member 130.

[0069] The first cover member 130 includes a base wall 131 extending along the Y-axis direction (more specifically, the XY plane), and side walls 132 and 133 projecting toward the second cover member 140 from both ends of the base wall 131 in the Y-axis direction. A welding plate 108 is provided on the outer surface of the base wall 131, similar to the first cover member 110. The first cover member 130 also has side walls 134 and 135 extending toward the second cover member 140 from both ends of the base wall 131 in the X-axis direction. In the illustrated example, a notched portion for arranging the connector unit 30 is formed at the end where the side wall 134 is formed. The connection portion between the base wall 131 and the side wall 132, the connection portion between the base wall 131 and the side wall 134, and the connection portion between the side wall 132 and the side wall 134 are curved to correspond to the structure of the first cover member 110. The first cover member 130 has a plurality of first ribs 137. The first ribs 137 are plate-shaped and extend along the YZ plane, and are connected to the base wall 131, the side wall 132, and the side wall 133. The base wall 131 of the first cover member 130 has a first surface 131a that extends in the Y-axis direction (more specifically in the XY plane) and faces toward the second cover member 140. The first surface 131a is provided with a support column 139 that extends along the Z-axis direction and protrudes toward the second cover member 140.

[0070] The second cover member 140 has a structure corresponding to the first cover member 130, just as the second cover member 120 has a structure corresponding to the first cover member 110. That is, the second cover member 140 has a structure that faces the first cover member 130 in the Z-axis direction and has a structure that does not have a support column 139.

[0071] The cover member 103 has the same configuration as the cover member 101 and includes a first cover member 150 and a second cover member 160. The structure of the first cover member 150 and the second cover member 160 is the same as that of the first cover member 110 and the second cover member 120, and only the planar shape differs, so a detailed explanation is omitted. As shown in Figures 1 and 6, in this embodiment, a pair of cover members 103 are arranged adjacent to each other in the X-axis direction. The first cover member 150 is joined to the first outer packaging 90A by a welding plate 108. Similarly, the second cover member 160 is joined to the second outer packaging 90B by a welding plate 108.

[0072] Figures 11 and 12 are schematic diagrams illustrating the function of the support columns of the cover member. Figures 11(a) and 11(b) show a first cover member 110 having a plurality of support columns 119 and a second cover member 120 facing the first cover member 110. In this example, the Z-axis length of all support columns 119 is equal at both ends and the center in the X-axis direction. As shown in Figure 11(a), for example, if no distortion occurs in the base walls 111 and 121, the tips of all support columns 119 will abut against the base wall 121 of the second cover member 120, thereby controlling the height of the cover member in the Z-axis direction.

[0073] For example, when the first cover member 110 and the second cover member 120 are manufactured by injection molding, as shown in Figure 11(b), the first cover member 110 and the second cover member 120 may warp due to volume contraction during cooling, causing their centers in the X-axis direction to move closer together. If all the support columns 119 are of equal length, only the support columns 119 closer to the center in the X-axis direction will contact the base wall 121 of the second cover member 120. In this case, the height H1 of the cover member is controlled by the support columns 119 closer to the center in the X-axis direction. Height H1 is the height of the corner of the cover member, and is the height at a position away from the central support column 119. Therefore, there are limitations to height control by the support columns 119 closer to the center.

[0074] Figures 12(a) and (b) show an example of a first cover member 110 including a support column 119A positioned at the end in the X-axis direction and a support column 119B positioned in the center in the X-axis direction. In this example, the height of the support column 119B in the Z-axis direction is lower than that of the support column 119A. More specifically, the heights of the support columns 119A and 119B are set so that at least the support column 119A abuts against the base wall 121 of the second cover member 120 if warping occurs in the first cover member 110 and the second cover member 120. If the amount of warping can be controlled, both the support column 119A and 119B are controlled to abut against the base wall 121 of the second cover member 120. By having the support column 119A near the corner abut against the second cover member 120, the height H2 of the cover member 101 can be appropriately controlled. In one example, the height H2 may be controlled to be the same as the thickness of the energy storage module 1A. In this case, the length of the support column 119B may be the length obtained by subtracting the thickness of the base walls 111 and 121 from the thickness of the energy storage module 1A.

[0075] Although Figures 11 and 12 illustrate the first cover member 110 and the second cover member 120, the explanation regarding the function of the support columns described above is the same for the first cover members 130, 150 and the second cover members 140, 160. That is, in the first cover members 130 and 150, the support column formed in the center in the X-axis direction may be shorter than the support column formed at the end in the X-axis direction.

[0076] Next, the manufacturing method of the energy storage device 1 will be described. Figure 13 is a flowchart showing an example of the manufacturing process of the energy storage device. In this example of a manufacturing method, first, the cover member 100 and the outer pack 90 are prepared (preparation step S1). The cover member 100 is manufactured by injection molding. The outer pack 90 is prepared with the first outer pack 90A and the second outer pack 90B separated from each other. Subsequently, the cover member 100 is joined to the housing portion 94 of the outer pack 90 so that the cover member 100 abuts against the first portion 91, the second portion 92, and the third portion 93 of the outer pack 90 (fixing step S2).

[0077] In other words, in fixing step S2, the first cover member 110, the first cover member 130, and the first cover member 150 are joined to the housing portion 94A of the first outer pack 90A. At this time, the first cover member 110 is joined such that its base wall 111 abuts against the first portion 91A of the first outer pack 90A, its side wall 112 abuts against the second portion 92A of the first outer pack 90A, and its side wall 114 abuts against the third portion 93A. Similarly, the first cover members 130 and 150 are joined to the first outer pack 90A so as to abut against the first portion 91A, the second portion 92A, and the third portion 93A of the first outer pack 90A. As described above, each first cover member and the first outer pack 90A are joined by welding a welding plate 108 to the first outer pack 90A. For example, the first cover member 110 is positioned within the housing portion 94A of the first outer packaging pack 90A, which is prepared so that the opening of the housing portion 94A faces upward, and is in contact with the first portion 91A, the second portion 92A, and the third portion 93A. The welding plate 108 of the first cover member 110 is heated from the outer surface of the outer packaging film 96A by a heat source such as a hot plate, and the welding plate 108 and the outer packaging film 96A are welded together, thereby joining the first cover member 110 to the first outer packaging pack 90A.

[0078] Furthermore, in fixing step S2, the second cover member 120, the second cover member 140, and the second cover member 160 are joined to the housing portion 94B of the second outer pack 90B. At this time, the second cover member 120 is joined such that the base wall 121 abuts against the fourth portion 91B of the second outer pack 90B, the side wall 122 abuts against the fifth portion 92B of the second outer pack 90B, and the side wall 124 abuts against the sixth portion 93B. Similarly, the second cover members 140 and 160 are joined so that they abut against the fourth portion 91B, the fifth portion 92B, and the sixth portion 93B of the second outer pack 90B.

[0079] Next, the energy storage module 1A is housed in the housing section 94 to which the cover member 100 is fixed, and the outer surfaces 20sA and 20sB of the energy storage module 1A are covered by the cover member 100 when viewed from the Y-axis direction (covering step S3). In one example of the covering step S3, the first outer packaging pack 90A to which the first cover members 110, 130, and 150 are fixed is placed with the opening of the housing section 94A facing upward, and the energy storage module 1A is positioned between the first cover member 110 and the first cover member 130 and the first cover member 150 within the housing section 94A of the first outer packaging pack 90A. In this state, the negative side in the Z-axis direction of the energy storage module 1A is housed in the housing section 94A of the first outer packaging pack 90A to which the first cover members 110, 130, and 150 are joined.

[0080] Then, the second outer pack 90B, to which the second cover members 120, 140, and 160 are joined, is placed over the first outer pack 90A in which the energy storage module 1A is arranged, with the opening of the housing section 94B facing downwards. In this state, the positive side in the Z-axis direction of the energy storage module 1A is housed in the housing section 94B of the second outer pack 90B to which the second cover members 120, 140, and 160 are joined. As a result, the outer surface 20sA of the energy storage module 1A is covered by the first cover members 110, 130 and the second cover members 120, 140, and the outer surface 20sB of the energy storage module 1A is covered by the first cover member 150 and the second cover member 160. In this state, the flange portion 94Aa of the first outer pack 90A and the flange portion 94Ba of the second outer pack 90B are welded to each other, thereby manufacturing the energy storage device 1.

[0081] As described above, an example of an energy storage device 1 includes an energy storage module 1A comprising a plurality of electrodes stacked along the Z-axis direction, an outer pack 90 having a housing portion 94 for housing the energy storage module 1A, and a cover member 101 which is arranged along the end of the energy storage module 1A when viewed from the Z-axis direction and is housed together with the energy storage module 1A in the housing portion 94 of the outer pack 90. ​​The outer pack 90 has a first outer pack 90A and a second outer pack 90B which are arranged side by side in the Z-axis direction and joined to each other. The cover member 101 has a first cover member 110 fixed to the first outer pack 90A and a second cover member 120 which is arranged opposite to the first cover member 110 in the Z-axis direction and is fixed to the second outer pack 90B. The first cover member 110 has an inner surface 111a (first inner surface) that extends in the Y direction intersecting the Z-axis direction and faces toward the second cover member 120, and at least one support column 119 that protrudes from the inner surface 111a toward the second cover member 120 along the Z-axis direction.

[0082] The energy storage device 1 is manufactured by housing an internal component such as an energy storage module 1A in a housing section 94 formed in an outer pack 90, and then sealing the outer pack 90 under reduced pressure. In this case, if a gap is formed between the housing section 94 and the internal component before sealing under reduced pressure, wrinkles may form in the outer pack 90 after sealing under reduced pressure. Wrinkles are particularly likely to form in the corners of the housing section 94 (i.e., the corners of the internal component).

[0083] In the above-described energy storage device 1, the first cover member 110 and the second cover member 120, which are arranged opposite each other in the Z-axis direction, are located at the ends of the energy storage module 1A and are housed together with the energy storage module 1A in the housing section 94 of the outer pack 90. ​​The outer pack 90 is composed of a first outer pack 90A and a second outer pack 90B, which are arranged side by side in the Z-axis direction, and the first cover member 110 and the second cover member 120 are fixed to the first outer pack 90A and the second outer pack 90B, respectively. As a result, since the first cover member 110 and the second cover member 120 are fixed to the first outer pack 90A and the second outer pack 90B, respectively, while housed in the housing section 94 of the outer pack 90, misalignment of the cover member 101 relative to the outer pack 90 is suppressed, and the formation of wrinkles in the outer pack 90 is suppressed. Furthermore, in the above-described energy storage device, since the first cover member 110 has a support column 119 that protrudes toward the second cover member 120, even if deformation or the like occurs in the cover member 101, it is possible to suppress a shift in the relative positional relationship between the first cover member 110 and the second cover member 120. This further suppresses misalignment between the outer packaging 90 and the cover member 101.

[0084] At least one support column 119 can abut against the second cover member 120. In this configuration, the heights H1 and H2 from the first cover member 110 to the second cover member 120 can be controlled by the length of the support column 119. This further suppresses misalignment between the corner portion of the outer packaging 90 and the corner portion of the cover member.

[0085] The energy storage module 1A may have an upper surface 10a (first surface) intersecting in the Z-axis direction, an outer surface 20sA (second surface) continuous with the upper surface 10a and intersecting in the Y-axis direction, and outer surfaces 20sC and 20sD (third surface) continuous with the upper surface 10a and the outer surface 20sA and intersecting in the X-axis direction. The first cover member 110 has a base wall 111 (first wall) intersecting in the Z-axis direction, a side wall 112 (second wall) continuous with the base wall 111 and intersecting in the Y-axis direction, and a side wall 114 (third wall) continuous with the base wall 111 and the side wall 112 and intersecting in the X-axis direction, and may be arranged to cover one side of the outer surface 20sA of the energy storage module 1A in the Z-axis direction when viewed from the Y-axis direction. The second cover member 120 has a base wall 121 (fourth wall) that intersects in the Z-axis direction, a side wall 122 (fifth wall) that is continuous with the base wall 121 and intersects in the Y-axis direction, and a side wall 124 (sixth wall) that is continuous with the base wall 121 and the side wall 122 and intersects in the X-axis direction, and may be arranged to cover the other side of the outer surface 20sA of the energy storage module 1A in the Z-axis direction when viewed from the Y-axis direction.

[0086] The first outer packaging 90A has a housing section 94A (first housing section). The housing section 94A is formed by a first portion 91A that intersects in the Z-axis direction, a second portion 92A that is continuous with the first portion 91A and intersects in the Y-axis direction, and a third portion 93A that is continuous with the first portion 91A and the second portion 92A and intersects in the X-axis direction. The first outer packaging 90A houses the first cover member 110 and one side of the energy storage module 1A in the Z-axis direction within the housing section 94A. The second outer packaging 90B has a housing section 94B (second housing section). The housing section 94B is formed by a fourth portion 91B that intersects in the Z-axis direction, a fifth portion 92B that is continuous with the fourth portion 91B and intersects in the Y-axis direction, and a sixth portion 93B that is continuous with the fourth portion 91B and the fifth portion 92B and intersects in the X-axis direction. The second outer pack 90B houses the second cover member 120 and the other side of the energy storage module 1A in the Z-axis direction within the housing section 94B. The first cover member 110 is joined to the inner surface of the first outer pack 90A with its base wall 111, side wall 112, and side wall 114 in contact with the first portion 91A, second portion 92A, and third portion 93A of the first outer pack 90A, respectively. The second cover member 120 is joined to the inner surface of the second outer pack 90B with its base wall 121, side wall 122, and side wall 124 in contact with the fourth portion 91B, fifth portion 92B, and sixth portion 93B of the second outer pack, respectively. In this configuration, misalignment of the corner portions of the first cover member 110 (connection portion 118a between the base wall 111 and the side wall 112, connection portion 118b between the base wall 111 and the side wall 114, and connection portion 118c between the side wall 112 and the side wall 114) with respect to the corner portions of the housing portion 94A (connection portion between the first portion 91A and the second portion 92A, connection portion between the first portion 91A and the third portion 93A, and connection portion between the second portion 92A and the third portion 93A) is suppressed, and the formation of wrinkles in the corner portions of the housing portion is suppressed.

[0087] The multiple support columns 119 may include support columns 119A (first support columns) positioned at both ends of the first cover member 110 in the X-axis direction, and support column 119B (second support column) positioned in the center of the first cover member 110 in the X-axis direction. Support column 119B may be shorter in the Z-axis direction than support column 119A. In this configuration, the tip of support column 119A is more likely to come into contact with the second cover member 120. Therefore, the height H2 of the corners of the cover member 101 can be appropriately controlled.

[0088] 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.

[0089] Figure 14 is a schematic cross-sectional view showing yet another example of an energy storage device. The energy storage device 1C shown in Figure 14 differs from the energy storage device 1 described above in that it has a cover member 300 instead of a cover member 100. In Figure 14, the cover member 301 is shown, which corresponds to the cover member 101. Below, the differences between the cover member 301 and the cover member 101 will be explained, and the explanation of the similarities will be omitted. The cover member 301 has a first cover member 310, which corresponds to the first cover member 110, and a second cover member 320, which corresponds to the second cover member 120. Compared to the first cover member 110, the first cover member 310 does not have a side wall 113. Also, compared to the second cover member 120, the second cover member 320 does not have a side wall 123. Other configurations of the cover member 301 may be the same as those of the cover member 101.

[0090] Figure 15 is a perspective view showing a modified example of the second cover member 120. The second cover member 120 shown in Figure 15 has a receiving portion 129 at a position opposite to the support column 119 of the first cover member 110 in the Y-axis direction. The receiving portion 129 suppresses displacement between the first cover member 110 and the second cover member 120 in the XY plane. The receiving portion 129 has a shape that can accommodate the tip of the support column 119. One example of the receiving portion 129 has a rectangular frame shape that protrudes in the Y-axis direction. When the tip of the support column 119 is housed inside the receiving portion 129, the tip of the support column 119 may be fitted into the receiving portion 129. Alternatively, when the tip of the support column 119 is housed inside the receiving portion 129, the tip of the support column 119 may be separated from the inner edge of the receiving portion 129. In this case, a slight misalignment between the first cover member 110 and the second cover member 120 in the XY plane is permissible.

[0091] In Figure 8, etc., an example is shown in which the welding plate 108 is provided in a rectangular recess 111d in plan view. However, the welding plate 108 only needs to face the outer film constituting the outer packaging, and the specific shape and arrangement of the welding plate 108 are not particularly limited. For example, the welding plate may be provided over the entire area of ​​the base wall in the Y-axis direction. Also, although an example is shown in which the welding plate 108 is provided on the base wall (for example, base wall 111), the welding plate 108 may also be provided on the side walls (for example, side walls 112, side walls 114).

[0092] Furthermore, while an example of a hollow rectangular prism-shaped support has been shown, the structure of the support is not limited to this. For example, the support may be a solid rectangular prism-shaped support with no internal space. Moreover, the support is not limited to a rectangular shape; for example, it may be cylindrical.

[0093] Furthermore, while examples have been shown where the support columns are formed independently (separated) from the side walls and ribs, the invention is not limited to these. For example, the support columns may be formed integrally with the side walls or ribs. In particular, when the support columns formed at the X-axis end are formed integrally with the side walls, the position of the support columns becomes closer to the corners of the cover member, allowing for more precise control of the height of the cover member in the Z-axis direction.

[0094] Furthermore, while an example has been shown in which the first outer packaging and the second outer packaging have concave storage compartments of the same depth, the invention is not limited to this. The depths of the first storage compartment of the first outer packaging and the second storage compartment of the second outer packaging may be different. Also, for example, only the first outer packaging may have a storage compartment, while the second outer packaging does not.

[0095] Figure 16 is a schematic perspective view showing another modified example of the cover member, and shows a support column formed on the cover member. The first cover member 210 shown in Figure 16 is a member corresponding to the first cover member 110 and can be housed in the outer packaging pack 90 in place of the first cover member 110. The first cover member 210 has a base wall 211 corresponding to the base wall 111 of the first cover member 110, and also has side walls 212, 213, 214, etc. corresponding to the side walls 112, 113, 114, etc. The first cover member 210 also has a support column 219 that has the same function as the support column 119 of the first cover member 110. The support column 219 protrudes along the Z-axis direction from the base wall 111 toward the second cover member 120 (see Figure 9, etc.). The support column 219 has a hollow rectangular prism shape. A notched portion 219a is formed at the tip of the support column 219, having a shape in which a part of the surface that abuts the second cover member 120 is missing. The notched portion 219a only needs to be provided at least at one location on the support column 219, and may be provided at two or more locations. In the illustrated example, the notched portions 219a are formed on a pair of opposing walls of the rectangular prism-shaped support column 219. The notched portion 219a is a groove-shaped recess formed from the tip of the support column 219 toward the base end, and is formed to connect the hollow portion of the support column 219 to the outside. The shape of the notched portion 219a may be any shape, such as a semicircular groove, a rectangular groove, or a V-shape. The notched portion 219a connects the hollow portion of the support column 219 to the outside. This prevents air from remaining in the hollow portion of the support column 219 when the first cover member 210 and the second cover member 120 are assembled and the inside of the outer pack 90 is depressurized. Therefore, damage to the cover members caused by the pressure difference during depressurization can be suppressed.

[0096] Embodiments of the present disclosure may be shown as follows: [1] A power storage device comprising: a power storage module comprising a plurality of electrodes stacked along a first direction; an outer casing having a housing portion for housing the power storage module; and a cover member positioned along the end of the power storage module when viewed from the first direction and housed together with the power storage module in the housing portion of the outer casing, wherein the outer casing comprises a first outer casing and a second outer casing positioned side by side in the first direction and joined to each other; the cover member comprises a first cover member fixed to the first outer casing and a second cover member positioned opposite to the first cover member in the first direction and fixed to the second outer casing, wherein the first cover member comprises a first inner surface extending in a second direction intersecting the first direction and facing toward the second cover member, and at least one support column projecting from the first inner surface toward the second cover member along the first direction. [2] The power storage device according to [1], wherein the at least one support column abuts toward the second cover member. [3] The energy storage module has a first surface intersecting in the first direction, a second surface continuous with the first surface and intersecting in the second direction, and a third surface continuous with the first surface and the second surface and intersecting in a third direction that intersects the first and second directions, and the first cover member has a first wall intersecting in the first direction, a second wall continuous with the first wall and intersecting in the second direction, and a third wall continuous with the first wall and the second wall and intersecting in the third direction, and is arranged to cover one side of the second surface of the energy storage module in the first direction when viewed from the second direction, and the second cover member has a fourth wall intersecting in the first direction, a fifth wall continuous with the fourth wall and intersecting in the second direction, and a sixth wall continuous with the fourth wall and the fifth wall and intersecting in the third direction, and is arranged to cover the other side of the second surface of the energy storage module in the first direction when viewed from the second direction, as described in [1] or [2].[4] The first exterior body has a first housing portion formed by a first portion intersecting in the first direction, a second portion continuous with the first portion and intersecting in the second direction, and a third portion continuous with the first portion and the second portion and intersecting in the third direction, and the first cover member and one side of the energy storage module in the first direction are housed in the first housing portion; the second exterior body has a second housing portion formed by a fourth portion intersecting in the first direction, a fifth portion continuous with the fourth portion and intersecting in the second direction, and a sixth portion continuous with the fourth portion and the fifth portion and intersecting in the third direction, and the second cover member and the other side of the energy storage module in the first direction are housed in the second housing portion; the first cover member is joined to the inner surface of the first exterior body with the first wall, second wall and third wall in contact with the first portion, second portion and third portion of the first exterior body, respectively. [3] The energy storage device according to any one of [1] to [4], wherein the second cover member is joined to the inner surface of the second outer casing such that the fourth wall, fifth wall, and sixth wall abut against the fourth, fifth, and sixth portions of the second outer casing, respectively. [5] The energy storage device according to any one of [1] to [4], wherein the at least one support is a plurality of support protruding from the first inner surface, and the plurality of support is a first support located at both ends of a third direction intersecting the first and second directions in the first cover member, and a second support located in the center of the third direction in the first cover member, and the second support is shorter in the first direction than the first support. [6] The energy storage device according to any one of [1] to [5], wherein the second cover member has a second inner surface facing the first inner surface, and the second inner surface has a receiving portion into which the tip of the at least one support is accommodated. [7] The energy storage device according to any one of [1] to [6], wherein the at least one support column has a columnar shape with a hollow portion on the inside, and a groove-shaped recess connecting the hollow portion to the outside is formed at the tip of the at least one support column.

[0097] 1...Energy storage device, 1A...Energy storage module, 11...Bipolar electrode (electrode), 12...Positive terminal electrode (electrode), 13...Negative terminal electrode (electrode), 100...Cover member, 90...Outer pack (outer body).

Claims

1. An energy storage device comprising: an energy storage module comprising a plurality of electrodes stacked along a first direction; an outer casing having a housing portion for housing the energy storage module; and a cover member positioned along the end of the energy storage module when viewed from the first direction and housed together with the energy storage module in the housing portion of the outer casing, wherein the outer casing has a first outer casing and a second outer casing positioned side by side in the first direction and joined to each other; the cover member has a first cover member fixed to the first outer casing and a second cover member positioned opposite to the first cover member in the first direction and fixed to the second outer casing; and the first cover member has a first inner surface extending in a second direction intersecting the first direction and facing toward the second cover member, and at least one support column projecting from the first inner surface toward the second cover member along the first direction.

2. The energy storage device according to claim 1, wherein at least one support column abuts against the second cover member.

3. The energy storage device according to claim 1 or 2, wherein the energy storage module has a first surface intersecting in the first direction, a second surface continuous with the first surface intersecting in the second direction, and a third surface continuous with the first and second surfaces intersecting in a third direction that intersects the first and second directions, the first cover member has a first wall intersecting in the first direction, a second wall continuous with the first wall intersecting in the second direction, and a third wall continuous with the first and second walls intersecting in the third direction, and is arranged to cover one side of the second surface of the energy storage module in the first direction when viewed from the second direction, the second cover member has a fourth wall intersecting in the first direction, a fifth wall continuous with the fourth wall intersecting in the second direction, and a sixth wall continuous with the fourth and fifth walls intersecting in the third direction, and is arranged to cover the other side of the second surface of the energy storage module in the first direction when viewed from the second direction.

4. The first exterior body has a first housing portion formed by a first portion intersecting in the first direction, a second portion continuous with the first portion and intersecting in the second direction, and a third portion continuous with the first portion and the second portion and intersecting in the third direction, and the first cover member and one side of the energy storage module in the first direction are housed in the first housing portion. The second exterior body has a second housing portion formed by a fourth portion intersecting in the first direction, a fifth portion continuous with the fourth portion and intersecting in the second direction, and a sixth portion continuous with the fourth portion and the fifth portion and intersecting in the third direction, and the second cover member and the other side of the energy storage module in the first direction are housed in the second housing portion. The first cover member is joined to the inner surface of the first exterior body with the first wall, second wall, and third wall in contact with the first portion, second portion, and third portion of the first exterior body, respectively. The energy storage device according to claim 3, wherein the second cover member is joined to the inner surface of the second outer casing such that the fourth wall, fifth wall, and sixth wall are in contact with the fourth, fifth, and sixth portions of the second outer casing, respectively.

5. The energy storage device according to claim 1 or 2, wherein the at least one support column is a plurality of support columns protruding from the first inner surface, and the plurality of support columns includes first support columns positioned at both ends of a third direction intersecting the first and second directions in the first cover member, and a second support column positioned in the center of the third direction in the first cover member, wherein the second support column is formed to be shorter than the first support column in the first direction.

6. The energy storage device according to claim 1, wherein the second cover member has a second inner surface facing the first inner surface, and the second inner surface has a receiving portion into which the tip of at least one support column is accommodated.

7. The energy storage device according to claim 1, wherein at least one support column has a columnar shape with a hollow portion on the inside, and a groove-shaped recess is formed at the tip of the at least one support column to connect the hollow portion to the outside.

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