Power storage device

Abstract

This power storage device comprises: a power storage module that has an electrode laminate and a sealing body which seals the electrode laminate; an exterior pack that contains the power storage module; and a cover member that is interposed between the exterior pack and a first side surface of the sealing body which extends in a first direction and a second direction. The sealing body has a liquid injection opening part which includes a plurality of frames that protrude in a third direction. As viewed from the third direction, the first side surface has a first portion region that is provided with the liquid injection opening part and a second portion region that sandwiches the first portion region in the second direction. The cover member has a first surface that faces the first portion region and a second surface that faces the second portion region. As viewed from the first direction, first surface is further recessed than the second surface.

Description

Power storage device

[0001] The present disclosure relates to an electricity storage device.

[0002] Patent Document 1 discloses a bipolar battery having multiple current collector plates stacked with separators interposed between them. In this bipolar battery, the current collector plates are surrounded by frame members, and adjacent frame members in the stacking direction are airtightly joined. Separators arranged between the current collector plates are impregnated with an electrolyte.

[0003] Japanese Unexamined Patent Publication No. 2-177268

[0004] In the bipolar battery described above, if a liquid injection port for introducing electrolyte between the current collector plates is provided in the frame member (sealing body), for example, when the bipolar battery is covered with an exterior film, the exterior film may be damaged by the liquid injection port, or the liquid injection port may be damaged by the exterior film.

[0005] The present disclosure provides an electricity storage device that can suppress damage to an exterior film and a liquid filling port.

[0006] According to one aspect of the present disclosure, there is provided an energy storage device including: an electrode stack including multiple electrodes stacked in a first direction, each electrode including a current collector; a sealing body provided on the electrode stack so as to surround the outer periphery of the electrode stack as viewed from the first direction and configured to seal multiple internal spaces formed between adjacent electrodes in the first direction; an exterior pack containing the energy storage module; and a cover member interposed between the exterior pack and a first side surface of the sealing body extending in the first direction and a second direction intersecting the first direction. The sealing body has a liquid inlet portion on the first side surface, the liquid inlet portion including multiple openings communicating with the multiple internal spaces, and multiple frames surrounding the multiple openings as viewed from a third direction intersecting the first and second directions and protruding in the third direction. As viewed from the third direction, the first side surface has a first partial region in which the liquid inlet portion is provided and a second partial region sandwiching the first partial region in the second direction. The cover member has a first surface facing the first partial region and a second surface facing the second partial region, and the first surface is recessed in a direction away from the first side surface more than the second surface when viewed from the first direction.

[0007] In the above-described energy storage device, a cover member is interposed between the sealing body and the exterior pack, whereby the liquid inlet formed in the sealing body does not come into direct contact with the exterior fill, thereby preventing the exterior pack from being damaged by the liquid inlet and the liquid inlet from being damaged by the exterior pack.

[0008] In one example, the first surface may be spaced apart from the first sub-region and the second surface may be in contact with the second sub-region.

[0009] In one example, the second partial region may have a terminal portion formed on a first side in the second direction relative to the plurality of frames, the terminal portion including a plurality of terminals electrically connected to the plurality of electrodes, and the cover member may be configured with a first cover member having a first surface and a second surface, and a second cover member covering the first side surface on the first side in the second direction relative to the terminal portion.

[0010] In one example, the sealing body may have a rectangular frame shape when viewed from the first direction. The sealing body may have a second side surface facing the first side surface in a third direction intersecting the first and second directions. A third cover member may be disposed between the second side surface and the outer pack facing the second side surface, covering the second side surface when viewed from the third direction.

[0011] In one example, the cover member may have a substantially rectangular shape when viewed from the first direction, and a corner where an end face of the cover member in the second direction and an end face in a third direction intersecting the first and second directions are connected to each other may be curved when viewed from the first direction.

[0012] In one example, the cover member may be hollow.

[0013] According to the present disclosure, it is possible to provide an electricity storage device that suppresses damage to the exterior film and the liquid injection port.

[0014] FIG. 1 is a schematic exploded perspective view of an example of a power storage device. FIG. 2 is a schematic view showing a cross section of the example of the power storage device. FIG. 3 is a schematic view showing one side of a power storage module constituting the example of the power storage device. FIG. 4 is a cross section taken along line IV-IV in FIG. 3. FIG. 5 is a perspective view showing an example of a cover member. FIG. 6 is a partial plan view for explaining the example of the cover member. FIG. 7 is a partial enlarged view of FIG. 6.

[0015] An embodiment will be described below with reference to the drawings. In the description of the drawings, identical or equivalent elements are denoted by the same reference numerals, and redundant description may be omitted. In the description, a Cartesian coordinate system defined by the X-axis, Y-axis, and Z-axis shown in the drawings may be referenced.

[0016] FIG. 1 is a schematic exploded perspective view showing a power storage device according to this embodiment. FIG. 2 is a schematic cross-sectional view of the power storage device along the YZ plane. Note that FIG. 2 shows a simplified depiction of a power storage module 1A included in the power storage device 1. The power storage device 1 is a power storage device used in batteries for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage device 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case is shown in which the power storage device 1 is a lithium-ion secondary battery.

[0017] The energy storage device 1 includes an energy storage module 1A, a cover member 60A, a connector unit 30, and an exterior pack 90. ​​In FIG. 1 , the energy storage module 1A and the exterior pack 90 constituting the energy storage device 1 are shown disassembled from each other. In FIG. 2 , the energy storage module 1A is shown housed in the space inside the exterior 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 extending in the Z-axis direction. The outer surfaces 20s are composed of outer surfaces 20sA and 20sB facing each other in the Y-axis direction (third direction) and outer surfaces 20sC and 20sD facing each other in the X-axis direction (second direction). Note that both end surfaces in the Z-axis direction of the energy storage module 1A are composed of a positive terminal electrode 12 and a negative terminal electrode 13, as described below, and are used for extracting power.

[0018] The cover member 60A in one example is configured to include a first cover member 60, a second cover member 70, and a third cover member 80. The first cover member 60 and the second cover member 70 are arranged to cover the outer surface 20sA (first side surface) when viewed from the Y-axis direction (third direction). The third cover member 80 is arranged to cover the outer surface 20sB (second side surface) when viewed from the Y-axis direction. The connector unit 30 is arranged between the first cover member 60 and the second cover member 70 in the X-axis direction (second direction).

[0019] FIG. 3 is a schematic diagram showing one outer side surface 20sA of the energy storage module 1A. FIG. 4 is a schematic cross-sectional view of an example energy storage module 1A. FIG. 4 shows a cross-section taken along line IV-IV in FIG. 3. The outer side surface 20sA of the energy storage module 1A includes a region R1 (first partial region) in which a liquid injection port 53A of the additional member 50 (described later) is provided, and regions R2 and R3 (second partial regions) adjacent to the region R1. In the example shown in FIG. 3, the region R2 is located on the negative side (second side) of the region R1 in the X-axis direction, and the region R3 is located on the positive side (first side) of the region R1 in the X-axis direction. The liquid injection port 53A of the additional member 50 is used when injecting an electrolyte solution into the energy storage module 1A. In this specification, the outer side surface 20sA may be referred to as the liquid injection port surface.

[0020] As shown in Fig. 4, 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 multiple electrodes stacked along the Z-axis direction, which is the stacking direction of the electrodes and corresponds to the height direction of the energy storage device 1. The multiple electrodes include multiple bipolar electrodes 11, a positive terminal electrode 12, and a negative terminal electrode 13. Separators 14 are interposed between adjacent electrodes.

[0021] 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 rectangular and sheet-shaped when viewed from the Z-axis direction. The active material layers (positive electrode active material layer 16, negative electrode active material layer 17) are provided in the center of the current collector 15 when viewed from the Z-axis direction, and are not provided on the peripheral edge portion 15c of the current collector 15. The positive electrode active material layer 16 is provided on a first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on a 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 FIG. 4), and the second surface 15b of the current collector 15 faces the other side in the Z-axis direction (the side where the positive electrode terminal electrode 12 is located in FIG. 4). The plurality of 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 the other bipolar electrode 11 adjacent in the stacking direction face each other.

[0022] The positive terminal electrode 12 has a current collector 15 and a positive electrode active material layer 16 provided on a first surface 15a of the current collector 15. No active material layer is provided on a second surface 15b of the current collector 15 of the positive terminal electrode 12. The positive terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the Z-axis direction. The positive terminal electrode 12 is laminated on the bipolar electrode 11 so that the 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 a second surface 15b of the current collector 15. No active material layer is provided on a first surface 15a of the current collector 15 of the negative electrode terminal electrode 13. 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 the end on which the positive electrode terminal electrode 12 is provided. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 so that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11. Note that in this embodiment, the current collectors of the bipolar electrode 11, the positive electrode terminal electrode 12, and the negative electrode terminal electrode 13 are each referred to as a current collector 15 and are denoted by the same reference numeral; however, the current collectors of the bipolar electrode 11, the positive electrode terminal electrode 12, and the negative electrode terminal electrode 13 may be the same or different from one another.

[0024] Separators 14 are disposed 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 separators 14 are interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, and separate the positive electrode active material layer 16 from the negative electrode active material layer 17. The separators 14 allow charge carriers such as lithium ions to pass through while preventing short circuits due to contact between adjacent electrodes.

[0025] The current collector 15 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charge 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 resins obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed. The current collector 15 may have 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. The coating layer may be formed by a known method such as plating or spray coating. The current collector 15 may be, for example, in the form of a plate, foil (e.g., metal foil), film, or mesh. Examples of metal foil include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The current collector 15 may be an alloy foil or clad foil of the above metals. When the current collector 15 is in the form of a foil, the thickness of the current collector 15 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 together, or an aluminum foil.

[0027] The positive electrode active material layer 16 contains a positive electrode active material capable of absorbing 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, and polyanion compounds. The positive electrode active material may be any material that can be used in lithium ion secondary batteries. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains an olivine-type lithium iron phosphate (LiFePO ) as a composite oxide. ４ )

[0028] The negative electrode active material layer 17 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be a simple substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element or a compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (non-graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 17 includes 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 "active material layer") may further contain, as necessary, a conductive additive to enhance electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conductive polymer, electrolyte solution, etc.), an electrolyte supporting salt (lithium salt) to enhance ionic conductivity, etc. The conductive additive is added to enhance the conductivity of each electrode (bipolar electrode 11, positive terminal electrode 12, negative terminal electrode 13). Examples of the conductive additive include acetylene black, carbon black, and graphite.

[0030] Examples of binders include fluorine-containing resins 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 and methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders may be used alone or in combination. Examples of solvents that may be used 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 an electrolyte. 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 the electrolyte impregnated in the separator 14 include a liquid electrolyte (electrolytic solution) containing a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent, and a polymer gel electrolyte containing an electrolyte retained in a polymer matrix.

[0032] When the separator 14 is impregnated with an electrolyte solution, 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 those listed above may be used. Furthermore, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers may be used as the nonaqueous solvent. Two or more of these known solvent materials may be used in combination.

[0033] The seal 29 includes a seal main body 20 and an additional member 50. The seal main body 20 is formed in a frame shape around the periphery of the electrode stack 10 so as to surround the periphery of the electrode stack 10 when viewed in the Z-axis direction. The seal main body 20 can be joined to the first surface 15a and the second surface 15b of each current collector 15 at the peripheral portion 15c of each current collector 15. The seal main body 20 can form an internal space S between adjacent current collectors 15 in the Z-axis direction and seal each of the internal spaces S. In this embodiment, each internal space S contains an electrolyte (not shown). That is, the seal main body 20 cooperates with adjacent current collectors 15 in the Z-axis direction to define an internal space S in which the electrolyte is contained. The seal main body 20 can prevent the electrolyte contained in the internal space S from leaking out to the outside.

[0034] The seal body 20 can prevent air, moisture, and the like from entering and leaving between the outside of the electrode stack 10 and the internal space S. The seal body 20 can prevent, for example, gas generated in each electrode due to a charge / discharge reaction or the like from leaking to the outside of the energy storage module 1A. The edge of the separator 14 is joined to the seal body 20. The seal body 20 includes an insulating material. Examples of materials for the seal body 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile-styrene resin.

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

[0036] The end seal material 24 has a frame shape when viewed in 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. Therefore, the end seal material 24 is arranged to sandwich the plurality of seal materials 21 in 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 arranged so as to be interposed between the seal materials 21 adjacent to each other in the Z-axis direction. The spacer 22 is also arranged so as to be interposed between the seal materials 21 and the end seal materials 24 adjacent to each other in the Z-axis direction. The spacer 22 can maintain the distance between the current collectors 15 adjacent to each other in the Z-axis direction. In other words, the spacer 22, the seal materials 21, and the end seal materials 24 define an internal space S between the adjacent current collectors 15.

[0038] The welded end portion 23 is formed by welding together and integrating the ends of the multiple seal materials 21, the pair of end seal materials 24, and the multiple spacers 22 on the opposite side to the internal space S. When viewed from the Z-axis direction, the welded end portion 23 has a frame shape that surrounds the electrode stack 10. The side of the welded end portion 23 on the opposite side to the internal space S extends along the Z-axis direction and forms the outer surface 20s of the seal main body 20. In other words, the seal main body 20 includes the outer surface 20s on the opposite side to the internal space S. The outer surface 20s may be formed as a flat surface.

[0039] The seal main body 20 has a plurality of communication holes 27 that communicate with each of the plurality of internal spaces S. As an example, the communication holes 27 are notched portions formed in the spacer 22, and are formed to penetrate the welded end portion 23. Each communication hole 27 has one opening in the internal space S and the other opening on the outer surface 20s of the seal main body 20. In the illustrated example, an opening is formed on the outer surface 20sA.

[0040] The additional member 50 is formed so as to overlap a region R1 of the outer surface 20sA in which the communication holes 27 are formed. The additional member 50 is molded into a predetermined shape to provide a liquid inlet portion 53A having a plurality of liquid inlets that respectively communicate with the plurality of communication holes 27. Region R1 may be the region in which the liquid inlet portion 53A is formed. 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 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 in which a plurality of communication holes 27 are formed on the outer surface 20sA. As described above, the plurality of communication holes 27 are respectively connected to a plurality of internal spaces S. In the example shown in FIG. 3 , 30 communication holes 27 corresponding to the 30 internal spaces formed between the 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 of the first to tenth layers, with the positive terminal electrode 12 as the base end, are arranged evenly spaced apart along the X-axis direction, and the communication holes 27 corresponding to the internal spaces of the eleventh to twentieth layers and the communication holes 27 corresponding to the internal spaces of the twenty-first to thirtieth layers are arranged sequentially below the internal spaces of the first to tenth layers in the Z-axis direction. The main body 51 extends in a rectangular shape along the X-axis direction and the Z-axis direction to cover the region R1 in which the 30 communication holes 27 are formed.

[0042] The main body 51 is formed in the shape of a rectangular plate having a predetermined thickness in the Y-axis direction. The main body 51 has openings 52 at positions corresponding to the communication holes 27. The main body 51 also has protruding frame portions 53 that protrude from the outer surface 20sA in the Y-axis direction intersecting (orthogonal to) the outer surface 20sA. The protruding frame portions 53 surround each opening 52 as viewed from the Y-axis direction and function as partition walls that separate the openings 52. In the example of FIG. 3 , ten protruding frame portions 53, each having three spaces formed therein to separate three openings 52 lined up vertically, are arranged in the X-axis direction.

[0043] As an example, the protruding frame portions 53 are used when injecting an electrolyte solution into each of the internal spaces S. For example, when injecting the electrolyte solution, a nozzle of a liquid injection device is brought into close contact with the top surface of the protruding frame portions 53 (frame), and the electrolyte solution is introduced from the nozzle into the spaces of each of the protruding frame portions 53. This makes it possible to inject the electrolyte solution into the internal spaces S through the openings 52 and the communication holes 27. After the electrolyte solution is injected, a laminate sheet 54 for sealing the protruding frame portions 53 may be provided on the protruding frame portions 53. The laminate sheet 54 may be, for example, a sheet in which a metal layer such as aluminum is coated with a resin layer. The laminate sheet 54 may be fused to the top surface of the protruding frame portions 53, for example.

[0044] In one example, the main body 51 includes a terminal 58 for voltage detection. The terminal 58 is formed in the main body 51 at a position offset toward the positive side of the X-axis direction from the liquid inlet 53A formed by the multiple protruding frame portions 53. For example, the terminal 58 is provided adjacent to the protruding frame portion 53 formed at the end on the positive side of the X-axis direction, with the flat surface 51a interposed therebetween. In one example, the terminal 58 is provided at the end on the positive side of the X-axis direction of the main body 51. The terminal 58 provides multiple terminals 58a electrically connected to the multiple current collectors 15, respectively. One end of the terminal 58a is connected to the corresponding current collector 15, and the other end of the terminal 58a is exposed from the main body 51. The terminals 58a may be, for example, metal pins, as long as they are electrically connected to the current collectors 15. A connector unit 30 is fixed to the terminal 58 (see FIGS. 6 and 7 ). The connector unit 30 as an example includes a housing 31 having a plurality of contacts connected to a plurality of terminals 58 a, and an FPC connector 33 for connecting the plurality of contacts to a flexible printed circuit (FPC) 32 .

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

[0046] The second overhang portion 57 partially covers the other edge of the welded end portion 23 in the Z-axis direction (negative side in the Z-axis direction). For example, the second overhang portion 57 partially covers the end seal material 24 joined to the negative terminal electrode 13. In the illustrated example, the edge 57a of the second overhang portion 57 extends from the 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 in the Z-axis direction, but this is not limited to this. The second overhang portion 57 may be formed in a rectangular plate shape having the same length in the X-axis direction as the main body portion 51.

[0047] Referring again to FIGS. 1 and 2 , the exterior pack 90 houses the energy storage module 1A, the cover member 60A, and the connector unit 30. An example of the exterior pack 90 includes a conductive member 91 and an exterior film 93. The conductive member 91 is composed of a first conductive member 91A and a second conductive member 91B, each of which has a rectangular sheet shape. The first conductive member 91A 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 second conductive member 91B 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 conductive member 91 may be, for example, a metal foil, such as aluminum foil. The planar size of the conductive member 91 may be equal to or smaller than that of the current collector 15.

[0048] The exterior film 93 is configured to surround the outer periphery of the contents (here, the energy storage module 1A, the cover member 60A, and the connector unit 30) when viewed from the Z-axis direction. For example, the exterior film 93 may cover at least the sealing body 29 of the energy storage module 1A. In the illustrated example, the exterior film 93 is configured with a first exterior film 93A connected to the first conductive member 91A and a second exterior film 93B connected to the second conductive member 91B. The exterior film 93 has a rectangular frame shape. For example, the exterior film 93 may be formed by welding four strip-shaped sheets 94 along each of the four sides of the rectangle. In the illustrated example, the first exterior film 93A is deformed so that its outer edge is located closer to the second exterior film 93B than its inner edge. The second exterior film 93B is deformed so that its outer edge is located closer to the first exterior film 93A than its inner edge.

[0049] The inner edge of the rectangular frame-shaped exterior film 93 is located inside the periphery of the conductive member 91 when viewed from the Z-axis direction. The inner edge of the exterior film 93 and the periphery of the conductive member 91 are joined together in an overlapping state. In one example, the inner edge of the exterior film 93 and the periphery of the conductive member 91 may be joined together by a resin material 95. The resin material 95 may be a rectangular frame-shaped sealing resin formed in a sheet. For example, the inner edge of the rectangular frame-shaped resin material 95 may be located inside the inner edge of the exterior film 93, and the outer edge of the resin material 95 may coincide with the periphery of the conductive member 91.

[0050] The outer edge of the exterior film 93 is located outside the periphery of the contents when viewed from the Z-axis direction. The outer edges of the first exterior film 93A and the second exterior film 93B are joined to each other. As an example, the outer edges of the first exterior film 93A and the second exterior film 93B may be welded to each other. The periphery of the conductive member 91 and the inner edge of the exterior film 93 are sealed to each other, and the outer edges of the first exterior film 93A and the second exterior film 93B are sealed to each other, thereby forming a sealed space inside the exterior pack 90. ​​After the energy storage module 1A and the like are housed in the exterior pack 90, the interior of the exterior pack 90 may be sealed in a depressurized state. In this case, atmospheric pressure presses the exterior pack 90, causing the pair of conductive members 91 to come into close contact with the positive terminal electrode 12 and the negative terminal electrode 13, respectively. When the first exterior film 93A and the second exterior film 93B are joined together, the flexible substrate 32 is exposed to the outside of the exterior pack 90 from the joining surface between the first exterior film 93A and the second exterior film 93B.

[0051] The exterior film 93 may be, for example, a laminate film including a metal layer, that is, the exterior film 93 may be a sheet-like member in which both sides of a metal layer 93a such as aluminum are covered with resin layers 93b and 93c.

[0052] The cover member 60A is disposed between the outer surface 20s of the power storage module 1A and the exterior film 93, and is housed in the exterior pack 90 together with the power storage module 1A and the connector unit 30. That is, the cover member 60A is interposed between the outer surface 20s and the exterior film 93. In the exemplary power storage device 1, the cover member 60A is composed of a first cover member 60 and a second cover member 70 disposed between the outer surface 20sA of the power storage module 1A and the exterior film 93, and a third cover member 80 disposed between the outer surface 20sB of the power storage module 1A and the exterior film 93. The first cover member 60 is disposed on the outer surface 20sA on the negative side (second side) of the terminal portion 58 in the X-axis direction. The second cover member 70 is disposed on the outer surface 20sA so as to cover the positive side (first side) of the terminal portion 58 in the X-axis direction.

[0053] Fig. 5 is a perspective view showing the first cover member 60 and the second cover member 70. The first cover member 60 and the second cover member 70 in Fig. 5 are shown in a positional relationship when housed in an exterior pack 90. ​​Fig. 6 is a partial plan view for explaining the relationship between the first cover member 60 and the second cover member 70 and the energy storage module 1A, showing the periphery of the outer surface 20sA of the energy storage device 1 with the exterior pack 90 removed. Fig. 7 is a partial enlarged view of Fig. 6.

[0054] The first cover member 60 includes a first wall portion 61 and a second wall portion 62 that face each other in the Z-axis direction, and a third wall portion 63 that extends in the XZ plane to connect the first wall portion 61 and the second wall portion 62. The first cover member 60 also includes a fourth wall portion 64 and a fifth wall portion 65 that face each other in the X-axis direction and extend in the YZ plane to connect the first wall portion 61, the second wall portion 62, and the third wall portion 63.

[0055] The connection portion 60a between the first wall portion 61 and the third wall portion 63, the connection portion 60b between the second wall portion 62 and the third wall portion 63, the connection portion 60c between the first wall portion 61 and the fourth wall portion 64, the connection portion 60d between the second wall portion 62 and the fifth wall portion 65, and the connection portion 60e between the third wall portion 63 and the fourth wall portion 64 are formed with chamfered corners. The chamfered shape may be, for example, a rounded chamfer. In other words, the corners formed by the connections between the wall portions may be curved in an arc shape when viewed from any of the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0056] One or more reinforcing ribs 67 are provided within the hollow interior of the first cover member 60. The ribs 67 are plate-shaped and extend along the YZ plane, connecting the first wall portion 61, the second wall portion 62, and the third wall portion 63 to one another. The multiple ribs 67 may be arranged at equal intervals in the X-axis direction. For example, the interval between adjacent ribs 67 is greater than the interval between the first wall portion 61 and the second wall portion 62 and less than twice the interval between the first wall portion 61 and the second wall portion 62. The end faces of the first wall portion 61, the second wall portion 62, the fourth wall portion 64, the fifth wall portion 65, and the ribs 67 facing away from the third wall portion 63 form a wall surface 69 facing the third wall portion 63.

[0057] The first wall portion 61 and the second wall portion 62 each have a first region 60R1 connected to the fourth wall portion 64, a second region 60R2 connected to the fifth wall portion 65, and a third region 60R3 sandwiched between the first region 60R1 and the second region 60R2. The first region 60R1 and the second region 60R2 have the same length in the Y-axis direction. The third region 60R3 has a shorter length in the Y-axis direction than the first region 60R1 and the second region 60R2. In the illustrated example, the connection positions of the first wall portion 61 and the second wall portion 62 with the third wall portion 63 are constant in the Y-axis direction. Therefore, the position of the wall surface 69 in the third region 60R3 is closer to the third wall portion 63 in the Y-axis direction than the positions of the wall surfaces 69 in the first region 60R1 and the second region 60R2.

[0058] The first region 60R1 faces the region R2 of the outer surface 20sA. The second region 60R2 faces the flat surface 51a (region R3) of the additional member 50 provided on the outer surface 20sA. The third region 60R3 faces the liquid inlet portion 53A (region R1) of the additional member 50 provided on the outer surface 20sA. In the first region 60R1, the wall surface 69 of the first cover member 60 has a contact surface 69a (second surface) that contacts the region R2 of the outer surface 20sA. In the second region 60R2, the wall surface 69 of the first cover member 60 has a contact surface 69b (second surface) that contacts the flat surface 51a of the additional member 50. In the third region 60R3, the wall surface 69 of the first cover member 60 forms a non-contact surface 69c (first surface) that is separated from the liquid inlet portion 53A of the additional member 50. The non-contact surface 69c is recessed in a direction away from the outer surface 20sA relative to the contact surfaces 69a and 69b when viewed in the Z-axis direction (i.e., in the opposite direction from the outer surface 20sA in the Y-axis direction). In the third region 60R3, a gap is formed between the wall surface 69 of the first cover member 60 and the additional member 50.

[0059] In the illustrated example, a notch-shaped portion 68 that avoids interference with the end of the additional member 50 is formed in the first wall portion 61 and the second wall portion 62 at the boundary between the first region 60R1 and the third region 60R3. For example, the notch-shaped portion 68 diagonally connects the contact surface 69a of the first region 60R1 and the non-contact surface 69c of the third region 60R3 when viewed from the Z-axis direction. In one example, when the additional member 50 is formed by injection molding, resin may protrude from the main body portion 51 of the additional member 50 along the outer surface 20sA. In this case, the protruding resin portion can be accommodated in the space formed by the notch-shaped portion 68.

[0060] The second cover member 70 includes a first wall portion 71 and a second wall portion 72 that face each other in the Z-axis direction, and a third wall portion 73 that extends in the XZ plane to connect the first wall portion 71 and the second wall portion 72. The second cover member 70 also includes a fourth wall portion 74 and a fifth wall portion 75 that face each other in the X-axis direction and extend in the YZ plane to connect the first wall portion 71, the second wall portion 72, and the third wall portion 73.

[0061] The connection portion 70a between the first wall portion 71 and the third wall portion 73, the connection portion 70b between the second wall portion 72 and the third wall portion 73, the connection portion 70c between the third wall portion 73 and the fifth wall portion 75, the connection portion 70d between the second wall portion 72 and the fifth wall portion 75, and the connection portion 70e between the first wall portion 71 and the fifth wall portion 75 are formed with chamfered corners. The chamfered shape may be, for example, a rounded chamfer. In other words, the corners formed by the connections between the wall portions may be curved in an arc shape when viewed from any of the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0062] One or more reinforcing ribs 77 are provided within the hollow interior of the second cover member 70. The ribs 77 are plate-shaped and extend along the YZ plane, connecting the first wall portion 71, the second wall portion 72, and the third wall portion 73 to one another. The multiple ribs 77 may be arranged at equal intervals in the X-axis direction. For example, the interval between adjacent ribs 77 is greater than the interval between the first wall portion 71 and the second wall portion 72 and less than twice the interval between the first wall portion 71 and the second wall portion 72. The end faces of the first wall portion 71, the second wall portion 72, the fourth wall portion 74, the fifth wall portion 75, and the ribs 77 facing away from the third wall portion 73 form a wall surface 79 facing the third wall portion 73.

[0063] The illustrated second cover member 70 has a notched space 70S for accommodating an FPC connector. That is, in the second cover member 70, corners 70k of the first wall portion 71 and the second wall portion 72 that connect to the third wall portion 73 and the fourth wall portion 74 are formed in a recessed corner shape. As a result, the fourth wall portion 74 is divided into two at the center in the Y-axis direction. Furthermore, the third wall portion 73 is divided into two in the X-axis direction at a position close to the fourth wall portion 74.

[0064] A wall surface 79 of the second cover member 70 faces region R3 of the outer surface 20sA and is in contact with the outer surface 20sA. In the illustrated example, a notch-shaped portion 78 is formed in the first wall portion 71 and the second wall portion 72 near the fourth wall portion 74 to avoid interference with the end of the additional member 50. For example, the notch-shaped portion 78 connects the wall surface 79 and the fourth wall portion 74 at an angle when viewed from the Z-axis direction, and is formed so that the wall surface 79 near the fourth wall portion 74 is spaced apart from the outer surface 20sA. In one example, when the additional member 50 is formed by injection molding, resin may protrude from the main body of the additional member 50 along the outer surface 20sA. In that case, the protruding resin portion can be accommodated in the space formed by the notch-shaped portion 78.

[0065] The third cover member 80 has the same basic structure as the first cover member 60 and the second cover member 70 (see FIG. 1 ). Specifically, the third cover member 80 includes a first wall portion 81 and a second wall portion 82 that face each other in the Z-axis direction, a third wall portion 83 that extends in the X-Z plane to connect the first wall portion 81 and the second wall portion 82, and a fourth wall portion 84 and a fifth wall portion 85 that face each other in the X-axis direction and extend in the Y-Z plane to connect the first wall portion 81, the second wall portion 82, and the third wall portion 83. The third cover member 80, as an example, has a substantially rectangular shape when viewed from the Z-axis direction, and an end face 89 facing the outer surface 20sB is flat. This end face 89 may be in contact with the outer surface 20sB over the entire area in the X-axis direction. Corners connecting the walls may be chamfered when viewed from any of the X-axis, Y-axis, and Z-axis directions. The third cover member 80 may be divided into multiple parts.

[0066] The first cover member 60, the second cover member 70, and the third cover member 80 may restrict movement of the power storage module 1A in at least one of the X-axis direction and the Y-axis direction. The first cover member 60, the second cover member 70, and the third cover member 80 may be fixed to the power storage module 1A. For example, a protrusion or a recess may be formed on the sealing body 29 of the power storage module 1A, and the first cover member 60, the second cover member 70, and the third cover member 80 may be engaged with the protrusion or the recess. Furthermore, the first cover member 60, the second cover member 70, and the third cover member 80 may be fixed to the power storage module 1A by adhesive or the like.

[0067] As described above, the example energy storage device 1 includes an electrode stack 10 in which a plurality of electrodes, each including a current collector 15, are stacked in the Z-axis direction, a sealing body 29 that is provided on the electrode stack 10 so as to surround the outer periphery of the electrode stack 10 as viewed from the Z-axis direction and is configured to seal a plurality of internal spaces S formed between each of the electrodes adjacent in the Z-axis direction, an exterior pack 90 that is configured to surround at least the outer periphery of the sealing body 29 as viewed from the Z-axis direction, and a cover member 60A that is interposed between the exterior pack 90 and an outer surface 20sA of the sealing body 29 that extends in the Z-axis direction and the X-axis direction. The outer surface 20sA of the sealing body 29 has a region R1 in which a liquid injection port portion 53A including a protruding frame portion 53 that protrudes in the Y-axis direction is provided, and regions R2 and R3 that sandwich region R1 from the X-axis direction. The cover member 60A has a non-contact surface 69c facing the region R1, and contact surfaces 69a and 69b facing the regions R2 and R3.

[0068] In the above-described energy storage device 1, the cover member 60A is interposed between the sealed body 29 and the exterior pack 90. ​​As a result, the liquid inlet portion 53A formed in the sealed body 29 does not come into direct contact with the exterior film 93, thereby suppressing damage to the exterior pack 90 by the liquid inlet portion 53A and also suppressing damage to the liquid inlet portion 53A by the exterior pack 90. ​​Furthermore, when viewed from the Z-axis direction, the non-contact surface 69c is recessed in a direction away from the outer surface 20sA more than the contact surfaces 69a and 69b, and therefore the liquid inlet portion 53A can be accommodated in the recess formed by the non-contact surface 69c.

[0069] In one example, the non-contact surface 69c may be spaced apart from the outer surface 20sA (pouring port portion 53A), and the contact surfaces 69a, 69b may be in contact with the outer surface 20sA (or main body portion 51). This prevents the cover member 60A from coming into direct contact with the pouring port portion 53A, effectively preventing damage to the pouring port portion 53A by the cover member 60A.

[0070] In one example, the outer surface 20sA may have a terminal portion 58 formed shifted toward the positive side in the X-axis direction from the liquid inlet portion 53A. The terminal portion 58 includes a plurality of terminals 58a electrically connected to the plurality of electrodes, respectively. The cover member 60A includes a first cover member 60 disposed on the negative side of the terminal portion 58 in the X-axis direction, and a second cover member 70 covering the positive side of the terminal portion 58 in the X-axis direction. With this configuration, when an FPC is connected to the terminal portion 58 as an external lead wire, interference between the FPC and the cover member 60A is suppressed.

[0071] In one example, the sealing body 29 may have a rectangular frame shape when viewed from the Z-axis direction. The sealing body 29 may have an outer surface 20sB that faces the outer surface 20sA in the Y-axis direction. A third cover member 80 that covers the outer surface 20sB when viewed from the Y-axis direction may be disposed between the outer surface 20sB and the exterior film 93. In this configuration, the outer surfaces 20sA and 20sB that face each other are covered by the cover member 60A. In this case, contact between the corners of the sealing body 29, which has a rectangular frame shape, and the exterior film 93 is suppressed.

[0072] In one example, the first cover member 60 may have a substantially rectangular shape when viewed from the Z-axis direction. The corners where the end faces of the first cover member 60 in the X-axis direction and the end faces of the first cover member 60 in the Y-axis direction are connected to each other may be curved when viewed from the Z-axis direction. This configuration suppresses stress concentration at the contact portions of the exterior film 93 with the corners of the first cover member 60. In other words, damage to the exterior film 93 due to contact with the first cover member 60 is suppressed.

[0073] In one example, the cover member 60A may be hollow. This configuration can reduce the weight of the energy storage device 1. Furthermore, even if an external impact is applied, the force transmitted to the energy storage module 1A via the cover member 60A can be reduced.

[0074] Although examples of the embodiments of the present disclosure have been described above with reference to the drawings, the present disclosure is not limited to the above embodiments.

[0075] The exterior film 93 is not limited to a laminate film made of a metal layer and a resin layer. For example, the exterior film 93 may be a laminate film made of a resin film that does not include a metal layer. Such a resin film may be made of a resin layer with low moisture permeability.

[0076] The outer surfaces 20sC and 20sD may be covered by cover members having a configuration similar to that of the cover member 60A. In this case, the outer surface 20s is covered by four cover members combined to form a rectangular frame.

[0077] Although the example in which the outer surface 20sA is covered by the first cover member 60 and the second cover member 70 formed separately has been shown, for example, the first cover member 60 and the second cover member 70 may be formed integrally. In this case, a hole, a notch, or the like may be provided to expose the FPC to the outside of the cover member.

[0078] An embodiment of the present disclosure may be expressed as follows: [1] An electricity storage module including: an electrode stack in which a plurality of electrodes, each including a current collector, are stacked in a first direction; and a sealing body provided on the electrode stack so as to surround the outer periphery of the electrode stack as viewed from the first direction, and configured to seal a plurality of internal spaces formed between the electrodes adjacent in the first direction; an exterior pack containing the electricity storage module; and a cover member interposed between the exterior pack and a first side surface of the sealing body extending in the first direction and a second direction intersecting the first direction, wherein the sealing body has a liquid injection port portion on the first side surface, the liquid injection port portion including a plurality of openings communicating with the plurality of internal spaces, and a plurality of frames surrounding the plurality of openings as viewed from a third direction intersecting the first direction and the second direction and protruding in the third direction; and wherein, as viewed from the third direction, the first side surface has a first partial region in which the liquid injection port portion is provided, and a second partial region sandwiching the first partial region in the second direction.

[0016]

[0017] The power storage device according to [1], wherein the cover member has a first surface facing the first partial region and a second surface facing the second partial region, and the first surface is recessed in a direction away from the first side surface relative to the second surface when viewed from the first direction. [2] The power storage device according to [1], wherein the first surface is spaced apart from the first partial region, and the second surface is in contact with the second partial region. [3] The power storage module according to [1] or [2], wherein the second partial region has terminal portions formed on a first side in the second direction relative to the frames, the terminal portions including a plurality of terminals electrically connected to each of the plurality of electrodes, the cover member comprising: a first cover member having the first surface and the second surface; and a second cover member covering the first side surface on the first side in the second direction relative to the terminal portions.[4] The energy storage module according to any one of [1] to [3], wherein the sealing body has a rectangular frame shape when viewed from the first direction, the sealing body has a second side surface facing the first side surface in a third direction intersecting the first direction and the second direction, and a third cover member covering the second side surface when viewed from the third direction is disposed between the second side surface and the exterior pack facing the second side surface. [5] The energy storage module according to any one of [1] to [4], wherein the cover member has a substantially rectangular shape when viewed from the first direction, and a corner at which an end face of the cover member in the second direction and an end face in a third direction intersecting the first direction and the second direction are connected to each other is curved when viewed from the first direction. [6] The energy storage module according to any one of [1] to [5], wherein the cover member is hollow.

[0079] REFERENCE SIGNS LIST 1 Energy storage device 1A Energy storage module 10 Electrode stack 11 Bipolar electrode (electrode) 12 Positive terminal electrode (electrode) 13 Negative terminal electrode (electrode) 15 Current collector 20sA Outer surface (first side surface) 27 Communication hole 29 Sealing body 50 Additional member 52 Opening 58 Terminal portion 60A Cover member 60 First cover member 69a, 69b Contact surface (second surface) 69c Non-contact surface (first surface) 70 Second cover member 90 Outer package R1 Region (first partial region) R2, R3 Region (second partial region) S Internal space

Claims

1. An electricity storage module including: an electrode stack in which a plurality of electrodes, each including a current collector, are stacked in a first direction; and a sealing body provided on the electrode stack so as to surround an outer periphery of the electrode stack when viewed from the first direction, and configured to seal a plurality of internal spaces formed between the electrodes adjacent to each other in the first direction; an exterior pack containing the electricity storage module; and a cover member interposed between the exterior pack and a first side surface of the sealing body extending in the first direction and a second direction intersecting the first direction, wherein the sealing body has a liquid injection port portion on the first side surface, the liquid injection port portion including a plurality of openings each communicating with the plurality of internal spaces, and a plurality of frames surrounding the plurality of openings when viewed from a third direction intersecting the first direction and the second direction and protruding in the third direction, wherein when viewed from the third direction, the first side surface has a first partial region in which the liquid injection port portion is provided, and a second partial region sandwiching the first partial region in the second direction, The cover member has a first surface facing the first partial region and a second surface facing the second partial region, and the first surface is recessed in a direction away from the first side surface relative to the second surface when viewed from the first direction.

2. The power storage device according to claim 1, wherein the first surface is spaced apart from the first partial region, and the second surface is in contact with the second partial region.

3. The energy storage device described in claim 1, wherein the second partial region has a terminal portion formed on a first side in the second direction relative to the multiple frames, including a plurality of terminals electrically connected to each of the multiple electrodes, and the cover member is composed of: a first cover member arranged to face the first side surface on a second side opposite the first side in the second direction relative to the terminal portion, the first cover member having the first surface and the second surface, and a second cover member covering the first side surface on the first side in the second direction relative to the terminal portion.

4. The energy storage device described in claim 1, wherein the sealing body has a rectangular frame shape when viewed from the first direction, the sealing body has a second side surface facing the first side surface in a third direction intersecting the first direction and the second direction, and a third cover member covering the second side surface when viewed from the third direction is disposed between the second side surface and the exterior pack with which the second side surface faces.

5. The energy storage device according to claim 1, wherein the cover member has a substantially rectangular shape when viewed from the first direction, and a corner at which an end face of the cover member in the second direction and an end face in a third direction intersecting the first direction and the second direction are connected to each other is curved when viewed from the first direction.

6. The electricity storage device according to any one of claims 1 to 5, wherein the cover member is hollow.

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