Power storage module

Abstract

This power storage module includes: an electrode laminate in which a plurality of electrodes including a plurality of bipolar electrodes are laminated along a first direction; and a sealing body that is provided in the electrode laminate and that seals the electrode laminate. Each of the plurality of bipolar electrodes includes: a current collector including a first surface intersecting the first direction and a second surface on the side opposite to the first surface; a first active material layer provided on the first surface; and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer. The sealing body includes a plurality of sealing materials laminated along the first direction, and a plurality of spacers interposed between the sealing materials adjacent to each other along the first direction.

Description

Energy storage module

[0001] The present disclosure relates to an energy storage module.

[0002] Patent Document 1 describes a bipolar battery. This bipolar battery has a bipolar electrode in which a positive electrode active material layer is provided on one surface of a current collector and a negative electrode active material layer is provided on the other surface, a gel electrolyte sandwiched between the positive electrode active material layer and the negative electrode active material layer, and a seal layer provided between the current collectors and surrounding the periphery of a unit cell constituted by the positive electrode active material layer, the negative electrode active material layer, and the gel electrolyte, and has a structure in which a plurality of such unit cells are stacked.

[0003] Japanese Patent Application Laid-Open No. 2004-158343

[0004] In the bipolar battery described in Patent Document 1, the current collector has a region where neither the active material layer nor the sealing layer is provided between the region where the positive electrode active material layer and the negative electrode active material layer are provided and the region where the sealing layer is provided. This region where neither the active material layer nor the sealing layer is provided has lower rigidity than the other regions. Therefore, there is a risk that the current collector will deform in this region with lower rigidity.

[0005] An object of the present disclosure is to provide an electricity storage module that can suppress deformation of a current collector.

[0006] The energy storage module according to the present disclosure includes an electrode stack in which a plurality of electrodes, each including a plurality of bipolar electrodes, are stacked along a first direction, and a sealing body provided on the electrode stack for sealing the electrode stack, wherein each of the plurality of bipolar electrodes has a current collector including a first surface intersecting the first direction and a second surface opposite to the first surface, a first active material layer provided on the first surface, and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer, and the sealing body includes a plurality of sealing materials stacked along the first direction and a plurality of spacers interposed between adjacent sealing materials along the first direction. each of the plurality of sealing materials is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction, and is welded to the first surface and the second surface at the peripheral portion of the current collector; each of the plurality of spacers is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction, and together with sealing materials adjacent along the first direction, forms an internal space between current collectors adjacent in the first direction; when viewed from the first direction, the outer edge of the first active material layer is located outside the outer edge of the second active material layer; and when viewed from the first direction, the inner edge of the spacer is located between the outer edge of the first active material layer and the outer edge of the second active material layer.

[0007] This energy storage module includes an electrode stack including multiple stacked electrodes, each including multiple stacked bipolar electrodes. The bipolar electrode includes a current collector and a first active material layer and a second active material layer, respectively, provided on both sides of the current collector. When viewed in the stacking direction (first direction) of the electrodes, the outer edge of the first active material layer is located outside the outer edge of the second active material layer. In addition, this energy storage module includes a sealing body provided on the electrode stack. The sealing body includes multiple sealing materials welded to the current collector at the periphery of the bipolar electrode current collector and stacked in the stacking direction (first direction) of the bipolar electrode, and multiple spacers interposed between the sealing materials to form internal spaces between the current collectors. When viewed in the stacking direction of the electrodes, the inner edge of the spacer is located between the outer edge of the first active material layer and the outer edge of the second active material layer. In other words, the spacer extends from a position between adjacent sealing materials to the first active material layer. Therefore, the spacers are disposed in the regions of the current collector where neither the active material layer nor the sealing material is provided, ensuring the rigidity of the electricity storage module and suppressing deformation of the current collector.

[0008] In the energy storage module according to the present disclosure, the spacer may include an overlapping portion that overlaps the first active material layer when viewed from the first direction, and may be thinner than the second active material layer at the overlapping portion.

[0009] In the energy storage module according to the present disclosure, the spacer includes an overlapping portion that overlaps the first active material layer when viewed from the first direction, the plurality of electrodes include a first terminal electrode that is located at the outermost part of the electrode stack in the first direction and has a current collector and a second active material layer provided on the second surface, and the outermost spacer of the plurality of spacers in the first direction may be in contact with the current collector of the first terminal electrode at the overlapping portion.

[0010] In the energy storage module according to the present disclosure, the spacer may be sandwiched between a pair of first active material layers adjacent to each other in the first direction at the overlapping portion.

[0011] In the energy storage module according to the present disclosure, the first active material layer includes a first portion that overlaps with the second active material layer when viewed from the first direction, and a second portion that is located outside the outer edge of the second active material layer when viewed from the first direction and includes the outer edge of the first active material layer, and the thickness of the second portion in the first direction may be thicker than the thickness of the first portion in the first direction.

[0012] In the energy storage module according to the present disclosure, the outer edge of the sealant and the outer edge of the spacer may be welded to each other to form a welded portion.

[0013] In the energy storage module according to the present disclosure, the current collector includes a first region that does not overlap with the first active material layer and the sealing material when viewed from the first direction, and a second region that overlaps with the first active material layer when viewed from the first direction but does not overlap with the second active material layer, and the width of the first region when viewed from the first direction may be narrower than the width of the second region when viewed from the first direction.

[0014] In the energy storage module according to the present disclosure, the electrode stack includes a first stack portion in which the first active material layer and the second active material layer overlap when viewed from the first direction, and a second stack portion that is outer than the second active material layer when viewed from the first direction and in which the first active material layer and the spacer overlap, the sealing body includes a first sealing portion in which the sealant and the spacer overlap when viewed from the first direction, and the thickness of the second stack portion in the first direction may be thinner than the thickness of the first stack portion in the first direction, and the thickness of the first sealing portion in the first direction may be thinner than the thickness of the second stack portion in the first direction.

[0015] In the energy storage module according to the present disclosure, the spacer may include a protrusion that protrudes toward the first surface facing the spacer between the outer edge of the first active material layer and the inner edge of the sealing material when viewed from the first direction.

[0016] In the energy storage module according to the present disclosure, the spacer has a rectangular frame shape when viewed from the first direction, and the current collector has, on its second surface, a rectangular first region in which a second active material layer is provided, and a rectangular frame-shaped second region outside the first region when viewed from the first direction, and the outer edge of the rectangular first region is defined by a pair of first sides that face each other and a second side that connects the pair of first sides and faces each other, and when the spacer is divided by first partition lines that extend from the pair of first sides and second partition lines that extend from the pair of second sides when viewed from the first direction, the spacer is The spacer may be divided into a pair of first compartments separated by the second partition lines and along a pair of second sides, a pair of second compartments separated by the second partition lines and along the first sides, and four third compartments separated by the first partition line and the second partition line, connecting the first compartments and the second compartments, and including the four corners of the spacer, and at least one of the plurality of spacers may have a cutout portion formed in at least one third compartment such that the widthwise length of the spacer from the outer edge of the spacer to the internal space is shorter than the widthwise length of the spacer in the adjacent first compartment or second compartment.

[0017] According to the present disclosure, it is possible to provide an electricity storage module capable of suppressing deformation of a current collector.

[0018] FIG. 1 is a schematic cross-section of an energy storage module according to this embodiment. FIG. 2 is a schematic plan view of the energy storage module shown in FIG. 1. FIG. 3 is a schematic cross-sectional view showing an enlarged portion of the energy storage module shown in FIG. 1. FIG. 4 is a schematic cross-sectional view showing an enlarged portion of an energy storage module according to a first modified example. FIG. 5 is a schematic cross-sectional view showing an enlarged portion of an energy storage module according to a second modified example. FIG. 6 is a schematic cross-sectional view showing an enlarged portion of an energy storage module according to a third modified example. FIG. 7 is a schematic cross-sectional view showing an enlarged portion of an energy storage module according to a fourth modified example. FIG. 8 is a schematic plan view of a first aspect of the energy storage module shown in FIG. 7. FIG. 9 is a schematic plan view of a second aspect of the energy storage module shown in FIG. 7. FIG. 10 is a schematic plan view of a third aspect of the energy storage module shown in FIG. 7. FIG. 11 is a schematic plan view of an energy storage module 1 according to another modified example.

[0019] An energy storage module according to one embodiment will be described below with reference to the drawings. In the description of each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant description may be omitted. In addition, each drawing may show an orthogonal coordinate system that defines an X direction, a Y direction perpendicular to the X direction, and a Z direction perpendicular to the X and Y directions.

[0020] FIG. 1 is a schematic cross-section of an energy storage module according to this embodiment. FIG. 2 is a schematic plan view of the energy storage module shown in FIG. 1. The energy storage module 1 shown in FIGS. 1 and 2 is an energy storage module used in batteries for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage module 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the energy storage module 1 is a lithium-ion secondary battery is illustrated as an example.

[0021] The energy storage module 1 includes an electrode stack 10 and a sealing body 20. The electrode stack 10 includes a plurality of electrodes stacked along the Z direction (first direction). The plurality of electrodes includes a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13. Separators 14 are interposed between adjacent electrodes.

[0022] The bipolar electrode 11 includes a current collector 15, a positive electrode active material layer 16 (second active material layer), and a negative electrode active material layer 17 (first active material layer). The current collector 15 has, for example, a rectangular sheet shape. The current collector 15 includes one side 15a and another side 15b. As an example, the other side 15b is a first surface intersecting the Z direction, and the one side 15a is a second surface intersecting the Z direction and opposite the first surface. Here, the one side 15a of the current collector 15 faces one side of the Z direction (the direction from the positive electrode terminal electrode 13 toward the negative electrode terminal electrode 12 in FIG. 1 ), and the other side 15b of the current collector 15 faces the other side of the Z direction (the direction from the negative electrode terminal electrode 12 toward the positive electrode terminal electrode 13 in FIG. 1 ).

[0023] The positive electrode active material layer 16 (second active material layer) is provided on one surface 15a (second surface) of the current collector 15. The negative electrode active material layer 17 (first active material layer) is provided on the other surface 15b (first surface) of the current collector 15. The multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 faces the negative electrode active material layer 17 of another bipolar electrode 11. Grooves may be formed in the positive electrode active material layer 16 and the negative electrode active material layer 17.

[0024] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the Z direction. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the Z direction. That is, in a plan view when viewed from the Z direction, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17. In other words, when viewed from the Z direction, the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16.

[0025] The negative electrode terminal electrode 12 (second terminal electrode) has a current collector 15 and a negative electrode active material layer 17 provided on the other surface 15b of the current collector 15. The negative electrode terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on one surface 15a of the current collector 15. In other words, no active material layer is provided on one surface 15a of the current collector 15 of the negative electrode terminal electrode 12. The negative electrode terminal electrode 12 is located at the outermost side of the electrode laminate 10 in the opposite direction to the Z direction (negative Z direction), and is laminated on the bipolar electrode 11. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 so that the negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0026] The positive terminal electrode 13 (first terminal electrode) has a current collector 15 and a positive electrode active material layer 16 provided on one surface 15a of the current collector 15. The positive terminal electrode 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on the other surface 15b, which is the surface opposite to the one surface 15a of the current collector 15. In other words, no active material layer is provided on the other surface 15b of the current collector 15 of the positive terminal electrode 13. The positive terminal electrode 13 is located at the outermost portion in the Z direction of the electrode laminate 10 and is laminated on the bipolar electrode 11. The positive terminal electrode 13 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.

[0027] In this embodiment, the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 are denoted by the same reference numeral 15, but the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 may be the same as or different from one another. Furthermore, the surface of the negative terminal electrode 12 on which the negative electrode active material layer 17 is not provided and the surface of the positive terminal electrode 13 on which the positive electrode active material layer 16 is not provided come into contact with, for example, a tab for extracting current, and therefore do not come into contact with the electrolyte.

[0028] Separators 14 are disposed between adjacent bipolar electrodes 11, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive 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. The separators 14 are members that allow charge carriers such as lithium ions to pass through, and by isolating the positive electrode active material layer 16 and the negative electrode active material layer 17, they prevent short circuits due to contact between adjacent electrodes.

[0029] 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 and / or conductive resin material.

[0030] 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 foils include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The current collector 15 may be an alloy foil of the above metals or a foil obtained by integrating multiple metal foils. 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 200 μm. In this embodiment, the current collector 15 is a foil obtained by integrating aluminum foil and copper foil, or a foil obtained by vapor-depositing copper onto aluminum foil.

[0031] 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 )

[0032] 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.

[0033] 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, negative electrode terminal electrode 12, positive electrode terminal electrode 13). Examples of the conductive additive include acetylene black, carbon black, and graphite.

[0034] 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 can be used alone or in combination. Examples of solvents for binders include water and N-methyl-2-pyrrolidone (NMP).

[0035] 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 multi-layer structure. The multi-layer 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 electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0036] The electrolyte salt of the electrolyte solution is LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ ) ２ Known lithium salts such as 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.

[0037] The sealing body 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the Z direction, and is formed in a rectangular tubular shape on the peripheral portion of the electrode stack 10. The sealing body 20 can be joined (welded) to each of the one surface 15a and the other surface 15b of the current collector 15 at the peripheral portion 15c of each current collector 15. The sealing body 20 forms an internal space S between adjacent current collectors 15 in the Z direction and seals each of the internal spaces S (i.e., the electrode stack 10). An electrolyte (e.g., an electrolytic solution) is accommodated in each internal space S. The sealing body 20 can prevent the electrolytic solution accommodated in the internal space S from leaking to the outside. The sealing body 20 can also prevent air, moisture, and the like from entering the internal space S from outside the electrode stack 10.

[0038] The edge of the separator 14 is joined to the seal 20. The seal 20 contains an insulating material. Examples of the material for the seal 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile-styrene resin.

[0039] The sealing body 20 includes a plurality of resin sealants 21 and a plurality of resin spacers 22. A sealant 21 is provided on each current collector 15. Therefore, the plurality of sealants 21 are stacked along the Z direction. The sealant 21 has a frame shape (here, a rectangular frame shape) that follows the outer shape of the current collector 15 when viewed from the Z direction, and is provided on the peripheral edge portion 15c of the current collector 15. The sealant 21 is provided so as to extend from one surface 15a of the current collector 15, passing through the end face, to the other surface 15b, and covers the peripheral edge portion 15c.

[0040] That is, the sealing material 21 has, on one surface 15a and the other surface 15b of the current collector 15, an inner portion 21a that overlaps the current collector 15 and an outer portion 21b that is located outside the edge of the current collector 15, when viewed from the Z direction. A pair of adjacent portions of the sealing material 21 sandwiching the current collector 15 are connected to each other at the outer portion 21b. The inner portions 21a of the sealing material 21 are welded to the one surface 15a and the other surface 15b of the current collector 15, respectively. In this embodiment, the sealing material 21 is welded to both the one surface 15a and the other surface 15b of the current collector 15.

[0041] In this embodiment, the sealing materials provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the negative terminal electrode 12, and the current collector 15 of the positive terminal electrode 13 are each given the same reference numeral as a sealing material 21. However, the sealing material provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the negative terminal electrode 12, and the sealing material provided on the current collector 15 of the positive terminal electrode 13 may be the same as or different from one another.

[0042] The spacers 22 are arranged so as to be interposed between the respective sealing materials 21 adjacent to each other in the Z direction. As a result, the spacers 22, together with a pair of sealing materials 21 adjacent to each other in the Z direction, maintain the spacing between the current collectors 15 adjacent to each other in the Z direction. An internal space S is defined by the pair of current collectors 15 adjacent to each other in the Z direction, the spacers 22, and the pair of sealing materials 21 adjacent to the spacers 22. In this way, each of the multiple spacers 22, together with the sealing materials 21 adjacent to each other in the Z direction, forms the internal space S between the current collectors 15 adjacent to each other in the Z direction.

[0043] The spacer 22 has a frame shape (here, a rectangular frame shape) that follows the outer shape of the current collector 15 when viewed from the Z direction, and is disposed on the peripheral portion 15c of the current collector 15 when viewed from the Z direction. That is, the spacer 22 has an inner portion 22a that overlaps the current collector 15 when viewed from the Z direction, and an outer portion 22b that is located outside the outer edge 15e of the current collector 15. When viewed from the Z direction, the outer portion 22b of the spacer 22 does not overlap with the current collector 15. The inner portion 22a and the outer portion 22b each have a frame shape (here, a rectangular frame shape) when viewed from the Z direction.

[0044] The end of the separator 14 may be held by being sandwiched between the sealant 21 and the spacer 22. The end of the separator 14 may be fixed by being welded to at least one of the sealant 21 and the spacer 22.

[0045] A portion of each of the seal materials 21 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer portion 21b) and a portion of each of the spacers 22 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer portion 22b) are welded together and integrated to form a welded portion 23. That is, the sealing body 20 includes the welded portion 23 formed by welding the outer portions 21b of the seal materials 21 and the outer portions 22b of the spacers 22 together. When viewed from the Z direction, the welded portion 23 has a frame shape surrounding the electrode stack 10 and forms the outer periphery of the sealing body 20. Therefore, the outer surface of the welded portion 23 forms the outer surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer surfaces extending along the Z direction. The spacers 22 do not need to be welded to the sealing materials 21 at least at the inner portions 21a of the sealing materials 21 adjacent to each other in the Z direction. The corners of the welded portion 23 may include chamfered portions by performing chamfering such as light chamfering, C chamfering, and R chamfering.

[0046] Conductive members (not shown) are laminated on the other surface 15b of the current collector 15 of the negative terminal electrode 12 and on the portion of the one surface 15a of the current collector 15 of the positive terminal electrode 13 that is exposed from the sealing body 20 (i.e., the portion where the sealing material 21 is not provided when viewed from the Z direction). The conductive members are electrically connected to the current collector 15 of the negative terminal electrode 12 and the current collector 15 of the positive terminal electrode 13, respectively. The conductive members are interposed between adjacent power storage modules 1 and function as terminals for extracting current from the power storage modules 1. The conductive members can be used to electrically connect multiple power storage modules 1. Multiple power storage modules 1 may be arranged in series via the conductive members.

[0047] The conductive member may also be used as a member for applying a restraint load to the electrode stack 10. That is, when a restraint member (not shown) is arranged to restrain the energy storage module 1 from the Z direction, the restraint load may be applied to the electrode stack 10 via the conductive member. Furthermore, a cooling flow path may be formed in the conductive member. The energy storage module 1 can be cooled by circulating a cooling medium through the cooling flow path formed in the conductive member. Furthermore, members (not shown) configured integrally with or separately from the conductive member may be arranged on both sides of the sealing body 20 in the Z direction, and a restraint load may be applied to the sealing body 20 via these members.

[0048] Fig. 3 is a schematic cross-sectional view showing an enlarged portion of the electricity storage module shown in Fig. 1. In Fig. 1 and Fig. 3, the separator 14 is provided between the surface of the spacer 22 on the negative electrode active material layer 17 side and the sealing material 21 facing said surface, but the separator 14 is not limited to this as long as it can ensure insulation between the positive electrode active material layer 16 and the negative electrode active material layer 17.

[0049] 1 to 3, as viewed from the Z direction, the inner edge 22e of the spacer 22 (i.e., a part of the inner portion 22a) is located between the outer edge 17e of the negative electrode active material layer 17 and the outer edge 16e of the positive electrode active material layer 16. As a result, the spacer 22 includes an overlapping portion 22r that overlaps with the negative electrode active material layer 17 as viewed from the Z direction, and a non-overlapping portion 22p that does not overlap with the sealing material 21 and the negative electrode active material layer 17 as viewed from the Z direction.

[0050] Of the multiple spacers 22, the outermost spacer 22 in the Z direction (here, closest to the positive terminal electrode 13) may be sandwiched at an overlapping portion 22r between a pair of adjacent negative electrode active material layers 17 along the Z direction, with the separator 14 interposed therebetween. More specifically, the overlapping portion 22r of the outermost spacer 22 in the Z direction may be in contact with one surface 15a of the current collector 15 and the separator 14 facing the one surface 15a. In this case, the outermost spacer 22 in the Z direction may be joined (for example, welded) to the one surface 15a of the current collector 15 at the overlapping portion 22r.

[0051] In this embodiment, among the multiple spacers 22, the spacers 22 (intermediate spacers 22) other than the outermost spacers 22 in the Z direction are configured not to contact the current collector 15 of the adjacent bipolar electrode 11 at the overlapping portion 22r. That is, the thickness Ts of the spacers 22 in the Z direction is thinner than the thickness Tp of the positive electrode active material layer 16 in the Z direction. In other words, an internal space S is interposed between the intermediate spacer 22 and one surface 15a of the current collector 15 of the adjacent bipolar electrode. In this embodiment, the thickness Ts of the spacer 22 at the overlapping portion 22r may be equal to the thickness of the portion of the spacer 22 that overlaps with the sealing material 21 as viewed in the Z direction.

[0052] The negative electrode active material layer 17 includes a rectangular first portion 171 that overlaps the positive electrode active material layer 16 when viewed from the Z direction, and a frame-shaped (here, rectangular frame-shaped) second portion 172 that is located outside the outer edge 16 e of the positive electrode active material layer 16 when viewed from the Z direction and includes the outer edge 17 e of the negative electrode active material layer 17. The thickness Tn of the negative electrode active material layer 17 in the Z direction may be constant or different between the first portion 171 and the second portion 172. In this embodiment, the thickness T1 of the first portion 171 in the Z direction and the thickness T2 of the second portion 172 in the Z direction are the same.

[0053] The current collector 15 also includes a first region 151 that does not overlap the negative electrode active material layer 17 or the sealing material 21 when viewed from the Z direction, and a second region 152 that overlaps the negative electrode active material layer 17 but does not overlap the positive electrode active material layer 16 when viewed from the Z direction. The first region 151 is a region between an outer edge 17e of the negative electrode active material layer 17 and an inner edge 21e of the sealing material 21. That is, the first region 151 coincides with the non-overlapping portion 22p of the spacer 22 when viewed from the Z direction.

[0054] The second region 152 is a region between the outer edge 16 e of the positive electrode active material layer 16 and the outer edge 17 e of the negative electrode active material layer 17. In this embodiment, the width W1 of the first region 151 when viewed from the Z direction is narrower than the width W2 of the second region 152 when viewed from the Z direction. As described above, the spacer 22 includes the overlapping portion 22 r, and thus the spacer 22 is disposed between the current collectors 15 adjacent to each other in the Z direction in the first region 151.

[0055] Furthermore, the electrode laminate 10 includes a first laminate portion 101 in which the negative electrode active material layer 17 and the positive electrode active material layer 16 overlap as viewed from the Z direction, and a second laminate portion 102 including a portion in which the negative electrode active material layer 17 and the spacer 22 (overlapping portion 22r) overlap as viewed from the Z direction. As viewed from the Z direction, the second laminate portion 102 corresponds to the combined region of the first region 151 and the second region 152. The sealing body 20 includes a first sealing portion 201 in which the sealant 21 and the spacer 22 overlap as viewed from the Z direction. As viewed from the Z direction, the first sealing portion 201 does not overlap the overlapping portion 22r and the non-overlapping portion 22p of the spacer 22. In this embodiment, the thicknesses in the Z direction are thinner in the order of the first laminate portion 101, the second laminate portion 102, and the first sealing portion 201. That is, the thickness of the second stacked portion 102 in the Z direction is thinner than the thickness of the first stacked portion 101 in the Z direction, and the thickness of the first sealing portion 201 in the Z direction is thinner than the thickness of the second stacked portion 102 in the Z direction.

[0056] As described above, the energy storage module 1 according to this embodiment includes an electrode stack 10 in which a plurality of electrodes, each including a plurality of bipolar electrodes 11, are stacked along the Z direction. Each electrode includes a current collector 15 and a negative electrode active material layer 17 and a positive electrode active material layer 16 provided on both sides of the current collector 15. When viewed from the stacking direction of the electrodes (first direction, here the Z direction), the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16. In addition, in the energy storage module 1 according to this embodiment, a sealing body 20 is provided for the electrode stack 10. The sealing body 20 includes a plurality of sealing materials 21 welded to the current collector 15 at peripheral portions 15c of the electrode current collector 15 and stacked in the Z direction, and a plurality of spacers 22 interposed between the sealing materials 21 and forming an internal space S between the current collectors 15 together with the sealing materials 21.

[0057] When viewed from the Z direction, the inner edge 22e of the spacer 22 is located between the outer edge 17e of the negative electrode active material layer 17 and the outer edge 16e of the positive electrode active material layer 16. In other words, the spacer 22 extends from a position between adjacent seal materials 21 to the negative electrode active material layer 17. As a result, the spacer 22 is disposed in the first region 151 of the current collector 15 where neither an active material layer nor a seal material 21 is provided, thereby ensuring rigidity of the electricity storage module. Therefore, even when some force is applied to the electricity storage module 1, deformation of the current collector 15 is suppressed.

[0058] The energy storage module 1 according to this embodiment can also achieve the following effects. Specifically, the bipolar battery described in Patent Document 1 may encounter the following problems. For example, when a temperature change occurs in a bipolar battery, a force is applied to the current collector due to the difference in thermal expansion coefficient between the current collector and the seal layer, which may cause wrinkles (deformation) in the current collector in areas with relatively low rigidity. Furthermore, when a separate component (e.g., a liquid injection component used to inject an electrolyte) is formed on the outer surface of the seal layer by injection molding, a force is applied to the bipolar battery in a direction perpendicular to the stacking direction. This may cause wrinkles in the areas with relatively low rigidity. Furthermore, for example, when the internal space is depressurized, wrinkles may occur in the area, or the internal space may change due to deformation of the current collector. In contrast, the energy storage module 1 according to this embodiment solves the above problems by suppressing deformation of the current collector as described above.

[0059] Here, the overlapping portions 22r of the spacers 22 (intermediate spacers 22) other than the outermost spacers 22 in the Z direction are disposed in a region corresponding to the thickness of the positive electrode active material layer 16 between the negative electrode active material layer 17 of one bipolar electrode 11 and the current collector 15 of another bipolar electrode 11 adjacent to the one bipolar electrode 11. In contrast, in the energy storage module 1 according to this embodiment, the spacers 22 are thinner than the positive electrode active material layer 16 at least in the overlapping portions 22r. That is, the thickness Ts of the spacers 22 in the Z direction at the overlapping portions 22r is thinner than the thickness Tp of the positive electrode active material layer 16 in the Z direction. This allows the intermediate spacers 22 to be configured not to come into contact with the current collector 15 of the other bipolar electrode 11 at least in the overlapping portions 22r (as a whole in this embodiment). In this case, the intermediate spacers 22 can be configured not to come into contact with the current collector 15 of the other bipolar electrode 11 even when the active material layers expand. The outermost spacer 22 in the Z direction can come into contact with the current collector 15 of the positive terminal electrode 13 at least at the overlapping portion 22r.

[0060] Furthermore, in the energy storage module 1 according to this embodiment, the outer edge of the sealant 21 and the outer edge of the spacer 22 are welded to each other to form the welded portion 23. This reliably seals the internal space S. Furthermore, the spacer 22 is reliably supported between the sealants 21 adjacent to each other in the Z direction.

[0061] Furthermore, in the energy storage module 1 according to this embodiment, the current collector 15 includes a first region 151 that does not overlap with the negative electrode active material layer 17 and the sealing material 21 when viewed from the Z direction, and a second region 152 that overlaps with the negative electrode active material layer 17 but does not overlap with the positive electrode active material layer 16 when viewed from the Z direction. That is, one surface 15a and the other surface 15b of the current collector 15 include regions that are exposed to the internal space S. The width W1 of the first region 151 when viewed from the Z direction is narrower than the width W2 of the second region 152 when viewed from the Z direction. Therefore, the width of the first region 151 (a region where neither an active material layer nor the sealing material 21 is provided) in the current collector 15, which has a relatively low rigidity, becomes narrower, thereby further improving the rigidity.

[0062] Furthermore, in the energy storage module 1 according to this embodiment, the electrode stack 10 includes a first stack portion 101 in which the negative electrode active material layer 17 and the positive electrode active material layer 16 overlap as viewed from the Z direction, and a second stack portion 102 that is located outside the positive electrode active material layer 16 as viewed from the Z direction and in which the negative electrode active material layer 17 and the spacer 22 overlap as viewed from the Z direction. The sealing body 20 includes a first sealing portion 201 in which the sealant 21 and the spacer 22 overlap as viewed from the Z direction. The thickness of the second stack portion 102 in the Z direction is thinner than the thickness of the first stack portion 101 in the Z direction, and the thickness of the first sealing portion 201 in the Z direction is thinner than the thickness of the second stack portion 102 in the Z direction. In this way, in the energy storage module 1, the thicknesses are gradually reduced in the following order: the first laminated portion 101 provided with the negative electrode active material layer 17 and the positive electrode active material layer 16; the second laminated portion 102 provided with only the negative electrode active material layer 17 and with the spacer 22 overlapping the negative electrode active material layer 17; and the first sealing portion 201 provided with the sealing material 21 and the spacer 22. This prevents a sudden change in thickness in response to a change in position of the current collector 15.

[0063] The above embodiment has been described as one form of the energy storage module according to the present invention. Therefore, the energy storage module according to the present invention is not limited to the above embodiment and can be modified as desired. Next, modifications will be described. [First Modification]

[0064] FIG. 4 is a schematic cross-sectional view showing an enlarged portion of the energy storage module according to the first modification. As shown in FIG. 4 , the energy storage module 1A according to the first modification is different from the energy storage module 1 according to the above embodiment in that the thickness T2 in the Z direction of the second portion 172 of the negative electrode active material layer 17 is thicker than the thickness T1 in the Z direction of the first portion 171 of the negative electrode active material layer 17, but is otherwise identical. In the first modification, when viewed from the Z direction, the outer edge of the first portion 171 of the negative electrode active material layer 17 overlaps with the outer edge of the positive electrode active material layer 16 provided on one surface 15 a of the current collector 15 of the bipolar electrode 11 on which the negative electrode active material layer 17 is provided. That is, in the first modification, when the bipolar electrodes 11 are stacked along the Z direction, the negative electrode active material layer 17 is recessed so that the positive electrode active material layer 16 extends along the Z direction into the first portion 171 of the negative electrode active material layer 17. As a result, when viewed from the Z direction, the positive electrode active material layer 16 is surrounded by the relatively thick portion (second portion 172) of the negative electrode active material layer 17, so that the bipolar electrode 11 can be positioned in a plane intersecting the Z direction.

[0065] In the first modified example, the inner edge 22e of the spacer 22 overlaps a relatively thick portion (second portion 172) of the negative electrode active material layer 17. Also in the first modified example, the thickness Ts of the spacer 22 in the Z direction is made thinner than the thickness Tp of the positive electrode active material layer 16 in the Z direction so that the spacer 22 in the intermediate portion does not contact the current collector 15 of the adjacent bipolar electrode 11 at the overlapping portion 22r. Furthermore, in the Z direction, the sum of the thickness T2 of the second portion 172 of the negative electrode active material layer 17 and the thickness Ts of the spacer 22 at the overlapping portion 22r is thinner than the sum of the thickness T1 of the first portion 171 of the negative electrode active material layer 17 and the thickness Tp of the positive electrode active material layer 16. Therefore, even if the second portion 172 that is relatively thicker than the negative electrode active material layer 17 is provided as in the first modified example, the spacer 22 in the middle portion does not come into contact with the current collector 15 facing the spacer 22 on the positive electrode active material layer 16 side even when the active material layer expands. [Second Modification]

[0066] 5 is a schematic cross-sectional view showing an enlarged portion of the power storage module according to the second modification. As shown in FIG. 5, the power storage module 1B according to the second modification is different from the power storage module 1A according to the first modification in that the negative electrode active material layer 17 has a tapered portion 17p, but is the same in other respects. The tapered portion 17p is an outer edge portion including the outer edge 17e of the negative electrode active material layer 17. The thickness of the tapered portion 17p in the Z direction gradually decreases from the center of the negative electrode active material layer 17 toward the outer edge 17e due to an inclined surface that is inclined toward the other surface 15b of the current collector 15 on which the negative electrode active material layer 17 is provided.

[0067] In the energy storage module 1B according to the second modification, the corners of the negative electrode active material layers 17 that face the spacers 22 via the separators 14 are chamfered. This reduces the slope of the portions of the spacers 22 that contact the tapered portions 17p via the separators 14, and prevents the portions of the spacers 22 from being damaged by contact with the sharper corners of the negative electrode active material layers 17. [Third Modification]

[0068] Fig. 6 is a schematic cross-sectional view showing an enlarged portion of the energy storage module according to the third modification. As shown in Fig. 6, the energy storage module 1C according to the third modification is different from the energy storage module 1 according to the above embodiment in that the thickness in the Z direction of the first stack unit 101, the thickness in the Z direction of the second stack unit 102, and the thickness in the Z direction of the first sealing unit 201 are all substantially the same, but are the same in other respects.

[0069] In this way, the thickness in the Z direction of the first stacked portion 101, the second stacked portion 102, and the first sealing portion 201 is not limited to being changed so as to become thinner in order as in the storage module 1 of the above embodiment (when there are two steps), but may be constant as in the storage module 1B (when there are no steps).

[0070] Furthermore, the thicknesses of the first laminated portion 101, the second laminated portion 102, and the first sealing portion 201 in the Z direction are not limited to the above examples, and may be, for example, an embodiment in which the thickness of the first laminated portion 101 in the Z direction and the thickness of the second laminated portion 102 in the Z direction are substantially the same, and the thickness of the first sealing portion 201 in the Z direction is thinner than the thicknesses of the first laminated portion 101 and the second laminated portion 102 in the Z direction (an embodiment in which there is one step). [Fourth Modification]

[0071] 7 is a schematic cross-sectional view showing an enlarged portion of a power storage module according to the fourth modification. As shown in FIG. 7 , the power storage module 1D according to the fourth modification is different from the power storage module 1C according to the third modification in that the spacer 22 includes a protrusion 22t, but is otherwise identical. The protrusion 22t protrudes toward the other surface 15b of the current collector 15 facing the spacer 22 in a region (i.e., a first region 151) between the outer edge 17e of the negative electrode active material layer 17 and the inner edge 21e of the sealing material 21 as viewed in the Z direction. The thickness of the protrusion 22t in the Z direction is greater than the thickness Ts of the spacer 22 at the overlapping portion 22r in the Z direction.

[0072] More specifically, the protruding portion 22t of one spacer 22 protrudes toward the other surface 15b of the current collector 15 on which the negative electrode active material layer 17, which the one spacer 22 contacts via the separator 14, is provided. The top surface of the protruding portion 22t may be in contact with the other surface 15b via the separator 14, or may be spaced from the other surface 15b by a distance equal to or greater than the thickness of the separator 14. According to the energy storage module 1D of the fourth modification, the protruding portion 22t of the spacer 22 can support a region (first region 151) of the current collector 15 where neither an active material layer nor a sealant 21 is provided. This more reliably prevents wrinkles from forming in the current collector 15 in the first region 151.

[0073] Note that various modes may be adopted for the formation range of the protrusions 22t as viewed from the Z direction. As an example, as shown in Fig. 8 , the protrusions 22t may be provided only at positions facing each of the four corners of the region between the outer edge 17e of the negative electrode active material layer 17 and the inner edge 21e of the sealing material 21 (the rectangular annular first region 151 of the current collector 15) as viewed from the Z direction.

[0074] Alternatively, as shown in FIG. 9 , the protrusions 22t may be provided only at locations facing each of two side portions (here, short side portions) of the region between the outer edge 17e of the negative electrode active material layer 17 and the inner edge 21e of the sealing material 21 (the rectangular annular first region 151 of the current collector 15) when viewed from the Z direction.

[0075] 10 , the protrusion 22t may be provided over the entire region between the outer edge 17e of the negative electrode active material layer 17 and the inner edge 21e of the sealing material 21 (the rectangular annular first region 151 of the current collector 15) when viewed from the Z direction.

[0076] In the above embodiment, an example has been described in which the width W1 of the first region 151 of the current collector 15 when viewed from the Z direction is narrower than the width W2 of the second region 152 of the current collector 15 when viewed from the Z direction. However, the width W1 of the first region 151 when viewed from the Z direction and the width W2 of the second region 152 when viewed from the Z direction may be the same, or the width W1 of the first region 151 when viewed from the Z direction may be wider than the width W2 of the second region 152 when viewed from the Z direction.

[0077] In addition, in the above embodiment, an example was described in which the outermost spacer 22 in the Z direction is in contact with the current collector 15 of the positive terminal electrode 13 at the overlapping portion 22r, but the spacer 22 does not have to be in contact with the current collector 15 of the positive terminal electrode 13 at the overlapping portion 22r.

[0078] Furthermore, the elements of the energy storage module 1 according to the above embodiment and the elements of the energy storage modules 1A to 1D according to the modifications can be applied to one another in any desired manner. As an example, the protrusion 22t of the spacer 22 according to the fourth modification may be applied to the energy storage module 1 according to the above embodiment or to the energy storage modules according to the other modifications. Furthermore, the tapered portion 17p of the negative electrode active material layer 17 according to the second modification may be applied to the negative electrode active material layer 17 of the energy storage module 1 according to the above embodiment, the energy storage module 1C according to the third modification, or the energy storage module 1D according to the fourth modification.

[0079] Here, Fig. 11 is a schematic plan view of a power storage module 1 according to another modification. Fig. 11 is a plan view of a bipolar electrode 11 and a spacer 22 according to the modification, viewed from one surface 15a (second surface) of a current collector 15 of the bipolar electrode 11. As shown in Fig. 11, one surface 15a of the current collector 15 of the bipolar electrode 11 is divided into a rectangular first region 15T where the positive electrode active material layer 16 is formed and a second region 15M outside the first region 15T. In this case, the spacer 22 can be divided by an extension line L1 (first partition line) of a long side (first side) of the first region 15T and an extension line L2 (second partition line) of a short side (second side) of the first region 15T. The spacer 22 is divided into a short side portion (first section) 22S along the short side, separated by a pair of extension lines L1, a long side portion (second section) 22L along the long side, separated by a pair of extension lines L2, and a corner portion (third section) 22C connecting the long side portion 22L and the short side portion 22S, separated by extension lines L1 and L2.

[0080] A notched portion 22m is formed in at least one corner portion 22C of the spacer 22. In the illustrated example, the notched portions 22m are formed in four corner portions 22C. Note that the notched portion may be a region that has a notched or cut-out shape when viewed from the stacking direction (Z direction) in the rectangular frame-shaped spacer 22 defined by inner and outer edges of a rectangular shape.

[0081] In other words, when viewed from the stacking direction, at least one side of the spacer 22 may include a wide portion 22W having a large widthwise length and a notched portion 22K having a widthwise length smaller than that of the wide portion 22W. The widthwise length may be the length of each side of the spacer 22 in the width direction perpendicular to the longitudinal direction of the side. That is, the widthwise length of the short side portion 22S is the length in the X direction, and the widthwise length of the long side portion 22L is the length in the Y direction. If the spacer 22 has a cutout portion such as a hole, the widthwise length of the spacer 22 may be defined as the length from the inner edge to the outer edge minus the length of the cutout portion. In the following description, the "widthwise length" may be simply referred to as "width."

[0082] The cutout portion 22m has a notched shape in which the widthwise length of the spacer 22 narrows from the inner edge toward the outer edge of the spacer 22. The cutout portion 22m may be formed in a region of the spacer 22 other than the welded portion 23, and is provided in at least a region where the spacer 22 and the negative electrode active material layer 17 overlap when viewed from the stacking direction. That is, when viewed from the stacking direction, the cutout portion 22m and the welded portion 23 do not need to overlap each other. In one example, the cutout portion 22m has a quadrangular shape that includes a corner of the inner edge of the corner portion 22C of the spacer 22. That is, while the inner edge of a rectangular frame-shaped spacer is normally rectangular with four corners, the inner edge of the spacer 22 shown in FIG. 11 has a shape in which the four corners of the inner edge are cut off by the cutout portion 22m. In this modification, the notched portion 22 m is provided inside the outer edge of the current collector 15 when viewed from the stacking direction, and therefore does not need to reach the welded portion 23 .

[0083] As described above, in this modification, the spacer 22 has a rectangular frame shape when viewed from the Z direction, and the current collector 15 has, on one surface 15 a, a rectangular first region 15T in which the positive electrode active material layer 16 is provided, and a rectangular frame-shaped second region 15M that is located outside the first region 15T when viewed from the Z direction. The outer edge of the rectangular first region 15T is defined by a pair of opposing first sides (long sides) and opposing second sides (short sides) that connect the pair of first sides. Furthermore, when the spacer 22 is divided, as viewed from the Z direction, by first partition lines (extension lines L1) extending from a pair of first sides and second partition lines (extension lines L2) extending from a pair of second sides, the spacer 22 is divided into a pair of first sections (short side portions 22S) separated by the first partition lines and extending along the pair of second sides, a pair of second sections (long side portions 22L) separated by the second partition lines and extending along the first sides, and four third sections (corner portions 22C) separated by the first partition lines and second partition lines, connecting the first and second sections, and including the four corners of the spacer 22. At least one of the spacers 22 has a notched portion 22m formed in at least one third section such that the widthwise length of the spacer 22 from an outer edge 22f of the spacer 22 to the internal space S is shorter than the widthwise length of the spacer 22 in the adjacent first section or second section.

[0084] As a result, the cutout portion 22m can expose an area near the outer edge 17e of the negative electrode active material layer 17 from the spacer 22. When the spacer 22 is configured, for example, by arranging a plurality of rectangular (strip-shaped) base materials to form a rectangular frame, the corners of the spacer 22 can be relatively thick due to the longitudinal end of one base material overlapping with the longitudinal end of another base material. In contrast, in the example shown in FIG. 11 , by providing the cutout portion 22m at the corners, which are areas that can be thick, the spacer 22 is prevented from protruding in the Z direction at the corners, i.e., the protrusion of the spacer 22 in the Z direction can be prevented from creating a step in the energy storage module 1.

[0085] Note that the cutout portions 22m can be formed by any method, such as, for example, forming cutouts in advance in overlapping portions of the base materials and then arranging the base materials in a rectangular frame shape to form the spacer 22, or forming cutouts in the overlapping portions after arranging the base materials in a rectangular frame shape. If the cutout portions 22m are formed before welding the spacers 22, resin may get into the cutout portions 22m when welding the spacers 22. Even in this case, protrusion of the spacers 22 in the Z direction can be suppressed compared to when the cutout portions 22m are not formed in the spacers 22.

[0086] The following additional notes will be made regarding the above embodiment.

[0087] The energy storage module according to [Addendum 1] includes: "an electrode stack in which a plurality of electrodes, each including a plurality of bipolar electrodes, are stacked along a first direction; and a sealing body provided on the electrode stack for sealing the electrode stack, wherein each of the plurality of bipolar electrodes has a current collector including a first surface intersecting the first direction and a second surface opposite to the first surface, a first active material layer provided on the first surface, and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer; and the sealing body includes a plurality of sealing materials stacked along the first direction and a plurality of spacers interposed between the sealing materials adjacent to each other along the first direction, and the plurality of sealing materials each of the plurality of spacers is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction and is welded to the first surface and the second surface at the peripheral portion of the current collector; each of the plurality of spacers is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction and, together with the sealing materials adjacent along the first direction, forms an internal space between the current collectors adjacent in the first direction; when viewed from the first direction, the outer edge of the first active material layer is located outside the outer edge of the second active material layer; and when viewed from the first direction, the inner edge of the spacer is located between the outer edge of the first active material layer and the outer edge of the second active material layer.

[0088] The energy storage module according to [Second Appendix] may be "the energy storage module described in First Appendix, in which the spacer includes an overlapping portion that overlaps the first active material layer when viewed from the first direction, and is thinner than the second active material layer at the overlapping portion."

[0089] The energy storage module according to [Appendix 3] may be "the energy storage module according to Appendix 1 or Appendix 2, wherein the spacer includes an overlapping portion that overlaps the first active material layer when viewed from the first direction, the plurality of electrodes include a first terminal electrode that is located at the outermost part of the electrode stack in the first direction and has the current collector and the second active material layer provided on the second surface, and the outermost spacer in the first direction among the plurality of spacers is in contact with the current collector of the first terminal electrode at the overlapping portion."

[0090] The energy storage module according to [Appendix 4] may be "the energy storage module according to any one of Appendices 1 to 3, wherein the first active material layer includes a first portion that overlaps with the second active material layer when viewed from the first direction, and a second portion that is located outside the outer edge of the second active material layer when viewed from the first direction and includes the outer edge of the first active material layer, and wherein the thickness of the second portion in the first direction is greater than the thickness of the first portion in the first direction."

[0091] The energy storage module according to [Appendix 5] may be "an energy storage module according to any one of Appendices 1 to 4, in which the outer edge of the sealing material and the outer edge of the spacer are welded to each other to form a welded portion."

[0092] The energy storage module according to [Appendix 6] may be "the energy storage module according to any one of Appendices 1 to 5, in which the current collector includes a first region that does not overlap with the first active material layer and the sealing material when viewed from the first direction, and a second region that overlaps with the first active material layer when viewed from the first direction and does not overlap with the second active material layer, and the width of the first region when viewed from the first direction is narrower than the width of the second region when viewed from the first direction."

[0093] The energy storage module according to [Supplementary Note 7] may be "the energy storage module according to any one of Supplementary Notes 1 to 6, wherein the electrode stack includes a first stack portion in which the first active material layer and the second active material layer overlap when viewed from the first direction, and a second stack portion that is outer than the second active material layer when viewed from the first direction and in which the first active material layer and the spacer overlap; the sealing body includes a first sealing portion in which the sealant and the spacer overlap when viewed from the first direction; the thickness of the second stack portion in the first direction is thinner than the thickness of the first stack portion in the first direction, and the thickness of the first sealing portion in the first direction is thinner than the thickness of the second stack portion in the first direction."

[0094] The energy storage module according to [Appendix 8] may be "an energy storage module according to any one of Appendices 1 to 7, in which the spacer includes a protrusion that protrudes toward the first surface facing the spacer between the outer edge of the first active material layer and the inner edge of the sealing material when viewed from the first direction."

[0095] The energy storage module according to [Supplementary Note 9] is a module in which "the spacer has a rectangular frame shape when viewed from the first direction, and the current collector has, on the second surface, a rectangular first region in which the second active material layer is provided, and a rectangular frame-shaped second region outside the first region when viewed from the first direction, and an outer edge of the rectangular first region is defined by a pair of first sides that face each other and a second side that connects the pair of first sides and faces each other, and when the spacer is divided, when viewed from the first direction, by first partition lines that extend from the pair of first sides and second partition lines that extend from the pair of second sides, the spacer is divided by the first partition lines and has a rectangular frame shape along the pair of second sides. a pair of first compartments separated by the second partition line and along the first side; and four third compartments separated by the first partition line and the second partition line and connecting the first compartments and the second compartments, and including four corners of the spacer, wherein at least one of the plurality of spacers has a notched portion formed in at least one third compartment such that a widthwise length of the spacer from an outer edge of the spacer to the internal space is shorter than the widthwise length of the spacer in the adjacent first compartment or the adjacent second compartment.

[0096] REFERENCE SIGNS 1, 1A, 1B, 1C... energy storage module, 10... electrode laminate, 11... bipolar electrode, 15... current collector, 15a... one side (second surface), 15b... other side (first surface), 16... positive electrode active material layer (second active material layer), 16e... outer edge, 17... negative electrode active material layer (first active material layer), 17e... outer edge, 20... sealing body, 21... sealing material, 21e... inner edge, 22... spacer, 22e... inner edge, 22t... protruding portion, 22r... overlapping portion, 23... welded portion, 101... first laminated portion, 102... second laminated portion, 151... first region, 152... second region, 171... first portion, 172... second portion, 201... first sealing portion, S... internal space.

Claims

1. An electrode laminate comprising a plurality of electrodes, each of which includes a plurality of bipolar electrodes, stacked along a first direction; and a sealing body provided on the electrode laminate for sealing the electrode laminate, wherein each of the plurality of bipolar electrodes comprises: a current collector including a first surface intersecting the first direction and a second surface opposite to the first surface; a first active material layer provided on the first surface; and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer, wherein the sealing body comprises: a plurality of sealing materials stacked along the first direction; and a plurality of spacers interposed between the sealing materials adjacent to each other along the first direction, wherein each of the plurality of sealing materials is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction, and is welded to the first surface and the second surface at the periphery of the current collector, each of the spacers is formed in a frame shape that follows the outer shape of the current collector when viewed from the first direction, and together with the sealing materials adjacent along the first direction, forms an internal space between the current collectors adjacent in the first direction; when viewed from the first direction, an outer edge of the first active material layer is positioned outward from an outer edge of the second active material layer; and when viewed from the first direction, an inner edge of the spacer is positioned between the outer edge of the first active material layer and the outer edge of the second active material layer.

2. The energy storage module according to claim 1, wherein the spacer includes an overlapping portion that overlaps the first active material layer when viewed from the first direction, and the spacer is thinner than the second active material layer at the overlapping portion.

3. The energy storage module described in claim 1 or 2, wherein the spacer includes an overlapping portion that overlaps the first active material layer when viewed from the first direction, the plurality of electrodes include a first terminal electrode located at the outermost part of the electrode stack in the first direction and having the current collector and the second active material layer provided on the second surface, and the outermost spacer in the first direction among the plurality of spacers is in contact with the current collector of the first terminal electrode at the overlapping portion.

4. A storage module as described in any one of claims 1 to 3, wherein the first active material layer includes a first portion overlapping the second active material layer when viewed from the first direction, and a second portion located outside the outer edge of the second active material layer when viewed from the first direction and including the outer edge of the first active material layer, and the thickness of the second portion in the first direction is thicker than the thickness of the first portion in the first direction.

5. The energy storage module according to any one of claims 1 to 4, wherein an outer edge of the sealing material and an outer edge of the spacer are welded to each other to form a welded portion.

6. The energy storage module described in any one of claims 1 to 5, wherein the current collector includes a first region that does not overlap with the first active material layer and the sealing material when viewed from the first direction, and a second region that overlaps with the first active material layer when viewed from the first direction and does not overlap with the second active material layer, and the width of the first region when viewed from the first direction is narrower than the width of the second region when viewed from the first direction.

7. The energy storage module described in any one of claims 1 to 6, wherein the electrode stack includes a first stack portion in which the first active material layer and the second active material layer overlap when viewed from the first direction, and a second stack portion outer than the second active material layer when viewed from the first direction and in which the first active material layer and the spacer overlap; the sealing body includes a first sealing portion in which the sealant and the spacer overlap when viewed from the first direction, the thickness of the second stack portion in the first direction is thinner than the thickness of the first stack portion in the first direction, and the thickness of the first sealing portion in the first direction is thinner than the thickness of the second stack portion in the first direction.

8. The energy storage module according to any one of claims 1 to 7, wherein the spacer includes a protrusion that protrudes toward the first surface side facing the spacer, between an outer edge of the first active material layer and an inner edge of the sealing material when viewed from the first direction.

9. The spacer has a rectangular frame shape when viewed from the first direction, and the current collector has, on the second surface, a rectangular first region in which the second active material layer is provided, and a rectangular frame-shaped second region outside the first region, and an outer edge of the rectangular first region is defined by a pair of first sides opposed to each other and a second side connecting the pair of first sides and opposed to each other, and when the spacer is divided, as viewed from the first direction, by a first partition line extending from the pair of first sides and a second partition line extending from the pair of second sides, the spacer is divided into a pair of first sections separated by the first partition lines and extending along the pair of second sides, a pair of second sections separated by the second partition lines and extending along the first sides, and four third sections separated by the first partition line and the second partition line, connecting the first section and the second section, and including the four corners of the spacer, 9. The energy storage module according to claim 1, wherein at least one of the plurality of spacers has a cutout portion formed in at least one third compartment such that a widthwise length of the spacer from an outer edge of the spacer to the internal space is shorter than the widthwise length of the spacer in an adjacent first compartment or second compartment.

Images