Electric power storage module

Abstract

The present invention provides an electric power storage module which comprises an electrode stack, a sealing body that is provided on the electrode stack, and a frame member that is bonded to the sealing body, while being configured separately from the sealing body, wherein: the sealing body comprises a welded end part that is formed by welding a sealing material and an end of a spacer to each other, and a communicating pore that has an opening in the outer surface of the welded end part; the frame member comprises a frame part that surrounds the opening of the communicating pore; and the frame part has a first end face that is bonded to the outer surface so as to surround the opening, and a second end face that is formed so as to surround the opening, while being opposite to the first end face.

Description

Energy storage module

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

[0002] Patent Document 1 describes an energy storage module. The energy storage module includes an electrode stack including multiple electrodes stacked with separators interposed therebetween, and a sealing body arranged to surround the electrode stack. The sealing body includes a first resin portion provided on the peripheral edge of the electrode plate and a second resin portion provided outside the multiple first resin portions so as to surround the multiple first resin portions. The sealing body has multiple communication holes communicating with different internal spaces formed between the electrodes. The communication holes are used, for example, to supply an electrolyte solution to the internal spaces. One of the four wall portions constituting the sealing body has multiple communication hole regions formed therein, each with an equal number of communication holes. In this energy storage module, the electrolyte solution is supplied to the internal spaces while the tip surface of a nozzle of an electrolyte solution supply device is pressed against the communication hole region of the sealing body via a packing. At this time, the packing is strongly compressed by multiple protrusions provided in the communication hole region so as to surround each of the multiple communication holes.

[0003] Patent Document 2 describes an energy storage module. This energy storage module includes an electrode stack including multiple electrodes stacked with separators interposed therebetween, a frame body arranged to surround the electrode stack, and a pressure regulating valve attached to the frame body. The frame body includes a first sealing portion provided on the periphery of the electrode plate and a second sealing portion provided outside the first sealing portion. One wall portion constituting the frame body is provided with multiple mounting areas for mounting the pressure regulating valve. In each mounting area, the frame body is provided with a communication hole communicating with an internal space formed between the electrodes. The communication hole is used, for example, to supply an electrolyte to the internal space. In this energy storage module, the communication hole can be sealed by attaching a pressure regulating valve to the mounting area. The frame body is provided with a frame-shaped protrusion in the mounting area, which is used for joining the pressure regulating valve by thermal welding.

[0004] JP 2020-035665 A JP 2021-009795 A

[0005] In Patent Documents 1 and 2, a frame-shaped ridge or protrusion is formed by injection molding together with the second resin portion and the second sealing portion. As a specific example, a laminate formed by stacking electrode plates each having a first sealing portion is placed in an injection mold and resin is injected into the laminate by insert molding, forming the frame-shaped protrusion together with the second sealing portion. At this time, the resin injected into the mold flows over the entire outer surface of the first sealing portion, including the opening of the communication hole. This can result in defects such as the resin clogging the communication hole, potentially reducing reliability.

[0006] An object of the present disclosure is to provide an energy storage module that can suppress a decrease in reliability.

[0007] The electricity storage module according to the present disclosure includes an electrode stack including a plurality of electrodes stacked along a first direction, each electrode including a current collector and an active material layer formed on the current collector; a seal provided in the electrode stack to form an internal space between adjacent current collectors and seal the internal space; an electrolyte solution contained in the internal space; and a frame member formed separately from the seal and joined to the seal, wherein the seal includes a plurality of frame-shaped seal materials provided on the peripheries of the plurality of current collectors, and a plurality of spacers interposed between adjacent seal materials in the first direction and forming an internal space between the current collectors together with the plurality of seal materials. The frame member includes welded ends formed by welding the ends of the multiple sealing materials and the multiple spacers opposite the internal spaces, and communication holes that communicate with each of the multiple internal spaces and have openings on the outer surface opposite the internal spaces of the welded ends, and the frame member includes multiple frame portions that surround the openings of each of the multiple communication holes when viewed from a second direction that intersects the outer surface, and each of the multiple frame portions has a first end face joined to the outer surface so as to surround the openings of each of the multiple communication holes when viewed from the second direction, and a second end face that is an end face opposite to the first end face and is formed so as to surround the openings of each of the multiple communication holes when viewed from the second direction.

[0008] In this energy storage module, a sealing body provided in the electrode stack has a communication hole communicating with an internal space between the current collectors of the electrodes that contains an electrolyte. The sealing body includes a welded end portion formed by welding a sealant provided on the periphery of the current collectors to an end portion of a spacer interposed between the sealants. The welded end portion has an opening for the communication hole formed on the outer surface of the welded end portion. The sealing body is provided with a frame member having a frame portion surrounding the opening for the communication hole on the outer surface of the welded end portion. Therefore, the frame member can be used, for example, to seal by pressing a nozzle against the sealing body when injecting an electrolyte or when joining another member to the sealing body. In this energy storage module, the frame member is formed separately from the sealing body and is joined to the sealing body at a portion surrounding the opening for the communication hole on the outer surface. This makes it less likely that the communication hole will be blocked by the resin used for injection molding, unlike when the frame member is integrally formed with the sealing body by injection molding. This reduces the risk of a decrease in reliability.

[0009] In the energy storage module according to the present disclosure, the frame member may further include a flange that protrudes along the outer surface from an end portion of each of the frame portions on the first end face side and is joined to the outer surface. With this configuration, for example, when a nozzle of an electrolyte injection device or the like is pressed against the frame member or when another member is joined to the frame member, stress applied to the end surface of the frame member is distributed between the frame portion and the flange, thereby reducing stress on the sealing body. Therefore, compared to when the frame member does not have a flange, it is possible to increase the surface pressure applied to the end surface of the frame member and suppress poor sealing or joining while suppressing damage to the sealing body structure.

[0010] In the energy storage module according to the present disclosure, the flange may protrude from the frame toward the inside of the area surrounded by the frame when viewed from the second direction, in which case it is possible to obtain the above-described effect of having the flange while maintaining the outer dimensions of the frame member.

[0011] The energy storage module according to the present disclosure may include a plurality of frame members arranged along a third direction that intersects the first direction and the second direction and is a direction along the outer surface, each of the plurality of frame members having a group of openings that are different from one another and are arranged so as to surround the group of openings arranged along the first direction as viewed from the second direction, and a flange may protrude from the frame portion along the third direction. In this way, by using a plurality of frame members and providing a flange on each frame member, it is possible to reliably reduce stress applied to the sealing body side.

[0012] In the energy storage module according to the present disclosure, the plurality of frame members may include at least two frame portions that are different in size in the first direction, thereby including a frame member having an asymmetric shape in the first direction. In this case, the position of the area surrounded by the frame portions in the first direction can be changed depending on whether the frame member is arranged so that one of the two frame portions that are different in size in the first direction faces one side (e.g., upward) in the first direction relative to the other frame portion or the frame member is arranged in the opposite direction. Thus, it is possible to surround the openings of the plurality of communication holes that are positioned at different positions in the first direction with fewer types of frame members (i.e., while reducing the number of parts) without interference.

[0013] In the energy storage module according to the present disclosure, the sealing body may be made of resin, and the frame member may be made of a resin that has the same base resin as the sealing body resin but a melting point higher than that of the sealing body resin. In this case, when the frame member is joined to the sealing body by welding, for example, deformation of the frame member due to shrinkage is suppressed.

[0014] According to the present disclosure, it is possible to provide an energy storage module that can improve reliability.

[0015] FIG. 1 is a schematic cross-sectional view of an energy storage module according to this embodiment. FIG. 2 is a schematic cross-sectional view showing an enlarged portion of the energy storage module shown in FIG. 1. FIG. 3 is a schematic side view of the energy storage module shown in FIG. 1. FIG. 4 is a schematic cross-sectional view showing several examples of the frame member shown in FIG. 1. FIG. 5 is a schematic cross-sectional view for explaining a step of a method for manufacturing the energy storage module shown in FIGS. 1 to 4. FIG. 6 is a schematic cross-sectional view for explaining a step of a method for manufacturing the energy storage module shown in FIGS. 1 to 4. FIG. 7 is a schematic plan view showing a frame member according to a modified example. FIG. 8 is a schematic cross-sectional view of the frame member shown in FIG. 7. A diagram showing a step of providing the frame member shown in FIGS. 7 and 8. A diagram showing a step of providing the frame member shown in FIGS. 7 and 8.

[0016] 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. A Cartesian coordinate system is shown, which is defined by a coordinate axis indicating a first direction D1, a coordinate axis indicating a second direction D2, and a coordinate axis indicating a third direction D3.

[0017] Fig. 1 is a schematic cross-sectional view of an energy storage module according to this embodiment. The energy storage module 1 shown in Fig. 1 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.

[0018] The energy storage module 1 includes an electrode stack 10, a sealing body 20, a frame member 30, and a sheet member 40. The electrode stack 10 includes a plurality of electrodes stacked along a first direction D1. The first direction D1 is the stacking direction of the electrodes, which is the height direction of the energy storage module 1. The plurality of electrodes includes a plurality of bipolar electrodes 11, a positive terminal electrode 12, and a negative terminal electrode 13. A separator 14 is interposed between adjacent electrodes. The electrode stack 10 is formed by stacking a plurality of bipolar electrodes 11 between the positive terminal electrode 12 and the negative terminal electrode 13.

[0019] 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 has, for example, a rectangular sheet shape. The current collector 15 includes a first main surface 15a, which is one surface, and a second main surface 15b, which is the other surface opposite the first main surface 15a. That is, the current collector 15 has the first main surface 15a and the second main surface 15b, which face opposite each other in the stacking direction D. The positive electrode active material layer 16 is provided on the first main surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the second main surface 15b 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. Here, the first major surface 15a of the current collector 15 is a surface facing one side of the first direction D1, and the second major surface 15b of the current collector 15 is a surface facing the other side of the first direction D1.

[0020] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the first direction D1. In other words, in a plan view when viewed from the first direction D1, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17.

[0021] The positive terminal electrode 12 has a current collector 15 and a positive electrode active material layer 16 provided on a first main surface 15a of the current collector 15. The positive terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a second main surface 15b of the current collector 15. In other words, no active material layer is provided on the second main surface 15b of the current collector 15 of the positive terminal electrode 12. The second main surface 15b of the current collector 15 of the positive terminal electrode 12 serves as a positive electrode terminal surface of the energy storage module 1. The positive terminal electrode 12 is stacked on the bipolar electrode 11 at one end of the electrode stack 10 in the first direction D1. The positive terminal electrode 12 is stacked 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.

[0022] The negative electrode terminal electrode 13 has a current collector 15 and a negative electrode active material layer 17 provided on a second main surface 15b of the current collector 15. The negative electrode terminal electrode 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a first main surface 15a of the current collector 15. In other words, no active material layer is provided on the first main surface 15a of the current collector 15 of the negative electrode terminal electrode 13. The first main surface 15a of the current collector 15 of the negative electrode terminal electrode 13 serves as a negative electrode terminal surface of the energy storage module 1. The negative electrode terminal electrode 13 is stacked on the bipolar electrode 11 at the other end of the electrode stack 10 in the first direction D1. In other words, the negative electrode terminal electrode 13 is arranged on the opposite side of the positive electrode terminal electrode 12 with respect to the multiple bipolar electrodes 11. The negative terminal electrode 13 is laminated on the bipolar electrode 11 so that its negative active material layer 17 faces the positive active material layer 16 of the bipolar electrode 11 .

[0023] The separators 14 are respectively arranged between adjacent bipolar electrodes 11 in the first direction D1, 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. By isolating the positive electrode active material layer 16 and the negative electrode active material layer 17, the separators 14 prevent short circuits due to contact between adjacent electrodes while allowing charge carriers such as lithium ions to pass through.

[0024] 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.

[0025] 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 of the above metals, or a plurality of sheets of the above metal foils may be integrated by lamination or the like. 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. Note that, for example, some of the current collectors 15 of the bipolar electrode 11, the positive terminal electrode 12, and the negative terminal electrode 13 may have a thickness of 100 μm or more. In this case, the structural stability of the electrode stack 10 is enhanced.

[0026] 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 )

[0027] 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 an element, 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.

[0028] 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.

[0029] 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).

[0030] 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.

[0031] When the separator 14 is impregnated with an electrolyte solution, the electrolyte salt 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.

[0032] The sealing body 20 is formed in a frame shape on the peripheral portion of the electrode stack 10 so as to surround the electrode stack 10. The sealing body 20 can be joined to each of the first main surface 15a and the second main 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 the current collectors 15 adjacent to each other in the first direction D1 and seals each of the internal spaces S. An electrolyte (not shown) is accommodated in each internal space S. That is, the sealing body 20, together with the current collectors 15 adjacent to each other in the first direction D1, defines an internal space S that accommodates the electrolyte. The sealing body 20 prevents the electrolyte from permeating to the outside.

[0033] The seal 20 prevents moisture, gas, and the like from entering the internal space S from the outside of the electrode stack 10, and also prevents the electrolyte contained in the electrode stack 10 from leaking to the outside. The edges of the separator 14 are joined to the seal 20. The seal 20 contains an insulating material. Examples of materials 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.

[0034] The sealing body 20 includes a plurality of sealing materials 21, a plurality of spacers 22, and a welded end portion 23. The sealing materials 21 are provided on each of the current collectors 15. Accordingly, the sealing materials 21 are stacked one on top of the other along the first direction D1. The sealing material 21 is frame-shaped and provided on the peripheral portion 15c of the current collector 15. In other words, the sealing material 21 is provided so as to extend from the first main surface 15a of the current collector 15, passing through the end face, to the second main surface 15b, and covers the peripheral portion 15c. The sealing material 21 can be welded to at least one of the first main surface 15a and the second main surface 15b of the current collector 15.

[0035] The spacer 22 is disposed so as to be interposed between adjacent seal materials 21 in the first direction D1. As a result, the spacer 22 maintains a space between adjacent seal materials 21 in the first direction D1, i.e., between adjacent current collectors 15 in the first direction D1. The spacer 22 has a frame shape having an inner peripheral end face and an outer peripheral end face, and is disposed on the peripheral portion 15c of the current collector 15 as viewed from the first direction D1. Here, the end of the separator 14 is sandwiched and fixed between the seal material 21 and the spacer 22. The end of the separator 14 can be welded to at least one of the seal material 21 and the spacer 22.

[0036] The welded end 23 is formed by welding and integrating the ends of the plurality of sealants 21 and the plurality of spacers 22 opposite the internal space S. More specifically, the welded end 23 is formed by welding together portions of the plurality of sealants 21 and the plurality of spacers 22 that are positioned outside the current collector 15 as viewed from the first direction D1. The welded end 23 has a frame shape as viewed from the first direction D1, surrounding the electrode stack 10. An outer surface 23s of the welded end 23 opposite the internal space S extends along the first direction D1 and constitutes the outer surface of the sealing body 20.

[0037] The sealing body 20 has a raised portion 25. The raised portion 25 is disposed on the outer surface in the first direction D1 of the sealing material 21 provided on the current collector 15 of the positive terminal electrode 12 and the negative terminal electrode 13. The raised portion 25 is bonded to the sealing material 21. An end of the raised portion 25 located outside the current collector 15 as viewed in the first direction D1 is welded to an end of the sealing material 21 and forms part of the welded end portion 23. The sealing body 20 has a polygonal outer shape as viewed in the first direction D1 and includes each side of the polygon. For example, if the outer shape of the sealing body 20 as viewed in the first direction D1 is a rectangle, the sealing body 20 includes four sides. A communication hole 27, which will be described later, is provided on one of the multiple sides of the sealing body 20. Here, the raised portion 25 is provided only on the side on which the communication hole 27 is provided.

[0038] Furthermore, conductive members 50 functioning as terminals for extracting current from the energy storage module 1 are disposed on and electrically connected to the first main surface 15 a of the current collector 15 of the positive terminal electrode 12 and the second main surface 15 b of the current collector 15 of the negative terminal electrode 13, which are exposed from the sealing body 20. The conductive members 50 can be used to electrically connect multiple energy storage modules 1. The conductive members 50 can also be used as restraining members for applying a restraining load to the electrode stack 10. Furthermore, a cooling flow path may be formed in the conductive member 50. The electrode stack 10 can be cooled by circulating a cooling medium through the cooling flow path formed in the conductive member 50.

[0039] The frame member 30 is formed separately from the sealing body 20 and is joined to the sealing body 20. Here, the frame member 30 is joined (e.g., welded) to the outer surface 23s of the welding end portion 23, which is the outer surface of the sealing body 20. The frame member 30 extends in the first direction D1 from one of the raised portions 25 (the raised portion 25 on the positive terminal electrode 12 side) to the other raised portion 25 (the raised portion 25 on the negative terminal electrode 13 side). Therefore, the outer edge of the frame member 30 in the first direction D1 is located on the raised portion 25 and, for example, coincides with the outer edge of the raised portion 25. The sheet member 40 is joined (attached) to the end surface 30s of the frame member 30 opposite the sealing body 20. The sheet member 40 is, for example, a laminate film. Next, the frame member 30 will be described in detail.

[0040] Fig. 2 is a schematic cross-sectional view showing an enlarged portion of the energy storage module shown in Fig. 1. Fig. 3 is a schematic side view of the energy storage module shown in Fig. 1. Fig. 4(a) is a schematic cross-sectional view taken along line IV-IV in Fig. 3. Fig. 3(a) shows a state in which the sealing body 20 is not provided with a frame member 30, and Fig. 3(b) shows a state in which the sealing body 20 is provided with a frame member 30. As shown in Figs. 2, 3 and 4(a), the sealing body 20 has communication holes 27 formed therein that communicate with each of the multiple internal spaces S.

[0041] As an example, the communication hole 27 is formed by cutting out a portion of the spacer 22 and penetrates the spacer 22 and the welded end portion 23. The communication hole 27 has one opening in the internal space S and the other opening 27h on the outer surface 23s of the welded end portion 23. In the energy storage module 1, a pair of adjacent current collectors 15 forms a cell C including one internal space S. Here, one communication hole 27 is formed for one cell C. When viewed from the second direction D2 intersecting (orthogonal to) the outer surface 23s (see FIG. 3A), the openings 27h of the communication holes 27 are arranged such that their positions in the third direction D3 differ for each cell C. The third direction D3 is a direction intersecting the first direction D1 and the second direction D2 and is the width direction of the energy storage module 1 along the outer surface 23s.

[0042] As an example, the positions of the openings 27h in the third direction D3 are staggered from the cell C on one end side to the cell C on the other end side in the first direction D1. Therefore, here, a plurality of openings 27h having approximately the same positions in the third direction D3 are provided corresponding to every other cell C and are arranged along the first direction D1. In other words, here, the plurality of openings 27h include, as viewed from the second direction D2, a group of openings 28 arranged along the first direction D1 and another group of openings 29 arranged along the first direction D1 at positions different from the openings 28 in the third direction D3.

[0043] The frame member 30 is joined (e.g., welded) to the outer surface 23s of the weld end portion 23. The frame member 30 includes a plurality of frame portions 31 surrounding the respective openings 27h of the plurality of communication holes 27 as viewed from the second direction D2. A plurality of frame members 30 are used here. The frame members 30 are arranged spaced apart from one another along the third direction D3. Here, the frame portions 31 of one frame member 30 are arranged to surround a respective one of the groups of openings 28, and the frame portions 31 of another frame member 30 are arranged to surround a respective one of the groups of openings 29. That is, each of the frame members 30 is a different group of openings 27h, and is arranged so that the frame portions 31 surround the groups of openings 28, 29 arranged in the first direction D1 as viewed from the second direction D2.

[0044] The frame portion 31 includes a first end face 31a joined (e.g., welded) to the outer surface 23s so as to surround the openings 27h of the plurality of communication holes 27 as viewed from the second direction D2, and a second end face 31b opposite the first end face 31a and formed so as to surround the openings 27h of the plurality of communication holes 27 as viewed from the second direction D2. Each frame member 30 further includes a flange 32 that protrudes along the outer surface 23s from the end of the frame portion 31 on the first end face 31a side and is joined (e.g., welded) to the outer surface 23s. Here, the frame portion 31 has a rectangular frame shape. Therefore, a region 33 surrounded by the frame portion 31 as viewed from the second direction D2 is rectangular. The bottom surface of this region 33 corresponds to the outer surface 23s of the welded end portion 23 (the outer surface of the sealing body 20). In this example, when viewed from the second direction D2, the flange 32 protrudes in the third direction D3 from a portion of the frame 31 extending in the first direction D1 toward the inside of the region 33 surrounded by the frame 31. When viewed from the second direction D2, the flange 32 is formed in each of the regions 33 so as to be spaced apart from the openings 27h (i.e., does not reach the openings 27h).

[0045] However, as shown in (b) of Fig. 4, the flange 32 may be provided so as to protrude from a portion of the frame portion 31 extending in the first direction D1 along the third direction D3 toward the outside of the region 33 surrounded by the frame portion 31. Alternatively, as shown in (c) of Fig. 4, the flange 32 may be provided so as to protrude both toward the inside and the outside of the region 33 surrounded by the frame portion 31. Furthermore, as shown in (b) of Fig. 3, the frame member 30 may be provided with another flange 34 that protrudes from a portion of the frame portion 31 extending in the third direction D3 along the first direction D1 toward the inside of the region 33 surrounded by the frame portion 31. In this case, the flange 34 is also formed in each region 33 so as to be spaced apart from the opening 27h when viewed from the second direction (i.e., does not reach the opening 27h).

[0046] 2 to 4 again. In one frame member 30, a plurality of frame portions 31 define a plurality of regions 33 (three in the illustrated example) arranged along the first direction D1, and the openings 27h of the communication holes 27 are positioned within each of the regions 33 when viewed from the second direction. The frame member 30 also has an end face 30s (second end face 31b) opposite the outer surface 23s of the welded end portion 23 (i.e., opposite the sealing body 20). Therefore, as described below, by introducing electrolyte into each region 33 from a nozzle of an electrolyte injection device while the nozzle is in close contact with the end face 30s, it becomes possible to inject electrolyte into the internal space S from the communication holes 27 that connect to each region 33 via the openings 27h.

[0047] The sheet member 40 is joined (for example, glued) to the end surface 30s to seal the region 33 (i.e., the internal space S). In the energy storage module 1, one sheet member 40 may be provided across multiple frame members 30, or one sheet member 40 may be provided for each frame member 30.

[0048] 3B, the frame members 30 each have an asymmetric shape in the first direction D1 by including at least two frame portions 31 that are different in size in the first direction D1. Here, for one frame member 30, the size in the first direction D1 of one of the three frame portions 31 (i.e., region 33) is larger than the sizes in the first direction D1 of the other two frame portions 31 (i.e., regions 33).

[0049] Such asymmetrical frame members 30 are arranged in different orientations (flipped in the first direction D1), so that the position of the region 33 surrounded by the frame portion 31 in the first direction D1 differs between the frame members 30 oriented in different directions. As a result, it is possible to surround the openings 27h of the communication holes 27 positioned at different positions in the first direction D1 with fewer types of frame members 30.

[0050] The frame member 30 as described above may be formed from a resin having a melting point higher than that of the resin of the sealing body 20. Furthermore, the resin of the sealing body 20 and the resin of the frame member 30 may each have the same base resin. As an example, when the sealing body 20 is formed from low-density polyethylene, the frame member 30 may be formed from high-density polyethylene. Note that, when the sealing body 20 is composed of multiple resins, the frame member 30 may be formed from a resin having a melting point higher than that of at least one of the multiple resins that constitute the sealing body 20. As an example, when the sealing material 21 of the sealing body 20 is formed from low-density polyethylene and the spacer 22 and the padding portion 25 are formed from high-density polyethylene, the frame member 30 may be formed from high-density polyethylene.

[0051] Next, a method for manufacturing the energy storage module 1 will be described. Figures 5 and 6 are schematic cross-sectional views for explaining one step of the method for manufacturing the energy storage module shown in Figures 1 to 4. As shown in Figure 5, here, the electrode stack 10, the sealing body 20, and the frame member 30 are prepared separately. The sealing body 20 is provided on and integrated with the electrode stack 10. Note that only a portion of the electrode stack 10 and the sealing body 20 is shown in Figures 5 and 6.

[0052] Next, heater H1 is placed on the outer surface of sealing body 20 (outer surface 23s of welding end portion 23). Furthermore, heater H2 is placed on the end surface 30r (first end surface 31a) of frame member 30 opposite end surface 30s. Heater H1 has a lower temperature than heater H2. Next, heater H1 heats sealing body 20, melting a portion of sealing body 20 from the outer surface 23s side. Furthermore, heater H2 heats frame member 30, melting a portion of frame member 30 from the end surface 30r side. By using an infrared heater as heater H1 and a hot plate heater as heater H2, for example, frame member 30 can be selectively melted only in the vicinity of end surface 30r, while sealing body 20 can be melted to a relatively deep position from the outer surface 23s.

[0053] 6 , in a state in which a portion of the outer surface 23s of the sealing body 20 and a portion of the end surface 30r of the frame member 30 are molten, the frame member 30 is pressed against the sealing body 20, so that the portion of the outer surface 23s of the sealing body 20 and the portion of the end surface 30r of the frame member 30 are fused together.

[0054] Next, a nozzle 60 of an electrolyte injection device is pressed against the end face 30s of the frame member 30 to bring it into close contact, and the electrolyte is introduced into the region 33 of the frame member 30 from the injection port 61 of the nozzle 60. As a result, the electrolyte is injected into the internal space S of each cell C from the communication holes 27 that connect to the respective regions 33 via the openings 27h of the sealing body 20. Thereafter, the nozzle 60 is removed from the end face 30s of the frame member 30, and a sheet member 40 is attached to the end face 30s so as to seal the region 33. As a result, the internal space S in which the electrolyte is disposed is sealed, and the energy storage module 1 is manufactured.

[0055] As described above, in the energy storage module 1, the sealing body 20 provided in the electrode stack 10 is provided with a communication hole 27 that communicates with the internal space S that accommodates the electrolyte between the current collectors 15 of the electrodes. The sealing body 20 includes a welded end portion 23 formed by welding the sealant 21 provided on the peripheral portion 15 c of the current collector 15 to the end of the spacer 22 interposed between the sealant 21. An opening 27 h of the communication hole 27 is formed in an outer surface 23 s of the welded end portion 23. The sealing body 20 is also provided with a frame member 30 having a frame portion 31 that surrounds the opening 27 h of the communication hole 27 on the outer surface 23 s of the welded end portion 23.

[0056] Therefore, for example, the frame member 30 can be used for sealing by pressing the nozzle 60 when injecting the electrolyte, or when joining another member to the sealing body 20. In this energy storage module 1, the frame member 30 is formed separately from the sealing body 20 and is joined to the sealing body 20 at a portion surrounding the opening 27h of the communication hole 27 on the outer surface 23s. This makes it less likely that the communication hole 27 will be blocked by the resin used for injection molding, as opposed to when the frame member 30 is integrally formed with the sealing body 20 by injection molding. This prevents a decrease in reliability.

[0057] Furthermore, in the energy storage module 1, the frame member 30 further includes a flange 32 that protrudes along the outer surface 23 s from an end portion of each of the plurality of frame portions 31 on the first end surface 31 a side and is joined to the outer surface 23 s. Therefore, for example, when a nozzle 60 of an electrolyte injection device or the like is pressed against the frame member 30 or when another member is joined to the frame member 30, the stress applied to the end surface 30 s of the frame member 30 is distributed between the frame portion 31 and the flange 32, thereby reducing the stress applied to the sealing body 20 side. Therefore, compared to when the frame member 30 does not have the flange 32, it is possible to increase the surface pressure applied to the end surface 30 s of the frame member 30 and suppress poor sealing or joining while suppressing damage to the structure of the sealing body 20 side.

[0058] Furthermore, in the energy storage module 1, the flange 32 protrudes from the frame portion 31 toward the inside of the area 33 surrounded by the frame portion 31 when viewed from the second direction D2. Therefore, it is possible to obtain the above-described effect of having the flange 32 while maintaining the external dimensions of the frame member 30.

[0059] The energy storage module 1 also includes a plurality of frame members 30 arranged along a third direction D3 that intersects the first direction D1 and the second direction D2 and is a direction along the outer surface 23s. Each of the plurality of frame members 30 has a group of openings 27h that are different from one another, and is arranged such that the frame portion 31 surrounds a group of openings 28, 29 that are arranged along the first direction D1 as viewed from the second direction D2. The flange 32 protrudes from the frame portion 31 along the third direction D3. In this way, by using a plurality of frame members 30 and providing the flange 32 on each of the frame members 30, it is possible to reliably reduce stress acting on the sealing body 20.

[0060] Furthermore, in the energy storage module 1, the multiple frame members 30 include at least two frame portions 31 that are different in size in the first direction D1, and thus include frame members 30 that have an asymmetric shape in the first direction D1. Therefore, the position of the region 33 surrounded by the frame portions 31 in the first direction D1 can be changed depending on whether the frame members 30 are arranged so that one of the two frame portions 31 that are different in size in the first direction D1 faces one side (e.g., upward) in the first direction D1 relative to the other frame portion 31 or whether the frame members 30 are arranged in the opposite direction. Therefore, it is possible to surround the openings 27h of the multiple communication holes 27 that are positioned at different positions in the first direction D1 with fewer types of frame members 30 (i.e., while reducing the number of parts) without interference between the frame portions 31 and the openings 27h.

[0061] Furthermore, in the energy storage module 1, the sealing body 20 is made of resin, and the frame member 30 is made of resin having a melting point higher than that of the resin of the sealing body 20. Furthermore, the resin of the frame member 30 can use the same main resin as that of the resin of the sealing body 20. As a result, when the frame member 30 is joined to the sealing body 20 by welding, for example, the sealing body 20 to be joined can be melted at a lower temperature, so that the frame member 30 is not heated to a higher temperature when pressed against the sealing body 20, and deformation of the frame member 30 due to thermal expansion and contraction is suppressed.

[0062] The above embodiment describes one aspect of the energy storage module according to the present disclosure. Therefore, the energy storage module according to the present disclosure is not limited to the above-described energy storage module 1 and can be modified as desired.

[0063] For example, in the above embodiment, the case where the frame member 30 is welded to the sealing body 20 has been described, but a known method such as bonding using an adhesive can also be used to join the frame member 30 to the sealing body 20. That is, in the energy storage module 1, it is sufficient that the frame member 30, which is formed separately from the sealing body 20, is joined to the sealing body 20.

[0064] In the above embodiment, the frame member 30 has the flange 32, but the flange 32 is not essential. The frame member 30 is not limited to having an asymmetric shape in the first direction D1, and may have a symmetric shape in the first direction D1. Furthermore, the frame member 30 may include three or more frame portions 31 that are different in size from one another in the first direction D1.

[0065] FIG. 7 is a schematic plan view showing a frame member according to a modified example. FIG. 8 is a schematic cross-sectional view of the frame member shown in FIG. 7. FIG. 8(a) is a cross-sectional view taken along line XIIIa-XIIIa in FIG. 7, and FIG. 8(b) is a cross-sectional view taken along line XIIIb-XIIIb in FIG. 7. The energy storage module 1 may include a frame member 30A shown in FIGS. 7 and 8 instead of the frame member 30 according to the above embodiment. The frame member 30A differs from the frame member 30 according to the above embodiment in that it includes a flange 32A instead of the flange 32, but is otherwise identical. The flange 32A differs from the flange 32 in that the ratio of the length along the height direction (second direction D2) of the frame portion 31 to the amount of protrusion (thickness) from the frame portion 31 is larger than the flange 32 (here, the flange 32A is longer in the second direction D2 than the flange 32), and is formed elongated in the second direction D2. Such a flange 32A can also be considered a relatively thick portion of the frame portion 31.

[0066] 7 and 8 show an example of flange 32A that protrudes toward the inside of region 33 surrounded by frame portion 31, but flange 32A may be provided so as to protrude toward the outside of region 33 surrounded by frame portion 31, as in flange 32 shown in (b) and (c) of FIG. 4, or may be provided so as to protrude toward both the inside and outside of region 33.

[0067] When providing the frame member 30A described above to the sealing body 20, first, as shown in FIG. 9 , a heater H1 is disposed on the outer surface of the sealing body 20 (the outer surface 23s of the welding end 23). A heater H2 is disposed on the end surface 30r (first end surface 31a) of the frame member 30A opposite the end surface 30s. The sealing body 20 is then heated by the heater H1, melting a portion of the sealing body 20 from the outer surface 23s side. The frame member 30A is then heated by the heater H2, melting a portion of the frame member 30 from the end surface 30r side. By using an infrared heater as the heater H1 and a hot plate heater as the heater H2, for example, the frame member 30A can be selectively melted only in the vicinity of the end surface 30r, while the sealing body 20 can be melted to a relatively deep position from the outer surface 23s.

[0068] Next, as shown in FIG. 10 , while a portion of the outer surface 23s of the sealing body 20 and a portion of the end surface 30r of the frame member 30A are melted, the frame member 30A is pressed against the sealing body 20, and the frame member 30A is pushed into the sealing body 20 from the outer surface 23s side. In the illustrated example, the flange 32A, which is the thick portion of the frame member 30A, is pushed entirely into the weld end portion 23, causing the flange 32A and the weld end portion 23 to melt together. Therefore, after this step, the portion of the frame portion 31 of the frame member 30A other than the flange 32A protrudes from the outer surface 23s of the sealing body 20. However, when the frame member 30A is pushed into the sealing body 20 from the outer surface 23s side, only a portion of the flange 32A may be pushed into the weld end portion 23. In this case, the remaining portion of the flange 32A protrudes from the outer surface 23s of the sealing body 20.

[0069] When the frame member 30A described above is used, in addition to the same effects as when the frame member 30 according to the above embodiment is used, the following effect can be achieved. That is, when the frame member 30A is used, when the frame member 30A is welded to the sealing body 20, the tip end portion of the frame member 30A (at least a part of the flange 32A) enters the welding end portion 23 of the sealing body 20, and the tip end portion of the frame member 30A and the sealing body 20 are compatible with each other. Therefore, it is possible to reliably weld the tip end portion of the frame member 30A and the welding end portion 23 in an airtight manner.

[0070] Furthermore, when an attempt is made to press the leading end of a frame member that does not have a thick portion into the welded end portion 23, the leading end of the frame member may be deformed. However, in the frame member 30A, by providing the flange 32A as a thick portion, deformation of the leading end of the frame member 30A when the leading end is pressed into the welded end portion 23 is suppressed. Note that in the frame member 30A, a relatively large force is applied to the edge portion along the stacking direction (first direction D1) of the sealing materials 21 and the spacers 22 when the edge portion is pressed across the plurality of sealing materials 21 and the spacers 22, so it is effective to form the flange 32 as a thick portion in the deformed portion to reinforce it.

[0071] The following additional notes are provided regarding this embodiment. The energy storage module according to the present disclosure includes: [1] an electrode stack including a plurality of electrodes stacked along a first direction, each electrode including a current collector and an active material layer formed on the current collector; a seal provided on the electrode stack to form an internal space between adjacent current collectors and seal the internal space; an electrolyte solution contained in the internal space; and a frame member configured separately from the seal and joined to the seal, wherein the seal includes a plurality of frame-shaped seal materials provided on peripheral portions of each of the plurality of current collectors; a plurality of spacers interposed between adjacent seal materials in the first direction and forming the internal space between the current collectors together with the plurality of seal materials; and the frame member includes a plurality of frame portions surrounding the openings of the plurality of communication holes when viewed from a second direction intersecting the outer surface, and each of the plurality of frame portions has a first end face joined to the outer surface so as to surround the openings of the plurality of communication holes when viewed from the second direction, and a second end face that is an end face opposite to the first end face and is formed so as to surround the openings of the plurality of communication holes when viewed from the second direction.

[0072] The energy storage module according to the present disclosure may be [2] "the energy storage module described in [1] above, wherein the frame member further includes a flange that protrudes along the outer surface from the end portion on the first end face side of each of the plurality of frame portions and is joined to the outer surface."

[0073] The energy storage module according to the present disclosure may be [3] "the energy storage module described in [2] above, in which the flange protrudes from the frame portion toward the inside of the area surrounded by the frame portion when viewed from the second direction."

[0074] The energy storage module according to the present disclosure may be [4] "the energy storage module described in [2] or [3] above, which includes a plurality of frame members arranged along a third direction that intersects the first direction and the second direction and is a direction along the outer surface, each of the plurality of frame members being a group of the openings that are different from one another, and which are arranged so that the frame portion surrounds the group of the openings arranged along the first direction as viewed from the second direction, and the flange protrudes from the frame portion along the third direction."

[0075] The energy storage module according to the present disclosure may be [5] "the energy storage module described in [4] above, in which the plurality of frame members include at least two frame portions that are different in size in the first direction, and thus the frame members have an asymmetric shape in the first direction."

[0076] The energy storage module according to the present disclosure may be [6] "the energy storage module according to any one of [1] to [5] above, wherein the sealing body is made of resin, and the frame member is made of resin that has the same main component as the resin of the sealing body and has a melting point higher than the melting point of the resin of the sealing body."

[0077] 1...energy storage module, 10...electrode laminate, 11...bipolar electrode (electrode), 12...positive electrode terminal electrode (electrode), 13...negative electrode terminal electrode (electrode), 15...current collector, 16...positive electrode active material layer (active material layer), 17...negative electrode active material layer (active material layer), 20...sealing body, 21...sealing material, 22...spacer, 23...welded end portion, 23s...outer surface, 27...communicating hole, 27h...opening, 30, 30A...frame member, 30s...end surface, 31...frame portion, 31a...first end surface, 31b...second end surface, 32, 32A...flange, 33...area, D1...first direction, D2...second direction, D3...third direction, S...internal space.

Claims

1. an electrode stack including a current collector and an active material layer formed on the current collector, the electrode stack including a plurality of electrodes stacked along a first direction; a sealant provided on the electrode stack so as to form an internal space between adjacent current collectors and seal the internal space; An electrolyte solution contained in the internal space; a frame member formed separately from the sealing body and joined to the sealing body; Equipped with The sealing body is a plurality of frame-shaped seal members provided on the periphery of each of the plurality of current collectors; a plurality of spacers interposed between the sealing materials adjacent to each other in the first direction and forming the internal space between the current collectors together with the sealing materials; a welded end portion formed by welding an end portion of each of the plurality of sealing materials and the plurality of spacers opposite to the internal space; A plurality of communication holes each communicating with the plurality of internal spaces and having an opening on an outer surface of the welded end portion opposite the internal spaces; Including, the frame member includes a plurality of frame portions surrounding the openings of the plurality of communication holes when viewed from a second direction intersecting the outer surface, Each of the plurality of frame portions is a first end surface joined to the outer surface so as to surround the openings of each of the plurality of communication holes when viewed from the second direction; a second end surface that is an end surface opposite to the first end surface and is formed so as to surround the openings of each of the plurality of communication holes when viewed from the second direction; having The frame member is formed so as to be spaced apart from the openings of the communication holes when viewed from the second direction. Energy storage module.

2. An electrode stack including a current collector and an active material layer formed on the current collector, the electrode stack including a plurality of electrodes stacked along a first direction; a sealant provided on the electrode stack so as to form an internal space between adjacent current collectors and seal the internal space; An electrolyte solution contained in the internal space; a frame member formed separately from the sealing body and joined to the sealing body; Equipped with The sealing body is a plurality of frame-shaped seal members provided on the periphery of each of the plurality of current collectors; a plurality of spacers interposed between the sealing materials adjacent to each other in the first direction and forming the internal space between the current collectors together with the sealing materials; a welded end portion formed by welding an end portion of each of the plurality of sealing materials and the plurality of spacers opposite to the internal space; A plurality of communication holes each communicating with the plurality of internal spaces and having an opening on an outer surface of the welded end portion opposite the internal spaces; Including, the frame member includes a plurality of frame portions surrounding the openings of the plurality of communication holes when viewed from a second direction intersecting the outer surface, Each of the plurality of frame portions is a first end surface joined to the outer surface so as to surround the openings of each of the plurality of communication holes when viewed from the second direction; a second end surface that is an end surface opposite to the first end surface and is formed so as to surround the openings of each of the plurality of communication holes when viewed from the second direction; having The frame member further includes a flange protruding along the outer side surface from an end portion on the first end surface side of each of the plurality of frame portions and joined to the outer side surface. Energy storage module.

3. The flange protrudes from the frame portion toward an inside of a region surrounded by the frame portion when viewed from the second direction. The power storage module according to claim 2 .

4. a plurality of the frame members arranged along a third direction that intersects the first direction and the second direction and is a direction along the outer surface, Each of the plurality of frame members is a group of the openings that are different from each other, and is arranged so as to surround the group of the openings that are arranged along the first direction when viewed from the second direction, with the frame portion; The flange protrudes from the frame portion along the third direction. The power storage module according to claim 2 .

5. The plurality of frame members include at least two of the frame portions having different sizes in the first direction, and thus include the frame member having an asymmetric shape in the first direction. The power storage module according to claim 4 .

6. The sealing body is made of resin, the frame member is made of a resin having the same main component as the resin of the sealing body and a melting point higher than the melting point of the resin of the sealing body; The storage module according to any one of claims 1 to 5.