Energy storage module

Abstract

To provide a power storage module capable of having higher reliability.SOLUTION: A power storage module 1 includes an electrode laminate body 10, a sealing body 20, and a plurality of laminate films 30 welded to an outer side surface 20s of the sealing body 20. The outer side surface 20s is formed in a rectangular shape, and includes a first side surface 20s1 and a second side surface 20s2 that are adjacent to each other. The laminate films 30 include a first laminate film 31 provided on the first side surface 20s1, and a second laminate film 32 provided on the second side surface 20s2. The first laminate film 31 and the second laminate film 32 are bonded together by being overlapped on each other at a corner part 20r1 connecting the first side surface 20s1 and the second side surface 20s2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 describes an energy storage device. The energy storage device includes a stack formed by stacking a plurality of energy storage cells, and a reinforcing member provided on the stack. The outer surface of the stack is rectangular when viewed from the stacking direction of the energy storage cells. The reinforcing member is a film-like member formed by stacking a first resin layer, a metal layer, and a second resin layer in this order and integrating them. When viewed from the stacking direction of the energy storage cells, the reinforcing member extends in an annular shape so as to surround the outer surface of the stack, and is adhered to the outer surface of the stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-27201 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned energy storage device, as described above, a film-like reinforcing member (laminate film) including a metal layer is provided on the outer surface of the stack of energy storage cells, thereby suppressing moisture permeation at least through the stack.

[0005] However, when a laminate film is wrapped around and welded to the outer surface of a laminate, if the laminate expands or contracts due to temperature changes, stress may be concentrated in the portions of the laminate film welded to the corners of the laminate. For this reason, there is a demand for ensuring the strength of the laminate film at the corners of the laminate and improving reliability.

[0006] An object of the present disclosure is to provide an energy storage module that can improve reliability. [Means for solving the problem]

[0007] The energy storage module according to the present disclosure comprises an electrode stack formed by stacking a plurality of electrodes, each including a current collector having an active material layer, along a first direction; a resin sealing body provided on the electrode stack so as to surround the electrode stack and sealing the internal space between adjacent current collectors; and a plurality of laminate films welded to the outer surface of the sealing body, each including a metal layer and a resin layer covering both sides of the metal layer. The sealing body is formed in a rectangular frame shape when viewed from the first direction, and the outer surface includes a first side surface and a second side surface that are adjacent to each other when viewed from the first direction. The plurality of laminate films include a first laminate film welded to the first side surface and a second laminate film welded to the second side surface. The first laminate film is welded to a corner of the outer surface connecting the first side surface and the second side surface when viewed from the first direction, and the second laminate film is joined to overlap the first laminate film at the corner.

[0008] In this energy storage module, a resin sealing body is provided around an electrode stack including multiple electrodes stacked in a first direction. Furthermore, multiple laminate films, each including a metal layer and a resin layer covering both sides of the metal layer, are welded to the outer surface of the sealing body. The multiple laminate films include a first laminate film welded to a first side of the outer surface of the sealing body and a second laminate film welded to a second side of the outer surface of the sealing body adjacent to the first side. The first laminate film is welded to a corner connecting the first and second sides of the outer surface of the sealing body, and the second laminate film is joined to overlap the first laminate film at the corner. As a result, the strength of the laminate film is ensured at the corner where stress concentration may occur during expansion and contraction of the sealing body, improving reliability.

[0009] In the energy storage module according to the present disclosure, the corners may be formed in an arc shape when viewed from the first direction. In this case, stress that may occur during expansion and contraction of the sealing body is dispersed at the corners. This reduces the strength requirement of the laminate film that overlaps the corners.

[0010] In the energy storage module according to the present disclosure, the overlapping portion of the first laminate film and the second laminate film may cover the center of the corner when viewed from the first direction. In this case, the reliability is reliably improved by covering the center of the corner, where stress during expansion and contraction of the sealing body is thought to be most concentrated, with the stronger overlapping portion of the laminate film.

[0011] In the energy storage module according to the present disclosure, the first laminate film and the second laminate film each include a first portion welded to at least one of the first end face and the second end face of the sealing body that are adjacent to the outer surface of the sealing body in the first direction, and a notch may be formed in a portion of the first portion corresponding to a corner of the sealing body. In this case, wrinkles are less likely to occur in the portions of the laminate film that correspond to the corners of the sealing body in the first portion welded to the top and bottom surfaces of the sealing body. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide an energy storage module that can improve reliability. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic plan view of the electricity storage module according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic plan view showing an enlarged portion of FIG. [Figure 4] FIG. 4 is a development view of the laminate film shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0014] 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 given the same reference numerals, and redundant description may be omitted. In addition, each drawing may show an orthogonal coordinate system consisting of a first axis defining a first direction D1, a second axis defining a second direction D2, and a third axis defining a third direction D3.

[0015] FIG. 1 is a schematic plan view of an energy storage module according to this embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II 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 will be illustrated as an example.

[0016] 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 a first direction D1. 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.

[0017] 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 positive electrode active material layer 16 is provided on one surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the other 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 one surface 15a of the current collector 15 faces one side of the first direction D1, and the other surface 15b of the current collector 15 faces the other side of the first direction D1.

[0018] 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.

[0019] The positive terminal electrode 12 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 12 does not have the positive electrode active material layer 16 or the negative electrode active material layer 17 on the other surface 15b 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 12. The positive terminal electrode 12 is stacked on the bipolar electrode 11 at one end of the electrode laminate 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.

[0020] The negative electrode terminal electrode 13 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 13 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 13. The negative electrode terminal electrode 13 is stacked on the bipolar electrode 11 at the end of the electrode laminate 10 opposite the positive electrode terminal electrode 12 in the first direction D1. The negative electrode terminal electrode 13 is stacked 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. In this way, the electrode laminate 10 is configured by stacking multiple electrodes, including current collectors on which active material layers are provided, along the first direction D1.

[0021] Separators 14 are disposed between adjacent bipolar electrodes 11, between the positive terminal electrode 12 and the bipolar electrode 11, and between the negative terminal electrode 13 and the bipolar electrode 11. The separators 14 are interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17. 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.

[0022] 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 charging or discharging 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.

[0023] 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 an aluminum foil or a foil obtained by integrating aluminum foil and copper foil.

[0024] 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. Any positive electrode active material may be used as long as it is usable in lithium ion secondary batteries. The positive electrode active material layer 16 may contain multiple positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0025] The negative electrode active material layer 17 contains a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be any of 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 contains graphite as a carbon-based material.

[0026] 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.

[0027] 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 crosslinks; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Examples of binder solvents include water and N-methyl-2-pyrrolidone (NMP).

[0028] 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.

[0029] As the electrolyte salt of the electrolytic solution, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 may be used. As the nonaqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers may be used. Two or more of these known solvent materials may be used in combination.

[0030] The sealing body 20 is formed in a frame shape on the peripheral edge portion of the electrode stack 10 so as to surround the electrode stack 10 when viewed from the first direction D1. 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 edge 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 (e.g., an electrolytic solution) is accommodated in each internal space S. The sealing body 20 can prevent the electrolytic solution from permeating to the outside. Furthermore, the sealing body 20 can suppress the intrusion of moisture and the like into the internal space S from the outside of the electrode stack 10.

[0031] The edge of the separator 14 is bonded 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.

[0032] 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. Accordingly, the sealants 21 are stacked one on top of the other along the first direction D1. The sealant 21 has a frame shape (here, a rectangular frame shape) when viewed from the first direction D1, 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. The sealant 21 can be welded to the one surface 15a and the other surface 15b of the current collector 15.

[0033] The spacers 22 are disposed so as to be interposed between the adjacent seal materials 21 in the first direction D1. As a result, the spacers 22 maintain the space between the adjacent seal materials 21, i.e., between the adjacent current collectors 15, and together with the seal materials 21, form an internal space S. The spacers 22 have a frame shape (here, a rectangular frame shape) when viewed from the first direction D1, and are disposed on the peripheral edge portions 15c of the current collectors 15 when viewed from the first direction D1. Here, the ends of the separators 14 are sandwiched and held between the seal materials 21 and the spacers 22. The separators 14 can be welded to at least one of the seal materials 21 and the spacers 22.

[0034] The sealing body 20 further includes a welded end portion 23 formed by welding and integrating the ends of the plurality of sealing materials 21 and the plurality of spacers 22 opposite the internal space S. The welded end portion 23 has a frame shape surrounding the electrode stack 10 when viewed from the first direction D1, and constitutes the outer periphery of the sealing body 20. Therefore, by welding the sealing materials 21 and the spacers 22 to each other, the sealing body 20 has an outer surface 20s (outer surface of the welded end portion 23) formed by the end face of the sealing material 21 opposite the internal space S and the end face of the spacer 22 opposite the internal space S.

[0035] Conductive members 50 functioning as terminals for extracting current from the energy storage module 1 are disposed and electrically connected to the other surface 15b of the current collector 15 of the positive terminal electrode 12 and the one surface 15a of the current collector 15 of the negative terminal electrode 13, respectively, in portions exposed from the sealing body 20. The conductive members 50 can be used to electrically connect a plurality of 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.

[0036] Here, the energy storage module 1 includes a plurality of (here, five) laminate films 30. The laminate film 30 includes a metal layer 30a and a pair of resin layers 30b, 30c provided on both sides of the metal layer 30a. The resin layers 30b, 30c cover both sides of the metal layer 30a. The laminate film 30 is welded to at least the outer surface 20s of the sealing body 20. As an example, the metal layer 30a is made of aluminum, and the resin layer 30b can be made of the same resin material as the sealing body 20 to improve weldability with the sealing body 20. Also, as an example, the resin layers 30b, 30c can be made of the same resin material to improve weldability between the laminate films 30 at an overlapping portion P described below.

[0037] The sealing body 20 is formed in a rectangular frame shape when viewed from the first direction D1. The outer surface 20s is formed in a rectangular frame shape when viewed from the first direction D1. Therefore, the outer surface 20s includes a first side surface 20s1, a second side surface 20s2, a third side surface 20s3, and a fourth side surface 20s4, which correspond to each side of the rectangle when viewed from the first direction D1. The first side surface 20s1 is adjacent to the second side surface 20s2 and the fourth side surface 20s4, the second side surface 20s2 is adjacent to the first side surface 20s1 and the third side surface 20s3, and the third side surface 20s3 is adjacent to the second side surface 20s2 and the fourth side surface 20s4. On the fourth side surface 20s4, a structure 60 other than the sealing body 20 is arranged, such as a resin frame protruding from the outer surface 20s to be used when injecting an electrolyte into the internal space S or a voltage detection wire drawn from the sealing body 20.

[0038] The sealing body 20 also includes a first end face 20a and a second end face 20b adjacent to the outer surface 20s in the first direction D1. The first end face 20a is one end face of the sealing body 20 in the first direction D1, and in this case, is a face that includes the outer surface of the sealing material 21 provided on the positive terminal electrode 12. The second end face 20b is the other end face of the sealing body 20 in the first direction D1, and is a face that includes the outer surface of the sealing material 21 provided on the negative terminal electrode 13.

[0039] The laminate film 30 includes a main body portion 41 disposed on the outer surface 20s and welded thereto, a first extension portion (first part) 42 extending from one end of the main body portion 41 in a first direction D1 in a direction intersecting the first direction D1 (an in-plane direction including the second direction D2 and the third direction D3), and a second extension portion (first part) 43 extending from the other end of the main body portion 41 in the first direction D1 in a direction intersecting the first direction D1 (an in-plane direction including the second direction D2 and the third direction D3). The first extension portion 42 is disposed on the first end surface 20a and welded thereto. The second extension portion 43 is disposed on the second end surface 20b and welded thereto.

[0040] The first extension portion 42 and the second extension portion 43 extend at least to a position where the sealing material 21, the current collector 15, and the spacer 22 overlap when viewed from the first direction D1. On the other hand, the first extension portion 42 and the second extension portion 43 terminate at a position that does not go beyond one of the end of the sealing material 21 on the internal space S side and the end of the spacer 22 on the internal space S side, which is located more outward (the end of the spacer 22 in the illustrated example). Note that in FIG. 1, the rectangular frame-shaped first extension portion 42 is shown in a see-through manner.

[0041] The multiple laminate films 30 include a first laminate film 31, a second laminate film 32, a third laminate film 33, a fourth laminate film 34, and a fifth laminate film 35. The first laminate film 31 is disposed on the first side surface 20s1 of the main body portion 41 and is welded to the first side surface 20s1. The second laminate film 32 is disposed on the second side surface 20s2 of the main body portion 41 and is welded to the second side surface 20s2.

[0042] The third laminate film 33 is disposed on the third side surface 20s3 in the main body 41 and is welded to the third side surface 20s3. The fourth laminate film 34 is disposed on a corner 20r3 of the outer side surface 20s connecting the first side surface 20s1 and the fourth side surface 20s4 in the main body 41 and is welded to one end of the fourth side surface 20s4 in the second direction D2. The fifth laminate film 35 is disposed on a corner 20r4 of the outer side surface 20s connecting the third side surface 20s3 and the fourth side surface 20s4 in the main body 41 and is welded to the other end of the fourth side surface 20s4 in the second direction D2.

[0043] The above welding of the laminate film 30 and the sealing body 20 is performed by pressing the laminate film 30 toward the sealing body 20 while the sealing body 20 and the resin layer 30b of the laminate film 30 are in a melted state. As an example, the laminate film 30 is welded to the sealing body 20 using a heat bar.

[0044] As shown in FIG. 3 , the first laminate film 31 and the second laminate film 32 are joined to each other at a corner 20r1 of the outer surface 20s that connects the first side surface 20s1 and the second side surface 20s2 when viewed from the first direction D1. The corner 20r1 is a curved surface formed in an arc shape when viewed from the first direction D1. An overlapping portion P between the first laminate film 31 and the second laminate film 32 covers the center C of the corner 20r1 when viewed from the first direction D1. Here, as an example, the first laminate film 31 is located closer to the outer surface 20s than the second laminate film 32. That is, in this embodiment, the first laminate film 31 is welded to the corner 20r1, and the second laminate film 32 is joined (welded) to the first laminate film 31 at the corner 20r1 so as to overlap the first laminate film 31.

[0045] When viewed from the first direction D1, the first laminate film 31 may extend from the first side surface 20s1, past the corner 20r1, and to the second side surface 20s2. However, in this example, the first laminate film 31 terminates within the corner 20r1. This is to prevent insufficient heating and welding of the portion (corner) of the first laminate film 31 extending to the second side surface 20s2 when, for example, the sealing body 20 and / or the first laminate film 31 are heated and welded together from the first side surface 20s1 side. For the same reason, the second laminate film 32 terminates within the corner 20r1. Note that, if the corner 20r1 is arc-shaped, the center C of the corner 20r1 (and the same applies to the other corners 20r2 to 20r4) is the midpoint of the arc. The inside of the corner 20r1 (similarly for the other corners 20r2 to 20r4) does not mean a flat region such as the first side surface 20s1 or the second side surface 20s2 on the outer surface 20s, but means the inside of a curved region on the outer surface 20s.

[0046] As shown in FIG. 1 , the second laminate film 32 and the third laminate film 33 are joined to each other at a corner 20r2 of the outer surface 20s that connects the second side surface 20s2 and the third side surface 20s3 when viewed from the first direction D1. Here, the corner 20r2 is a curved surface formed in an arc shape when viewed from the first direction D1. The overlapping portion of the second laminate film 32 and the third laminate film 33 covers the center of the corner 20r2 when viewed from the first direction D1. Here, as an example, the third laminate film 33 is located closer to the outer surface 20s than the second laminate film 32. That is, in this embodiment, the third laminate film 33 is welded to the corner 20r2, and the second laminate film 32 is joined (welded) to the third laminate film 33 at the corner 20r2 so as to overlap the third laminate film 33.

[0047] When viewed from the first direction D1, the second laminate film 32 may extend from the second side surface 20s2, past the corner 20r2, and to the third side surface 20s3, but here it terminates within the corner 20r2 for the reasons described above. The third laminate film 33 also terminates within the corner 20r2 for the same reasons.

[0048] The first laminate film 31 and the fourth laminate film 34 are joined to each other at a corner 20r3 of the outer surface 20s that connects the first side surface 20s1 and the fourth side surface 20s4 when viewed from the first direction D1. Here, the corner 20r3 is a curved surface that is formed in an arc shape when viewed from the first direction D1. The overlapping portion of the first laminate film 31 and the fourth laminate film 34 covers the center of the corner 20r3 when viewed from the first direction D1. Here, as an example, the first laminate film 31 is located closer to the outer surface 20s than the fourth laminate film 34. That is, in this embodiment, the first laminate film 31 is welded to the corner 20r3, and the fourth laminate film 34 is joined (welded) to the first laminate film 31 at the corner 20r3 so as to overlap the first laminate film 31.

[0049] When viewed from the first direction D1, the first laminate film 31 may extend from the first side surface 20s1, past the corner 20r3, and to the fourth side surface 20s4. However, in this example, it terminates within the corner 20r3. The reason for this is as described above. The fourth laminate film 34 also terminates within the corner 20r3 for the same reason. The fourth laminate film 34 is provided from the corner 20r3 to the fourth side surface 20s4. The portion of the fourth laminate film 34 that does not overlap the first laminate film 31 is welded to the fourth side surface 20s4.

[0050] Furthermore, the third laminate film 33 and the fifth laminate film 35 are joined to each other at a corner 20r4 of the outer surface 20s that connects the third side surface 20s3 and the fourth side surface 20s4 when viewed from the first direction D1. Here, the corner 20r4 is a curved surface formed in an arc shape when viewed from the first direction D1. The overlapping portion between the third laminate film 33 and the fifth laminate film 35 covers the center of the corner 20r4 when viewed from the first direction D1. Here, as an example, the third laminate film 33 is located closer to the outer surface 20s than the fifth laminate film 35. That is, in this embodiment, the third laminate film 33 is welded to the corner 20r4, and the fifth laminate film 35 is joined to the third laminate film 33 at the corner 20r4 so as to overlap the third laminate film 33.

[0051] When viewed from the first direction D1, the third laminate film 33 may extend from the third side surface 20s3, past the corner 20r4, and to the fourth side surface 20s4, but here it terminates within the corner 20r4. The reason for this is as described above. The fifth laminate film 35 also terminates within the corner 20r4 for the same reason. The fifth laminate film 35 is provided from the corner 20r4 to the fourth side surface 20s4. The portion of the fifth laminate film 35 that does not overlap the third laminate film 33 is welded to the fourth side surface 20s4.

[0052] 4 is a development view of the laminate film shown in FIGS. 1 to 3. As shown in FIG. 4, the laminate film 30 (at least the first laminate film 31, the second laminate film 32, and the third laminate film 33) includes the main body portion 41, the first extending portion 42, and the second extending portion 43 as described above. The first extending portion 42 and the second extending portion 43 are portions (first portions) that are welded to the first end face 20a0 and the second end face 20b of the sealing body 20, respectively, that are adjacent to the outer surface 20s of the sealing body 20 in the first direction D1. Notches 30p are formed in the first extending portion 42 and the second extending portion 43 in portions that correspond to (are welded to) the corners 20r1, 20r2, 20r3, and 20r4.

[0053] In the example shown in FIG. 4(a), the notches 30p are pairs of slits formed in portions corresponding to the corners 20r1, 20r2, 20r3, and 20r4. In the example shown in FIG. 4(b), the notches 30p are wedge-shaped notches formed in portions corresponding to the corners 20r1, 20r2, 20r3, and 20r4. In the example shown in FIG. 4(c), the notches 30p are rectangular notches formed in portions corresponding to the corners 20r1, 20r2, 20r3, and 20r4. In particular, in the example shown in FIG. 4(c), the notches 30p are formed by cutting out rectangular shapes at the four corners of the laminate film 30. The notches 30p can be configured by appropriately combining the examples shown in FIGS. 4(a) to 4(c) and other examples.

[0054] As described above, in the energy storage module 1 according to this embodiment, the resin sealing body 20 is provided around the electrode stack 10, which includes a plurality of electrodes stacked in the first direction D1. Furthermore, a plurality of laminate films 30, each including a metal layer 30a and a resin layer 30b covering both sides of the metal layer 30a, are welded to the outer surface 20s of the sealing body 20. The plurality of laminate films 30 include a first laminate film 31 welded to a first side surface 20s1 of the outer surface 20s of the sealing body 20, and a second laminate film 32 welded to a second side surface 20s2 of the outer surface 20s of the sealing body 20, the second side surface 20s being adjacent to the first side surface 20s1. The first laminate film 31 is welded to a corner 20r1 connecting the first side surface 20s1 and the second side surface 20s2 of the sealing body 20, and the second laminate film 32 is joined to overlap the first laminate film 31 at the corner 20r1. As a result, the strength of the laminate film 30 is ensured at the corner 20r1 where stress concentration may occur during expansion and contraction of the sealing body 20, improving reliability.

[0055] Furthermore, in the energy storage module 1 according to this embodiment, the corners 20r1 are formed in an arc shape when viewed from the first direction D1. Therefore, stress that may occur when the sealing body 20 expands and contracts is dispersed at the corners 20r1. This reduces the required strength of the laminate film 30 that overlaps the corners 20r1.

[0056] Furthermore, in the energy storage module 1 according to this embodiment, the overlapping portion P between the first laminate film 31 and the second laminate film 32 may cover the center C of the corner 20r1 when viewed from the first direction D1. In this case, by covering the center C of the corner 20r1, where stress is thought to be most concentrated during expansion and contraction of the sealing body 20, with the stronger overlapping portion P of the laminate film 30, reliability is reliably improved.

[0057] Furthermore, in the energy storage module 1 according to this embodiment, the first laminate film 31 and the second laminate film 32 each include a first extension portion 42 and a second extension portion 43 that are welded to the first end surface 20a and the second end surface 20b of the sealing body 20, respectively, that are adjacent in the first direction D1 to the outer surface 20s of the sealing body 20. Notches 30p are formed in portions of the first extension portion 42 and the second extension portion 43 that correspond to the corners 20r1. For this reason, wrinkles are less likely to occur in the portions of the laminate film 30 that correspond to the corners 20r1 of the first extension portion 42 and the second extension portion 43 that are welded to the top and bottom surfaces of the sealing body 20.

[0058] The above embodiment has been described as one aspect of the present invention, and therefore the present invention is not limited to the above embodiment and can be modified as desired.

[0059] For example, the laminate film 30 may not be provided on the fourth side surface 20s4 of the outer surface 20s of the sealing body 20, on which a structure 60, such as a resin frame for injecting an electrolyte solution, is disposed. In other words, the first laminate film 31 does not have to be welded to one corner 20r3 of the fourth side surface 20s4. In this case, the fourth laminate film 34 may be omitted. The third laminate film 33 does not have to be welded to the other corner 20r4 of the fourth side surface 20s4. In this case, the fifth laminate film 35 may be omitted. Even in this case, the strength of the laminate film 30 can be ensured at least at the corner 20r1 where the first laminate film 31 and the second laminate film 32 are joined together and overlap, and at the corner 20r2 where the second laminate film 32 and the third laminate film 33 are joined together and overlap.

[0060] The fourth laminate film 34 may not extend from the corner 20r3 to the fourth side surface 20s4, but may be provided only within the corner 20r3. Similarly, the fifth laminate film 35 may not extend from the corner 20r4 to the fourth side surface 20s4, but may be provided only within the corner 20r4.

[0061] Furthermore, the four corners of the sealing body 20 when viewed from the first direction D1 do not have to be chamfered. In this case, the corners 20r1, 20r2, 20r3, and 20r4 may be right-angled rather than arc-shaped. Furthermore, the first extension portion 42 and the second extension portion 43 do not have to have the notch 30p.

[0062] At the four corners of the sealing body 20 when viewed from the first direction D1, the ends of the first extension portion 42 (and the second extension portion 43) of adjacent laminate films 30 may be overlapped and joined together (or may not be overlapped).

[0063] Furthermore, when another laminate film 30 is joined to overlap the laminate film 30 welded to the corners 20r1, 20r2, 20r3, and 20r4, the laminate films 30 may be joined to each other by a method other than welding, such as adhesion. In this case, the resin layers 30b and 30c of the laminate film 30 may be made of different resin materials.

[0064] Furthermore, the fourth laminate film 34 may be welded to the corner 20r3, and the fifth laminate film 35 may be welded to the corner 20r4. In this case, the first laminate film 31 may be joined to overlap the fourth laminate film 34 at the corner 20r3, and the third laminate film 33 may be joined to overlap the fifth laminate film 35 at the corner 20r4. [Explanation of symbols]

[0065] 1...storage module, 10...electrode laminate, 20...sealing body, 20s...outer surface, 20s1...first side surface, 20s2...second side surface, 20r1...corner portion, 30...laminate film, 30p...notch, 31...first laminate film, 32...second laminate film, 33...third laminate film, 34...fourth laminate film, 35...fifth laminate film, C...center, P...overlapping portion, S...internal space.

Claims

1. an electrode stack formed by stacking a plurality of electrodes, each of which includes a current collector provided with an active material layer, along a first direction; a resin sealing body provided on the electrode stack so as to surround the electrode stack and sealing an internal space between adjacent current collectors; a plurality of laminate films welded to the outer surface of the sealing body, the laminate films including a metal layer and a resin layer covering both sides of the metal layer; Equipped with the sealing body is formed in a rectangular frame shape when viewed from the first direction, and the outer surface includes a first side surface and a second side surface that are adjacent to each other when viewed from the first direction, The plurality of laminate films include a first laminate film welded to the first side surface and a second laminate film welded to the second side surface, the first laminate film is welded to a corner of the outer surface that connects the first side surface and the second side surface when viewed from the first direction, The second laminate film is joined to the first laminate film at the corner portion so as to overlap the first laminate film. Energy storage module.

2. The corner portion is formed in an arc shape when viewed from the first direction. The energy storage module according to claim 1 .

3. an overlapping portion between the first laminate film and the second laminate film covers the center of the corner portion when viewed from the first direction; The energy storage module according to claim 2 .

4. the first laminate film and the second laminate film each include a first portion welded to at least one of a first end surface and a second end surface of the sealing body that are adjacent to the outer surface of the sealing body in the first direction, A notch is formed in a portion of the first portion corresponding to the corner portion. The storage module according to any one of claims 1 to 3.

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