Method for manufacturing electrode for electric power storage module, and method for manufacturing electric power storage module

Abstract

This method for manufacturing an electrode 4 for an electric power storage module comprises: a disposing step of disposing, along an outer edge portion 42c of an electrode foil 42, a first resin member 45 on a first surface 42a and a second resin member 46 on a second surface 42b; a temporary fixing step of temporarily fixing each of the first resin member 45 and the second resin member 46 to the electrode foil 42 by point welding using heat irons 81, 82; and a main welding step of thermally welding each of the first resin member 45 and the second resin member 46 to the electrode foil 42, wherein, in the temporary fixing step, a pressing member is disposed on at least one side of the first resin member 45 and the second resin member 46 in a wider range than tip portions 81a, 82a of the heat irons 81, 82, and the first resin member and the second resin member are point-welded to the electrode foil 42 in a state where the resin member around the welding point is pressed by the pressing member.

Description

Method for manufacturing an electrode for a storage module and method for manufacturing a storage module

[0001] The present disclosure relates to a method for manufacturing an electrode for a storage module and a method for manufacturing a storage module.

[0002] A conventional method for manufacturing an energy storage module is described in, for example, Patent Document 1. In the method of Patent Document 1, a bipolar electrode and a resin frame are prepared (preparation step), and the resin frame is welded to the peripheral edge of the electrode plate of the bipolar electrode while applying pressure to form a bipolar electrode unit (welding step).

[0003] JP 2020-95909 A JP 2022-175293 A

[0004] The welding process may include two steps: a temporary fixing step in which a resin frame is temporarily welded to the edge of the electrode foil of the bipolar electrode, and a fixing step in which the resin frame is permanently welded to the edge of the electrode foil using an impulse heater. For example, Patent Document 2 discloses a temporary welding method in which a resin piece is spot-welded to the electrode foil using a heater device such as a hot iron.

[0005] When spot welding the edges of the electrode foil to the resin frame using a hot iron, the generation of burrs at the welding points becomes an issue. If an impulse heater is used to fully weld the resin frame to the electrode foil when burrs have formed at the welding points of the resin frame, the surface pressure applied when the impulse heater is pressed against the burr-formed areas will vary from areas where burrs have formed to areas where burrs have not formed, which may result in buckling and wrinkles in the electrode foil.

[0006] An object of the present disclosure is to provide a method for manufacturing an energy storage module electrode and a method for manufacturing an energy storage module that can suppress the generation of burrs at the welding point when a resin frame is temporarily welded to an electrode foil.

[0007] A manufacturing method of an electrode for a storage module according to one aspect of the present disclosure includes an arrangement step of arranging a first resin member on a first surface along the outer edge of an electrode foil on which an active material layer is provided, and arranging a second resin member on a second surface along the outer edge of the electrode foil; a temporary fixing step of temporarily fixing each of the first resin member and the second resin member arranged along the outer edge to the electrode foil by spot welding using a hot iron; and a main welding step of thermally welding each of the temporarily fixed first resin member and second resin member to the electrode foil, to form an electrode for a storage module. In the temporary fixing step, a pressing member is placed on at least one side of the first resin member and the second resin member over a wider area than the tip of the hot iron, and the first resin member and the second resin member are spot-welded to the electrode foil while the pressing member presses down on the resin member around the welding point.

[0008] In a manufacturing method of an electrode for a storage module according to one aspect of the present disclosure, in the temporary fixing step, a presser member is arranged over a wider area than the tip portion, and the presser member presses the resin member around the welding point. This allows the molten resin to flow along the surface of the presser member, preventing the resin from bulging due to the application of a hot iron. This prevents burrs from occurring at the welding point in the temporary fixing step. Therefore, it is possible to prevent buckling wrinkles from occurring in the electrode foil in the main fixing step.

[0009] The electrode foil may have a rectangular shape in a plan view, and in the arranging step, a strip-shaped first resin member may be arranged on a first surface so as to correspond to one side of the electrode foil, and a strip-shaped second resin member may be arranged on a second surface so as to correspond to one side of the electrode foil, and in the temporary fixing step, the strip-shaped first resin member may be spot-welded to the first surface, and the strip-shaped second resin member may be spot-welded to the second surface. In this case, the step of arranging the first resin member on the first surface and the step of arranging the second resin member on the second surface may be performed simultaneously, and the step of spot-welding the first resin member to the first surface and the step of point-welding the second resin member to the second surface may be performed simultaneously, thereby efficiently temporarily fixing the first resin member and the second resin member to the electrode foil.

[0010] In the temporary fixing process, the tip of the hot iron may be pressed against the resin member via a sheet member as a pressing member. In this case, the sheet member prevents the hot iron from directly contacting the resin and sinking into the resin, further reducing the occurrence of burrs at the welding point.

[0011] In the temporary fixing step, tension may be applied to the sheet member. This configuration can prevent the sheet member from bending when the molten resin flows along the surface of the sheet member. This maintains the flatness of the resin and more reliably prevents burrs from occurring at the welding points.

[0012] In the temporary fixing step, a ceramic member as a pressing member may be fixed around the tip of the hot iron, and the tip may be pressed against the resin member while the ceramic member is in contact with the resin member around the tip. In this case, the resin melted by being pressed against the tip of the hot iron flows along the surface of the ceramic member, and the resin is prevented from bulging due to the pressing of the hot iron.

[0013] In the temporary fixing step, a hot iron with a concavely curved tip surface may be pressed against the first or second resin member that does not have a pressing member disposed thereon to perform spot welding. In this case, the resin easily flows into the concavely curved tip surface during the temporary fixing step. This makes it difficult for the resin to bulge along the outer edge of the tip, thereby reducing burrs at the welding point.

[0014] In the temporary fixing step, a pair of hot irons corresponding to the first resin member and the second resin member, respectively, may be used, and the heating temperature of the hot iron corresponding to the resin member without the pressing member may be lower than the heating temperature of the hot iron corresponding to the resin member with the pressing member. In this case, the heating temperature of the hot iron corresponding to the resin member without the pressing member is lower than the heating temperature of the hot iron corresponding to the resin member with the pressing member, thereby preventing burrs from occurring at the welding points of the resin member without the pressing member.

[0015] In this welding process, a pair of elongated heaters are prepared, each disposed opposite the electrode foil, and one of the heaters heats and presses a wide area including the temporary welding point where the electrode foil and the first resin member overlap, where the electrode foil and the first resin member are temporarily welded, while the other heater of the pair heats and presses a wide area including the temporary welding point where the electrode foil and the second resin member overlap, where the electrode foil and the second resin member are temporarily welded. In this case, by heating and pressurizing an area wider than the temporary welding point, the electrode foil and the first resin member, and the electrode foil and the second resin member can be reliably permanently welded.

[0016] In the method for manufacturing an energy storage module according to one aspect of the present disclosure, the occurrence of buckling wrinkles in the energy storage module electrodes in which the resin frame is welded to the electrode foil is suppressed, and therefore, when a stack formed by stacking a plurality of energy storage module electrodes is restrained in the stacking direction of the energy storage module electrodes, sufficient adhesion can be ensured between the energy storage module electrodes and the spacer resin frames that are adjacent in the stacking direction. As a result, in the end face welding step, welding of the outer edges of the energy storage module electrodes and the outer edges of the spacer resin frames can be favorably achieved, and sealing defects in the energy storage module can be suppressed.

[0017] According to the present disclosure, it is possible to provide a method for manufacturing an electrode for a storage module and a method for manufacturing a storage module that can suppress the occurrence of burrs at welding points.

[0018] FIG. 1 is a schematic cross-sectional view of a power storage module including a power storage module electrode. FIG. 2( a) is a cross-sectional view of the power storage module electrode, and FIG. 2( b) is a plan view of the power storage module electrode. FIG. 3 is a flowchart showing one step of a method for manufacturing a power storage module electrode. FIG. 4 is a diagram for explaining an arrangement step. FIG. 5 is a perspective view of a heat iron and a sheet member used in the temporary fixing step shown in FIG. 3. FIG. 6 is a diagram for explaining the temporary fixing step shown in FIG. 3. FIG. 7( a) is a diagram showing the state of spot welding in the temporary fixing step according to a comparative example, and FIG. 7( b) is a diagram for explaining the welding points in the temporary fixing step according to the comparative example. FIG. 8( a) is a diagram showing the state of spot welding in the temporary fixing step according to the embodiment, and FIG. 8( b) is a diagram for explaining the welding points in the temporary fixing step according to the embodiment. FIG. 9( a) is a plan view of the electrode foil in a state in which a first temporary resin frame is temporarily fixed, viewed from the first surface side. FIG. 9( b) is a plan view of the electrode foil with the second temporary resin frame temporarily fixed thereto, as viewed from the second surface side. FIG. 10 is a diagram for explaining the fixing process shown in FIG. 3. FIG. 11( a) is a diagram showing the state of permanent welding in the fixing process according to a comparative example, and FIG. 11( b) is a diagram for explaining the occurrence of buckling wrinkles in the fixing process according to the comparative example. FIG. 12( a) is a diagram showing the state of permanent welding in the fixing process according to the first embodiment, and FIG. 12( b) is a diagram for explaining the suppression of buckling wrinkles in the fixing process according to the first embodiment. FIG. 13 is a diagram for explaining the temporary fixing process according to the second embodiment. FIG. 14 is a diagram for explaining the temporary fixing process according to the first modified example. FIG. 15 is a diagram for explaining the temporary fixing process according to the second modified example. FIG. 16 is a diagram showing an example of the arrangement process and the temporary fixing process using a suction plate.

[0019] Hereinafter, preferred embodiments of a manufacturing method and welding apparatus for an electrode for a storage module according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0020] 1 is a schematic cross-sectional view of an energy storage module including an electrode for an energy storage module manufactured by a method for manufacturing an electrode for an energy storage module according to a first embodiment. The energy storage module 1 is a energy storage module used in batteries for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage module 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the energy storage module 1 is a lithium-ion secondary battery is illustrated as an example.

[0021] The energy storage module 1 includes an electrode stack 2 and a sealing portion 20. The electrode stack 2 includes a plurality of bipolar electrodes 11 stacked in a stacking direction D1, a positive terminal electrode 13, and a negative terminal electrode 12. That is, the electrode stack 2 is formed by stacking a plurality of bipolar electrodes 11 between the positive terminal electrode 13 and the negative terminal electrode 12. The sealing portion 20 is provided on the periphery of the electrode stack 2 and seals a plurality of spaces formed inside the electrode stack 2.

[0022] The bipolar electrode 11 includes an electrode foil 42, a positive electrode active material layer 44, and a negative electrode active material layer 43. When viewed from the stacking direction D1 (in a plan view), the electrode foil 42 has a four-sided rectangular shape. The negative electrode active material layer 43 is provided on a first surface 42a of the electrode foil 42. The positive electrode active material layer 44 is provided on a second surface 42b of the electrode foil 42 opposite the first surface 42a. That is, in the bipolar electrode 11, the first surface 42a of the electrode foil 42 functions as a negative electrode, and the second surface 42b of the electrode foil 42 functions as a positive electrode. Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 44 of one bipolar electrode 11 faces the negative electrode active material layer 43 of another bipolar electrode 11. Here, as shown in FIG. 1 , the bipolar electrode 11 has a first surface 42 a of the electrode foil 42 facing the positive terminal electrode 13 side, and a second surface 42 b of the electrode foil 42 facing the negative terminal electrode 12 side.

[0023] The positive electrode active material layer 44 and the negative electrode active material layer 43 have a rectangular shape with four sides when viewed from the stacking direction D1. The negative electrode active material layer 43 is slightly larger than the positive electrode active material layer 44 when viewed from the stacking direction D1. That is, when viewed from the stacking direction D1, the outer edge of the positive electrode active material layer 44 is located more inward than the outer edge of the negative electrode active material layer 43. Furthermore, the electrode foil 42 is slightly larger than the negative electrode active material layer 43 and the positive electrode active material layer 44 when viewed from the stacking direction D1. That is, when viewed from the stacking direction D1, the outer edge of the electrode foil 42 is located more outward than the outer edge of the negative electrode active material layer 43 on the first surface 42a. As a result, an uncoated region 42a1 where the negative electrode active material layer 43 is not formed is formed on the first surface 42a so as to surround the outer edge of the negative electrode active material layer 43. Similarly, on the second surface 42b, the outer edge of the electrode foil 42 is located outside the outer edge of the positive electrode active material layer 44. As a result, on the second surface 42b, an uncoated region 42b1 where the positive electrode active material layer 44 is not formed is formed so as to surround the outer edge of the positive electrode active material layer 44.

[0024] The negative terminal electrode 12 has an electrode foil 42 and a negative electrode active material layer 43 provided on a first surface 42a of the electrode foil 42. The negative terminal electrode 12 does not have a positive electrode active material layer 44. That is, in the negative terminal electrode 12, no active material layer is provided on a second surface 42b of the electrode foil 42. The negative terminal electrode 12 is stacked on the bipolar electrode 11 at one end in the stacking direction D1. The negative terminal electrode 12 is stacked on the bipolar electrode 11 so that the negative electrode active material layer 43 faces the positive electrode active material layer 44 of the bipolar electrode 11. Therefore, the second surface 42b of the electrode foil 42 of the negative terminal electrode 12 faces outside the electrode stack 2 and serves as the negative electrode terminal surface of the energy storage module 1.

[0025] The positive terminal electrode 13 has an electrode foil 42 and a positive electrode active material layer 44 provided on a second surface 42b of the electrode foil 42. The positive terminal electrode 13 does not have a negative electrode active material layer 43. That is, in the positive terminal electrode 13, no active material layer is provided on a first surface 42a of the electrode foil 42. The positive terminal electrode 13 is laminated on the bipolar electrode 11 at the other end in the lamination direction D1. The positive terminal electrode 13 is laminated on the bipolar electrode 11 so that its positive electrode active material layer 44 faces the negative electrode active material layer 43 of the bipolar electrode 11. Therefore, the first surface 42a of the electrode foil 42 of the positive terminal electrode 13 faces outside the electrode stack 2 and serves as the positive electrode terminal surface of the energy storage module 1.

[0026] The electrode foil 42 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer 44 and the negative electrode active material layer 43 during discharge or charge of the lithium ion secondary battery. The material of the electrode foil 42 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. The conductive resin material is, for example, a conductive polymer material or a resin in which a conductive filler is added to a non-conductive polymer material. The electrode foil 42 may have multiple layers. In this case, each layer of the electrode foil 42 may contain the above-mentioned metal material or conductive resin material.

[0027] A coating layer may be formed on the electrode foil 42. The coating layer may be formed by a known method such as plating or spray coating. The electrode foil 42 may be, for example, in the form of a plate, foil, film, or mesh. The electrode foil 42 may be, for example, a metal foil. Examples of metal foils include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The electrode foil 42 may be an alloy foil of the above metals or a foil formed by integrating multiple metal foils. In this embodiment, the electrode foil 42 of the bipolar electrode 11 is a laminated foil formed by bonding a first electrode foil 421 and a second electrode foil 422 together via a conductive adhesive layer. The thickness of the first electrode foil 421 is thicker than the thickness of the second electrode foil 422. The thickness of the first electrode foil 421 is, for example, 30 μm to 100 μm. The thickness of the second electrode foil 422 is, for example, 5 μm to 10 μm. The first electrode foil 421 is, for example, an aluminum foil, and the second electrode foil 422 is, for example, a copper foil.

[0028] The positive electrode active material layer 44 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 44 may contain a plurality of positive electrode active materials. In this embodiment, the positive electrode active material layer 44 contains an olivine-type lithium iron phosphate (LiFePO ) as a composite oxide. ４ )

[0029] The negative electrode active material layer 43 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be a simple substance, an alloy, or a compound. Examples of the negative electrode active material include metallic lithium (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 (Si) and tin. In this embodiment, the negative electrode active material layer 43 includes graphite as a carbon-based material.

[0030] Each of the positive electrode active material layer 44 and the negative electrode active material layer 43 (hereinafter sometimes simply referred to as "active material layer") may further contain, as necessary, a conductive additive for improving electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conductive polymer, electrolyte solution, etc.), an electrolyte supporting salt (lithium salt) for improving ionic conductivity, etc. The conductive additive is added to improve the conductivity of each electrode (bipolar electrode 11, negative electrode terminal electrode 12, positive electrode terminal electrode 13). Examples of the conductive additive include acetylene black, carbon black, and graphite.

[0031] 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).

[0032] Separators 6 are disposed between adjacent bipolar electrodes 11, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive terminal electrode 13 and the bipolar electrode 11. The separators 6 are interposed between the positive electrode active material layer 44 and the negative electrode active material layer 43, which face each other in the stacking direction D1. The separators 6 separate the positive and negative electrodes, preventing short circuits due to contact between adjacent electrodes, while allowing charge carriers such as lithium ions to pass through. The positive electrode includes one electrode foil 42 and the positive electrode active material layer 44 formed on the second surface 42b of one electrode foil 42. The negative electrode includes the electrode foil 42 facing the positive electrode via the separator 6 and the negative electrode active material layer 43 formed on the first surface 42a of the opposing electrode foil 42.

[0033] The separator 6 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 6 include polypropylene, polyethylene, polyolefin, and polyester. The separator 6 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 6 may be impregnated with an electrolyte. The separator 6 may be composed of an electrolyte such as a polymer electrolyte or an inorganic electrolyte. Examples of the electrolyte impregnated in the separator 6 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.

[0034] When the separator 6 is impregnated with an electrolyte solution, the electrolyte salt may be LiFSI, LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ ) ２Known 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.

[0035] The sealing unit 20 includes a first resin frame 41 and a second resin frame 5. The first resin frame 41 and the second resin frame 5 are each made of resin. The sealing unit 20 is bonded to the first surface 42a and the second surface 42b of each electrode foil 42 at the outer edge 42c of each electrode foil 42. The sealing unit 20 maintains a gap between adjacent electrode foils 42 so that a pair of adjacent electrode foils 42 in the stacking direction D1 do not contact each other. The sealing unit 20 seals each space S between adjacent electrode foils 42 in the stacking direction D1. That is, a space S is defined by the electrode foils 42 adjacent in the stacking direction D1 and the sealing unit 20. Each space S contains a positive electrode active material layer 44, a negative electrode active material layer 43, a separator 6, and an electrolyte. The electrolyte to be contained in the space S is injected into the space S through a through-hole 20a formed in the sealing unit 20 during the manufacturing process. The through-hole 20a is a hole for injecting the electrolyte. After the electrolyte is accommodated in the space S, the through-hole 20a is finally sealed with a separate member. The sealing portion 20 prevents the electrolyte from permeating to the outside. The sealing portion 20 suppresses the intrusion of moisture and the like into the space S from the outside of the energy storage module 1.

[0036] The outer edge 6a of each separator 6 is fixed to a sealing portion 20. The sealing portion 20 contains an insulating material. Examples of resin materials that form the sealing portion 20 include polypropylene, polyethylene, acid-modified polypropylene (acid-modified PP), acid-modified polyethylene (acid-modified PE), polystyrene, ABS resin, and acrylonitrile-styrene resin. The resin materials that form the first resin frame 41 and the second resin frame 5 may be the same or different.

[0037] The first resin frame 41 is joined to the first surface 42a and the second surface 42b of each electrode foil 42 at the outer edge 42c of each electrode foil 42. The first resin frame 41 is a rectangular frame-shaped member in a plan view. The first resin frame 41 is provided so as to extend from the first surface 42a of the electrode foil 42 through the outer edge 42d to the second surface 42b. In other words, the first resin frame 41 has a portion covering the outer edge 42c. The first resin frame 41 includes an overlapping portion 411 that overlaps the electrode foil 42 in the stacking direction D, and a protruding portion 412 that protrudes outward beyond the outer edge 42c of the electrode foil 42 and does not overlap the electrode foil 42 in the stacking direction D. The first resin frame 41 is welded to the first surface 42a and the second surface 42b of the electrode foil 42 at the overlapping portion 411. Examples of resin materials that can be used to form the first resin frame 41 include polypropylene, polyethylene, acid-modified polypropylene (acid-modified PP), acid-modified polyethylene (acid-modified PE), polystyrene, ABS resin, acrylonitrile-styrene resin, etc. The outer edge 6 a of the separator 6 may be fixed to the first resin frame 41 by welding.

[0038] The second resin frame 5 (spacer resin frame) is disposed between adjacent first resin frames 41 in the stacking direction D1. The first resin frames 41 and the second resin frames 5 are alternately stacked along the stacking direction D1. The second resin frame 5 is sandwiched between adjacent first resin frames 41. The second resin frame 5, together with adjacent first resin frames 41, defines a space S between adjacent electrode foils 42. The second resin frame 5 has a rectangular frame shape in plan view and includes an overlapping portion 51 that overlaps the electrode foil 42 in the stacking direction D1 and a protruding portion 52 that protrudes outward beyond the outer edge portion 42c of the electrode foil 42 and does not overlap the electrode foil 42 in the stacking direction D1. The second resin frame 5 is welded to each of a pair of adjacent first resin frames 41 in the stacking direction D1 at the edge of the protruding portion 52. Examples of resin materials that can be used to form the second resin frame 5 include polypropylene, polyethylene, acid-modified polypropylene (acid-modified PP), acid-modified polyethylene (acid-modified PE), polystyrene, ABS resin, acrylonitrile-styrene resin, etc. The outer edge 6 a of the separator 6 may be sandwiched between the first resin frame 41 and the second resin frame 5.

[0039] The welded end 7 is formed by integrally welding the end faces of the first resin frames 41 and the second resin frames 5 stacked in the stacking direction D1. The welded end 7 seals each of the spaces S by welding the outer edge 41 a of the first resin frame 41 to the outer edge 5 a of the second resin frame 5. The sealed outer edges 41 a and 5 a form the outer surface 7 s of the energy storage module 1. In this embodiment, the resin material forming the first resin frame 41 is acid-modified polyethylene or acid-modified polypropylene, and the resin material forming the second resin frame 5 is polyethylene or polypropylene. Acid-modified polyethylene and acid-modified polypropylene have properties that make them more easily adhere to metals than non-acid-modified polyethylene and non-acid-modified polypropylene. In this embodiment, in which the electrode foil 42 is made of a metal foil such as copper foil or aluminum foil, forming the first resin frame 41 from acid-modified polyethylene or acid-modified polypropylene can improve the adhesive strength (bonding strength) of the resin frame to the electrode foil. On the other hand, the second resin frame 5 , which does not require adhesion to the electrode foil, can be made of inexpensive polyethylene or polypropylene, thereby reducing the cost of the energy storage module 1 .

[0040] The laminate 30 is formed, for example, by stacking a plurality of laminate units 3 in the stacking direction D1. The laminate unit 3 is a unit in which a storage module electrode 4, a second resin frame 5, and a separator 6 constitute one unit. FIG. 2( a) is a cross-sectional view of the storage module electrode 4, and FIG. 2( b) is a plan view of the storage module electrode 4. Here, the storage module electrode 4 is formed by joining a first resin frame 41 to each electrode (bipolar electrode 11, negative terminal electrode 12, positive terminal electrode 13) that constitutes the electrode laminate 2. The storage module electrode 4 including the bipolar electrode 11 includes the first resin frame 41, an electrode foil 42, a negative electrode active material layer 43, and a positive electrode active material layer 44. The storage module electrode 4 including the negative electrode terminal electrode 12 includes the first resin frame 41, an electrode foil 42, and a negative electrode active material layer 43. The energy storage module electrode 4, including the positive terminal electrode 13, includes a first resin frame 41, an electrode foil 42, and a positive active material layer 44. In other words, the electrode foil 42 is a component of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13, as well as a component of the laminate unit 3. The first surface 42a and the second surface 42b of the electrode foil 42 of each electrode constituting the electrode laminate 2 include coated regions where active material layers (positive active material layer 44 and negative active material layer 43) are formed, and uncoated regions 42a1, 42b1 where no active material layers are formed. The uncoated regions 42a1, 42b1 may be provided to surround the coated regions. The first resin frame 41 is welded to the first surface 42a and the second surface 42b of the electrode foil 42 in the uncoated regions 42a1, 42b1 of the electrode foil 42. FIG. 2 shows the storage module electrode 4 including an electrode foil 42 which is a component of the bipolar electrode 11 .

[0041] 2B, the first resin frame 41 is formed in a frame shape. In the example of FIG. 2, the outer edge 42d of the electrode foil 42 is located between the outer edge 41a of the first resin frame 41 and the inner edge 41b of the first resin frame 41.

[0042] Next, one embodiment of a method for manufacturing the energy storage module electrode 4 will be described. FIG. 3 is a flowchart showing one step of the method for manufacturing the energy storage module electrode 4. In this manufacturing method, first, a first resin member 45 is placed on the first surface 42a along the outer edge 42c of the electrode foil 42, and a second resin member 46 is placed on the second surface 42b along the outer edge 42c of the electrode foil (arrangement step ST1: see FIG. 4 ). The first resin member 45 and the second resin member 46 are each a strip-shaped resin member. The first resin member 45 and the second resin member 46 correspond to each side of the electrode foil 42. In the arrangement step ST1, the strip-shaped first resin member 45 is placed on the first surface 42a so as to correspond to one side of the electrode foil 42, and the strip-shaped second resin member 46 is placed on the second surface 42b so as to correspond to one side of the electrode foil 42. After the placement step ST1, a first temporary resin frame 450 is provided on the first surface 42a by temporarily fixing a first resin member 45 to the first surface 42a so as to correspond to each side of the electrode foil 42, and a second temporary resin frame 460 is provided on the second surface 42b by temporarily fixing a second resin member 46 to the second surface 42b so as to correspond to each side of the electrode foil 42 (temporary fixing step ST2: see FIG. 9 ). Then, regions of the first temporary resin frame 450 and the second temporary resin frame 460 that overlap with the electrode foil 42 are welded to the electrode foil 42, and regions of the first temporary resin frame 450 and the second temporary resin frame 460 that do not overlap with the electrode foil 42 (regions corresponding to the protruding portions 412) are welded to each other to form the first resin frame 41 (full fixing step ST3: see FIG. 10 ).

[0043] FIG. 4 is a diagram illustrating the arrangement step ST1. As shown in FIG. 4, in the arrangement step ST1, the first resin member 45 and the second resin member 46 are arranged to sandwich the outer edge portion 42c. Specifically, the first resin member 45 is arranged on the first surface 42a so as to extend from the outer edge portion 42c to the outside of the electrode foil 42 (the side opposite the area where the active material layer is formed) and straddle the outer edge 42d. At the same time, the second resin member 46 is arranged on the second surface 42b so as to extend from the outer edge portion 42c to the outside of the electrode foil 42 (the side opposite the area where the active material layer is formed) and straddle the outer edge 42d. When viewed from the stacking direction D1, the first resin member 45 and the second resin member 46 are arranged so that the outer edge 45a of the first resin member 45 and the outer edge 46a of the second resin member 46 extend outward beyond the outer edge 42d of the electrode foil 42 (the side opposite the area where the active material layer is formed). Furthermore, the first resin member 45 and the second resin member 46 are arranged so that the outer edge 45a of the first resin member 45 and the outer edge 46a of the second resin member 46 are aligned when viewed from the stacking direction D1.

[0044] Next, the first resin member 45 and the second resin member 46 arranged along the outer edge 42c are temporarily fixed to the electrode foil 42 by spot welding using a hot iron (temporary fixing process ST2). In the temporary fixing process ST2, after the arrangement process ST1, the first resin member 45 is spot-welded to the first surface 42a, and the second resin member 46 is spot-welded to the second surface 42b. In the temporary fixing process ST2, a pair of hot irons 81, 82 and a pair of sheet members 91, 92 are used for the spot welding. The pair of sheet members 91, 92 correspond to the pressing members of the present disclosure. FIG. 5 is a perspective view of the hot iron 81 and the sheet member 91. The hot iron 81 has, for example, a cylindrical main body 81c and a tip end 81a tapered from the main body 81c toward the tip end surface 81b. The other hot iron 82 has the same configuration as the hot iron 81. The other sheet member 92 has the same configuration as the sheet member 91 .

[0045] The pair of sheet members 91, 92 are members that have excellent heat resistance and thermal conductivity and high releasability from the resins to be welded. The pair of sheet members 91, 92 may be, for example, glass cloth, a sheet-like member made of glass fiber. The glass cloth may be, for example, glass fiber impregnated with a fluorine-based compound. The impregnation of the glass cloth with a fluorine-based compound sufficiently improves the releasability of the sheet member 91 from the first resin member 45 after spot welding, and similarly, sufficiently improves the releasability of the sheet member 92 from the second resin member 46 after spot welding. Meanwhile, glass fiber has a higher thermal conductivity than fluorine-based compounds, which prevents the heat applied from the hot iron 8 to the first resin member 45 from being blocked by the sheet member 91, and similarly prevents the heat applied from the hot iron 8 to the second resin member 46 from being blocked by the sheet member 92. The pair of sheet members 91, 92 are not limited to the glass cloth described above; known release sheets may be used. For example, the pair of sheet members 91, 92 may be a multilayer film including a heat-resistant base layer and a release layer formed on the surface of the base layer. Here, the base layer may be, for example, CFRP or polypropylene. The release layer may be, for example, fluororesin, polystyrene resin, or silicone resin. In this embodiment, a manufacturing method will be described in which glass cloth is used as the pair of sheet members 91, 92.

[0046] In the temporary fixing process ST2, a sheet member 91 is placed over a wider area than the tip 81a of the hot iron 81. Here, the area of ​​the sheet member 91 is set, for example, several times to several tens of times the area of ​​the tip surface 81b, and the center of the sheet member 91 is aligned with the center of the tip 81a of the hot iron 81. As a result, the sheet member 91 is placed between the tip 81a of the hot iron 81 and the first resin member 45 so that the outer edge of the tip surface 81b and the outer edge of the main body 81c are within the area of ​​the sheet member 91 when viewed from the stacking direction D1. Similarly, the sheet member 92 is placed between the tip 82a of the hot iron 82 and the second resin member 46 so that the outer edge of the tip surface 82b and the outer edge of the main body 82c are within the area of ​​the sheet member 92 when viewed from the stacking direction D1.

[0047] When arranging the pair of sheet members 91, 92, tension may be applied to the pair of sheet members 91, 92. There are no particular limitations on the method of applying tension, but the pair of sheet members 91, 92 may be spanned across a pair of support members (not shown) and tension may be applied to each of the pair of sheet members 91, 92 outside the pair of support members, thereby applying tension in the in-plane direction (the in-plane direction of the surfaces of the first resin member 45 and the second resin member 46) to the pair of sheet members 91, 92 between the pair of support members. For example, tensile tension may be applied to the portion of the sheet member 91 where the hot iron 8 abuts by pulling both ends of the sheet member 91 in the direction opposite to the direction in which the hot iron 8 is pressed against the sheet member 91 (the direction toward the first resin member 45).

[0048] In the temporary fixing step ST2, a pair of sheet members 91, 92 is arranged on at least one side of the first resin member 45 and the second resin member 46, over a wider area than the tip 81a of the hot iron 81. Then, the pair of sheet members 91, 92 presses down on the resin member (the resin member on which the pair of sheet members 91, 92 are arranged) around the welding point, and the resin member and the electrode foil 42 are spot-welded from the resin member side. In the example shown in FIG. 6 , the pair of sheet members 91, 92 are arranged on both sides of the first resin member 45 and the second resin member 46. As shown in FIG. 6 , the first resin member 45 and the second resin member 46 are spot-welded to the outer edge portion 42c of the electrode foil 42 from the first resin member 45 and the second resin member 46 side via the pair of sheet members 91, 92. In other words, the first resin member 45 and the second resin member 46 are spot-welded to the outer edge 42c by the pair of sheet members 91, 92 while pressing the resin members around the welding points of the first resin member 45 and the second resin member 46. Various arrangements of the pair of sheet members 91, 92 between the tip ends 81a, 82a of the pair of hot irons 81, 82 and the electrode foil 42 may be employed. For example, the sheet member 91 may be placed on the first resin member 45, and the hot iron 81 may be pressed against the sheet member 91 on the first resin member 45. Alternatively, the sheet member 91 may be brought into contact with the tip surface 81b of the hot iron 81 in advance, and the tip surface 81b with the sheet member 91 in contact may be pressed against the first resin member 45. In either arrangement, the sheet member 91 may be in intimate contact with the surface of the first resin member 45 when the tip surface 81b of the hot iron 81 is pressed against the surface.

[0049] In this embodiment, the spot welding positions are positions where the first resin member 45 and the second resin member 46 overlap the electrode foil 42, as viewed from the stacking direction D1. A pair of hot irons 81, 82 are placed at these positions. In this embodiment, the heating temperature of the hot iron 81 is set to the same temperature as the heating temperature of the hot iron 82. The heating temperature is set to a temperature higher than the melting points of the first resin member 45 and the second resin member 46. When polyethylene is used for the first resin member 45 and the second resin member 46, the melting point of polyethylene is approximately 120°C. In this case, the heating temperature is set to, for example, 130°C to 150°C. The pressing time of the hot iron 81 is very short, for example, 1 to 3 seconds. The force with which the hot iron 81 is pressed against the first resin member 45 is, for example, 10N to 15N.

[0050] In the temporary fixing step ST2, if the sheet member 91 is not placed between the tip 81a of the hot iron 81 and the first resin member 45, the heat from the hot iron 81 melts the resin constituting the first resin member 45. As a result, as shown in FIG. 7A , the tip 81a of the hot iron 81 pressed against the first resin member 45 sinks into the first resin member 45, resulting in a protrusion of the molten resin along the outer surface of the hot iron. Then, as shown in FIG. 7B , the protruding resin cools and hardens, resulting in a burr B protruding from the surface of the first resin member 45 around the welding point HP of the first resin member 45. Furthermore, as shown in FIG. 7A , the tip 81a sinks into the first resin member 45 at the welding point HP, causing the tip 81a to be recessed relative to the area outside the welding point HP. These burrs B and dents can cause buckling and wrinkles to occur in the electrode foil 42 in the subsequent main fixing step.

[0051] In contrast, if a sheet member 91 is placed between the tip 81a of the hot iron 81 and the first resin member 45 in the temporary fixing step ST2, as shown in FIG. 8A , the heat from the hot iron 81 melts the resin constituting the first resin member 45. This causes the molten resin to flow along the surface 91a of the sheet member 91 (the surface opposite to the surface in contact with the tip surface 81b) that is in close contact with the surface of the first resin member 45. Because the sheet member 91 is positioned over a wider area than the tip 81a of the hot iron 81, the molten resin flows along the surface of the sheet member 91 to a position away from the welding point HP, thereby suppressing the resin from protruding due to the application of the hot iron 81. Additionally, because the tip 81a does not directly contact the first resin member 45, the tip 81a is prevented from sinking into the first resin member 45. As a result, as shown in Fig. 8(b), even after the protruding resin cools and hardens, it is possible to prevent the formation of burrs B around the welding point HP of the first resin member 45. In addition, it is possible to prevent the formation of depressions at the welding point HP due to sinking of the tip portion 81a. The effects of preventing the formation of burrs B and depressions described in Fig. 8 are also achieved in the welding of the second resin member 46 and the electrode foil 42 using the hot iron 82 and the sheet member 92.

[0052] In this embodiment, in the arrangement step ST1, one first resin member 45 and one second resin member 46 are arranged to correspond to one side of the electrode foil 42, and in the temporary fixing step ST2, the one first resin member 45 and the one second resin member 46 are temporarily fixed to the one side of the electrode foil 42. By repeating the arrangement step ST1 and the temporary fixing step ST2, the first resin member 45 is temporarily fixed to the first surface 42a so as to correspond to each side of the electrode foil 42. As a result, the first resin member 45 arranged in a frame shape on the first surface 42a of the electrode foil 42 is temporarily fixed to the electrode foil 42, and a first temporary resin frame 450 is provided on the first surface 42a. FIG. 9A is a plan view of the electrode foil 42 with the first temporary resin frame 450 temporarily fixed thereto, viewed from the first surface 42a. As shown in FIG. 9A , the first temporary resin frame 450 is formed by arranging the first resin members 45 in a frame shape along each side of the electrode foil 42, and each first resin member 45 is temporarily fixed to the electrode foil 42. In other words, the first temporary resin frame 450 is not formed by integrating the first resin members 45 together, but is a temporary resin frame formed on the first surface 42a of the electrode foil 42. Similarly, by repeating the placement step ST2 and the temporary fixing step ST2, the second resin members 46 are temporarily fixed to the second surface 42b of the electrode foil 42 so as to correspond to each side of the electrode foil 42. As a result, the second resin members 46 arranged in a frame shape on the second surface 42b of the electrode foil 42 are temporarily fixed to the electrode foil 42, and the second temporary resin frame 460 is provided on the second surface 42b. FIG. 9B is a plan view of the electrode foil 42 with the second temporary resin frame 460 temporarily fixed thereto, viewed from the second surface 42b. 9( b), second temporary resin frame 460 is formed by arranging second resin members 46 in a frame shape along each side of electrode foil 42, and each second resin member 46 is temporarily fixed to electrode foil 42. In other words, second temporary resin frame 460 is not formed by integrating second resin members 46 with one another, but is a temporary resin frame formed on second surface 42 b of electrode foil 42.

[0053] The four rectangular first resin members 45 and the four rectangular second resin members 46 corresponding to each side of the electrode foil 42 are arranged so that the longitudinal ends of the first resin members 45 and the second resin members 46 overlap each other, thereby defining a rectangular frame-like first temporary resin frame 450 and a rectangular frame-like second temporary resin frame 460 as a whole. The overlapping portions of the ends of the first resin members 45 along adjacent sides are located at corners of the first temporary resin frame 450. The overlapping portions of the ends of the second resin members 46 along adjacent sides are located at corners of the second temporary resin frame 460. In the example of FIG. 9 , the welding points HP of the first resin member 45 and the welding points HP of the second resin member 46 are arranged at equal intervals along each side of the electrode foil 42, avoiding the corners.

[0054] The process of providing a first temporary resin frame 450 by positioning and temporarily fixing a first resin member 45 on the first surface 42a and the process of providing a second temporary resin frame 460 by positioning and temporarily fixing a second resin member 46 on the second surface 42b may be performed simultaneously.

[0055] Next, the temporarily fixed first resin member 45 and second resin member 46 are thermally welded to the electrode foil 42 to form the energy storage module electrode 4 (full-fixing process ST3). Hereinafter, the application of pressure and heat in the full-fixing process ST3 will be referred to as full-welding. A pair of impulse heaters 10A and 10B are used for the full-welding process in the full-fixing process ST3. In the full-fixing process ST3, one impulse heater 10A is disposed on the first resin member 45 side, and the other impulse heater 10B is disposed on the second resin member 46 side. As shown in FIG. 10 , in the full-fixing process ST3, a sheet member 91 is disposed on the first resin member 45, and a sheet member 92 is disposed on the second resin member 46. Then, impulse heaters 10A and 10B are disposed on the pair of sheet members 91 and 92, respectively. Then, the pair of impulse heaters 10A and 10B are pressed against the first resin member 45 and the second resin member 46 via the pair of sheet members 91 and 92, and are permanently welded.

[0056] Each of the pair of impulse heaters 10A, 10B may include a heater wire, a buffer layer, and a base. In this case, the heater wire contacts the first resin member 45 and the second resin member 46 via the sheet members 91, 92. The surface of the heater wire opposite the surface that contacts the first resin member 45 and the second resin member 46 contacts the base via the buffer layer. The buffer layer is made of, for example, silicone rubber. The base supports the heater wire and the buffer layer. The heater wire of the pair of impulse heaters 10A, 10B is ribbon-shaped and generates heat by instantaneously passing a low voltage and high current through it, allowing it to heat up to a predetermined temperature in an extremely short time.

[0057] Each of the pair of impulse heaters 10A, 10B includes, for example, four elongated heaters corresponding to each side of electrode foil 42. The longitudinal length of each of the four heaters is, for example, equal to or greater than the lengths of first resin member 45 and second resin member 46 arranged on each side of electrode foil 42. In other words, the longitudinal length of each of the four heaters corresponds to the lengths of each side of first temporary resin frame 450 and second temporary resin frame 460. In this fixing process ST3, impulse heater 10A heats and pressurizes a portion of first resin member 45 that overlaps electrode foil 42 (overlapping portion 411a corresponding to overlapping portion 411), thereby welding overlapping portion 411a to electrode foil 42. At this time, impulse heater 10A heats and pressurizes overlapping portion 411a so as to include the temporary welding points at which electrode foil 42 and first resin member 45 are temporarily welded in overlapping portion 411a. At the same time, impulse heater 10A heats and pressurizes the portion of second resin member 46 that overlaps electrode foil 42 (overlapping portion 411b corresponding to overlapping portion 411) to weld overlapping portion 411b to electrode foil 42. At this time, impulse heater 10B heats and pressurizes overlapping portion 411b so as to include the temporary welding points at which electrode foil 42 and second resin member 46 are temporarily welded in overlapping portion 411b. In the final fixing step ST3, for example, the electrode foil 42, the first resin member 45 arranged on the first surface 42a of the electrode foil 42, and the second resin member 46 arranged on the second surface 42b of the electrode foil 42 are sandwiched between a pair of impulse heaters 10A, 10B along each side of the electrode foil 42, thereby performing final welding on both sides of the electrode foil 42 simultaneously. At this time, each of the pair of impulse heaters 10A, 10B functions as a support member that bears the load of the impulse heaters 10A, 10B arranged on opposite sides of the object to be welded. Note that the final welding in the final fixing step ST3 may be performed on each of the four opposing sides of the electrode foil 42, on all four sides simultaneously, or on each side sequentially.

[0058] In the main fixing process ST3, the electrode foil 42 is permanently welded to the first resin member 45 and the second resin member 46, melting the first resin member 45 and the second resin member 46 and welding the first resin member 45 and the second resin member 46 to the electrode foil 42. At the same time, the first resin member 45 and the second resin member 46 are heated and pressurized by a pair of impulse heaters 10A and 10B so that the portions of the first resin member 45 and the second resin member 46 that do not overlap the electrode foil 42 are also welded to each other. The first resin frame 41 is formed by welding the portions of the first temporary resin frame 450 and the second temporary resin frame 460 that do not overlap the electrode foil 42 when viewed from the stacking direction D1 (portions corresponding to the protruding portions 412). The portions corresponding to the protruding portions 412 to be welded are located adjacent to at least the overlapping portions 411 to be welded to the electrode foil 42. The first resin frame 41 is provided so as to extend from the first surface 42a of the electrode foil 42 through the outer edge 42d to the second surface 42b, and covers the outer edge portion 42c.

[0059] Next, the difference between the case of performing final welding on the first resin member 45 in a state where burrs B and dents at the weld points HP have occurred around the weld points HP as described in FIG. 7B and the case of performing final welding on the first resin member 45 in a state where burrs B and dents at the weld points HP have been suppressed as described in FIG. 8B will be described. FIG. 11 is a diagram illustrating the final welding in the final fixing step according to a comparative example, and FIG. 12 is a diagram illustrating the final welding in the final fixing step ST3 according to the first embodiment. In the examples of FIGS. 11 and 12, the sheet member 91 is omitted. When performing final welding on the first resin member 45 in a state where burrs B have occurred around the weld points HP, as shown in FIG. 11A, when the impulse heater 10A is pressed against the first resin member 45, the surface pressure at the location where the burrs B have occurred is relatively high, while the surface pressure at the dent at the weld points HP is relatively low. That is, variations in the surface pressure occur. As a result, at welding points HP where the surface pressure is low, the electrode foil 42 is not sufficiently restrained during welding. At locations where the restraint is insufficient, the electrode foil 42 may deform due to the difference in the thermal shrinkage rate between the first resin member 45 and the electrode foil 42, and buckling wrinkles W may occur in the electrode foil 42, as shown in FIG. 11( b). The occurrence of buckling wrinkles W in the electrode foil 42 at the welding points HP of the first resin member 45 may cause poor sealing, and is therefore undesirable.

[0060] In contrast, in the main fixing step ST3, when main welding is performed on the first resin member 45 in a state in which the generation of burrs B around the welding points HP and the generation of dents at the welding points HP are suppressed, as shown in Fig. 12(a) , when the impulse heater 10A is pressed against the first resin member 45, a uniform surface pressure is applied to the first resin member 45. This makes it easier to suppress the generation of buckling wrinkles W in the electrode foil 42, as shown in Fig. 12(b) .

[0061] As an example of a method for manufacturing the energy storage module 1, a lamination step may be performed in which the energy storage module electrodes 4 formed in the main fixing step ST3 are stacked to form a stack, and an end surface welding step may be performed in which end surfaces of the stack are welded to form the welded end portions 7. In the lamination step, a plurality of energy storage module electrodes 4 are stacked via second resin frames 5 to form a stack. In the lamination step, the second resin frames 5 are disposed so as to be interposed between the first resin frames 41 adjacent to each other in the stacking direction D1. In the end surface welding step, the outer edges of the energy storage module electrodes adjacent to each other in the stacking direction D1 (the outer edges 41 a of the first resin frames 41) and the outer edges 5 a of the second resin frames 5 are welded to each other in the stacking direction D1, while the stack is restrained in the stacking direction D1. In the end surface welding step, the plurality of first resin frames 41 and the second resin frames 5 are integrated to form the welded end portions 7, thereby manufacturing the energy storage module 1.

[0062] As described above, in the manufacturing method of the energy storage module electrode 4 according to one aspect of the present disclosure, in the temporary fixing step ST2, the presser members are arranged over a wider area than the tip portions 81 a, 82 a, and the presser members press the first resin member 45 and the second resin member 46 around the welding points. This allows the molten resin to flow along the surfaces of the presser members, thereby preventing the resin from bulging due to the application of the hot irons 81, 82. This prevents burrs from occurring at the welding points in the temporary fixing step ST2. Therefore, the occurrence of buckling wrinkles W in the electrode foil 42 can be prevented in the main fixing step ST3.

[0063] Electrode foil 42 has a rectangular shape in a plan view, and in an arrangement step ST1, a strip-shaped first resin member 45 is arranged on first surface 42a so as to correspond to one side of electrode foil 42, and a strip-shaped second resin member 46 is arranged on second surface 42b so as to correspond to one side of electrode foil 42. In a temporary fixing step ST2, strip-shaped first resin member 45 is spot-welded to first surface 42a, and strip-shaped second resin member 46 is spot-welded to second surface 42b. In this case, the process of placing the first resin member 45 on the first surface 42a and the process of placing the second resin member 46 on the second surface 42b are performed simultaneously, and the process of spot welding the first resin member 45 to the first surface 42a and the process of spot welding the second resin member 46 to the second surface 42b are performed simultaneously, thereby making it possible to efficiently temporarily fix the first resin member 45 and the second resin member 46 to the electrode foil 42.

[0064] In the temporary fixing step ST2, the tips 81a, 82a of the hot irons 81, 82 are pressed against the first resin member 45 and the second resin member 46 via the sheet members 91, 92 as pressing members. By arranging the sheet members 91, 92, the hot irons 81, 82 do not come into direct contact with the resin, and therefore do not sink into the resin. This further reduces the occurrence of burrs at the welding points.

[0065] In the temporary fixing step ST2, tension is applied to the sheet members 91, 92. This configuration can prevent the sheet members 91, 92 from bending when the molten resin flows along the surfaces of the sheet members 91, 92. Therefore, the flatness of the resin is maintained, and the occurrence of burrs at the welding points can be more reliably prevented.

[0066] In the final fixing step ST3, a pair of elongated impulse heaters 10A, 10B are prepared, which are arranged opposite each other with electrode foil 42 sandwiched therebetween, and one of the pair of impulse heaters 10A, 10B, impulse heater 10A, heats and pressurizes a wide area including the temporary welding points where electrode foil 42 and first resin member 45 overlap with electrode foil 42, using impulse heater 10A, and one of the pair of impulse heaters, impulse heater 10B, heats and pressurizes a wide area including the temporary welding points where electrode foil 42 and second resin member 46 overlap with electrode foil 42, using impulse heater 10B, using impulse heater 10B, in this case. By applying heat and pressure to an area wider than the temporary welding points, the electrode foil 42 and first resin member 45 and the electrode foil 42 and second resin member 46 can be reliably permanently welded together.

[0067] In the manufacturing method for the energy storage module 1 according to one aspect of the present disclosure, the occurrence of buckling wrinkles W in the energy storage module electrode 4 in which the first resin frame 41 is welded to the electrode foil 42 is suppressed, and therefore, when a stack formed by stacking a plurality of energy storage module electrodes 4 is restrained in the stacking direction D1 of the energy storage module electrodes 4, sufficient adhesion can be ensured between the energy storage module electrodes 4 and the second resin frame 5 that are adjacent in the stacking direction D1. Therefore, in the end face welding step, welding of the outer edges of the energy storage module electrodes 4 (the outer edges 41 a of the first resin frame 41) and the outer edges 5 a of the second resin frame 5 can be favorably performed, and sealing defects in the energy storage module 1 can be suppressed.

[0068] Second Embodiment FIG. 13 is a diagram illustrating a temporary fixing step ST2A according to a second embodiment. In the temporary fixing step ST2A, a pair of ceramic members 14A and 14B are used as the presser members instead of the pair of sheet members 91 and 92. Other aspects are the same as the temporary fixing step ST2 according to the first embodiment. The pair of ceramic members 14A and 14B contain ceramic having a thermal conductivity lower than that of metals such as aluminum and copper. This reduces the absorption of heat from the tip portions 81a and 82a by the pair of ceramic members 14A and 14B, allowing the heat to be sufficiently transferred to the first resin member 45 and the second resin member 46.

[0069] In the temporary fixing process ST2A, the pair of ceramic members 14A, 14B are fixed around the tip ends 81a, 82a of the pair of hot irons 81, 82. Each of the pair of ceramic members 14A, 14B is an annular member including a through hole 14a. In the temporary fixing process ST2A, the tip end 81a is fixed to the ceramic member 14A so that the tip end surface 81b is exposed from the through hole 14a, and the tip end 82a is fixed to the ceramic member 14B so that the tip end surface 82b is slightly exposed from the through hole 14a. In the temporary fixing process ST2A, the pair of ceramic members 14A, 14B are abutted against the resin members surrounding the tip ends 81a, 82a, and the tip ends 81a, 82a are pressed against the first resin member 45 and the second resin member 46. Since the tip surfaces 81b, 82b are exposed from the through hole 14a, the tip surfaces 81b, 82b are in direct contact with the first resin member 45 and the second resin member 46, making it easier for heat to be transferred from the tip portions 81a, 82a to the first resin member 45 and the second resin member 46.

[0070] In the manufacturing method of the energy storage module electrode 4 according to the second embodiment, the pair of ceramic members 14A, 14B are also arranged over a wider area than the tip portions 81a, 82a, and the pair of ceramic members 14A, 14B press the first resin member 45 and the second resin member 46 around the welding point with each other, so that the molten resin flows along the surfaces of the pair of ceramic members 14A, 14B, and it is possible to prevent the resin from bulging due to the application of the hot irons 81, 82. This allows the resin to cool and harden in a flattened state, and it is possible to prevent burrs from occurring at the welding point.

[0071] [Modifications] Although the embodiments of the present disclosure have been described above, the present disclosure is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0072] FIG. 14 is a diagram illustrating a temporary fixing step ST2B according to a first modified example of the second embodiment. In the temporary fixing step ST2B, a hot iron 81A is used instead of the hot iron 81 used in the temporary fixing step ST2A according to the second embodiment. Otherwise, the process is the same as the temporary fixing step ST2A. In the temporary fixing step ST2B, the hot iron 81A, whose tip surface 81b is concavely curved, is pressed against the resin member (first resin member 45) that does not have a pressing member disposed therein, of the first and second resin members 45 and 46, to perform spot welding. In this modified example, the tip surface 81b of the hot iron 81A is not flat but includes a concavely curved curved portion 81b1. Furthermore, the edge 81b2 of the tip surface 81b is rounded. In other words, the edge 81b2 is convexly curved in the direction opposite to the concave recess of the curved portion 81b1. In the heat iron 81A, the resin of the first resin member 45 can easily flow into the curved portion 81b1, which is the concavely curved portion of the tip surface 81b. This makes it possible to reduce the size of burrs that occur at the welding point.

[0073] FIG. 15 is a diagram illustrating a temporary fixing process ST2C according to a second modification of the second embodiment. In the temporary fixing process ST2C, a pair of hot irons 81, 82 are used, corresponding to the first resin member 45 and the second resin member 46, respectively. In the example of FIG. 15, the hot iron 81, to which the ceramic member 14A is fixed as a pressing member, is positioned on the first resin member 45 side. In the temporary fixing process ST2C, the heating temperature of the hot iron 82 corresponding to the resin member (second resin member 46) without a pressing member is set lower than the heating temperature of the hot iron 81 corresponding to the resin member (first resin member 45) with a pressing member. In the temporary fixing process ST2C, the heating temperature of the hot iron 81 is set to, for example, 260°C. In the temporary fixing process ST2C, the heating temperature of the hot iron 82 is set lower than the heating temperature of the hot iron 81. For example, the heating temperature of the hot iron 82 may be set to a temperature lower than the melting points of the first resin member 45 and the second resin member 46. The heating temperature of the hot iron 82 may be set to, for example, 60°C. The heating by the hot iron 82 functions to support the heating by the hot iron 81. With this configuration, the heating temperature by the hot iron 82 is lower than the heating temperature by the hot iron 81, which prevents the first resin member 45 corresponding to the hot iron 81 from being heated to a temperature higher than necessary from the hot iron 82 side, and further prevents burrs from being generated at the welding points of the resin member (second resin member 46) where no pressing member is disposed.

[0074] The temporary fixing step ST2C described above may be combined with the temporary fixing step ST2 according to the second embodiment. For example, when spot welding the first resin member 45 and the second resin member 46 to the electrode foil 42, the sheet member 91 may be placed only on the first resin member 45, and the heating temperature of the hot iron 82 on the second resin member 46 side where the sheet member 92 is not placed may be set to a lower temperature than the heating temperature of the hot iron 81 on the first resin member 45 side where the sheet member 91 is placed. Furthermore, in the temporary fixing step ST2A according to the second embodiment, the tip end surface 81b may be flush with the surface of the ceramic member 14A on the first resin member 45 side, and the tip end portion 82a may be flush with the surface of the ceramic member 14B on the second resin member 46 side. Even in this case, the tip surfaces 81b, 82b are in direct contact with the first resin member 45 and the second resin member 46, allowing heat to be sufficiently transferred from the tip portions 81a, 82a to the first resin member 45 and the second resin member 46. Additionally, the design flexibility of the through holes 14a of the pair of ceramic members 14A, 14B can be improved. Alternatively, the pair of ceramic members 14A, 14B may be fixed to the pair of hot irons 81, 82, with the heating temperature of one of the pair of hot irons 81 being lower than the heating temperature of the other hot iron 82. Alternatively, a sheet member 91 may be placed on the first resin member 45, and the sheet member 92 may be placed on the second resin member 46, with the heating temperature of one of the pair of hot irons 81, 82 being lower than the heating temperature of the other hot iron 82.

[0075] FIG. 16 illustrates an example of the arrangement process and the temporary fixing process using a suction plate. In the above-described embodiment and modified example, in the arrangement process ST1, when one first resin member 45 is arranged so as to correspond to one side of the electrode foil 42, the first resin member 45 may be held by suction using a suction plate 83. Similarly, in the arrangement process ST1, when one second resin member 46 is arranged so as to correspond to one side of the electrode foil 42, the second resin member 46 may be held by a holding plate 84. That is, the holding plate 84 may hold the second resin member 46 without suction. Then, in the temporary fixing process ST2, while the first resin member 45 and the electrode foil 42 are sandwiched between the suction plate 83 and the holding plate 84, a hot iron 81 is brought into contact with the first resin member 45. As a result, the first resin member 45 is temporarily fixed to one side of the electrode foil 42 by spot welding. Similarly, in temporary fixing step ST2, while the second resin member 46 and the electrode foil 42 are sandwiched between the holding plate 84 and the suction plate 83, the hot iron 82 is brought into contact with the second resin member 46. As a result, the second resin member 46 is temporarily fixed to one side of the electrode foil 42 by spot welding. By repeating the arrangement step ST1 and the temporary fixing step ST2, the first resin member 45 is temporarily fixed to the first surface 42a and the second resin member 46 is temporarily fixed to the second surface 42b so as to correspond to each side of the electrode foil 42. By using the suction plate 83 and the holding plate 84, the arrangement of the first resin member 45 and the second resin member 46 on the electrode foil 42 and the spot welding of the first resin member 45 and the second resin member 46 to the electrode foil 42 can be performed with high precision.

[0076] The suction plate 83 has, for example, a rectangular shape that overlaps the first resin member 45. The outer edge of the suction plate 83 may coincide with the outer edge of the first resin member 45 or may be larger than the outer edge of the first resin member 45. The suction plate 83 and the holding plate 84 are made of, for example, metal. The suction plate 83 includes, for example, a suction portion and an air pipe (not shown). By drawing air through the air pipe, the first resin member 45 is adsorbed to the suction portion of the suction plate 83. The holding plate 84 has, for example, a rectangular shape that overlaps the second resin member 46. The outer edge of the holding plate 84 may coincide with the outer edge of the second resin member 46 or may be larger than the outer edge of the second resin member 46.

[0077] The suction plate 83 includes a plurality of through holes 83a. The plurality of through holes 83a are formed to penetrate the suction plate 83. The positions of the plurality of through holes 83a correspond to the positions of the welding points HP of the first resin member 45. In the example of FIG. 16 , the plurality of through holes 83a are arranged at equal intervals along each side of the electrode foil 42. The first resin member 45 is exposed in the plurality of through holes 83a in a plan view. Thus, in the temporary fixing step ST2, the plurality of heat irons 81 may be inserted into the plurality of through holes 83a and pressed against the first resin member 45, thereby performing spot welding on one side of the electrode foil 42 all at once.

[0078] The holding plate 84 includes a plurality of through holes 84a. The through holes 84a are formed to penetrate the holding plate 84. The positions of the through holes 84a correspond to the positions of the welding points HP of the second resin member 46. In the example of FIG. 16 , the through holes 84a are arranged at equal intervals along each side of the electrode foil 42. The second resin member 46 is exposed in the through holes 84a in a plan view. This allows for simultaneous spot welding of one side of the electrode foil 42 by inserting a plurality of heat irons 82 into the through holes 84a and pressing the heat irons 82 against the second resin member 46 in the temporary fixing step ST2. Instead of having a rectangular shape, the holding plate 84 may be formed of a plurality of divided pieces arranged at predetermined intervals. The second resin member 46 is exposed in the gaps between adjacent divided pieces in a plan view. In this case, the heat iron 82 is pressed against the second resin member 46 through the gap between the divided pieces.

[0079] In the placement process ST1, two first resin members 45 may be placed so as to correspond to two opposing sides of the electrode foil 42. In this case, the two first resin members 45 may be simultaneously adsorbed by two suction plates 83. Then, in the temporary fixing process ST2, with the two first resin members 45 adsorbed to the two suction plates 83, the two first resin members 45 and the electrode foil 42 may be simultaneously spot-welded along their opposing sides via the suction plates 83. The suction plates 83 are not limited to being rectangular and may, for example, be frame-shaped so as to overlap the first temporary resin frame 450. The above example may also be applied to the placement of the second resin member 46 using the holding plate 84 and the welding of the second resin member 46 to the electrode foil 42. The holding plate 84 may have a function of adsorbing the second resin member 46. For example, the holding plate 84 may include an adsorption portion and an air pipe.

[0080] The gist of the present disclosure is as follows: [1] to [9]: [1] A method for manufacturing an electrode for an energy storage module, comprising: an arrangement step of arranging a first resin member on a first surface along an outer edge portion of an electrode foil provided with an active material layer and arranging a second resin member on a second surface along the outer edge portion of the electrode foil, a temporary fixing step of temporarily fixing the first resin member and the second resin member arranged along the outer edge portion to the electrode foil by spot welding using a hot iron, and a main welding step of thermally welding the temporarily fixed first resin member and the second resin member to the electrode foil, wherein in the temporary fixing step, a press member is arranged on at least one side of the first resin member and the second resin member over a wider area than a tip of the hot iron, and the first resin member and the second resin member are spot-welded to the electrode foil while the press member presses the resin member around a welding point. [2] The electrode foil has a rectangular shape in a plan view, and in the arranging step, the rectangular first resin member is arranged on the first surface so as to correspond to one side of the electrode foil, and the rectangular second resin member is arranged on the second surface so as to correspond to one side of the electrode foil, and in the temporary fixing step, the rectangular first resin member is spot-welded to the first surface, and the rectangular second resin member is spot-welded to the second surface. [3] The method for manufacturing an electrode for an energy storage module according to [1] or [2], in the temporary fixing step, a tip of the hot iron is pressed against the resin member via a sheet member serving as the pressing member. [4] The method for manufacturing an electrode for an energy storage module according to [3], [5] A method for manufacturing an electrode for a storage module according to any one of [1] to [4], wherein in the temporary fixing step, a ceramic member as the pressing member is fixed around the tip of the hot iron, and the tip is pressed against the resin member while the ceramic member is abutted against the resin member around the tip.[6] The method for manufacturing an electrode for an electric storage module according to any one of [1] to [5], wherein the temporary fixing step is performed by pressing a hot iron having a concavely curved tip surface against one of the first resin member and the second resin member on which the pressing member is not disposed to perform spot welding. [7] The method for manufacturing an electrode for an electric storage module according to any one of [1] to [6], wherein the temporary fixing step is performed by using a pair of hot irons corresponding to the first resin member and the second resin member, respectively, and by setting the heating temperature of the hot iron corresponding to the resin member on which the pressing member is not disposed lower than the heating temperature of the hot iron corresponding to the resin member on which the pressing member is disposed. [8] In the welding process, a pair of elongated heaters are prepared that are arranged opposite each other with the electrode foil sandwiched therebetween, and a wide area including the temporary welding points where the electrode foil and the first resin member are temporarily welded at the overlapping portion of the electrode foil and the first resin member is heated and pressurized by one of the pair of heaters, and a wide area including the temporary welding points where the electrode foil and the second resin member are temporarily welded at the overlapping portion of the electrode foil and the second resin member is heated and pressurized by the other of the pair of heaters.[9] An arrangement step of arranging a first resin member on a first surface along an outer edge portion of an electrode foil provided with an active material layer and arranging a second resin member on a second surface along the outer edge portion of the electrode foil; a temporary fixing step of temporarily fixing the first resin member and the second resin member arranged along the outer edge portion to the electrode foil by spot welding using a hot iron; a main welding step of forming an energy storage module electrode by thermally welding the temporarily fixed first resin member and the second resin member to the electrode foil; and a main welding step of attaching a plurality of the energy storage module electrodes to a spacer resin. and an end face welding process in which, while the stack is restrained in the stacking direction of the electrodes for the storage module, outer edges of the electrodes for the storage module and outer edges of the spacer resin frames that are adjacent to each other in the stacking direction are welded together, wherein in the temporary fixing process, a pressing member is disposed on at least one side of the first resin member and the second resin member over a wider area than the tip of the hot iron, and the first resin member and the second resin member are spot-welded to the electrode foil while the pressing member is pressing down on the resin member around the welding point.

[0081] 1...storage module, 14A, 14B...ceramic members, 4...electrode for storage module, 42a...first surface, 42b...second surface, 42c...outer edge portion of electrode foil, 41...third resin frame, 45...first resin member, 46...second resin member, 42...electrode foil, 450...first temporary resin frame, 460...second temporary resin frame, 81, 82...heating iron, 81a, 82a...tip portion, 81b, 82b...tip surface, 91, 92...sheet member, ST1...placement process, ST2, ST2A, ST2B, ST2C...temporary fixing process, ST3...actual fixing process.

Claims

1. The arrangement step involves arranging a first resin member on a first surface along the outer edge of an electrode foil on which an active material layer is provided, and arranging a second resin member on a second surface along the outer edge of the electrode foil, A temporary fixing step is performed in which the first resin member and the second resin member, which are arranged along the outer edge, are temporarily fixed to the electrode foil by spot welding using a hot iron, The process includes a main welding step of forming electrodes for an energy storage module by heat welding the temporarily fixed first resin member and the second resin member to the electrode foil, respectively. A method for manufacturing electrodes for an energy storage module, wherein in the temporary fixing step, a pressing member is positioned over a wider area than the tip of the hot iron on at least one side of the first resin member and the second resin member, and the first resin member and the second resin member are spot-welded to the electrode foil while the pressing member holds down the resin member around the welding point.

2. The electrode foil has a rectangular shape when viewed from above. In the arrangement step, the strip-shaped first resin member is placed on the first surface so as to correspond to one side of the electrode foil, and the strip-shaped second resin member is placed on the second surface so as to correspond to one side of the electrode foil. The method for manufacturing an electrode for a power storage module according to claim 1, wherein in the temporary fixing step, the strip-shaped first resin member is spot-welded to the first surface and the strip-shaped second resin member is spot-welded to the second surface.

3. The method for manufacturing an electrode for a power storage module according to claim 1 or 2, wherein in the temporary fixing step, the tip of the hot iron is pressed against the resin member via the sheet member acting as the pressing member.

4. The method for manufacturing an electrode for a power storage module according to claim 3, wherein tension is applied to the sheet member in the temporary fixing step.

5. The method for manufacturing an electrode for a power storage module according to claim 1 or 2, wherein in the temporary fixing step, the ceramic member as a pressing member is fixed around the tip of the hot iron, and the tip is pressed against the resin member while the ceramic member is in contact with the resin member around the tip.

6. The method for manufacturing electrodes for an energy storage module according to claim 1 or 2, wherein in the temporary fixing step, a hot iron with a concavely curved tip is pressed against the resin member of the first resin member and the second resin member that does not have the pressing member, and spot welds them.

7. In the temporary fixing step, a pair of hot irons corresponding to the first resin member and the second resin member are used, A method for manufacturing an electrode for a power storage module according to claim 1 or 2, wherein the heating temperature of the hot iron corresponding to the resin member without the pressing member is lower than the heating temperature of the hot iron corresponding to the resin member with the pressing member.

8. In the welding process described above, a pair of elongated heaters are prepared, which are positioned opposite each other with the electrode foil in between. A method for manufacturing an electrode for a storage module according to claim 1 or 2, wherein a wide area including a temporary welding point where the electrode foil and the first resin member are temporarily welded together in the portion where the electrode foil and the first resin member overlap is heated and pressurized with one of the pair of heaters, and a wide area including a temporary welding point where the electrode foil and the second resin member are temporarily welded together in the portion where the electrode foil and the second resin member overlap is heated and pressurized with the other of the pair of heaters.

9. The arrangement step involves arranging a first resin member on a first surface along the outer edge of an electrode foil on which an active material layer is provided, and arranging a second resin member on a second surface along the outer edge of the electrode foil, A temporary fixing step is performed in which the first resin member and the second resin member, which are arranged along the outer edge, are temporarily fixed to the electrode foil by spot welding using a hot iron, The main welding process involves heat-welding the temporarily fixed first resin member and the second resin member to the electrode foil to form electrodes for the energy storage module, A lamination step in which multiple electrodes for the energy storage module are stacked via a resin frame for spacers to form a laminate, The process includes an end-face welding step in which, while the laminate is constrained in the stacking direction of the electrodes for the energy storage module, the outer edges of adjacent electrodes for the energy storage module and the outer edges of the resin frame for the spacer are welded together in the stacking direction, A method for manufacturing an energy storage module, wherein in the temporary fixing step, a pressing member is positioned over a wider area than the tip of the hot iron on at least one side of the first resin member and the second resin member, and the first resin member and the second resin member are spot-welded to the electrode foil while the pressing member holds down the resin member around the welding point.