Method for manufacturing an electrical storage module and electrical storage module

Abstract

A method for manufacturing an energy storage module includes: a resin frame assembly step to form electrodes with resin frames; a lamination step to alternately stack electrodes with resin frames and nesting members in a first direction, such that metal nesting members are disposed between adjacent resin frames, to form a laminate; a constraint step to constrain the laminate in the first direction by a pair of constraint plates; and a welding step to melt the end of an outer portion separated from an inner portion by a heater, as viewed from the first direction, to form a welded portion. In the lamination step, the laminate is formed such that the nesting member extends in a second direction intersecting the first direction, and as viewed from the first direction, the first end of the nesting member in the second direction overlaps with the inner portion, and the second end of the nesting member in the second direction protrudes from the outer portion. In the welding step, the nesting member is heated to above the melting temperature of the resin frame.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing an energy storage module and an energy storage module. Background Technology

[0002] Patent document 1 discloses a bipolar battery. This bipolar battery is constructed by stacking bipolar plates, one side of which has an anode active material coating, and the other side of which has a cathode active material coating. An electrically insulating frame is adhered to the periphery of the conductive plates. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent No. 2623311 Summary of the Invention The problem the invention aims to solve

[0004] In the battery (energy storage module) disclosed in Patent Document 1, sometimes the ends of an electrically insulating surrounding frame (sealing layer) are integrated with each other by welding to form a resin-made sealing portion that seals the internal space between the electrodes. When welding the ends of the sealing layers together, a connecting hole that functions as a liquid injection port can be formed in the sealing portion by inserting a metal nesting member between the sealing layers. However, near the nesting member, because the nesting member is prone to heat dissipation, the end face weld portion is sometimes not formed with sufficient thickness. As a result, the sealing performance may decrease.

[0005] The purpose of this disclosure is to provide a method for manufacturing an energy storage module and an energy storage module that can suppress the decline in sealing performance. Solution for solving the problem

[0006] One aspect of this disclosure relates to a method for manufacturing an energy storage module. The energy storage module includes: a laminated body, which is formed by stacking a plurality of electrodes, each including a bipolar electrode, in a first direction; and a sealing portion, which is formed by stacking a plurality of resin frame portions disposed on the outer edge of the electrodes in a first direction, as viewed from the first direction, in a manner surrounding the laminated body. Each of the plurality of resin frame portions has, as viewed from the first direction, an outer portion disposed on the outer side of the electrode and an inner portion disposed on the inner side of the electrode. The method for manufacturing the energy storage module includes: a resin frame portion assembly step, wherein the inner portion is joined to the outer edge of the electrode to form an electrode with a resin frame portion; and a stacking step, wherein adjacent portions in the first direction are... The method involves arranging metal nesting members between resin frames, alternatingly stacking electrodes with resin frames and nesting members in a first direction to form a laminate; a constraint process in which a pair of constraint plates constrain the laminate in the first direction; and a welding process in which, viewed from the first direction, a heater melts the ends of multiple outer portions to form an integrated welded portion. In the stacking process, the laminate is formed such that the nesting members extend in a second direction intersecting the first direction, and viewed from the first direction, the first end of the nesting members in the second direction overlaps with the inner portion, and the second end of the nesting members in the second direction protrudes from the outer portion. In the welding process, the nesting members are heated to above the melting temperature of the resin frames.

[0007] In the above-described method for manufacturing the energy storage module, since the nesting component is heated by a non-contact heater to a temperature above the melting point of the resin frame, heat from the resin frame is less likely to transfer from the periphery of the nesting component to the nesting component itself. Consequently, the welded portion at the periphery of the nesting component is also formed with sufficient thickness. As a result, a decrease in sealing performance can be suppressed.

[0008] Alternatively, the heater can be a non-contact heater, in which the nested parts are heated by the heat from the non-contact heater during the welding process.

[0009] Alternatively, in the constraint process, viewed from the first direction, the end of the outer portion is positioned on the outside of the constraint plate.

[0010] Alternatively, during the welding process, the nesting component is heated in such a way that the thickness of the peripheral portion of the nesting component in the welding part is equal to or greater than the thickness of the non-peripheral portion of the welding part.

[0011] Alternatively, the heater may have a shape that extends in the first direction, and the heater is longer than the laminate in the first direction. In the welding process, multiple heaters are arranged in a direction that intersects the first direction.

[0012] Alternatively, the resin frame portion of the bipolar electrode may have: a first sealing layer bonded to the outer edge of the first surface of the electrode; a second sealing layer bonded to the outer edge of the second surface of the electrode on the side opposite to the first surface; and a spacer layer disposed on the first sealing layer or the second sealing layer.

[0013] One embodiment of the energy storage module disclosed herein includes: a laminate formed by stacking a plurality of electrodes, including bipolar electrodes, in a first direction; and a resin-made sealing portion disposed on the outer edge of the electrodes in a manner surrounding the laminate when viewed from the first direction. The sealing portion, viewed from the first direction, has: an inner portion disposed on the inner side of the outer edge of the electrodes and joined to the outer edge; an outer portion disposed on the outer side of the outer edge of the electrodes; and a welded portion formed by welding the ends of the outer portion, which are separate from the inner portion. A connecting hole is formed in the sealing portion, extending in a second direction intersecting the first direction and communicating with the internal space formed between the electrodes. The welded portion includes a peripheral portion of the connecting hole, and the thickness of the peripheral portion of the welded portion is greater than the thickness of the non-peripheral portion of the welded portion.

[0014] In the aforementioned energy storage module, the welded portion is also formed with sufficient thickness in the periphery of the connecting hole. As a result, a decrease in sealing performance can be suppressed.

[0015] Alternatively, the thickness of the welded portion may increase as it approaches the connecting hole in the peripheral area. Invention Effects

[0016] According to this disclosure, a method for manufacturing an energy storage module and an energy storage module that can suppress the decline in sealing performance can be provided. Attached Figure Description

[0017] Figure 1 This is a schematic top view illustrating the energy storage module involved in the embodiment. Figure 2 Along Figure 1 A cross-sectional view of line II-II. Figure 3 yes Figure 2 A magnified view of a portion of the image. Figure 4 This is a flowchart illustrating a method for manufacturing an energy storage module according to an embodiment. Figure 5 This is a cross-sectional view used to illustrate the manufacturing method of the energy storage module involved in the implementation method. Figure 6 This is a cross-sectional view showing an example of an end-face welded portion formed by the welding process involved in the comparative example. Figure 7 This is a cross-sectional view showing an example of an end-face welded portion formed by the welding process involved in the embodiment. Figure 8 This is a cross-sectional view showing another example of an end-face welded portion formed by the welding process involved in the embodiment. Detailed Implementation

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted. During the description, an orthogonal coordinate system defined by the X-axis, Y-axis, and Z-axis may be referenced.

[0019] (Energy Storage Module) Figure 1 This is a schematic top view of the energy storage module in the implementation method. Figure 2 It is along Figure 1 A cross-sectional view of line II-II. Figure 3 yes Figure 2 A magnified view of a portion of the image. Figures 1-3 The energy storage module 1 shown in the embodiment can be used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage module 1 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 1 can also be an electric double-layer capacitor or an all-solid-state battery. In this embodiment, a bipolar lithium-ion secondary battery is exemplified as the energy storage module 1.

[0020] The energy storage module 1 has a module body 2 and a pair of conductive plates (not shown). The module body 2 is disposed between the pair of conductive plates in the Z-axis direction. The pair of conductive plates apply a constraint load in the Z-axis direction to the module body 2. The conductive plates are conductive and also function as terminals for extracting current from the energy storage module 1. The conductive plates can be used to electrically connect multiple energy storage modules 1. Cooling flow paths can also be formed in the conductive plates. By allowing a cooling medium to flow through the cooling flow paths formed in the conductive plates, the energy storage module 1 can be cooled.

[0021] The main body 2 includes an electrode stack 12 and a resin-made sealing portion 13. The electrode stack 12 is composed of multiple electrodes stacked in the Z-axis direction (first direction). The Z-axis direction is the stacking direction of the multiple electrodes. The multiple electrodes include multiple bipolar electrodes 14, a positive terminal electrode 16, and a negative terminal electrode 17. Separators 15 are placed between adjacent electrodes.

[0022] Multiple bipolar electrodes 14 are arranged in the Z-axis direction between the positive terminal electrode 16 and the negative terminal electrode 17. Each bipolar electrode 14 includes a current collector 21, a positive active material layer 22, and a negative active material layer 23. The current collector 21 is a chemically inert conductor used to continuously allow current to flow through the positive active material layer 22 and the negative active material layer 23 during the discharge or charging of the lithium-ion secondary battery.

[0023] The current collector 21 is a rectangular sheet-like conductive member when viewed from above. The current collector 21 has a first surface 21a and a second surface 21b. The first surface 21a and the second surface 21b face opposite sides in the Z-axis direction. The current collector 21 is made of metal, for example, a metal foil or an alloy foil. Examples of metal foils include copper foil, aluminum foil, titanium foil, and nickel foil. Examples of alloy foils include stainless steel foil (e.g., SUS304, SUS316, SUS301, etc. as specified in JIS G 4305:2015), plated steel foil, or stainless steel foil. The alloy foil can also be an alloy foil of the metal exemplified by the aforementioned metal foil materials. The current collector 21 can be formed by integrally or stacked multiple metal foils, or by plating another metal layer onto the surface of a single metal foil.

[0024] In the illustrated example, the current collector 21 is formed by bonding aluminum foil 21A and copper foil 21B such that the first side 21a is an aluminum layer and the second side 21b is a copper layer. The current collector 21 can also be a clad foil formed by stacking and rolling aluminum foil 21A and copper foil 21B. The current collector 21 can also be a laminated foil. That is, the current collector 21 can also be formed by bonding aluminum foil 21A and copper foil 21B together with conductive adhesive resin (adhesive layer) so that the first side 21a is an aluminum layer and the second side 21b is a copper layer. The current collector 21 can also be formed by copper vapor deposition or copper plating on one side of the aluminum foil such that the first side 21a is an aluminum layer and the second side 21b is a copper layer. Furthermore, the aluminum layer on the first side 21a of the current collector 21 may be subjected to chromate treatment. Alternatively, nickel plating may be applied to the copper layer on the second surface 21b of the current collector 21. In this case, the nickel plating layer can be a roughened surface with a raised plating surface having fine protrusions. Furthermore, the roughened surface only needs to be rougher than the unprocessed metal foil; for example, it can be formed by roughening processes such as etching or electric field plating. For example, the thickness of the current collector 21 can be about 30 μm to 150 μm, but is not limited to this.

[0025] A positive electrode active material layer 22 is disposed on the first surface 21a of the current collector 21. The current collector 21 and the positive electrode active material layer 22 disposed on the first surface 21a of the current collector 21 constitute the positive electrode of the bipolar electrode 14. The positive electrode active material layer 22 is formed in a rectangular shape at the center of the first surface 21a such that the peripheral portion 21c of the current collector 21 is exposed.

[0026] In one example, the positive electrode active material layer 22 is disposed on the first surface 21a of the current collector 21 via an adhesive layer. For example, the adhesive layer may be formed of an adhesive such as acetylene black. In another example, the adhesive layer may be disposed on the entire surface of the first surface 21a of the current collector 21. Furthermore, the end edge of the adhesive layer, viewed from the Z-axis direction, may also be formed along the end edge of the negative electrode active material layer 23 surrounding the positive electrode active material layer 22.

[0027] The positive electrode active material layer 22 is a layered structure comprising a positive electrode active material, a conductive additive, and a binder. Examples of positive electrode active materials include composite oxides, metallic lithium, and sulfur. The composite oxide may contain, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, as well as lithium. Examples of composite oxides include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2.

[0028] The binder serves to bind the active material or conductive additive to the surface of the current collector 21 and maintain the conductive network in the electrode. Examples of binders include fluorinated resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamide-imide; resins containing alkoxysilyl groups; acrylic resins containing monomer units such as acrylic acid or methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; sodium alginate; ammonium alginate; water-soluble cellulose ester crosslinks; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Examples of conductive additives include acetylene black, carbon black, and graphite. A viscosity-adjusting solvent, such as N-methyl-2-pyrrolidone (NMP), can also be used in the positive electrode active material layer 22.

[0029] A negative electrode active material layer 23 is disposed on the second surface 21b of the current collector 21. The current collector 21 and the negative electrode active material layer 23 disposed on the second surface 21b of the current collector 21 constitute the negative electrode of the bipolar electrode 14. The negative electrode active material layer 23 is formed in a rectangular shape at the center of the second surface 21b, with the peripheral portion 21c of the current collector 21 exposed. In one example, viewed from the Z-axis direction, the positive electrode active material layer 22 is contained within the region of the negative electrode active material layer 23. That is, the outer edge of the positive electrode active material layer 22 is smaller than the outer edge of the negative electrode active material layer 23. In another example, viewed from the Z-axis direction, the negative electrode active material layer 23 is contained within the region of the conductive plate. That is, the outer edge of the negative electrode active material layer 23 may also be smaller than the outer edge of the conductive plate.

[0030] In one example, the negative electrode active material layer 23 can be disposed on the second surface 21b of the current collector 21 via an adhesive layer. The adhesive layer used for the active material layer 23 can be the same as the adhesive layer used for the positive electrode active material layer 22. In another example, the adhesive layer can be disposed on the entire surface of the second surface 21b of the current collector 21.

[0031] The negative electrode active material layer 23 is a layered structure comprising a negative electrode active material, a conductive additive, and a binder. Examples of negative electrode active materials include graphite, artificial graphite, highly oriented graphite, mesophase carbon microspheres, hard carbon, soft carbon, and other carbons, metal compounds, elements capable of alloying with lithium or compounds of such elements, and carbon with added boron. Examples of elements capable of alloying with lithium include silicon and tin. The conductive additive and binder used in the negative electrode active material layer 23 can be the same as those used in the positive electrode active material layer 22.

[0032] To form the positive electrode active material layer 22 and the negative electrode active material layer 23 on the current collector 21, conventionally known methods such as roller coating, mold coating, dip coating, doctor blade coating, spray coating, and curtain coating are used. Specifically, an active material, solvent, and, if necessary, binder and conductive additive are mixed to prepare a slurry-like composition for forming the active material layer. After coating the composition for forming the active material layer onto the first surface 21a and the second surface 21b, it is dried. Solvents such as N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water are also used. To increase the electrode density, compression may be performed after drying.

[0033] In the electrode stack 12, adjacent bipolar electrodes 14, 14 in the Z-axis direction are arranged such that the positive active material layer 22 of one bipolar electrode 14 and the negative active material layer 23 of the other bipolar electrode 14 face each other. A spacer 15 is disposed between adjacent bipolar electrodes 14, 14 in the Z-axis direction. In this embodiment, the spacer 15 is a rectangular sheet-like member when viewed from above, preventing short circuits between adjacent bipolar electrodes 14, 14 in the Z-axis direction.

[0034] The separator 15, viewed from the Z-axis, is rectangular in shape, larger than the positive electrode active material layer 22 and the negative electrode active material layer 23, and smaller than the current collector 21. The end portion 15a of the separator 15, viewed from the Z-axis, is located outside the positive electrode active material layer 22 and the negative electrode active material layer 23. That is, the end portion 15a of the separator 15, viewed from the Z-axis, does not overlap with either the positive electrode active material layer 22 or the negative electrode active material layer 23.

[0035] The separator 15 is formed, for example, in sheet form. The separator 15 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. Examples of materials constituting the separator 15 include polypropylene, polyethylene, polyolefins, and polyester. The separator 15 can be a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, the separator 15 may, for example, include a substrate layer and a pair of adhesive layers, which are bonded to the positive electrode active material layer 22 and the negative electrode active material layer 23 by the pair of adhesive layers. The separator 15 may also include a ceramic layer as a heat-resistant layer. The separator 15 may also be reinforced with a vinylidene fluoride resin compound.

[0036] The separator 15 is formed by stretching molten resin using either a dry or wet process. In this case, depending on the stretching process, the separator 15 has a direction with large shrinkage and a direction with small shrinkage. The separator 15 can be rectangular with the direction of large shrinkage along the short side and the direction of small shrinkage along the long side. An example separator 15 is formed using a wet process, with the TD (Transverse Direction) direction (large shrinkage) along the short side and the MD (Machine Direction) direction (small shrinkage) along the long side.

[0037] Examples of electrolytes impregnated in the separator 15 include liquid electrolytes (electrolytes) comprising a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent, or polymeric gel electrolytes comprising an electrolyte retained in a polymer matrix. When an electrolyte is impregnated in the separator 15, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiFSi, and LiN(CF3SO2)2 can be used as the electrolyte salt. Furthermore, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as the non-aqueous solvent. In addition, combinations of two or more of these known solvent materials can be used.

[0038] The positive terminal electrode 16 is composed of a current collector 21 and a positive active material layer 22 disposed on the first surface 21a of the current collector 21. The positive terminal electrode 16 is arranged at one end of the electrode stack 12 in the Z-axis direction with the positive active material layer 22 of the first surface 21a facing the negative active material layer 23 of the bipolar electrode 14 at the end. In the positive terminal electrode 16, the second surface 21b of the current collector 21 does not have a positive active material layer 22 or a negative active material layer 23; this second surface 21b is electrically connected to an adjacent conductive plate. The current collector 21 used in the positive terminal electrode 16 can be made of aluminum foil.

[0039] The negative terminal electrode 17 is composed of a current collector 21 and a negative active material layer 23 disposed on the second surface 21b of the current collector 21. The negative terminal electrode 17 is arranged on the other end of the electrode stack 12 in the Z-axis direction, with the negative active material layer 23 on the second surface 21b facing the positive active material layer 22 of the bipolar electrode 14 at the end. In the negative terminal electrode 17, neither the positive active material layer 22 nor the negative active material layer 23 is disposed on the first surface 21a of the current collector 21; this first surface 21a is electrically connected to an adjacent conductive plate. The current collector 21 used in the negative terminal electrode 17 can be made of copper foil.

[0040] The aforementioned separator 15 is disposed not only between adjacent bipolar electrodes 14, 14 in the Z-axis direction, but also between bipolar electrode 14 and positive terminal electrode 16, and between bipolar electrode 14 and negative terminal electrode 17. The arrangement of the separator 15 prevents short circuits between bipolar electrode 14 and positive terminal electrode 16, and between bipolar electrode 14 and negative terminal electrode 17.

[0041] The sealing portion 13 is a component that encloses the internal space S between adjacent current collectors 21, 21 in the Z-axis direction. The sealing portion 13 is electrically insulating. Viewed from the Z-axis direction, the sealing portion 13 is disposed on the periphery 21c of the current collector 21 in a manner that surrounds the electrode stack 12. The sealing portion 13 is joined to the outer edge 21c of the current collector 21. For example, viewed from the Z-axis direction, the sealing portion 13 is separate from the positive electrode active material layer 22 and the negative electrode active material layer 23. The inner edge of the sealing portion 13 may also overlap with the positive electrode active material layer 22 and the negative electrode active material layer 23 in the Z-axis direction. The sealing portion 13 is rectangular in shape when viewed from the Z-axis direction. The sealing portion 13 is arranged between adjacent current collectors 21, 21 in the Z-axis direction in a manner that surrounds the periphery of the positive electrode active material layer 22 and the negative electrode active material layer 23. In the energy storage module 1, an internal space S is defined by adjacent current collectors 21, 21 in the Z-axis direction and a closure 13. An electrolyte (not shown) containing an electrolyte is contained within the internal space S. The closure 13, by being positioned between adjacent current collectors 21, 21 in the Z-axis direction, also functions as a spacer maintaining the distance between adjacent current collectors 21, 21.

[0042] The sealing portion 13 has multiple first sealing layers 31 made of resin, multiple second sealing layers 32 made of resin, and multiple spacer layers 33 made of resin. The first sealing layers 31 are separate from the positive electrode active material layer 22 and are bonded to the outer edge 21c of the first surface 21a of each current collector 21. The second sealing layers 32 are separate from the negative electrode active material layer 23 and are bonded to the outer edge 21c of the second surface 21b of each current collector 21. The first sealing layers 31 can be separate from or overlap with the negative electrode active material layer 23 when viewed from the Z-axis direction. The first sealing layers 31 and the second sealing layers 32 are provided on the outer edge 21c of the current collector 21 such that they extend from the outer edge 21d of the current collector 21.

[0043] The first sealing layer 31 and the second sealing layer 32, viewed from the Z-axis direction, have a frame shape (here, a rectangular frame shape) along the outer edge 21d of the current collector 21. The outer edge 21d constitutes the outer edge of the electrode. Viewed from the Z-axis direction, the outer edge 21d of the current collector 21 is larger than the inner edge 31a of the first sealing layer 31 and the inner edge 32a of the second sealing layer 32, and smaller than the outer edges 31b of the first sealing layer 31 and the outer edge 32b of the second sealing layer 32. Viewed from the Z-axis direction, the first sealing layer 31 is bonded to the first surface 21a in the region from the inner edge 31a of the first sealing layer 31 to the outer edge 21d of the current collector 21. Viewed from the Z-axis direction, the second sealing layer 32 is bonded to the second surface 21b in the region from the inner edge 32a of the second sealing layer 32 to the outer edge 21d of the current collector 21.

[0044] The first sealing layer 31 and the second sealing layer 32 may have the same shape, for example. The thickness (length in the Z-axis direction) of the first sealing layer 31 and the second sealing layer 32 may be more than 100 μm and less than 200 μm. The first sealing layer 31 and the second sealing layer 32 may also have different shapes.

[0045] The first sealing layer 31 and the second sealing layer 32 are, for example, made of the same resin material. Alternatively, the first sealing layer 31 and the second sealing layer 32 may be made of an electrolyte-resistant polyolefin resin material such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene. The resin materials constituting the first sealing layer 31 and the second sealing layer 32 may also be different from each other.

[0046] A spacer layer 33 is disposed between two adjacent first sealing layers 31 and second sealing layers 32 in the Z-axis direction, without separating the current collectors 21. The spacer layer 33 is disposed between the first sealing layer 31 and second sealing layers 32 between adjacent current collectors 21, 21 in the Z-axis direction. One layer each of the first sealing layer 31, the second sealing layer 32, and the spacer layer 33 is disposed between adjacent current collectors 21, 21 in the Z-axis direction.

[0047] The spacer layer 33, together with the first sealing layer 31 and the second sealing layer 32, encloses the internal space S between adjacent current collectors 21, 21 in the Z-axis direction. The spacer layer 33, viewed from the Z-axis direction, has a frame shape (here, a rectangular frame shape) along the outer edge 21d of the current collector 21. The outer edge 33b of the spacer layer 33, viewed from the Z-axis direction, may be at the same position as the outer edges 31b of the first sealing layer 31 and 32b of the second sealing layer 32. The thickness (length in the Z-axis direction) of the spacer layer 33 may be greater than the thickness (length in the Z-axis direction) of the first sealing layer 31 and the second sealing layer 32, and may be more than 200 μm and less than 500 μm.

[0048] The spacer layer 33 is made of a resin material different from that of the first sealing layer 31 and the second sealing layer 32. For example, the spacer layer 33 is made of a polyolefin-based resin material with electrolyte resistance, such as acid-modified PE, acid-modified PP, polyethylene, or polypropylene. The spacer layer 33 may have higher crystallinity than the first sealing layer 31 and the second sealing layer 32. This suppresses the permeation of moisture into the sealing portion 13.

[0049] like Figure 2 As shown, the sealing portion 13 has an inner portion 13a and an outer portion 13b. The inner portion 13a, viewed from the Z-axis direction, is disposed inside the outer edge 21d of the current collector 21 and engages with the outer edge 21c. The outer portion 13b, viewed from the Z-axis direction, is disposed outside the outer edge 21d of the current collector 21. The inner portion 13a is configured to include inner portions of multiple first sealing layers 31, inner portions of multiple second sealing layers 32, and inner portions of multiple spacer layers 33. The outer portion 13b is configured to include outer portions of multiple first sealing layers 31, outer portions of multiple second sealing layers 32, and outer portions of multiple spacer layers 33.

[0050] The closure portion 13, viewed from the Z-axis direction, has an end face weld portion 34 (welded portion) formed by welding the end of the outer portion 13b, which is separate from the inner portion 13a, i.e., the outer edge of the closure portion 13. The end face weld portion 34, viewed from the Z-axis direction, is formed by welding together the outer edges of multiple first sealing layers 31, multiple second sealing layers 32, and multiple spacer layers 33, located outside the outer edge 21d of the current collector 21. As an example, the first sealing layers 31, second sealing layers 32, and spacer layers 33 are not welded together, but only in contact with each other outside the end face weld portion 34. A gap V is formed between the end face weld portion 34 and the outer edge 21d of the current collector 21. The first sealing layers 31 and second sealing layers 32 are separated from each other by the gap V.

[0051] The end-face weld portion 34, viewed from the Z-axis direction, is rectangular and surrounds the electrode stack 12. The side of the end-face weld portion 34 opposite to the internal space S extends along the Z-axis direction, forming the outer side of the closure portion 13. In other words, the closure portion 13 includes an inner side facing the internal space S and an outer side opposite to the inner side.

[0052] The thickness of the end-face weld portion 34 is defined by the distance between the inner and outer surfaces of the end-face weld portion 34. The thickness of the end-face weld portion 34 is the length of the end-face weld portion 34 in a direction orthogonal to the outer surface. The thickness of the end-face weld portion 34 is, for example, 1 mm or more and 10 mm or less. By making the thickness of the end-face weld portion 34 1 mm or more, a decrease in sealing performance can be suppressed. The thickness of the end-face weld portion 34 can also be 3 mm or more.

[0053] When the heating time for forming the end-face weld portion 34 is increased or the heating temperature is raised to thicken the end-face weld portion 34, the outer surface of the end-face weld portion 34 may sometimes scorch. Even if a resin layer is to be formed on such an outer surface, for example by injection molding, the resin layer is difficult to fuse to the end-face weld portion 34. By keeping the thickness of the end-face weld portion 34 to 10 mm or less, damage to the surface of the end-face weld portion 34 can be suppressed.

[0054] A connecting hole 35 is formed in the closed portion 13, communicating with the internal space S formed between the electrodes. The connecting hole 35 extends in a direction intersecting the Z-axis direction. In this embodiment, the connecting hole 35 extends in the X-axis direction. As an example, the connecting hole 35 is formed by partially cutting a notch in the spacer layer 33, passing through the spacer layer 33 and the end face weld portion 34. The connecting hole 35 has one opening in the internal space S and another opening on the outer surface of the closed portion 13 formed by the end face weld portion 34.

[0055] In the energy storage module 1, a single cell containing an internal space S is formed between adjacent current collectors 21, 21. Each single cell has a connecting hole 35. The connecting hole 35 can be used as an injection port for injecting electrolyte into the internal space S. That is, an injection port (the opening of the connecting hole 35) is provided on the outer surface of the closed portion 13. In the energy storage module 1, which is rectangular in shape when viewed from the Z-axis direction, the side where the connecting hole 35 is provided is called the injection port side. For example, the multiple connecting holes 35 are distributed in the Y-axis direction such that the connecting holes 35 in adjacent internal spaces S in the Z-axis direction do not overlap when viewed from the Z-axis direction. Figure 1 In the diagram, only one connecting hole 35 is shown by a dashed line, and the illustrations of other connecting holes 35 are omitted.

[0056] Viewed from the Z-axis direction, the inner edge 33a of the spacer layer 33 at the injection port edge is located further inward (towards the internal space S) than the inner edges 31a of the first sealing layer 31 and 32a of the second sealing layer 32. In this embodiment, the inner edge 33a of the spacer layer 33 at the injection port edge is located, for example, at least 1 mm inward than the inner edges 31a and 32a, and is exposed from the first sealing layer 31 and 32 facing the internal space S. Furthermore, viewed from the Z-axis direction, the inner edge 33a of the spacer layer 33 outside the injection port edge can be located either further outward than the inner edges 31a of the first sealing layer 31 and 32a of the second sealing layer 32, or further inward than the inner edges 31a of the first sealing layer 31 and 32a of the second sealing layer 32.

[0057] like Figure 3 As shown, the end-face weld portion 34 includes a peripheral portion 36 of the connecting hole 35. The peripheral portion 36 faces the internal space of the connecting hole 35. The peripheral portion 36 includes the end of the connecting hole 35 on the outer side of the closing portion 13 within the inner surface of the connecting hole 35. The peripheral portion 36 surrounds the connecting hole 35 when viewed in the X-axis direction. The thickness of the peripheral portion 36 is greater than the thickness of the portion of the end-face weld portion 34 that is not the peripheral portion 36. The portion of the end-face weld portion 34 that is not the peripheral portion 36 refers to the portion of the end-face weld portion 34 other than the peripheral portion 36, or the portion of the end-face weld portion 34 excluding the peripheral portion 36. The thickness of the end-face weld portion 34 increases as it approaches the connecting hole 35 within the peripheral portion 36. That is, at the injection port edge, the thickness of the end-face weld portion 34 is thickest at the inner surface of the connecting hole 35. The thickness of the end-face weld portion 34 at the injection port edge is the length of the end-face weld portion 34 in the X-axis direction. The thickness of the end face weld portion 34 opposite to the liquid injection port of the energy storage module 1 is also the length of the end face weld portion 34 in the X-axis direction. The thickness of the end face weld portion 34 on the two sides adjacent to the liquid injection port of the energy storage module 1 is the length of the end face weld portion 34 in the Y-axis direction.

[0058] (Manufacturing method of energy storage module) Figure 4 This is a flowchart illustrating a method for manufacturing an energy storage module according to an embodiment. Figure 5 This is a cross-sectional view used to illustrate the manufacturing method of the energy storage module involved in the embodiment. For example... Figure 4 As shown, the manufacturing method of the energy storage module 1 according to the embodiment includes a resin frame assembly process S1, a lamination process S2, a constraint process S3, and a welding process S4. By performing these processes in sequence, the energy storage module 1 can be obtained.

[0059] The resin frame assembly process S1 is the process of setting the resin frame 11 on the electrode. As an example, a first sealing layer 31, a second sealing layer 32, and a spacer layer 33 are provided as resin frame 11A on the bipolar electrode 14 and the negative terminal electrode 17. A first sealing layer 31 and a second sealing layer 32 are provided as resin frame 11B on the positive terminal electrode 16. In the resin frame assembly process S1, the inner portions of the first sealing layer 31 and the second sealing layer 32 are joined to the outer edges 21c of the first surface 21a and the second surface 21b of the plurality of electrodes. The outer portions of the first sealing layer 31 and the second sealing layer 32 extend beyond the outer edge 21d of the electrode. The joining of the first sealing layer 31 and the second sealing layer 32 can be performed using a contact heating device such as a pulse sealing machine or an ultrasonic sealing machine, or a non-contact heating device such as a laser sealing machine.

[0060] In the case of bipolar electrode 14 and negative terminal electrode 17, a spacer layer 33 is then provided on the second sealing layer 32. At this time, the end 15a of the spacer 15 is sandwiched between the second sealing layer 32 and the spacer layer 33. The spacer 15 and the spacer layer 33 can be partially fused to the second sealing layer 32, for example, by spot welding. The outer edge 33b of the spacer layer 33 is arranged in a manner that aligns with the outer edge 31b of the first sealing layer 31 and the outer edge 32b of the second sealing layer 32. As a result, an electrode with a resin frame portion can be obtained, in which the inner side 11a of the resin frame portion 11, which is disposed on the outer side of the outer edge 21d of the electrode, is joined to the outer edge portion 21c of the electrode.

[0061] The resin frame portion 11, viewed from the Z-axis direction, has an inner portion 11a disposed inside the outer edge portion 21c of the electrode and an outer portion 11b disposed outside the outer edge portion 21c of the electrode. The inner portion 11a is stacked in the Z-axis direction to form the inner portion 13a of the closed portion 13. The outer portion 11b is stacked in the Z-axis direction to form the outer portion 13b of the closed portion 13.

[0062] like Figure 5 As shown, the lamination process S2 is a process in which electrodes with resin frames and nesting members 4 are alternately laminated in the Z-axis direction to form a laminate 10 by arranging metal nesting members 4 between adjacent resin frames 11, 11. The laminate 10 is the laminate that forms the module body 2. The closing part 13 is formed by laminating multiple resin frames 11 in the Z-axis direction. The nesting member 4 is a rectangular metal plate viewed from the Z-axis direction. The nesting member 4 is, for example, made of stainless steel. The nesting member 4 is used to form a connecting hole 35 in the closing part 13. The thickness of the nesting member 4 is, for example, slightly thinner than the thickness of the spacer layer 33.

[0063] The laminate 10 is formed such that the nesting member 4 extends in the X-axis direction (second direction), and viewed from the Z-axis direction, the first end 4a of the nesting member 4 in the X-axis direction overlaps with the inner portion of the resin frame portion 11, and the second end 4b in the X-axis direction protrudes from the outer portion of the resin frame portion 11. The nesting member 4 is disposed at a cut partially provided in the spacer layer 33. This cut becomes a connecting hole 35. For easy peeling from the resin, a release layer such as a fluorine coating may also be provided on the surface of the nesting member 4. The release layer may be provided in the portion of the nesting member 4 biased towards the first end 4a disposed between the resin frames 11, but not in the portion of the nesting member 4 biased towards the second end 4b protruding from the outer portion of the resin frame portion 11.

[0064] The constraint process S3 is a process in which a pair of constraint plates 6 constrain the laminated body 10 in the Z-axis direction such that the outer portion 11b of the laminated resin frame portion 11 protrudes. The pair of constraint plates 6 are arranged such that, viewed from the Z-axis direction, the end 11c of the outer portion of the resin frame portion 11 protrudes from the constraint plate 6 together with the second end 4b of the nesting member 4. A resin portion 7, including polytetrafluoroethylene (PTFE), is disposed between the constraint plate 6 and the resin frame portion 11. The constraint plate 6 does not directly contact the resin frame portion 11.

[0065] like Figure 5 As shown, the welding process S4 is a process in which the heater 5 melts the end 11c of the outer portion 11b, which is separated from the inner portion 11a of the resin frame portion 11, to form the end face weld portion 34 when viewed from the Z-axis direction. That is, in the welding process S4, the end 11c of the resin frame portion 11 that protrudes from the constraint plate 6 when viewed from the Z-axis direction is welded. Since the end 11c protrudes from the constraint plate 6 in this way, welding can be performed easily.

[0066] The heater 5 has a shape extending in the Z-axis direction. The length of the heater 5 in the Z-axis direction is longer than the total length of the multiple resin frame portions 11 stacked in the Z-axis direction. The length of the heater 5 in the Z-axis direction is, for example, 30 mm or more. The total length of the multiple resin frame portions 11 stacked in the Z-axis direction is, for example, 20 mm. The heater 5 is, for example, a non-contact heater. The non-contact heater is, for example, an infrared (IR) heater. The non-contact heater is, for example, a carbon filament heater. A laser device such as an infrared laser can also be used as the heater 5. Alternatively, multiple heaters 5 can be arranged along the edge of the rectangular stack 10 when viewed from the Z-axis direction. That is, in the welding process S4, multiple heaters 5 can also be arranged in directions intersecting the Z-axis direction, specifically in the X-axis and Y-axis directions.

[0067] The heater 5 is disposed separately from the nesting member 4 and the resin frame portion 11. When the heater 5 is an IR heater, the multiple resin frames 11 are melted by absorbing infrared radiation. Specifically, in the resin material constituting the resin frame portion 11, the vibrational motion between molecules becomes active through the absorption of infrared radiation, and the energy of the vibrational motion is converted into heat, thereby melting the resin material. Metals are less likely to absorb infrared radiation than resins. Therefore, the nesting member 4 is less likely to be heated by infrared radiation than the resin frame portion 11. Furthermore, metals have higher heat dissipation than resins. Therefore, the nesting member 4 has higher heat dissipation than the resin frame portion 11, making heat dissipation easier. In a practical IR heater, a portion of the input power is not converted into infrared radiation, contributing to the heating of the filament itself, which is the source of infrared radiation. The heated filament heats the air near the filament. Therefore, when the nesting member 4 is disposed near the heater 5, the nesting member 4 is heated by the atmosphere through which the heat from the heater 5 is transferred to the nearby air.

[0068] When the distance between the heater 5 and the nesting member 4 is long or the output of the heater 5 is weak, the nesting member 4 is difficult to heat even by atmospheric heating. When the temperature of the nesting member 4 is lower than the temperature of the resin frame portion 11, heat moves from the infrared-heated resin frame portion 11 to the nesting member 4. This heat movement is more likely to occur closer to the nesting member 4. As a result, the end face weld portion 34 in the peripheral portion of the nesting member 4 may not be formed with sufficient thickness. Figure 6 This is a cross-sectional view showing an example of an end-face welded portion formed by the welding process involved in the comparative example. In the welding process involved in the comparative example, such as Figure 6 As shown, the end face weld portion 34 in the peripheral portion of the nested member 4 is not formed with sufficient thickness. This is because, since the temperature of the nested member 4 is lower than the temperature of the resin frame portion 11, the heat from the resin frame portion 11 in the peripheral portion of the nested member 4 moves to the nested member 4 and is dissipated from the nested member 4.

[0069] In contrast, in the welding process S4 of this embodiment, the nesting member 4 is heated by the heater 5 to a temperature above the melting temperature of the resin frame portion 11. This prevents heat from moving from the infrared-heated resin frame portion 11 to the nesting member 4. As a result, the end-face weld portion 34 is also formed with a thickness in the peripheral portion 36 that suppresses a decrease in sealing. Furthermore, when the heater 5 is placed too close to the resin frame portion 11, the resin material is heated not only by infrared radiation but also by heat transferred through conduction and convection to the air in contact with the heater 5, potentially causing it to scorch (turn brown). Therefore, it is necessary to maintain a distance between the heater 5 and the resin frame portion 11 such that the resin material does not scorch due to heat transferred from the heater 5 through conduction and convection. On the other hand, since metal and air cannot be heated by infrared radiation, it is necessary to heat the nesting member 4 by heat transferred from the heater 5 through conduction and convection. Therefore, in the welding process S4, while maintaining the distance between the heater 5 and the resin frame 11, the nesting part 4 is extended to the vicinity of the heater 5 and heated by conduction and convection.

[0070] Figure 7 This is a cross-sectional view showing an example of an end-face welded portion formed by the welding process involved in the embodiment. Figure 8 This is a cross-sectional view showing another example of an end-face welded portion formed by the welding process involved in the embodiment. (As shown) Figure 7 and Figure 8 As shown, the end-face weld portion 34 is also formed to a sufficient thickness in the peripheral portion 36. In the welding process S4, as... Figure 7 As shown, the nested member 4 can be heated in such a way that the thickness of the end face weld portion 34 is thicker in the peripheral portion 36 than in other portions. For example... Figure 8 As shown, the nesting member 4 can also be heated in such a way that the thickness of the end face weld portion 34 is equal to or greater than the thickness of the other portions in the peripheral portion 36. After the welding process S4, the nesting member 4 is pulled out, and electrolyte is injected into the internal space S through the connecting hole 35. The restraint plate 6 and the resin portion 7 are removed from the energy storage module 1 after the electrolyte injection.

[0071] As explained above, in the manufacturing method of the energy storage module 1, since the nesting member 4 is heated by the heater 5 to a temperature above the melting temperature of the resin frame portion 11, heat does not easily move from the peripheral portion of the nesting member 4 to the nesting member 4. Therefore, in the peripheral portion 36 of the connecting hole 35, the end face weld portion 34 is also formed with sufficient thickness. As a result, a decrease in sealing performance can be suppressed.

[0072] In the welding process S4, the nesting part 4 is heated by the heat from the heater 5, which acts as a non-contact heater. Thus, the heater 5 can heat the nesting part 4 to above the melting temperature of the resin frame portion 11.

[0073] In the welding process S4, the nesting member 4 can also be heated in such a way that the thickness of the peripheral portion 36 of the end face welding portion 34 is equal to or greater than the thickness of the portion of the end face welding portion 34 that is not the peripheral portion 36. In this case, the decrease in sealing can be reliably suppressed.

[0074] In the welding process S4, the nesting member 4 can also be heated such that the thickness of the peripheral portion 36 of the end-face weld portion 34 is greater than the thickness of the portion of the end-face weld portion 34 that is not the peripheral portion 36. In this case, the decrease in sealing performance can be suppressed more reliably. The thickness of the end-face weld portion 34 can also increase in the peripheral portion 36 as it approaches the connecting hole 35. In this case, the thickness of the end-face weld portion 34 is the thickest at the inner surface of the connecting hole 35. Thus, the decrease in sealing performance can be suppressed reliably.

[0075] The heater 5 has a shape that extends in the Z-axis direction. The heater 5 is longer than the laminate 10 in the Z-axis direction. In the welding process S4, multiple heaters 5 are arranged in a direction intersecting the Z-axis direction. As a result, the end face weld portion 34 can be formed efficiently.

[0076] The resin frame portion 11A of the bipolar electrode 14 includes: a first sealing layer 31 bonded to the outer edge 21c of the first surface 21a of the bipolar electrode 14; a second sealing layer 32 bonded to the outer edge 21c of the second surface 21b of the bipolar electrode 14; and a spacer layer 33 disposed on the first sealing layer 31. The first sealing layer 31 and the second sealing layer 32 improve the adhesion of the resin frame portion 11A to the bipolar electrode 14. The spacer layer 33 reliably separates adjacent electrodes.

[0077] In the energy storage module 1, the end face weld portion 34 in the peripheral portion 36 of the connecting hole 35 is also formed with sufficient thickness. As a result, the decrease in sealing performance can be suppressed.

[0078] The above describes one example of the manner in which this disclosure is made, but this disclosure is not limited to the manner and variations described above.

[0079] For example, in the welding process S4, the nesting member 4 only needs to be heated by the heater 5 to a temperature above the melting temperature of the resin frame portion 11, or it can be heated in such a way that the thickness of the end-face weld portion 34 is thinner in the peripheral portion 36 than in other portions. Even in this case, compared to a configuration where the nesting member 4 is not heated by the heater 5 to a temperature above the melting temperature of the resin frame portion 11, the thickness of the end-face weld portion 34 in the peripheral portion 36 is increased. Therefore, a decrease in sealing performance can be suppressed.

[0080] In the resin frame assembly process S1 described above, a spacer layer 33 is provided on the second sealing layer 32 of the bipolar electrode 14 and the negative terminal electrode 17, but the spacer layer 33 can also be provided on the first sealing layer 31 of the bipolar electrode 14 and the positive terminal electrode 16.

[0081] The manner in which this disclosure is made can be as follows. [Project 1] A method for manufacturing an energy storage module, the energy storage module comprising: a laminated body formed by stacking a plurality of electrodes including bipolar electrodes in a first direction; and a sealing portion formed by stacking a plurality of resin frame portions disposed on the outer edge of the electrodes in a first direction, which surround the laminated body when viewed from the first direction, each of the plurality of resin frame portions having an outer portion disposed on the outer side of the electrodes and an inner portion disposed on the inner side of the electrodes when viewed from the first direction, the method for manufacturing the energy storage module comprising: In the resin frame assembly process, the inner portion is joined to the outer edge of the electrode to form an electrode with a resin frame. In the lamination process, the electrodes with resin frames and the nesting members are alternately laminated in the first direction by arranging metal nesting members between adjacent resin frames in the first direction to form a laminate. The constraint process involves constraining the laminate by a pair of constraint plates in the first direction; and In the welding process, viewed from the first direction, a heater melts the ends of the plurality of outer portions to form an integral welded section. In the lamination process, the laminate is formed such that the nested member extends in a second direction intersecting the first direction, and viewed from the first direction, the first end of the nested member in the second direction overlaps with the inner portion, and the second end of the nested member in the second direction protrudes from the outer portion. During the welding process, the nesting component is heated to above the melting temperature of the resin frame. [Project 2] According to the manufacturing method of the energy storage module described in Project 1, wherein, The heater is a non-contact heater. In the welding process, the nested component is heated by the heat from the non-contact heater. [Project 3] According to the manufacturing method of the energy storage module described in Project 1 or 2, wherein, In the constraint process, viewed from the first direction, the end of the outer portion is located on the outer side of the constraint plate. [Project 4] The manufacturing method of the energy storage module according to any one of items 1 to 3, wherein, In the welding process, the nesting member is heated in such a way that the thickness of the peripheral portion of the nesting member of the welding part is equal to or greater than the thickness of the portion of the welding part that is not the peripheral portion. [Project 5] The manufacturing method of the energy storage module according to any one of items 1 to 4, wherein, The heater has a shape that extends in the first direction. The heater is longer than the laminate in the first direction. In the welding process, a plurality of heaters are arranged in a direction intersecting the first direction. [Project 6] The manufacturing method of the energy storage module according to any one of items 1 to 5, wherein, The resin frame portion disposed on the bipolar electrode includes: a first sealing layer bonded to the outer edge of the first surface of the bipolar electrode; a second sealing layer bonded to the outer edge of the second surface of the bipolar electrode on the side opposite to the first surface; and a spacer layer disposed on the first sealing layer or the second sealing layer. [Project 7] An energy storage module, comprising: A laminate, which is formed by stacking multiple electrodes, including bipolar electrodes, in a first direction; and A resin-made sealing portion, viewed from the first direction, is disposed on the outer edge of the electrode in a manner that surrounds the laminate. The closed portion, viewed from the first direction, has the following characteristics: The inner portion is disposed on the inner side of the outer edge of the electrode and is joined to the outer edge portion; The outer portion, which is disposed outside the outer edge of the electrode; and The welded portion is formed by welding the end of the outer portion, which is separate from the inner portion. A connecting hole is formed in the closed portion, extending in a second direction intersecting the first direction and communicating with the internal space formed between the electrodes. The welded portion includes the peripheral portion of the connecting hole. The thickness of the peripheral portion of the welded part is greater than the thickness of the portion of the welded part that is not the peripheral portion. [Project 8] According to the energy storage module described in Project 7, wherein, The thickness of the welded portion increases as it approaches the connecting hole in the peripheral portion. Explanation of reference numerals in the attached figures

[0082] 1…Energy storage module; 4…Nested component; 4a…First end; 4b…Second end; 5…Heater; 6…Constraint plate; 10…Laminated body; 11, 11A, 11B…Resin frame portion; 11a…Inner part; 11b…Outer part; 11c…End; 12…Electrode laminate (laminated body); 13…Sealed part; 13a…Inner part; 13b…Outer part; 14…Bipolar electrode; 21a…First surface; 21b…Second surface; 21c…Outer edge; 21d…Outer edge; 31…First sealing layer; 32…Second sealing layer; 33…Spacer layer; 34…End face weld portion (welded portion); 35…Connecting hole; 36…Peripheral portion; S…Internal space; S1…Resin frame assembly process; S2…Lamination process; S3…Constraint process; S4…Welding process.

Claims

1. A method for manufacturing an energy storage module, the energy storage module comprising: a laminated body formed by stacking a plurality of electrodes including bipolar electrodes in a first direction; and a sealing portion formed by stacking a plurality of resin frame portions disposed on the outer edge of the electrodes in a first direction, as viewed from the first direction, surrounding the laminated body, each of the plurality of resin frame portions having, as viewed from the first direction, an outer portion disposed on the outer side of the electrodes and an inner portion disposed on the inner side of the electrodes, the method for manufacturing the energy storage module being characterized in that it comprises: In the resin frame assembly process, the inner portion is joined to the outer edge of the electrode to form an electrode with a resin frame. In the lamination process, the electrodes with resin frames and the nesting members are alternately laminated in the first direction by arranging metal nesting members between adjacent resin frames in the first direction to form a laminate. The constraint process involves constraining the laminate by a pair of constraint plates in the first direction; and In the welding process, viewed from the first direction, a heater melts the ends of the plurality of outer portions to form an integral welded section. In the lamination process, the laminate is formed such that the nested member extends in a second direction intersecting the first direction, and viewed from the first direction, the first end of the nested member in the second direction overlaps with the inner portion, and the second end of the nested member in the second direction protrudes from the outer portion. During the welding process, the nesting component is heated to above the melting temperature of the resin frame.

2. The method for manufacturing a battery storage module according to claim 1, wherein, The heater is a non-contact heater. In the welding process, the nested component is heated by the heat from the non-contact heater.

3. The method for manufacturing a battery storage module according to claim 1 or 2, wherein, In the constraint process, viewed from the first direction, the end of the outer portion is located on the outer side of the constraint plate.

4. The method for manufacturing a battery storage module according to claim 1 or 2, wherein, In the welding process, the nesting member is heated in such a way that the thickness of the peripheral portion of the nesting member of the welding part is equal to or greater than the thickness of the portion of the welding part that is not the peripheral portion.

5. The method for manufacturing a battery storage module according to claim 1 or 2, wherein, The heater has a shape that extends in the first direction. The heater is longer than the laminate in the first direction. In the welding process, a plurality of heaters are arranged in a direction intersecting the first direction.

6. The method for manufacturing a battery storage module according to claim 1 or 2, wherein, The resin frame portion disposed on the bipolar electrode includes: a first sealing layer bonded to the outer edge of the first surface of the bipolar electrode; a second sealing layer bonded to the outer edge of the second surface of the bipolar electrode on the side opposite to the first surface; and a spacer layer disposed on the first sealing layer or the second sealing layer.

7. A power storage module, characterized in that, have: A laminate, which is formed by stacking multiple electrodes, including bipolar electrodes, in a first direction; and A resin-made sealing portion, viewed from the first direction, is disposed on the outer edge of the electrode in a manner that surrounds the laminate. The closed portion, viewed from the first direction, has the following characteristics: The inner portion is disposed on the inner side of the outer edge of the electrode and is joined to the outer edge portion; The outer portion, which is disposed outside the outer edge of the electrode; and The welded portion is formed by welding the end of the outer portion, which is separate from the inner portion. A connecting hole is formed in the closed portion, extending in a second direction intersecting the first direction and communicating with the internal space formed between the electrodes. The welded portion includes the peripheral portion of the connecting hole. The thickness of the peripheral portion of the welded part is greater than the thickness of the portion of the welded part that is not the peripheral portion.

8. The energy storage module according to claim 7, wherein, The thickness of the welded portion increases as it approaches the connecting hole in the peripheral portion.

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