Manufacturing method of battery and the battery

Abstract

To provide a manufacturing method of a battery capable of suppressing the occurrence of wrinkles in a seal member.SOLUTION: A manufacturing method of a battery comprises steps of: preparing an electrode member; forming an electrode laminate EL by laminating the plurality of electrode members in a thickness direction; disposing a pair of restraining plates 6a and 6b at both ends of the electrode laminate in the thickness direction; and forming a seal member using each restraining plate. The electrode laminate has a first region R1 in which a first frame member and a second frame member face an outer edge of a current collector when viewed in the thickness direction; and a second region R2 in which the first frame member and the second frame member are located outside the current collector. In the manufacturing method of the battery, at least one of the pair of restraining plates has a convex portion 7 at a position facing the second region of the electrode laminate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a battery and the battery. [Background technology]

[0002] Patent Document 1 discloses an electricity storage device in which a module stack is restrained by a pair of end plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-091947 Summary of the Invention [Problem to be solved by the invention]

[0004] When welding the end faces (side faces, faces extending in the thickness direction) of an electrode laminate in which multiple electrode members are stacked, if the electrode laminate is restrained by a flat restraining plate, the resin that makes up the sealing member of the electrode laminate will expand horizontally in the area at the end of the sealing member that does not face the current collector, causing wrinkles in the sealing member and potentially increasing the size of the battery.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and has as its main object to provide a method for manufacturing a battery that can suppress the occurrence of wrinkles in a sealing member. [Means for solving the problem]

[0006] [1] A method for manufacturing a battery, comprising: a preparation step of preparing an electrode member including a current collector and an active material layer disposed on at least one surface of the current collector, with the outer edge of the current collector positioned outside the outer edge of the active material layer when viewed in the thickness direction; a first frame member made of resin welded onto one surface of the current collector along the outer edge of the current collector; and a second frame member made of resin welded onto the other surface of the current collector along the outer edge of the current collector; an electrode stack forming step of stacking a plurality of the electrode members in a thickness direction to form an electrode stack; a seal member forming step of arranging a pair of restraint plates at both ends in the thickness direction of the electrode stack, and applying heat while applying pressure to the first frame member and the second frame member using the restraint plates to weld the first frame member and the second frame member together, thereby forming a seal member; the electrode stack has, when viewed in the thickness direction, a first region in which the first frame member and the second frame member face an outer edge of the current collector, and a second region in which the first frame member and the second frame member are located outside the current collector, At least one of the pair of constraint plates has a protrusion at a position facing the second region of the electrode stack, A method of manufacturing a battery, wherein in the sealing member forming step, the second region is heated and pressurized to weld the first frame member and the second frame member together at least at the outer edge of the second region.

[0007] [2] A battery including an electrode stack in which a plurality of electrode members are stacked in a thickness direction, the electrode member includes a current collector and an active material layer disposed on at least one surface of the current collector, an electrode in which an outer edge of the current collector is positioned outside an outer edge of the active material layer when viewed in the thickness direction, and sealing members welded to both surfaces of the current collector and surrounding the electrode; the sealing member has a first region facing an outer edge of the current collector and a second region positioned outside the current collector when viewed in a thickness direction, The battery, wherein a step is formed between the first region and the second region at at least one end of the sealing member in the thickness direction. [Effects of the Invention]

[0008] The battery manufacturing method of the present disclosure can prevent wrinkles from forming in the sealing member. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow diagram illustrating a method for manufacturing a battery according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view illustrating an electrode member prepared in a preparation step in the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view illustrating an electrode laminate formed in the electrode laminate forming step in the present disclosure. [Figure 4] FIG. 4 is a schematic view illustrating the sealing member forming step in the present disclosure. [Figure 5] FIG. 5 is a schematic cross-sectional view illustrating a battery according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. For clarity, some repeated reference numerals may be omitted. The directions of a three-dimensional Cartesian coordinate system are also shown in the drawings. Here, the xy plane is the horizontal plane, the z-axis direction is the vertical direction, and the larger dimension in the z-axis direction is considered to be the upper side. Furthermore, in this specification, when describing the arrangement of another member relative to a certain member, the terms "above" or "below" simply refer to both the case where another member is arranged directly above or below the certain member so as to be in contact with the certain member, and the case where another member is arranged above or below the certain member via another member, unless otherwise specified.

[0011] Fig. 1 is a flow diagram illustrating a battery manufacturing method according to the present disclosure. As shown in Fig. 1, the battery manufacturing method according to the present disclosure includes at least a preparation step, an electrode stack formation step, and a seal member formation step. Typically, the seal member formation step is followed by an electrolyte solution supply step and a supply hole sealing step.

[0012] 1.Preparation process The preparation process in the present disclosure is a process of preparing an electrode member having a current collector and an active material layer disposed on at least one surface of the current collector, with the outer edge of the current collector positioned outside the outer edge of the active material layer when viewed in the thickness direction, a first frame member made of resin welded to one surface of the current collector along the outer edge of the current collector, and a second frame member made of resin welded to the other surface of the current collector along the outer edge of the current collector.

[0013] FIG. 2 is a schematic cross-sectional view illustrating an electrode member prepared in a preparation step in the present disclosure. The electrode member EM shown in FIG. 2 includes an electrode E, a first frame member 5a, and a second frame member 5b. The electrode E is a bipolar electrode BP including a current collector 1, a positive electrode active material layer 2 (first active material layer) disposed on one surface of the current collector 1, and a negative electrode active material layer 3 (second active material layer) disposed on the other surface of the current collector 1. As can be seen from FIG. 2, in plan view, the outer edge of the current collector 1 is located outside the outer edge of the positive electrode active material layer 2. In addition, in plan view, the outer edge of the current collector 1 is located outside the outer edge of the negative electrode active material layer 3. The first frame member 5a is welded to one surface of the current collector 1 along the outer edge of the current collector 1. The second frame member 5b is welded to the other surface of the current collector 1 along the outer edge of the current collector 1. The first frame member 5a and the second frame member 5b are arranged so that their inner edges, which are one end, are located on the outer edges of the current collector 1 so as to face the current collector 1, and their outer edges, which are the other ends, protrude outward from the current collector 1 so as not to face the current collector 1. A gap S exists between the outer edges of the first frame member 5a and the second frame member 5b.

[0014] The electrode member prepared in the preparation step includes an electrode, a first frame member, and a second frame member.

[0015] The electrode may be an electrode having a current collector and a positive electrode active material layer or a negative electrode active material layer disposed on one surface of the current collector, or may be a bipolar electrode having a positive electrode active material layer disposed on one surface of the current collector and a negative electrode active material layer disposed on the other surface of the current collector.

[0016] The current collector is a foil-shaped conductive member, such as a metal foil. The metal foil does not need to be a single-layer metal foil, but may be a clad foil or a laminated foil in which different metal foils are laminated. The type of metal is not particularly limited, but an example is a foil in which aluminum foil and copper foil are laminated so that the upper surface is an aluminum layer and the lower surface is a copper layer. Other metals include titanium, nickel, stainless steel (e.g., SUS304, SUS316, SUS301, etc. specified in JIS G 4305:2015), steel (e.g., cold-rolled steel sheet (SPCC, etc.) specified in JIS G 3141:2005), etc.

[0017] The positive electrode active material layer can include a positive electrode active material, a conductive additive, and a binder. Examples of the positive electrode active material include composite oxides, metallic lithium, and sulfur. The composite oxides contain at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxides include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2. The binder serves to anchor the active material or conductive additive to the surface of the current collector and maintain the conductive network in the electrode. Examples of binders include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins containing monomer units such as acrylic acid and methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinks; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Examples of the conductive aid include acetylene black, carbon black, and graphite.

[0018] The negative electrode active material layer may contain a negative electrode active material, a conductive additive, and a binder. The conductive additive and the binder may be considered to be similar to those in the positive electrode active material layer. Examples of the negative electrode active material include carbon such as graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, metal compounds, elements that can be alloyed with lithium or compounds of such elements, boron-doped carbon, etc. Examples of elements that can be alloyed with lithium include silicon and tin.

[0019] To form the positive electrode active material layer and the negative electrode active material layer on the current collector, conventional methods such as roll coating, die coating, dip coating, doctor blade coating, spray coating, and curtain coating are used. Specifically, an active material, a solvent, and optionally a binder and a conductive additive are mixed to produce a slurry-like active material layer-forming composition, which is then applied to the upper and lower surfaces of the current collector and dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water.

[0020] The shape of the electrode is not particularly limited, but examples thereof include quadrilaterals such as squares and rectangles in plan view.

[0021] The first frame member is welded onto one surface of the current collector along the outer edge of the current collector. The second frame member is welded onto the other surface of the current collector along the outer edge of the current collector. In the present disclosure, the first frame member, the second frame member, and a third frame member described below may be simply referred to as frame members. Examples of resins used for the frame member include thermoplastic resins, such as olefin-based resins such as polyethylene, polypropylene, acid-modified polyethylene, and acid-modified polypropylene.

[0022] The electrode member may have a functional member. The functional member is disposed so that one end is located between the first frame member and the current collector or between the second frame member and the current collector, and the other end is located outside the first frame member and the second frame member. The functional member may be fixed to the current collector by welding, for example, and then the frame member may be welded to the current collector. An example of the functional member is a terminal member. An example of the terminal member is a voltage detection terminal.

[0023] 2. Electrode laminate formation process The electrode stack forming step in the present disclosure is a step of forming an electrode stack by stacking a plurality of the electrode members in the thickness direction.

[0024] FIG. 3 is a schematic cross-sectional view illustrating an electrode laminate formed in the electrode laminate forming step in the present disclosure. As shown in Fig. 3, the electrode stack EL is a stack in which multiple electrode members EM are stacked in the thickness direction (z direction). Separators 4 are disposed between the electrodes E of each electrode member EM. The outer edges of the separators 4 are disposed between frame members 5 adjacent to each other in the stacking direction and are welded to the frame members 5. The electrode stack EL shown in Fig. 3 has, as the electrodes E, a bipolar electrode BP, a positive electrode end electrode CA, and a negative electrode end electrode AN. 3, the bipolar electrode BP has a current collector 1, a positive electrode active material layer 2 disposed on one surface of the current collector 1, and a negative electrode active material layer 3 disposed on the other surface of the current collector 1. The positive electrode end electrode CA has a current collector 1 and a positive electrode active material layer 2 disposed on one surface of the current collector 1. The negative electrode end electrode AN has a current collector 1 and a negative electrode active material layer 3 disposed on one surface of the current collector 1. The current collector 1, positive electrode active material layer 2, negative electrode active material layer 3, and separator 4 are configured to have different sizes in a planar view. As can be seen from Fig. 3, the current collector 1, positive electrode active material layer 2, negative electrode active material layer 3, and separator 4 are arranged with their centers aligned in a planar view, and the difference in size is reflected in the degree of protrusion (overhang) of their edges. Therefore, the edges of the current collector 1 and separator 4 protrude most, and the edges of the negative electrode active material layer 3 and positive electrode active material layer 2 protrude in that order, so that they are located inside them. A first frame member 5a and a second frame member 5b are disposed on the outer peripheral edge (outer edge) of each electrode E in the xy plane direction. A third frame member 5c is disposed as a spacer between adjacent electrodes E in the stacking direction. The third frame member 5c is disposed between the first frame member 5a of one electrode E and the second frame member 5b of the other adjacent electrode E. The first frame member 5a, the second frame member 5b, and the third frame member 5c are disposed such that their inner edges (one end) are positioned on the outer edge of the current collector 1 so as to face the current collector 1, and their outer edges (the other end) protrude outward from the current collector 1 so as not to face the current collector 1. The first frame member 5a, the second frame member 5b, and the third frame member 5c have the same shape in a plan view. The first frame member 5a, the second frame member 5b, and the third frame member 5c may be made of the same or different types of resin. The electrode stack EL has a first region R1 where each frame member 5 faces the outer edge of the current collector 1 when viewed in the thickness direction, and a second region R2 where each frame member 5 is located outside the current collector 1. There are gaps S between the outer edges of the first frame member 5a and the second frame member 5b, and between the outer edges of the first frame member 5a and the third frame member 5c. In the sealing member forming process described below, the adjacent first frame member 5a, second frame member 5b, and third frame member 5c are joined together, thereby filling the gaps S.

[0025] The separator 4 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains a liquid electrolyte, and in this embodiment, is disposed between the positive electrode active material layer 2 and the negative electrode active material layer 3 of the electrode E that are adjacent in the z direction. Examples of materials that can be used to form the separator 4 include polypropylene, polyethylene, polyester, etc. The separator 4 may have a single-layer structure or a multi-layer structure. The electrolyte absorbed and retained in the separator 4 may be, for example, a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. When the separator 4 is impregnated with an electrolyte, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte salt. In addition, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as the non-aqueous solvent.

[0026] The planar shape of the electrode laminate EL is not particularly limited, but examples thereof include quadrilaterals such as squares and rectangles. The length of each side constituting the planar shape of the electrode laminate is not particularly limited, but may be, for example, 30 cm or more, 50 cm or more, or 100 cm or more. On the other hand, the length of each of the above sides is, for example, 200 cm or less.

[0027] 3.Sealing material forming process The sealing member forming process in the present disclosure is a process of forming a sealing member by placing a pair of restraint plates at both ends of the electrode stack in the thickness direction, and using the restraint plates to apply pressure to the first frame member and the second frame member while heating them, thereby welding the first frame member and the second frame member together. In the seal member forming process, the second region is heated and pressurized to weld the first frame member and the second frame member at least to the outer edge of the second region. That is, the range in which the first frame member and the second frame member are welded does not necessarily have to be the entire second region, but only needs to be at least to the outer edge of the second region.

[0028] 4 is a schematic view illustrating the sealing member forming step in the present disclosure, in which the members and gaps that constitute the electrode stack EL are omitted for the sake of convenience. As shown in Fig. 4, a pair of restraint plates 6 are disposed at both ends in the thickness direction of the electrode laminate EL. The pair of restraint plates 6 may be disposed in positions facing the first region R1 and the second region R2 of the electrode laminate EL. One of the pair of restraint plates 6, the restraint plate 6a, has a protrusion 7 (narrowing projection) in a position facing the second region R2 of the electrode laminate EL. The size of the protrusion 7 does not have to be large enough to face the entire second region R2, but may be large enough to face at least the end portion (the end portion when viewed from the thickness direction) of the second region R2. The protrusion 7 only needs to be hard enough to crush the frame member 5 in the second region R2 and be made of a material with low thermal conductivity that makes it difficult for heat applied to the frame member 5 to escape.Examples of materials for the protrusion 7 include calcite and bakelite.

[0029] 4, the electrode stack EL is pressed from above and below in the z direction using restraint plates 6 in the first region R1 and the second region R2, while the side surfaces of the electrode stack EL are heated by an IR heater 9. As a result, although not shown, adjacent frame members 5 are welded together at least at the outer edges of the second region R2 (the outer edges when viewed from the thickness direction), and a seal member that surrounds the outer edges of the electrode E is formed.

[0030] By providing a protrusion 7 on one of the pair of constraining plates 6, the constraining plate 6a, with the flat constraining plate 6b as a reference, can be processed while pressing the constraining plate 6a against the electrode stack EL from above in the z direction, which is convenient from the viewpoint of measuring the dimensions of the electrode stack EL, etc. The constriction and restraint by the protrusion 7 creates a step 8, which is a constriction shape corresponding to the protrusion 7, on the upper surface in the stacking direction of the second region R2 of the electrode stack EL.

[0031] The convex portion 7 may be formed by processing the restraint plate 6 itself to provide a protrusion, or by attaching a separate rod member to the restraint plate 6. The protrusion 7 may be provided on at least one of the pair of restraint plates 6, ie, the restraint plate 6a, and may also be provided on the other restraint plate 6b. The inner corners of the protrusion 7 may be rounded, for example, from the viewpoint of preventing localized load concentration. The thickness of the protrusion 7 can be set appropriately taking into consideration the thickness of the gap S in the second region R2 and the expansion width of the frame member 5 during welding. The thickness of the protrusion 7 may be 60% or more, 80% or more, or 100% or less of the total thickness of the gap S. The depth (height difference, difference in the z direction) of the step 8 between the second region R2 and the first region R1 that occurs after the second region R2 is constricted and restrained may be 60% or more of the total thickness of the gap S, 80% or more, or 100% or less, from the viewpoint of filling the gap S and reducing the voids in the sealing member.

[0032] When the conventional method is used to weld the edges of the electrode laminate EL using a flat restraining plate that restrains the first region R1, including the frame member 5 and current collector 1, without restraining the second region R2, where only the frame member 5 is laminated, a gap S remains in the second region R2. When heated by a heater, the frame member 5 in the second region R2, where the gap S exists, expands in the xy plane. However, in the first region R1, where the frame member 5 is restrained by the restraining plate, the expansion of the frame member 5 in the xy plane is restricted, causing the frame member 5 to meander between the upper and lower restraining plates in the second region R2, where the gap S exists. This meandering of the frame member 5 during heating remains even after heating is completed, causing wrinkles (unevenness) to occur on the upper and lower surfaces of the electrode laminate EL after the restraint is released, increasing the size of the battery. On the other hand, in the present disclosure, by using a constraining plate 6 that constrains not only the first region R1 but also the second region R2 to eliminate the gap S in the second region R2, the flatness of the upper and lower surfaces in the z direction of the electrode stack EL can be improved and the increase in the battery's physical size can be reduced. Furthermore, compared to conventional construction methods, the gap S can be quantitatively closed, improving airtightness. Furthermore, if it becomes necessary to fix or constrain the second region R2 in a later process for vibration suppression measures or the like, it becomes possible to firmly fix or constrain the second region R2 using a rigid body, rather than constraining it with an elastic body such as rubber or urethane that can absorb unevenness.

[0033] In the sealing member forming step, the heating means for heating the frame member 5 and, if necessary, the restraint plate 6 may be any means capable of heating the electrode stack from the outside without contact, such as an IR heater or hot air. The frame member 5 and the restraint plate 6 may be heated by heating the end faces (side faces) of each member in the xy plane. The heating temperature in the sealing member forming step is not particularly limited as long as it is a temperature that can weld adjacent frame members 5 together, and is set appropriately depending on the material of the frame member 5. As described above, the heating temperature in the sealing member forming step is appropriately set depending on the material of the frame member 5. For example, when the resin constituting the frame member 5 is a polyethylene-based material with a melting point of 125°C, the heating temperature may be 140°C or higher and 190°C or lower. Furthermore, the pressure (surface pressure) applied in the sealing member forming step is, for example, 0.5 MPa or higher, or may be 2 MPa or higher, or 3 MPa or higher, from the viewpoint of filling the gap S between adjacent frame members 5 in the stacking direction. On the other hand, the pressure may be, for example, 32 MPa or lower and 20 MPa or lower. Furthermore, the heating time in the sealing member forming step is, for example, 0.5 seconds or longer and 5 seconds or shorter. When heating is performed using an IR heater, the IR heater may be set to a rated output of 2.8 to 5.6 kW, a voltage of 200 V, and a current of 8 to 12 A, and the distance between the IR heater and the welding end surface (side surface) of each member may be 45 to 50 mm. After the sealing member is formed in the sealing member forming step, the sealing member may be cooled by a cooling means, which may be a cooler, a precision air conditioner, a fan, a contact plate, or the like. In the seal member forming step, the timing for releasing the restraint by the restraint plate 6 may be when the temperature of the resin that constitutes the frame member 5 drops below the melting point of the resin.

[0034] 4. Other processes In the battery manufacturing method according to the present disclosure, when stacking the electrode members, a insert may be placed between adjacent frame members 5, and the insert may be removed after the sealing member forming step to form a supply hole for supplying the electrolyte solution to the second region R2 of the frame members 5 that are welded together. An electrolyte solution supplying step may be included in which the electrolyte solution is supplied to the inside of the electrode stack through the above-mentioned supply hole. Furthermore, the battery manufacturing method according to the present disclosure may include a supply hole sealing step in which the supply hole is sealed after the electrolyte solution supplying step.

[0035] 5.Battery FIG. 5 is a schematic cross-sectional view illustrating a battery according to the present disclosure. As shown in FIG. 5, a battery 10 according to the present disclosure includes an electrode stack EL in which a plurality of electrode members EM are stacked in the thickness direction. Electrodes E of the electrode members EM may contain an electrolyte. The electrode members EM are welded to both sides of a current collector 1 and include sealing members 50 that surround the current collector 1. The sealing members 50 cover the outer edge of one surface of the current collector 1, the outer edge of the other surface of the current collector 1, and the side surfaces of the current collector 1. The sealing members 50 also cover the outer edge of one surface of a separator 4, the outer edge of the other surface of the separator 4, and the side surfaces of the separator 4. The sealing members 50 are formed by welding frame members 5 adjacent to each other in the thickness direction in the sealing member formation process described above. The electrode laminate EL has a first region R1 facing the outer edge of the current collector 1 when viewed in the thickness direction, and a second region R2 located outside the current collector 1. The first region R1 is thicker than the second region R2, and a step 8 is formed by the first region R1 and the second region R2 at the upper end of the seal member 50 in the thickness direction. The step 8 is formed by constricting and restraining the second region R2 by the convex portion 7 of the restraint plate 6 in the seal member formation process. In FIG. 5, the step 8 is provided at the upper end of the seal member 50 in the z direction, but the step 8 may also be provided at both ends in the z direction. Although not shown, the battery 10 may have a functional member whose one end is electrically connected to the current collector 1 and whose other end protrudes from the sealing member 50.

[0036] The battery in the present disclosure may be a secondary battery such as a lithium-ion secondary battery. Furthermore, examples of uses of the battery in the present disclosure include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. It is particularly preferable that the battery be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). Furthermore, the battery in the present disclosure may be used as a power source for mobile objects other than vehicles (e.g., trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0037] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Explanation of symbols]

[0038] 1...Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4...Separator 5...Frame member 6…Restraint plate 7...Convex part 8...Step 9...IR heater 10...Battery

Claims

1. A method for manufacturing a battery, comprising: a preparation step of preparing an electrode member including a current collector and an active material layer disposed on at least one surface of the current collector, with the outer edge of the current collector being positioned outside the outer edge of the active material layer when viewed in the thickness direction; a first frame member made of resin welded onto one surface of the current collector along the outer edge of the current collector; and a second frame member made of resin welded onto the other surface of the current collector along the outer edge of the current collector; an electrode stack forming step of stacking a plurality of the electrode members in a thickness direction to form an electrode stack; a seal member forming step of arranging a pair of restraint plates at both ends in the thickness direction of the electrode stack, and applying heat while applying pressure to the first frame member and the second frame member using the restraint plates to weld the first frame member and the second frame member together, thereby forming a seal member; the electrode stack has, when viewed in a thickness direction, a first region in which the first frame member and the second frame member face an outer edge of the current collector, and a second region in which the first frame member and the second frame member are located outside the current collector, At least one of the pair of constraint plates has a protrusion at a position facing the second region of the electrode stack, In the sealing member forming step, the second region is heated and pressurized to weld the first frame member and the second frame member together at least at the outer edge of the second region.

2. A battery including an electrode stack in which a plurality of electrode members are stacked in a thickness direction, the electrode member includes a current collector and an active material layer disposed on at least one surface of the current collector, an electrode in which an outer edge of the current collector is positioned outside an outer edge of the active material layer when viewed in the thickness direction, and sealing members welded to both surfaces of the current collector and surrounding the electrode; the sealing member has a first region facing an outer edge of the current collector and a second region positioned outward from the current collector when viewed in a thickness direction, A battery, wherein a step is formed between the first region and the second region at at least one end of the sealing member in the thickness direction.

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