Method for manufacturing bipolar battery

Abstract

To provide a method for manufacturing a bipolar battery which can suppress formation of a recess.SOLUTION: A method for manufacturing a bipolar battery includes a manufacturing step of manufacturing bipolar electrode bodies in which seal members (a first seal member and a second seal member) are arranged around a rectangular current collector, and a positive electrode layer is arranged on a first surface of the current collector, while a negative electrode layer is arranged on a second surface thereof, a lamination step of laminating a plurality of bipolar electrode bodies through a separator, arranging spacers between each of the seal members of the bipolar electrode body adjacent to each other in a lamination direction, and thereby obtaining a bipolar electrode laminate, and a welding step of welding the seal members and the spacers aligned in the lamination direction while constraining the seal members and the spacer in the lamination direction. In the bipolar electrode laminate, when the first seal member, the second seal member and the spacer are formed of resin members, on at least one side face of the bipolar electrode laminate, and when a resin member whose MD and width directions coincide with each other is represented by a resin member MD, and a resin member whose TD and width directions coincide with each other is represented by a resin member TD, the resin member MD and the resin member TD are coexistent and laminated.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] This application relates to a method for manufacturing a bipolar battery. [Background technology]

[0002] Patent Documents 1 and 2 disclose a bipolar battery including a bipolar electrode stack in which a plurality of bipolar electrode bodies are stacked, and a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-102127 A [Patent Document 2] JP 2023-46589 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the batteries disclosed in Patent Documents 1 and 2, the current collector is made of a rectangular metal foil, and a frame-shaped member made of resin is provided on the periphery of the current collector. In such batteries, in the welding process for forming the frame-shaped member, the end faces of multiple sheet-shaped resin members aligned in the stacking direction are welded. Usually, multiple resin members aligned in the stacking direction are stacked with their respective MD (Machine Direction) and TD (Traverse Direction) aligned. If the welding process is performed in this state, there is a problem that each resin member significantly shrinks in the direction along the MD during cooling, resulting in the formation of a recess in the frame-shaped member.

[0005] In view of the above-mentioned circumstances, a main object of the present disclosure is to provide a manufacturing method for a bipolar battery that can suppress the formation of recesses. [Means for solving the problem]

[0006] The present disclosure provides at least the following aspects.

[0007] The first aspect is a manufacturing method for a bipolar battery including a bipolar electrode laminate in which a plurality of bipolar electrode bodies are laminated, and a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode laminate, the manufacturing method including a manufacturing step of manufacturing a bipolar electrode body in which a seal member is disposed around a rectangular current collector, and in which a positive electrode layer is disposed on a first surface of the current collector and a negative electrode layer is disposed on a second surface of the current collector; a stacking step of stacking a plurality of bipolar electrode bodies via separators and arranging spacers between the seal members of adjacent bipolar electrode bodies in the stacking direction to obtain a bipolar electrode laminate; and a stacking step of welding the seal members and spacers aligned in the stacking direction while restraining them in the stacking direction to seal the entire periphery of the side surface of the bipolar electrode laminate. and a welding process for forming a frame-shaped member having a current collector and a sealing member arranged on the first surface and a second surface opposite to the first surface, the sealing member having a first sealing member arranged on the first surface of the current collector and a second sealing member arranged on the second surface of the current collector, and in the bipolar electrode laminate, when the first sealing member, the second sealing member, and the spacer are made of resin members, each resin member has MD and TD, and on at least one side of the bipolar electrode laminate, when the resin member whose MD and width direction coincide is called the resin member MD and the resin member whose TD and width direction coincide is called the resin member TD, the resin members MD and TD are laminated in a mixed state.

[0008] A second aspect is the manufacturing method according to the first aspect, in which the resin members MD and TD are stacked adjacent to each other in the stacking direction on at least one side surface of the bipolar electrode laminate.

[0009] A third aspect is the manufacturing method according to the first or second aspect, in which resin members MD and resin members TD are alternately laminated on at least one side surface of the bipolar electrode laminate.

[0010] The fourth aspect is a manufacturing method described in the first aspect, in which, when a series of first sealing members, second sealing members, and spacers lined up in the stacking direction are considered to be a resin member group, the MD and TD of each resin member included in the resin member group are consistent, and on at least one side of the bipolar electrode stack, when a resin member group whose MD and width directions are consistent is called a resin member group MDG, and a resin member group whose TD and width directions are consistent is called a resin member group TDG, the resin member group MDG and the resin member group TDG are mixed.

[0011] A fifth aspect is the manufacturing method according to the fourth aspect, in which the resin member groups MDG and the resin member groups TDG are alternately laminated on at least one side surface of the bipolar electrode laminate. Effect of the Invention

[0012] According to the manufacturing method of the bipolar battery of the present disclosure, the occurrence of recesses in the welding process can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] 1A is a plan view of the bipolar electrode body 10. FIG. 1B is a cross-sectional view of the bipolar electrode body 10. [Diagram 2] 1 is a cross-sectional view of a bipolar electrode laminate 50 obtained in a lamination step S2. [Diagram 3] (A) shows a diagram illustrating a rectangular resin member MD, and (B) shows a diagram illustrating a rectangular resin member TD. [Figure 4] FIG. 1 is a side view of a conventional bipolar electrode laminate P, showing the state when it is heated in a welding process and the state when it is cooled after heating. [Diagram 5] 1A and 1B are side views of a bipolar electrode stack 50, showing the state when it is heated during the welding process and the state when it is cooled after heating. [Figure 6] FIG. 2 is a side view of a bipolar electrode stack 150. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The manufacturing method of the bipolar battery of the present disclosure will be described using one embodiment.

[0015] One embodiment is a method for manufacturing a bipolar battery including a bipolar electrode laminate in which a plurality of bipolar electrode bodies are laminated, and a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode laminate. The method includes a fabrication step S1, a lamination step S2, and a welding step S3. Each step will be described below.

[0016] <Production process S1> The fabrication process S1 is a process for fabricating a bipolar electrode body 10 in which a sealing member 14 is disposed around a rectangular current collector 11, and a positive electrode layer 12 is disposed on a first surface 11a of the current collector 11, and a negative electrode layer 13 is disposed on a second surface 11b of the current collector 11. Fig. 1 (A) shows a plan view of the bipolar electrode body 10, and (B) shows a cross-sectional view of the bipolar electrode body 10.

[0017] (Current collector 11) The current collector 11 is a rectangular sheet-like conductive member in a plan view. The current collector 11 has a first surface 11a and a second surface 11b located on the opposite side of the first surface 11a. The current collector 11 is made of, for example, a metal foil or an alloy foil. Examples of the metal foil include copper foil, aluminum foil, titanium foil, and nickel foil. Examples of the alloy foil include stainless steel foil, plated steel sheet, and plated stainless steel sheet. The alloy foil may be an alloy foil of the metals exemplified as the material of the metal foil. The current collector 11 may be formed by integrating or laminating a plurality of metal foils, or may be formed by plating the surface of a metal foil with another metal.

[0018] (Positive electrode layer 12) The positive electrode layer 12 is a rectangular sheet-like member in a plan view, and is disposed on the first surface 11a of the current collector 11. The positive electrode layer 12 includes a positive electrode active material. Examples of the positive electrode active material include a composite oxide, metallic lithium, and sulfur. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxide include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2.

[0019] The positive electrode layer 12 may contain a conductive additive. Examples of the conductive additive include acetylene black, carbon black, and graphite.

[0020] The positive electrode layer 12 may contain a binder. Examples of the binder 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 crosslinked bodies, and starch-acrylic acid graft polymers.

[0021] The method of forming the positive electrode layer 12 on the first surface 11a of the current collector 11 is not particularly limited, and a known method may be appropriately adopted. For example, a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, a curtain coating method, etc. may be mentioned. Specifically, the material constituting the positive electrode layer 12 is mixed with a solvent to obtain a slurry, and then the slurry is applied to the first surface 11a of the current collector 11 and dried to obtain the positive electrode layer 12. The solvent is, for example, N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, or water. In order to increase the electrode density, the positive electrode layer 12 after drying may be compressed.

[0022] (Negative electrode layer 13) The negative electrode layer 13 is a rectangular sheet-like member in a plan view, and is disposed on the second surface 11b of the current collector 11. The negative electrode layer 13 includes a negative electrode active material. 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 capable of forming an alloy with lithium or compounds of such elements, and boron-added carbon. Examples of elements capable of forming an alloy with lithium include silicon and tin.

[0023] The negative electrode layer 13 may contain a conductive assistant. The conductive assistant may be appropriately selected from those applicable to the positive electrode layer 12. The negative electrode layer 13 may also contain a binder. The binder may be appropriately selected from those applicable to the positive electrode active material layer 12.

[0024] The method for forming the negative electrode layer 13 on the second surface 11b of the current collector 11 is not particularly limited, and any known method may be appropriately adopted. For example, the method may be appropriately selected from those exemplified as the method for forming the positive electrode layer 12.

[0025] (Sealing member 14) The sealing member 14 is a rectangular frame-shaped member disposed around the current collector 11 in a plan view. As shown in Figures 1(A) and (B), the sealing member 14 is disposed at a position spaced apart from the positive electrode layer 12 and the negative electrode layer 13. The sealing member 14 includes a first sealing member 14a disposed on the first surface 11a of the current collector 11 and a second sealing member 14b disposed on the second surface 11b of the current collector 11.

[0026] The first seal member 14a is a rectangular frame-shaped member that is disposed along the periphery of the first surface 11a of the current collector 11 and is joined to the first surface 11a. The outer edge of the first seal member 14a is larger than the outer edge of the current collector 11, and the inner edge of the first seal member 14a is smaller than the outer edge of the current collector 11. In addition, in a plan view, the inner edge of the first seal member 14a is separated from the positive electrode layer 12. The first seal member 14a and the current collector 11 are welded to each other in an overlapping region in a plan view.

[0027] The second seal member 14b is different from the first seal member 14a in that it is disposed on the second surface 11b of the current collector 11, but the other configurations are the same as those of the first seal member 14a. That is, the second seal member 14b is a rectangular frame-shaped member, and is disposed along the periphery of the second surface 11b of the current collector 11 and is joined to the second surface 11b. As shown in FIG. 1(A)(B), the outer edge of the second seal member 14b is larger than the outer edge of the current collector 11, and the inner edge of the second seal member 14b is smaller than the outer edge of the current collector 11. In addition, in a plan view, the inner edge of the second seal member 14b is separated from the negative electrode layer 13. The second seal member 14b and the current collector 11 are welded in a region where they overlap each other in a plan view. In addition, the first seal member 14a and the second seal member 14b may be welded in a region where they contact each other.

[0028] The first seal member 14a and the second seal member 14b are made of a resin material having electrolyte resistance, such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, polypropylene, etc. The first seal member 14a and the second seal member 14b may be made of the same material or different materials.

[0029] The first sealing member 14a and the second sealing member 14b may each be a rectangular frame-shaped member formed by punching a single sheet-shaped member into a rectangular frame shape, or may be a rectangular frame-shaped member formed by arranging a plurality of strip-shaped members along the edge of a current collector and overlapping and welding the ends of adjacent strip-shaped members together.

[0030] The above describes the manufacturing process S1 of the bipolar electrode body 10. In the bipolar electrode stack 50 described below, a positive electrode terminal electrode body 21 and a negative electrode terminal electrode body 22 arranged at the ends in the stacking direction are used. Therefore, the positive electrode terminal electrode body 21 and the negative electrode terminal electrode body 22 may be manufactured in the manufacturing process. The positive electrode terminal electrode body 21 is the bipolar electrode body 10 without the negative electrode layer 13. The negative electrode terminal electrode body 22 is the bipolar electrode body 10 without the positive electrode layer 12.

[0031] <Lamination process S2> The lamination step S2 is a step of laminating a plurality of bipolar electrode bodies 10 with separators 30 interposed therebetween, and arranging spacers 40 between the sealing members 14 of the bipolar electrode bodies 10 adjacent in the lamination direction, to obtain a bipolar electrode laminate 50. Fig. 2 shows a cross-sectional view of the bipolar electrode laminate 50 obtained by the lamination step S2.

[0032] (Separator 30) The separators 30 are sheet-like members and are disposed between the bipolar electrode bodies 10. Specifically, they are disposed between the electrode layers (positive electrode layer 12 and negative electrode layer 13) of the bipolar electrode bodies 10 adjacent in the stacking direction. The separators 30 are, for example, porous sheets or nonwoven fabrics containing a polymer that absorbs and retains an electrolyte. Examples of materials constituting the separators 30 include polypropylene, polyethylene, polyolefin, and polyester. The separators 30 may have a single-layer structure or a multi-layer structure.

[0033] In a bipolar battery, the separator 30 is used in a state in which it is impregnated with an electrolyte. The electrolyte impregnated in the separator 30 may be, for example, an electrolyte containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte salt may be, for example, a lithium salt such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, or LiN(CF3SO2)2. The non-aqueous solvent may be, for example, a cyclic carbonate, a cyclic ester, a chain carbonate, a chain ester, or an ether. The electrolyte is injected into the space S after the welding step S3. This will be described in detail later.

[0034] (Spacer 40) The spacers 40 are rectangular frame-shaped members disposed between the bipolar electrode bodies 10. Specifically, the spacers 40 are disposed between the seal members 14 of the bipolar electrode bodies 10 adjacent in the stacking direction. More specifically, the spacers 40 are disposed between the first seal member 14a of one bipolar electrode body 10 and the second seal member 14b of the other bipolar electrode body 10 in the bipolar electrode bodies 10 adjacent in the stacking direction.

[0035] When viewed in the stacking direction, the outer edge of the spacer 40 coincides with the outer edge of the seal member 14 (the first seal member 14a and the second seal member 14b). Then, in a welding step S3 described later, the outer edges of the seal member 14 and the spacer 40 are welded to each other.

[0036] Spacer 40 may be a rectangular frame-shaped member formed by punching a single sheet-shaped member into a rectangular frame shape, or may be a rectangular frame-shaped member formed by arranging a plurality of strip-shaped members along the edge of a current collector and overlapping and welding the ends of adjacent strip-shaped members together.

[0037] The spacer 40 is made of an electrolyte-resistant resin material such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene, similar to the seal member 14. However, the spacer 40 may be made of the same material as the first seal member 14a and the second seal member 14b, or may be made of a different material.

[0038] (Layering method) The lamination method will be further described. First, a plurality of bipolar electrode bodies 10 are laminated via a separator. At this time, the bipolar electrode bodies 10 adjacent in the lamination direction are laminated so that the positive electrode layer 12 of one bipolar electrode body 10 faces the negative electrode layer 13 of the other bipolar electrode body 10. The separator 30 is disposed between these positive electrode layers 12 and negative electrode layers 13. In addition, a positive electrode terminal electrode body 21 is disposed at one end of the lamination direction of the bipolar electrode laminate 50, and a negative electrode terminal electrode body 22 is disposed at the other end. Furthermore, when laminating the bipolar electrode bodies 10, a spacer 40 is disposed between the sealing members 14 of the bipolar electrode bodies 10 adjacent in the lamination direction. As a result, the sealing members 14 and the spacers 40 are disposed alternately on each side of the bipolar electrode laminate 50.

[0039] <Welding process S3> The welding process S3 is a process for welding the end faces of the sealing members 14 and spacers 40 aligned in the stacking direction while restraining the sealing members 14 and spacers 40 aligned in the stacking direction in the stacking direction, to form a frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack 50. The frame-shaped member is a member in which the sealing members 14 and the spacers 40 are integrated by welding.

[0040] As shown in FIG. 2, in the bipolar electrode stack 50, the seal member 14 and the spacer 40 are arranged side by side in the stacking direction. In the welding step S3, the seal member 14 and the spacer 40 are restrained in the stacking direction. That is, the side portion of the bipolar electrode stack 50 is restrained in the stacking direction. The restraining method is not particularly limited, and for example, a restraining plate may be used to restrain the side of the bipolar electrode stack 50 so that pressure is applied to the inner side in the stacking direction. The restraining load is not particularly limited, and may be a restraining load that allows the seal member 14 and the spacer 40 to come into contact with each other and be appropriately welded. For example, the restraining load may be 1 MPa or more and 5 MPa or less.

[0041] Then, the seal member 14 and the spacer 40 are welded together after being restrained. The welding method is not particularly limited as long as it is possible to heat the side surface of the bipolar electrode stack 50. For example, the side surface of the bipolar electrode stack 50 may be heated with an IR heater. By carrying out this process on each side surface, the seal member 14 and the spacer 40 can be welded together on each side surface, and a frame-shaped member that seals the entire side surface can be formed.

[0042] In the welding step S3, the seal members 14 and the spacers 40 are welded to each side surface, and a frame-shaped member is formed over the entire side surface of the bipolar electrode stack 50. By forming the frame-shaped member, a plurality of spaces S are formed inside the bipolar electrode stack 50. Specifically, spaces S are formed between the bipolar electrodes 10, between the positive electrode terminal electrode body 21 and the bipolar electrode body 10, and between the negative electrode terminal electrode body 22 and the bipolar electrode body 10. An electrolyte is injected into each space S through an injection port provided in the frame-shaped member. The frame-shaped member is a member that seals the space S so that the electrolyte does not leak from the space S.

[0043] The electrolyte is injected into the space S after the welding step S3. The method of injecting the electrolyte is not particularly limited, but for example, by sandwiching a predetermined insert between the seal member 14 and the spacer and carrying out the welding step S3, an inlet (pouring hole) through which the electrolyte can be injected can be formed. Then, after the electrolyte is injected into the space S from the inlet, the inlet is blocked by heating, thereby preventing the electrolyte from leaking from the space S.

[0044] <Features> The features of one embodiment will be described. As described above, the seal member 14 (the first seal member 14a and the second seal member 14b) and the spacer 40 are made of a predetermined resin. Hereinafter, the first seal member 14a, the second seal member 14b, and the spacer 40 will be simply referred to as resin members.

[0045] In one embodiment, the resin member is a rectangular strip cut out of a sheet-like resin. The resin member cut out from the sheet-like resin has MD and TD. MD (Machine Direction) means the extrusion direction, and TD (Traverse Direction) means the direction perpendicular to MD (vertical direction). It is known that the physical properties of the resin member differ depending on MD and TD. For example, MD has a larger coefficient of thermal expansion and thermal shrinkage than TD. The MD and TD of a resin member can be determined by measuring the coefficient of thermal expansion. The one with the larger coefficient of thermal expansion is MD.

[0046] Based on the characteristics of such resin members, in one embodiment, when a resin member whose MD and width direction (the direction perpendicular to the lamination direction on each side) coincide with each other on all side surfaces of the bipolar electrode laminate 50 is defined as a resin member MD, and a resin member whose TD and width direction coincide with each other is defined as a resin member TD, the resin members MD and TD are alternately laminated on all side surfaces of the bipolar electrode laminate 50. Such a bipolar electrode laminate 50 can be realized by adjusting the arrangement of each resin member in the fabrication process S1 and the lamination process S2. For reference, a rectangular resin member MD is shown in FIG. 3(A), and a rectangular resin member TD is shown in FIG. 3(B).

[0047] Fig. 4 is a side view of a conventional bipolar electrode laminate P, showing how it is heated in a welding process and how it is cooled after heating. Fig. 5 is a side view of a bipolar electrode laminate 50 of one embodiment, showing how it is heated in a welding process and how it is cooled after heating. Figs. 4 and 5 are both schematic views focusing on the resin member.

[0048] In the conventional bipolar electrode laminate P, as shown in FIG. 4, only the resin member MD is laminated. When the welding process is carried out in this state, the resin member MD expands in the width direction, and then cools and shrinks in the width direction. At this time, since the resin member shrinks uniformly, there is a risk of a recess (a recessed portion inside the bipolar electrode laminate when viewed in the stacking direction) occurring at the end in the width direction. A bipolar battery with a recess is undesirable because it may not meet the external shape standard.

[0049] In contrast, in a bipolar electrode laminate according to one embodiment, as shown in FIG. 5, resin members MD and resin members TD are alternately laminated. When the welding step S3 is performed in this state, the resin member MD expands significantly along the width direction, while the resin member TD does not expand as much as the resin member MD. Furthermore, during cooling, the resin member MD contracts significantly along the width direction, while the resin member TD does not contract as much as the resin member MD. In this way, by making the expansion and contraction amounts of the resin members different in the width direction, the overall expansion and contraction amounts can be suppressed, and therefore, the occurrence of recesses at the ends in the width direction can be suppressed.

[0050] Here, in the bipolar electrode laminate 50, the resin members MD and the resin members TD are alternately laminated, but the laminated form is not limited to this. It is sufficient that the resin members MD and the resin members TD are mixed and laminated. Even in such a laminated form, it is possible to suppress the occurrence of recesses in the welding step S3. From the viewpoint of further enhancing the effect, the resin members MD and the resin members TD may be laminated adjacent to each other in the lamination direction. From the viewpoint of further enhancing the effect, the resin members MD and the resin members TD may be alternately laminated.

[0051] In addition, since the spacer of the resin member is formed relatively thick, a lamination form focusing on the spacer may be adopted. Specifically, a spacer MD whose MD and width direction coincide with each other and a spacer TD whose TD and width direction coincide with each other may be laminated together. In this case, the relationship between the MD or TD and the width direction of the seal member (first seal member and second seal member) is not particularly limited. From the viewpoint of further enhancing the effect, the spacer MD and the spacer TD may be laminated adjacent to each other in the lamination direction via the seal member. From the viewpoint of further enhancing the effect, the resin member MD and the resin member TD may be alternately laminated via the seal member.

[0052] In one embodiment, the above-mentioned lamination form is adopted on all side surfaces (four side surfaces) of the bipolar electrode stack 50, but is not limited thereto. It is sufficient that the above-mentioned lamination form is adopted on at least one side surface of the bipolar electrode stack.

[0053] (Modification) Next, a modified bipolar electrode laminate 150 will be described. Fig. 6 shows a side view of the bipolar electrode laminate 150. Fig. 6 is also a schematic view focusing on the resin member, similar to Figs. 4 and 5.

[0054] In the modified example, a series of the first seal member 14a, the second seal member 14b, and the spacer 40 arranged in the stacking direction is defined as a resin member group. The MD and TD of each resin member (the first seal member 14a, the second seal member 14b, and the spacer 40) included in the resin member group are the same. In addition, when the resin member group having the same MD and width direction is defined as the resin member group MDG on all side surfaces of the bipolar electrode laminate 150, and the resin member group having the same TD and width direction is defined as the resin member group TDG, the resin member group MDG and the resin member group TDG are alternately stacked (FIG. 6). Even with such a stacking form, it is possible to suppress the occurrence of recesses in the welding process S3.

[0055] Here, in the bipolar electrode laminate 150, the resin member groups MDG and the resin member groups TDG are alternately laminated, but the laminated form is not limited to this. It is sufficient that the resin member groups MDG and the resin member groups TDG are laminated in a mixed manner. Even in this laminated form, the occurrence of recesses in the welding step S3 can be suppressed. From the viewpoint of further enhancing the effect, the resin member groups MDG and the resin member groups TDG may be laminated adjacent to each other in the lamination direction. From the viewpoint of further enhancing the effect, the resin members MDG and the resin members TDG may be alternately laminated.

[0056] In a modified example, the above-mentioned lamination form is adopted on all side surfaces of the bipolar electrode stack 150, but is not limited thereto. It is sufficient that the above-mentioned lamination form is adopted on at least one side surface of the bipolar electrode stack.

[0057] The manufacturing method of the bipolar battery according to the present disclosure has been described above using one embodiment and a modified example. According to the manufacturing method of the bipolar battery according to the present disclosure, it is possible to suppress the occurrence of recesses in the welding process. [Explanation of symbols]

[0058] 10 Bipolar electrode body 11 Current collector 12 Positive electrode layer 13 Negative electrode layer 14 Sealing material 14a First seal member 14b Second seal member 21 Positive terminal electrode body 22 Negative terminal electrode body 30 Separator 40 Spacer 50, 150 Bipolar electrode stack

Claims

1. A method for manufacturing a bipolar battery comprising a bipolar electrode stack in which a plurality of bipolar electrode bodies are stacked, and a frame-shaped member that seals an entire periphery of a side surface of the bipolar electrode stack, comprising: a fabrication step of fabricating a bipolar electrode body in which a sealing member is disposed around a rectangular current collector, and a positive electrode layer is disposed on a first surface of the current collector and a negative electrode layer is disposed on a second surface of the current collector; a stacking step of stacking a plurality of the bipolar electrode bodies with separators interposed therebetween and disposing spacers between the sealing members of the bipolar electrode bodies adjacent in a stacking direction to obtain the bipolar electrode stack; a welding process for welding the sealing members and the spacers arranged in a stacking direction while constraining them in the stacking direction to form the frame-shaped member that seals the entire periphery of the side surface of the bipolar electrode stack, the sealing member includes a first sealing member disposed on a first surface of the current collector and a second sealing member disposed on the second surface of the current collector; In the bipolar electrode stack, when the first seal member, the second seal member, and the spacer are made of resin members, each of the resin members has an MD and a TD, In at least one side surface of the bipolar electrode laminate, when the resin member whose MD and width direction coincide is defined as a resin member MD and the resin member whose TD and width direction coincide is defined as a resin member TD, the resin member MD and the resin member TD are laminated in a mixed state. How to manufacture a bipolar battery.

2. The manufacturing method according to claim 1 , wherein the resin member MD and the resin member TD are stacked adjacent to each other in a stacking direction on at least one side surface of the bipolar electrode stack.

3. The manufacturing method according to claim 1 , wherein the resin members MD and the resin members TD are alternately laminated on at least one side surface of the bipolar electrode laminate.

4. When a series of the first sealing member, the second sealing member, and the spacer arranged in a stacking direction are regarded as a resin member group, the MD and the TD of each of the resin members included in the resin member group are consistent with each other, In at least one side surface of the bipolar electrode laminate, when the resin member group whose MD and width directions coincide is defined as a resin member group MDG and the resin member group whose TD and width directions coincide is defined as a resin member group TDG, the resin member group MDG and the resin member group TDG are mixed. The method of claim 1 .

5. The manufacturing method according to claim 4 , wherein the resin member groups MDG and the resin member groups TDG are alternately laminated on at least one side surface of the bipolar electrode laminate.

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