Method of manufacturing bipolar battery

Abstract

To provide a method of manufacturing a bipolar battery, capable of suppressing the formation of protrusions.SOLUTION: A method of manufacturing a bipolar battery includes: a manufacturing step of manufacturing a bipolar electrode body in which a seal member is arranged around a rectangular current collector and a positive electrode layer and a negative electrode layer are arranged on a first surface and a second surface of the current collector, respectively; a stacking step of stacking a plurality of the bipolar electrode bodies via a separator and arranging the spacer between the seal members of the bipolar electrode bodies adjacent in a stacking direction, thereby obtaining a bipolar electrode stacked body; and a welding step of welding the seal members and the spacers aligned in the stacking direction while restraining the seal members and the spacers in the stacking direction, thereby forming a frame-like member sealing the entire side face periphery of the bipolar electrode stacked body. At least one of the seal member and the spacer has a notch toward the inside of the bipolar electrode stacked body as viewed in the stacking direction, and the notch is located at a corner of the bipolar electrode stacked body as viewed in the stacking direction.SELECTED DRAWING: Figure 1

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 rectangular frame-shaped member made of resin is provided on the periphery of the current collector. Such batteries include a welding process in which the outer edges of a plurality of sealing members and spacers stacked in the stacking direction are welded to form the frame-shaped member. However, in the welding process, the sealing members and spacers expand and flow due to heating, resulting in the problem that resin gathers at the corners of the rectangular frame-shaped member, forming protrusions. A battery with a protrusion formed on the sealing member is not desirable because it does not meet the external shape standard.

[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 convex portions. [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 stacked, and a frame-shaped member that seals the entire periphery of the side of the bipolar electrode laminate, the manufacturing method for a bipolar battery including a manufacturing step of manufacturing a bipolar electrode body in which a sealing member is arranged around a rectangular current collector, and a positive electrode layer is arranged on a first surface of the current collector and a negative electrode layer is arranged 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 sealing members of adjacent bipolar electrode bodies in the stacking direction to obtain a bipolar electrode laminate; and a welding step of welding the sealing members and spacers aligned in the stacking direction while restraining them in the stacking direction to form a frame-shaped member that seals the entire periphery of the side of the bipolar electrode laminate, wherein at least one of the sealing members and the spacers has a notch that faces the inside of the bipolar electrode laminate when viewed in the stacking direction, and the notch is located at a corner of the bipolar electrode laminate when viewed in the stacking direction.

[0008] A second aspect is the manufacturing method according to the first aspect, wherein both the sealing member and the spacer have a notch.

[0009] A third aspect is a manufacturing method according to the first or second aspect, in which the welding step is performed by heating the side surface of the bipolar electrode stack with an IR heater while restraining the sealing members and spacers aligned in the stacking direction with a restraining load of 1 MPa or more and 5 MPa or less.

[0010] A fourth aspect is the manufacturing method according to any one of the first to third aspects, in which the shape of the cutout is a trapezoid, and one of the corners of the trapezoid coincides with a corner of the sealing member or the spacer.

[0011] In the fifth embodiment, the area of ​​the cutout is 10 mm 2 More than 100mm 2 The manufacturing method according to any one of the first to fourth aspects is as follows. Effect of the Invention

[0012] According to the manufacturing method of the bipolar battery disclosed herein, the notch provided in at least one of the sealing member and the spacer in the welding step can prevent a protrusion from being formed in the frame-shaped member. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view of the bipolar electrode body 10. [Diagram 2] FIG. 2 is a cross-sectional view of the bipolar electrode body 10. [Diagram 3] FIG. 2 is an enlarged view of a first cutout 15a. [Figure 4] 1 is a cross-sectional view of a bipolar electrode laminate 50 obtained in a lamination step S2. [Diagram 5] FIG. [Figure 6] The two side surfaces of the bipolar electrode stack 50 are heated using IR heaters H1 and H2. 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, 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. A plan view of the bipolar electrode body 10 is shown in Fig. 1. A cross-sectional view of the bipolar electrode body 10 is shown in Fig. 2.

[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 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 methods applicable to 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 Fig. 1 and Fig. 2, 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 otherwise has the same configuration as 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. 2, 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 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 the current collector and overlapping and welding the ends of adjacent strip-shaped members together.

[0030] Here, the sealing member 14 has a plurality of cutouts (first cutouts 15a to 15d) facing the inside of the bipolar electrode body 10 (the inside of the bipolar electrode laminate 50 after step S2) at each of the corners 14c to 14f of the rectangular shape in a plan view (as viewed in the stacking direction after step S2). As shown in FIG. 1, the first cutouts 15a to 15d are located at the corners of the bipolar electrode body 10 in a plan view. In FIG. 1, the first cutouts 15a to 15d are provided in pairs on each of two opposing sides of the sealing member 14. However, this is not limited to this form, and the first cutouts 15a to 15d may be provided on each side of the sealing member 14. In FIG. 1, the outer edge shape (rectangular shape) of the sealing member 14 before the cutouts 15a to 15d are provided is shown by a dotted line.

[0031] As described above, the first cutouts 15a to 15d are located at the corners of the outer edge of the bipolar electrode body 10. Specifically, they are located at the corners 14c to 14f of the seal member 14. The first cutouts 15a to 15d may include the corners 14c to 14f of the seal member 14, but the first cutouts 15a to 15d do not have to include the corners 14c to 14f. Specifically, the first cutouts 15a to 15d only need to be located near the corners 14c to 14f. However, from the viewpoint of suppressing the formation of a protrusion in the welding step S3, the first cutouts 15a to 15d may be arranged to include the corners 14c to 14f as shown in FIG. 1.

[0032] The first cutouts 15a to 15d penetrate the seal member 14 in the thickness direction. Specifically, they penetrate the first seal member 14a and the second seal member 14b in the thickness direction. The shape of the first cutouts 15a to 15d is not particularly limited, and examples thereof include a triangle, a rectangle, a trapezoid, a polygon, a semicircle, and a semiellipse. From the viewpoint of enhancing the effect of suppressing the formation of a protrusion, the shape of the first cutouts 15a to 15d may be a trapezoid in a plan view as shown in FIG. 2. More specifically, the shape may be a trapezoid whose upper base is located on the outside. In addition, when the first cutouts 15a to 15d are trapezoidal, one of the corners of the trapezoid may coincide with the corners 14c to 14f. This enhances the effect of suppressing the formation of a protrusion in the welding step S3.

[0033] The trapezoidal first cutouts 15a to 15d will be further described. FIG. 3 shows an enlarged view of the first cutout 15a. As shown in FIG. 3, the first cutout 15a is arranged so that the upper base is located on the outside (outer edge) of the seal member 14. The length X1 of the upper base is not particularly limited, but may be, for example, 5 mm or more and 20 mm or less. The length X2 of the lower base is not particularly limited, but may be, for example, 10 mm or more and 40 mm or less. The height X3 of the trapezoid is not particularly limited, but may be, for example, 1 mm or more and 5 mm or less. However, when setting the height X3, it is necessary to provide the cutouts outside the outer edge of the current collector 11. This is to appropriately weld the seal member 14 and the spacer 40 and suppress sealing failure.

[0034] The area of ​​the first notches 15a to 15d in a plan view is not particularly limited, but may be, for example, 10 mm 2 More than 100mm 2 The area of ​​the first notches 15a to 15d may be 10 mm 2 If the area of ​​the first notches 15a to 15d is less than 100 mm 2 If it exceeds this value, the notch will be too large, and there is a risk that the manufactured battery will not meet the external shape standard.

[0035] 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.

[0036] <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. 4 shows a cross-sectional view of the bipolar electrode laminate 50 obtained by the lamination step S2.

[0037] (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.

[0038] 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.

[0039] (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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] FIG. 5 shows a plan view of the spacer 40. The spacer 40 has a plurality of notches (second notches 41a-41d) facing the inside of the bipolar electrode laminate 50 at each of the corners 40a-40d of the rectangular shape as viewed in the stacking direction. The second notches 41a-41d are located at the corners of the bipolar electrode laminate 50 as viewed in the stacking direction. The second notches 41a-41d are located at the same positions as the first notches 15a-15d as viewed in the stacking direction. That is, the second notches 41a-41d are provided on two opposing sides of the spacer 40, two each. However, this is not limited to this form, and the second notches 41a-41d may be provided on each side of the spacer 40. In FIG. 5, the outer edge shape (rectangular shape) of the spacer 40 before the notches 41a-41d are provided is shown by a dotted line.

[0044] As described above, the second notches 41a to 41d are disposed at the same positions as the first notches 15a to 15d when viewed in the stacking direction. That is, the second notches 41a to 41d are located at the outer edge of the bipolar electrode stack 50 and at the corners. Specifically, they are located at the corners 40a to 40d of the spacer 40. The second notches 41a to 41d may include the corners 40a to 40d of the spacer 40, but the second notches 41a to 41d may not include the corners 40a to 40d of the spacer 40. Specifically, the second notches 41a to 41d may be located near the corners 40a to 40d. However, from the viewpoint of suppressing the formation of a convex portion in the welding step S3, the second notches 41a to 41d may be disposed so as to include the corners 40a to 40d as shown in FIG. 5.

[0045] The second cutouts 41a to 41d penetrate the spacer 40 in the thickness direction. The shape of the second cutouts 41a to 41d is not particularly limited, and may be, for example, a triangle, a rectangle, a trapezoid, a polygon, a semicircle, or a semi-ellipse. The second cutouts 41a to 41d may be trapezoidal in plan view in order to enhance the effect of suppressing the formation of a protrusion. More specifically, the second cutouts 41a to 41d may be trapezoidal in such a way that the upper base is located at the outer edge. In addition, when the second cutouts 41a to 41d are trapezoidal, one of the corners of the trapezoid may coincide with the corners 40a to 40d of the spacer 40. This can enhance the effect of suppressing the formation of a protrusion in the welding step S3.

[0046] The trapezoidal second cutouts 41a to 41d will be further described. For the trapezoidal shape of the second cutouts 41a to 41d, the shape of the first cutouts in FIG. 3 can be referred to. The second cutouts are arranged so that their upper bases are located on the outside (outer edge) of the spacer 40. The length of the upper base is not particularly limited, but may be, for example, 5 mm or more and 20 mm or less. The length of the lower base is not particularly limited, but may be, for example, 10 mm or more and 40 mm or less. The height of the trapezoid is not particularly limited, but may be, for example, 1 mm or more and 5 mm or less.

[0047] The area of ​​the second cutouts 41a to 41d as viewed in the stacking direction is not particularly limited, but may be, for example, 10 mm 2 More than 100mm 2 The area of ​​the second notches 41a to 41d may be 10 mm 2 If the area of ​​the second notches 41a to 41d is less than 100 mm 2 If it exceeds this value, the notch will be too large, and there is a risk that the manufactured battery will not meet the external shape standard.

[0048] Usually, the second cutouts 41a-41d have the same shape as the first cutouts 15a-15d and are arranged to line up in the stacking direction. That is, in the stacking step S2, the bipolar electrode body 10 and the spacer 40 are stacked so that the first cutouts 15a-15d and the second cutouts 41a-41d are aligned in the stacking direction. As a result, in the bipolar electrode stack 50, the first cutouts 15a-15d and the second cutouts 41a-41d are arranged to penetrate in the stacking direction.

[0049] (Layering method) The lamination method will be further described. First, a plurality of bipolar electrode bodies 10 are laminated with separators interposed therebetween. 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 bipolar electrode laminate 50 in the lamination direction, and a negative electrode terminal electrode body 22 is disposed at the other end.

[0050] Furthermore, when stacking the bipolar electrode bodies 10, spacers 40 are disposed between the sealing members 14 of the bipolar electrode bodies 10 adjacent in the stacking direction. As a result, the sealing members 14 and the spacers 40 are arranged alternately on each side of the bipolar electrode stack 50. Furthermore, the first cutouts 15a to 15d and the second cutouts 41a to 41d are also arranged alternately.

[0051] <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.

[0052] In the welding step S3, the sealing members 14 and the spacers 40 arranged in the stacking direction are welded on each side of the bipolar electrode laminate 50, thereby forming a frame-shaped member that seals the entire periphery of the side of the bipolar electrode laminate 50. Conventionally, the bipolar electrode laminate 50 does not have the above-mentioned predetermined notches. Therefore, as a result of the sealing members 14 and the spacers 40 expanding and flowing due to heating, resin gathers at the corners of the bipolar electrode laminate 50, and a convex portion is formed on the frame-shaped member. In contrast, when the bipolar electrode laminate 50 has notches (the first notches 14a to 14d and the second notches 41a to 41d), the notches are formed in advance at the corners where the convex portion is likely to occur, so that the occurrence of the convex portion can be suppressed. Therefore, according to the manufacturing method of one embodiment, a bipolar battery that meets the external shape standard can be manufactured.

[0053] The welding step S3 will be further described. As shown in FIG. 4, in the bipolar electrode stack 50, the seal member 14 and the spacer 40 are arranged in the stacking direction. In the welding step S3, the seal member 14 and the spacer 40 are constrained in the stacking direction. That is, the side portion of the bipolar electrode stack 50 is constrained in the stacking direction. The constraining method is not particularly limited, and for example, a constraining plate may be used to constrain the side of the bipolar electrode stack 50 so that pressure is applied to the inner side in the stacking direction. The constraining load is not particularly limited, and it is sufficient that the seal member 14 and the spacer 40 are in contact with each other and can be appropriately welded. For example, the constraining load may be 1 MPa or more and 5 MPa or less. If the constraining load is less than 1 MPa, there is a possibility that a hole will be formed during welding. If the constraining load is more than 5 MPa, there is a possibility that the resin will protrude significantly to the outside.

[0054] 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.

[0055] Here, an example of a method for heating the side surface of the bipolar electrode laminate 50 using an IR heater and welding the seal member 14 and the spacer 40 will be described. FIG. 6 shows how the two side surfaces of the bipolar electrode laminate 50 are heated using IR heaters H1 and H2. As shown in FIG. 6, the IR heaters H1 and H2 are arranged at a predetermined distance from the side surface of the bipolar electrode laminate 50 that is the heating target. The width of the IR heaters H1 and H2 is set to be equal to or greater than the length of the side surface of the heating target (length in the direction perpendicular to the lamination direction), and the height of the IR heaters H1 and H2 is set to be equal to or greater than the height of the side surface of the heating target (length in the lamination direction). This allows the entire side surface of the heating target to be heated. The heating method using the IR heaters H1 and H2 is not particularly limited, and may include, for example, a pre-heating process, a heating process, and a cooling process. After heating of the two side surfaces of the bipolar electrode laminate 50 is completed, heating is performed on the remaining two side surfaces.

[0056] 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.

[0057] 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.

[0058] <Supplementary Information> In one embodiment, the notches are provided in both the seal member 14 and the spacer 40, but the present invention is not limited to this. At least one of the seal member and the spacer may have a notch. For example, the notch may be provided only in the seal member, or only in the spacer. However, since the spacer may have a thickness, the notch may be provided at least in the spacer from the viewpoint of enhancing the protrusion suppression effect.

[0059] In one embodiment, the seal member 14 and the spacer 40 each have four notches, but are not limited to this form. The seal member only needs to have at least one notch. The spacer only needs to have at least one notch. Either the seal member or the spacer does not need to have a notch. Therefore, when the seal member has a notch, the number of notches may be at least one. Similarly, when the spacer has a notch, the number of notches may be at least one. However, from the viewpoint of enhancing the protrusion suppression effect, the seal member and / or the spacer may have a number of notches corresponding to the number of corners, that is, four notches.

[0060] The manufacturing method of the bipolar battery of the present disclosure has been described above using one embodiment. According to the manufacturing method of the bipolar battery of the present disclosure, in the welding process, the notch provided in at least one of the seal member and the spacer can suppress the formation of a protrusion on the frame member. [Explanation of symbols]

[0061] 10 Bipolar electrode body 11 Current collector 12 Positive electrode layer 13 Negative electrode layer 14 Sealing material 14a First sealing member 14b Second seal member 14c~14f Corner 15a~15d First notch 21 Positive terminal electrode body 22 Negative terminal electrode body 30 Separator 40 Spacer 40a~d corner 41a~41d Second notch 50 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, At least one of the sealing member and the spacer has a notch extending toward an inside of the bipolar electrode stack as viewed in a stacking direction, The notch is located at a corner of the bipolar electrode stack when viewed in the stacking direction. How to manufacture a bipolar battery.

2. The method of claim 1 , wherein both the seal member and the spacer have a notch.

3. 3. The manufacturing method according to claim 1, wherein the welding step is performed by heating a side surface of the bipolar electrode stack with an IR heater while restraining the sealing members and the spacers aligned in a stacking direction with a restraining load of 1 MPa or more and 5 MPa or less.

4. The manufacturing method according to claim 1 or 2, wherein the shape of the cutout is a trapezoid, and one of the corners of the trapezoid coincides with a corner of the sealing member or the spacer.

5. The area of ​​the cutout is 10 mm ２ More than 100 mm ２ The method according to claim 1 or 2, wherein:

Images