Manufacturing method for secondary battery

Abstract

To provide a manufacturing method for a secondary battery, in which the thickness of a frame member can be reduced.SOLUTION: A manufacturing method for a secondary battery includes: an electrode body manufacturing step of manufacturing an electrode body by forming electrode layers on both surfaces of a rectangular current collector; a disposing step of disposing a sealing member around the current collector by disposing a first resin sheet at each side of the current collector and welding the current collector and the first resin sheet together; a stacking step of stacking a plurality of layers of the electrode body through a separator to obtain an electrode multilayer body; and a welding step of welding the sealing member and a spacer arranged in the stacking direction to form a frame member that seals the entire periphery of a side surface of the electrode multilayer body. In the disposing step, a first overlap part where end parts of the first resin sheets disposed at the adjacent sides of the current collector overlap with each other is formed, one of the end parts of the first resin sheet forming the first overlap part includes a first concave part at the one of the end parts, and the first resins are bonded together by welding the first overlap part.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present application relates to a method for manufacturing a secondary battery. [Background technology]

[0002] Patent Document 1 discloses an electrode unit including a rectangular electrode and a frame-shaped sealing body joined to the edge of the electrode. In the electrode unit of Patent Document 1, the sealing body is composed of a plurality of sheet bodies arranged corresponding to each side of the rectangle formed by the electrode, and the ends of the sheet bodies corresponding to adjacent sides of the electrode overlap each other to form an overlapping portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-135935 A Summary of the Invention [Problem to be solved by the invention]

[0004] The overlapping portion is formed to prevent the edge of the electrode (current collector) from being left uncovered by the sealing material due to manufacturing tolerances. However, the overlapping portion increases the thickness of the frame-shaped member when the sealing materials are welded together to form a frame-shaped member that covers the entire periphery of the side surface of the battery after stacking multiple electrodes.

[0005] In view of the above circumstances, a main object of the present disclosure is to provide a manufacturing method for a secondary battery that can reduce the thickness of a frame-shaped member. [Means for solving the problem]

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

[0007] The first aspect is a method for manufacturing a secondary battery including an electrode laminate and a frame-shaped member that seals the entire periphery of the side surface of the electrode laminate, the method including an electrode body fabrication step of forming electrode layers on both sides of a rectangular current collector to fabricate an electrode body, an arrangement step of arranging a first resin sheet on each side of the current collector and welding the current collector and the first resin sheet to arrange a seal member around the current collector, an electrode body fabrication step of forming electrode layers on both sides of the current collector to fabricate an electrode body, and a method for stacking a plurality of electrode bodies with separators interposed therebetween, the method including a step of ... The method for manufacturing a secondary battery includes a lamination process in which an electrode laminate is obtained by arranging spacers, and a welding process in which sealing members and spacers arranged in the lamination direction are welded to form a frame-shaped member that seals the entire periphery of the side of the electrode laminate, in which in the arrangement process, the ends of the first resin sheets arranged on adjacent sides of the current collector overlap with each other to form a first overlapping portion, a first recess is formed in one of the ends of the first resin sheets forming the first overlapping portion, and the first resin sheets are joined by welding the first overlapping portion.

[0008] A second aspect is the manufacturing method according to the first aspect, wherein the first recess is disposed outside an outer edge of the current collector in the first overlapping portion.

[0009] A third aspect is a manufacturing method according to the first or second aspect, which includes a preparation step of cutting out a strip-shaped resin sheet to obtain a first resin sheet, and in the preparation step, the first resin sheet is cut out from the resin sheet so that a first recess is formed at one end of the first resin sheet and a protrusion is formed at the other end.

[0010] A fourth aspect is a manufacturing method according to any one of the first to third aspects, which includes a spacer production step of producing a spacer having a rectangular frame-like shape, in which a second resin sheet is arranged at a position corresponding to each side of the rectangular frame-like shape in the spacer production step, and in the second resin sheet arranged on adjacent sides, their ends overlap each other to form a second overlapping portion, and a second recess is formed in one of the ends of the second resin sheet forming the second overlapping portion, and the spacer is obtained by welding the second overlapping portion. Effect of the Invention

[0011] According to the method for manufacturing a secondary battery of the present disclosure, the thickness of the frame-shaped member can be reduced. [Brief description of the drawings]

[0012] [Figure 1] 1 is a flowchart of one embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a preparation step S1. [Diagram 3] 3 is a cross-sectional view of the electrode body 10 obtained in the electrode body fabrication step S2. FIG. [Figure 4] FIG. 11 is a plan view illustrating the arrangement step S3. [Diagram 5] 1 is a cross-sectional view of the electrode body 10 obtained in the arrangement step S3. [Figure 6] 11 is a plan view illustrating a method for producing a spacer 40 using a second resin sheet 241. FIG. [Figure 7] 1 is a cross-sectional view of an electrode laminate 50 obtained in a lamination step S5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The manufacturing method of the bipolar battery of the present disclosure will be described using one embodiment.

[0014] One embodiment is a method for manufacturing a secondary battery including an electrode laminate and a frame-shaped member that seals the entire periphery of the side surface of the electrode laminate. A flow chart of the embodiment is shown in Fig. 1. As shown in Fig. 1, the embodiment includes a preparation step S1, an electrode body fabrication step S2, an arrangement step S3, a spacer fabrication step S4, a stacking step S5, and a welding step S6. Each step will be described below.

[0015] <Preparation process S1> The preparation step S1 is a step of cutting out a strip-shaped resin sheet R to obtain a first resin sheet 141. The cut-out first resin sheet 141 has a rectangular shape. The first resin sheet 141 is used as a material for the seal member 14 to be disposed around the current collector 11.

[0016] Since the resin sheet R is the material of the sealing member 14 (ultimately the frame-shaped member), it is made of a resin resistant to electrolyte. For example, the resin sheet R is made of a polyolefin resin such as polyethylene or polypropylene. The resin sheet R has a band-like shape, and its width is set to the width of the first resin sheet 141 (sealing member 14). The length of the first resin sheet 141 in the longitudinal direction is set to be longer than the length of each side of the current collector 11 so as to form a first overlapping portion 141b described later. The length (width) of the first resin sheet 141 in the lateral direction is appropriately set so as to ensure an overlapping region 141a described later.

[0017] A schematic diagram of the preparation step S1 is shown in Fig. 2. As shown in Fig. 2, in the preparation step S1, a plurality of first resin sheets 141 are cut out from a resin sheet R. Specifically, the resin sheet R is cut in the width direction, and a recess or a protrusion is formed at the end of the cut first resin sheet 141. In Fig. 2, a recess is formed at the end of the cut first resin sheet 141. By repeating this process, the first resin sheet 141 can be cut out from the resin sheet R such that a recess (first recess 142) is formed at one end of the first resin sheet 141 and a protrusion (first protrusion 143) is formed at the other end.

[0018] The first recess 142 is a cutout formed at one end of the first resin sheet 141. The position of the first recess 142 is not particularly limited, and may be disposed at the center of the first resin sheet 141 in the short-side direction. The size of the first recess 142 is not particularly limited, and may be set appropriately depending on the size of the intended secondary battery. For example, the length of the first recess 142 in the short-side direction may be 20% to 80% of the total length of the first resin sheet 141 in the short-side direction, and the length in the longitudinal direction (depth of the recess) may be 0.5 mm to 2 mm.

[0019] The first convex portion 143 is a protrusion formed on the other end of the first resin sheet 141. The size of the first convex portion 143 is not particularly limited, but may be equal to the size of the first concave portion 142. This is because, as described above, the first convex portion 143 is a portion formed as a pair of the first concave portion 142 when the first resin sheet 141 is continuously cut out from the resin sheet R.

[0020] By carrying out the preparation step S1, the first resin sheet 141 having the first recesses 142 can be manufactured efficiently, and the yield during manufacturing can be suppressed.

[0021] <Electrode body fabrication process S2> The electrode body fabrication step S2 is a step of forming an electrode layer on both sides of a current collector to fabricate an electrode body. The type of electrode body varies depending on the target secondary battery. For example, if the target secondary battery is a monopolar secondary battery, a positive electrode body in which a positive electrode layer is formed on both sides of a current collector and a negative electrode body in which a negative electrode layer is formed on both sides of a current collector are fabricated in the electrode body fabrication step S3. If the target secondary battery is a bipolar secondary battery, a bipolar electrode body in which a positive electrode layer is formed on one side of a current collector and a negative electrode layer is formed on the other side is fabricated in the electrode body fabrication step S3. The electrode body fabrication step S2 for fabricating a bipolar electrode body (electrode body 10) will be described below.

[0022] The electrode body fabrication step S2 is a step of fabricating an electrode body 10 in which a positive electrode layer 12 is disposed on a first surface 11a of a current collector 11 and a negative electrode layer 13 is disposed on a second surface 11b of the current collector 11. A cross-sectional view of the electrode body 10 obtained in the electrode body fabrication step S2 is shown in FIG.

[0023] (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.

[0024] (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.

[0025] The positive electrode layer 12 may contain a conductive additive. Examples of the conductive additive include acetylene black, carbon black, and graphite.

[0026] 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.

[0027] 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. Typically, the positive electrode layer 12 can be obtained by mixing the material constituting the positive electrode layer 12 with a solvent to obtain a slurry, and then applying the slurry to the first surface 11a of the current collector 11 and drying it. 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.

[0028] (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.

[0029] The negative electrode layer 13 may contain a conductive assistant. The conductive assistant may be selected from those used in the positive electrode layer 12. The negative electrode layer 13 may also contain a binder. The binder may be selected from those used in the positive electrode active material layer 12.

[0030] 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 selected from the methods for forming the positive electrode layer 12.

[0031] The electrode assembly fabrication step S2 has been described above. In the 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 fabricated in the electrode assembly fabrication step S2. The positive electrode terminal electrode body 21 is the electrode assembly 10 from which the negative electrode layer 13 has been removed. The negative electrode terminal electrode body 22 is the electrode assembly 10 from which the positive electrode layer 12 has been removed.

[0032] <Placement process S3> The arrangement step S3 is a step of arranging a first resin sheet 141 on each side of a rectangular current collector 11 and welding the current collector 11 to the first resin sheet 141, thereby arranging a seal member 14 around the current collector 11. In the arrangement step S3, the seal members 14 may be arranged on the positive terminal electrode body 21 and the negative terminal electrode body 22 in the same manner.

[0033] Fig. 4 shows a plan view for explaining the arrangement step S3. Fig. 5 shows a cross-sectional view of the electrode body 10 obtained in the arrangement step S3.

[0034] As shown in FIG. 4, the first resin sheet 141 is disposed on each side of the rectangular current collector 11. In order to secure a welding area, each first resin sheet 141 is disposed along each side of the current collector 11 and has an overlapping area 141a overlapping each side. In addition, in order to secure a portion where the first resin sheets are welded to each other, the first resin sheets 141 disposed on adjacent sides of the current collector 11 form a first overlapping portion 141b where their ends overlap each other. As shown in FIG. 4, the first resin sheets forming the first overlapping portion 141b are disposed at approximately right angles. When the first resin sheet 141 having the recess 142 is used as a reference, the length W of the first overlapping portion 141b in the longitudinal direction (overlap in the longitudinal direction) is not particularly limited, but may be 0.5 mm to 2 mm.

[0035] Here, the first recess 142 is formed at one end of the ends of the first resin sheet 141 forming the first overlapping portion 141b. That is, the first overlapping portion 141b is a portion where the end of one of the first resin sheets 141 where the first recess 142 is formed and the end of the other first resin sheet 141 where the first protrusion 143 is formed (the end of the other first resin sheet 141 where the first recess 142 is not formed) overlap. This can reduce the area where the ends of the first resin sheets 141 overlap each other in the first overlapping portion 141b, and therefore the thickness of the first overlapping portion 141b after welding can be reduced. The first overlapping portion 141b may include the entire first recess 142. The area ratio of the first recess 142 in the first overlapping portion 141b (first recess 142 / first overlapping portion 141b) is not particularly limited and may be set appropriately.

[0036] In the first overlapping portion 141b, the first recess 142 may be disposed outside the outer edge 11c (dotted line in FIG. 4) of the current collector 11. This makes it possible to sufficiently secure the overlapping region 141a located on the current collector 11 side. Here, a part of the first recess 142 may be disposed outside the outer edge 11c of the current collector 11, but from the viewpoint of further enhancing the effect, the entire first recess 142 may be disposed outside the outer edge 11c of the current collector 11 as shown in FIG. 4.

[0037] After the first resin sheets 141 are arranged on each side of the current collector 11, each of the first resin sheets 141 is welded to the current collector 11. Specifically, the overlapping regions 141a and the first overlapping portions 141b are welded. This makes it possible to bond the first resin sheets 141 arranged on each side to the current collector 11, bond the first resin sheets 141 together, and arrange the seal member 14 around the current collector 11. An example of a welding method is welding by heat (for example, heat pressing).

[0038] 4, the sealing member 14 is a rectangular frame-shaped member disposed around the current collector 11 in a plan view. The outer edge of the sealing member 14 is larger than the outer edge of the current collector 11, and the inner edge of the sealing member 14 is smaller than the outer edge of the current collector 11. In addition, the positive electrode layer 12 is separated from the sealing member 14. In other words, the outer edge of the positive electrode layer 12 is smaller than the inner edge of the sealing member 14.

[0039] 4, each of the first convex portions 143 protrudes outward from the outer edge of the seal member 14. The first convex portions 143 are obtained in pairs with the first concave portions 142 in order to reduce the yield when obtaining the first resin sheet 141 having the first concave portions 142. Therefore, the first convex portions 143 may be cut off before or after welding.

[0040] In the disposing step S3, the seal member 14 may be disposed on one or both sides of the current collector 11. In Figs. 4 and 5, the seal member 14 is disposed on only one side of the current collector 11.

[0041] Furthermore, in the arrangement step S3, the seal member 14 is arranged around the current collector 11 on which the electrode layer is formed, but the present invention is not limited to this embodiment. For example, the seal member may be arranged on the current collector 11 before the electrode layer is formed. Then, the electrode layer may be formed on the current collector 11. That is, the arrangement step S3 may be performed before the electrode body fabrication step S2.

[0042] <Spacer manufacturing process S4> The spacer fabrication step S4 is a step of fabricating a spacer 40 having a rectangular frame shape. The spacer 40 is a member disposed between adjacent electrode assemblies 10 in the electrode stack 50, and a frame-shaped member is formed by welding the seal member 14 of the electrode stack 10 and the spacer 40.

[0043] The spacer preparation step S4 is not particularly limited as long as it can prepare the spacer 40. For example, the rectangular frame-shaped spacer 40 may be cut out from one sheet-shaped resin material. However, in this case, the portion other than the cut-out spacer 40 must be discarded. Therefore, the rectangular frame-shaped spacer 40 may be prepared in the spacer preparation step S4 using a plurality of rectangular resin sheets (second resin sheets 241). This makes it possible to reduce the amount of resin material to be discarded. This also applies to the reason for forming the seal member 14 using the rectangular first resin sheet 141 in the preparation step S1 and the arrangement step S3.

[0044] A method of producing the spacer 40 using the strip-shaped second resin sheet 241 will be described with reference to FIG. 5. First, the second resin sheet 241 is disposed at a position corresponding to each side of the rectangular frame shape. At this time, the second resin sheet 241 is disposed so that the ends of the second resin sheet 241 disposed on the adjacent sides overlap each other to form a second overlapping portion 241a. Then, the second overlapping portion 241a is welded to produce the spacer 40 having a rectangular frame shape. Here, a recess (second recess 242) may be formed at one end of the ends of the second resin sheet 241 forming the second overlapping portion 241a. This can reduce the area where the ends of the second resin sheet 241 overlap each other in the second overlapping portion 241a, and therefore the thickness of the second overlapping portion 241a after welding can be reduced.

[0045] The material of the second resin sheet 241 may be appropriately selected from the materials constituting the first resin sheet 141. However, the material of the second resin sheet 241 may be the same as that of the first resin sheet 141, or may be different.

[0046] The method for producing the second resin sheet 241 is not particularly limited, and may be obtained using a method similar to the method for obtaining the first resin sheet 141 (preparation step S1). That is, in the preparation step S1, the first resin sheet 141 may be cut out from the strip-shaped resin sheet R, and the second resin sheet 241 may be cut out. In this case, a recess (second recess 242) is formed at one end of the second resin sheet 241, and a protrusion (second protrusion 243) is formed at the other end of the second resin sheet 241. The second protrusion 243 may be cut out for the same reason as the first protrusion 143 is cut out.

[0047] In one embodiment, the spacer fabricating step S4 is performed after the preparation step S1 to the arrangement step S3, but is not limited to this. The spacer fabricating step S4 may be performed before the preparation step S1, or may be performed between the preparation step S1 to the arrangement step S3.

[0048] <Lamination process S5> The lamination step S5 is a step of laminating a plurality of electrode assemblies 10 with separators 30 interposed therebetween, and arranging spacers 40 between the sealing members 14 of the electrode assemblies 10 adjacent in the lamination direction, to obtain an electrode laminate 50. Fig. 7 shows a cross-sectional view of the electrode laminate 50 obtained by the lamination step S5.

[0049] (Separator 30) The separators 30 are sheet-like members and are disposed between the electrode assemblies 10. Specifically, they are disposed between the electrode layers (positive electrode layer 12 and negative electrode layer 13) of the electrode assemblies 10 adjacent in the stacking direction. The separators 30 are porous sheets or nonwoven fabrics containing a polymer that absorbs and retains an electrolyte in the case of a liquid secondary battery, and are solid electrolytes in the case of a solid secondary battery.

[0050] In the case of a liquid secondary battery, examples of materials constituting the separator 30 include polypropylene, polyethylene, polyolefin, and polyester. The separator 30 may have a single-layer structure or a multi-layer structure. The separator 30 is used in a state of being impregnated with an electrolytic solution. Examples of the electrolytic solution impregnated in the separator 30 include an electrolytic solution containing a non-aqueous solvent and an electrolytic salt dissolved in the non-aqueous solvent. Examples of the electrolytic salt include lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2. Examples of the non-aqueous solvent include cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers. The electrolytic solution is injected into the space S after the welding process S6. Details will be described later.

[0051] In the case of a solid secondary battery, examples of materials constituting the separator 30 include solid electrolytes such as oxide solid electrolytes, sulfide solid electrolytes, and nitride solid electrolytes.

[0052] (Layering method) The lamination method will be further described. First, a plurality of electrode bodies 10 are laminated via a separator. At this time, the electrode bodies 10 are laminated so that the positive electrode layer 12 of one electrode body 10 faces the negative electrode layer 13 of the other electrode body 10 in the lamination direction. The separator 30 is disposed between these positive electrode layers 12 and negative electrode layers 13. In addition, the positive electrode terminal electrode body 21 is disposed at one end of the electrode laminate 50 in the lamination direction, and the negative electrode terminal electrode body 22 is disposed at the other end. Furthermore, when the electrode bodies 10 are laminated, a spacer 40 is disposed between the sealing members 14 of the 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 electrode laminate 50.

[0053] <Welding process S6> The welding step S6 is a step of welding the sealing members 14 and the spacers 40 aligned in the stacking direction to form a frame-shaped member that seals the entire periphery of the side surface of the electrode stack 50. The obtained frame-shaped member is a member in which the sealing members 14 and the spacers 40 are integrated by welding.

[0054] As described above, when the seal member 14 is formed using the rectangular first resin seal 141, the first overlapping portion 141b where the ends of the first resin sheet 141 overlap is welded. In the first overlapping portion 141b, a first recess 142 is formed at an end of one of the first resin sheets 141. Therefore, the area where the ends of the first resin sheets 141 overlap in the first overlapping portion 141b is reduced, and the thickness of the first overlapping portion 141b after welding is reduced.

[0055] When forming the spacer 40 using the rectangular second resin seal 241, the second overlapping portion 241a where the ends of the second resin sheet 241 overlap is welded. In the second overlapping portion 241a, a second recess 242 is formed at an end of one of the second resin sheets 241. Therefore, the area where the ends of the second resin sheets 241 overlap in the second overlapping portion 241a is reduced, and the thickness of the second overlapping portion 241a after welding is reduced.

[0056] Therefore, since the thicknesses of the first overlapping portion 141b and the second overlapping portion 241a are reduced in the seal member 14 and the spacer 40, the thickness of the frame-shaped member at the positions corresponding to these is also reduced. Thus, according to one embodiment, the thickness of the frame-shaped member can be reduced.

[0057] The method of welding the seal member 14 and the spacer 40 is not particularly limited, and may be any method that heats each side surface of the electrode stack 50. The type of heat source for heating each side surface of the electrode stack 50 is not particularly limited, and may be, for example, an IR heater.

[0058] In the welding step S6, the seal members 14 and the spacers 40 on each side are welded, and a frame-shaped member is formed over the entire side of the electrode laminate 50. By forming the frame-shaped member, a space S is formed inside the electrode laminate 50. Specifically, a space S is formed between the electrode bodies 10, between the positive electrode terminal electrode body 21 and the electrode body 10, and between the negative electrode terminal electrode body 22 and the electrode body 10. When the target secondary battery is a liquid secondary battery, the space S is for storing the electrolyte, and therefore the space S is sealed by the frame-shaped member so that the electrolyte does not leak from the space S. In addition, the frame-shaped member ensures watertightness and airtightness, so the frame-shaped member is also useful in solid secondary batteries.

[0059] The electrolyte is injected into the space S after the welding step S6. 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 performing the welding step S6, an inlet 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.

[0060] The method for manufacturing a secondary battery according to the present disclosure has been described above using one embodiment. According to the method for manufacturing a secondary battery according to the present disclosure, the thickness of the frame member can be reduced. [Explanation of symbols]

[0061] 10 Electrode body 11 Current collector 12 Positive electrode layer 13 Negative electrode layer 14 Sealing material 141 First resin sheet 141a Overlapping area 141b 1st overlap part 142 First recess 143 First protrusion 21 Positive terminal electrode body 22 Negative terminal electrode body 30 Separator 40 Spacer 241 Second resin sheet 241a 2nd overlap part 242 Second recess 243 Second convex part 50 Electrode laminate

Claims

1. A method for manufacturing a secondary battery including an electrode stack and a frame-shaped member that seals an entire periphery of a side surface of the electrode stack, comprising the steps of: an electrode body fabrication step of forming electrode layers on both sides of a rectangular current collector to fabricate an electrode body; a positioning step of positioning a first resin sheet on each side of the current collector and welding the current collector and the first resin sheet to place a seal member around the current collector; a lamination step of laminating a plurality of the electrode assemblies with separators interposed therebetween and disposing spacers between the sealing members of the electrode assemblies adjacent to each other in a lamination direction to obtain the electrode laminate; a welding process of welding the sealing members and the spacers arranged in a stacking direction to form the frame-shaped member that seals the entire periphery of the side surface of the electrode stack, In the placing step, end portions of the first resin sheets arranged on adjacent sides of the current collector overlap each other to form a first overlapping portion; a first recess is formed in one end of the first resin sheet that forms the first overlapping portion, The first resins are joined to each other by welding the first overlapping portions. A method for manufacturing a secondary battery.

2. The method according to claim 1 , wherein the first recess is disposed outside an outer edge of the current collector in the first overlapping portion.

3. A preparation step of cutting a strip-shaped resin sheet to obtain the first resin sheet, In the preparation step, the first resin sheet is cut out from the resin sheet so that the first recess is formed at one end of the first resin sheet and the first protrusion is formed at the other end of the first resin sheet. The method according to claim 1 or 2.

4. a spacer manufacturing step of manufacturing the spacer having a rectangular frame shape, In the spacer manufacturing step, The second resin sheet is disposed at positions corresponding to each side of the rectangular frame shape, In the second resin sheets arranged on adjacent sides, ends of the second resin sheets overlap each other to form a second overlapping portion, a second recess is formed in one end of the second resin sheet that forms the second overlapping portion, The second overlapping portion is welded to obtain the spacer. The method according to claim 1 or 2.

Images