Manufacturing method for energy storage devices

Abstract

To provide a manufacturing method of a power storage device that can suppress sealing defects between a frame and a sealing member.SOLUTION: A manufacturing method of the power storage device includes a preparation step of preparing a module body having a sealing body provided on a side surface of a laminate including a plurality of electrodes, and a sealing step of sealing a liquid inlet 40a formed in the sealing body. The sealing body includes a frame body 50 including side portions 51, 53 that protrude from a side surface 40c of the sealing body 40 and are arranged to surround the liquid inlet 40a when viewed from a direction intersecting the side surface 40c. In the preparation step, the frame body 50 is formed such that widths D1, D3 of the side portions 51, 53 of the frame body 50 surrounding the liquid inlet 40a decrease from a base end 50b of the frame body 50 to a tip 50c of the frame body 50. In the sealing step, the sealing member 30 is welded to the frame body 50 such that the tip 50c of the frame body 50 is deformed while the tip 50c of the frame body 50 is pressed by the sealing member 30.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power storage device.

Background Art

[0002] As a conventional method for manufacturing a power storage device, an injection port for injecting an electrolytic solution into the power storage device is provided on one side surface of the power storage device, and a frame body having a plurality of side portions surrounding the injection port and protruding from one side surface of the power storage device is provided on one side surface of the power storage device. A technique for sealing the injection port by welding a sealing member to the tip of each side portion of the frame body is known (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described technology, it is desired to reduce a sealing defect between a sealing member for sealing an injection port and a frame body.

[0005] An object of the present invention is to provide a method for manufacturing a power storage device that can suppress a sealing defect between a frame body and a sealing member.

Means for Solving the Problems

[0006] The present invention provides a method for manufacturing an energy storage device, comprising a preparation step of preparing a module body having a laminate including a plurality of stacked electrodes and a sealing body provided on the side of the laminate, and a sealing step of sealing a liquid injection port formed in the sealing body and communicating with the internal space of the laminate, wherein the sealing body has a sealing body including a liquid injection port and a frame including a side portion that protrudes from the side of the sealing body and is arranged to surround the liquid injection port when viewed from a direction intersecting the side, the preparation step of forming the frame such that the width of the side portion surrounding the liquid injection port decreases from the base end to the tip of the frame, and the sealing step of welding the sealing member to the frame while pressing the tip of the frame with the sealing member so that the tip of the frame deforms.

[0007] In the sealing step of this energy storage device manufacturing method, the sealing member is welded to the frame so that the tip of the frame deforms as it is pressed against the frame. Furthermore, in the preparation step, the frame is formed such that the width of the edges surrounding the liquid injection port decreases from the base end to the tip of the frame. As a result, the width of the tip of the edge is smaller than the width of the base end, thus suppressing a decrease in the surface pressure from the sealing member received by the tip of the frame. Moreover, since the width of the base end of the edge is larger than the width of the tip of the edge, a decrease in the strength of the frame is suppressed. Therefore, it becomes easier to control the welding of the sealing member to the frame. Thus, according to this energy storage device manufacturing method, sealing defects between the frame and the sealing member can be suppressed.

[0008] In the preparation step, the frame may be formed such that the first outer surface of the frame intersecting the stacking direction of the multiple electrodes is flush with the second outer surface of the sealing body intersecting the stacking direction. Because the width of the tip of the edge is smaller than the width of the base of the edge, the amount of deformation of the tip of the edge during the sealing step is relatively small. As a result, the amount of burrs generated by the deformation of the tip of the edge is reduced, and consequently, the amount of burrs protruding beyond the first outer surface of the frame is reduced. Therefore, the size of the energy storage device in the stacking direction is suppressed.

[0009] The frame includes a first side portion that includes a first outer surface of the frame intersecting the stacking direction of the multiple electrodes, and a second side portion that, when viewed from a direction intersecting the side surface, is located on the opposite side from the first side portion with respect to the liquid injection port and is located inside both ends of the sealing body in the stacking direction. In the preparation step, the frame may be formed such that the width of the first side portion is smaller than the width of the second side portion. Because the width of the first side portion is smaller than the width of the second side portion, the amount of deformation of the first side portion during the sealing step is reduced. As a result, the amount of burrs generated by the deformation of the first side portion is reduced, and consequently, the amount of burrs protruding from the first outer surface of the frame portion is reduced. Therefore, the size of the energy storage device in the stacking direction is suppressed.

[0010] In the sealing process, after welding the sealing member to the tip of the frame such that, when viewed from a direction intersecting the side, one end of the sealing member in the stacking direction of the multiple electrodes protrudes beyond the first outer surface of the frame intersecting the stacking direction, the protruding portion of the sealing member that protrudes beyond the first outer surface of the frame may be welded to the first outer surface of the frame. When the sealing member is welded to the tip of the frame, burrs generated by deformation of the edge tip may protrude beyond the first outer surface of the frame. In such cases, by welding the protruding portion of the sealing member that protrudes beyond the first outer surface of the frame to the first outer surface of the frame, the thickness of the burrs protruding beyond the first outer surface of the frame can be reduced. Therefore, the enlargement of the energy storage device in the stacking direction is suppressed.

[0011] In the preparation process, the frame may be formed such that the rate of reduction in the width of the frame's edges at the leading edge is greater than the rate of reduction in the width of the frame's edges at the base end. This ensures a uniform distribution of surface pressure from the sealing member to the leading edge of the frame. Consequently, controlling the welding of the sealing member to the frame becomes easier, resulting in even more precise sealing of the liquid injection port. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for manufacturing an energy storage device that can suppress sealing defects between the frame and the sealing member. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a plan view of a power storage device according to an embodiment. [Figure 2] Figure 2 is a cross-sectional view taken along line II of Figure 1. [Figure 3] Figure 3 is a side view of the power storage device shown in Figure 1. [Figure 4] Figure 4 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 5] Figure 5 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 6] Figure 6 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 7] Figure 7 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 8] Figure 8 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 9] Figure 9 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 10] Figure 10 is a cross-sectional view taken along line X-X of Figure 9. [Figure 11] Figure 11 is a cross-sectional view taken along line XI-XI of Figure 9. [Figure 12] Figure 12 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 13] Figure 13 is a diagram showing the steps of a method for manufacturing the power storage device shown in Figure 1. [Figure 14] Figure 14 is a diagram showing the steps of a method for manufacturing a power storage device of a modified example. [Figure 15] Figure 15 is a diagram showing the steps of a method for manufacturing a power storage device of a modified example.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] As shown in FIGS. 1 and 2, the power storage device 1 includes a laminate 10, a sealing body 20, and a sealing member 30. The power storage device 1 is mounted on, for example, a forklift, a hybrid vehicle, or an electric vehicle. The power storage device 1 is, for example, a secondary battery. In the present embodiment, the power storage device 1 is a lithium-ion secondary battery. The power storage device 1 may be, for example, a nickel-hydrogen secondary battery or the like.

[0016] The laminate 10 includes a plurality of electrodes laminated in the Z-axis direction (lamination direction). Specifically, the laminate 10 includes a plurality of bipolar electrodes 11, a positive electrode terminal electrode 12, a negative electrode terminal electrode 13, and a plurality of separators 14.

[0017] The bipolar electrode 11 has a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 has, for example, a rectangular shape when viewed from the Z-axis direction. The current collector 15 includes a surface 15a and a surface 15b opposite to the surface 15a. For example, in FIG. 2, the surface 15a is illustrated as a surface facing the negative electrode terminal electrode 13 side described later, and the surface 15b is illustrated as a surface facing the positive electrode terminal electrode 12 side described later. The current collector 15 may have a plurality of layers laminated in the Z-axis direction. Each adjacent layer is electrically connected.

[0018] The positive electrode active material layer 16 is provided on surface 15a. When viewed from the Z-axis direction, the positive electrode active material layer 16 has, for example, a rectangular shape. Surface 15a includes an uncoated region where the positive electrode active material layer 16 is not provided. When viewed from the Z-axis direction, the uncoated region surrounds the positive electrode active material layer 16. The negative electrode active material layer 17 is provided on surface 15b. When viewed from the Z-axis direction, the negative electrode active material layer 17 has, for example, a rectangular shape. Surface 15b includes an uncoated region where the negative electrode active material layer 17 is not provided. When viewed from the Z-axis direction, the uncoated region surrounds the negative electrode active material layer 17.

[0019] Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 faces the negative electrode active material layer 17 of another bipolar electrode 11. In other words, the multiple bipolar electrodes 11 are stacked such that the surface 15a of the current collector 15 of one bipolar electrode 11 faces the surface 15b of the current collector 15 of the other bipolar electrode 11.

[0020] The positive terminal electrode 12 is positioned on one side in the Z-axis direction relative to the plurality of bipolar electrodes 11, and the negative terminal electrode 13 is positioned on the other side in the Z-axis direction relative to the plurality of bipolar electrodes 11. The positive terminal electrode 12 has a current collector 15 and a positive active material layer 16. The positive terminal electrode 12 differs from the bipolar electrode 11 in that it does not have a negative active material layer 17. The other configurations of the positive terminal electrode 12 are the same as those of the bipolar electrode 11. The positive terminal electrode 12 is positioned so that the positive active material layer 16 of the positive terminal electrode 12 faces the negative active material layer 17 of the bipolar electrode 11. That is, the positive terminal electrode 12 is laminated so that the surface 15a of the current collector 15 of the positive terminal electrode 12 faces the surface 15b of the current collector 15 of the bipolar electrode 11 adjacent to the positive terminal electrode 12.

[0021] The negative terminal electrode 13 comprises a current collector 15 and a negative electrode active material layer 17. The negative terminal electrode 13 differs from the bipolar electrode 11 in that it does not have a positive electrode active material layer 16. The other configurations of the negative terminal electrode 13 are the same as those of the bipolar electrode 11. The negative terminal electrode 13 is arranged such that the negative electrode active material layer 17 of the negative terminal electrode 13 faces the positive electrode active material layer 16 of the bipolar electrode 11. That is, the negative terminal electrode 13 is laminated such that the surface 15b of the current collector 15 of the negative terminal electrode 13 faces the surface 15a of the current collector 15 of the bipolar electrode 11 adjacent to the negative terminal electrode 13.

[0022] An internal space S containing electrolyte is formed between each bipolar electrode 11, between the bipolar electrode 11 and the positive terminal electrode 12, and between the bipolar electrode 11 and the negative terminal electrode 13. When viewed from the Z-axis direction, the area of ​​the positive electrode active material layer 16 is smaller than the area of ​​the negative electrode active material layer 17. When viewed from the Z-axis direction, the outer edge of the positive electrode active material layer 16 is located inward from the outer edge of the negative electrode active material layer 17. The thickness of the positive electrode active material layer 16 may be greater than the thickness of the negative electrode active material layer 17. The outer edges of the multiple current collectors 15 constitute the side surface 10c of the laminate 10.

[0023] The separator 14 is positioned between each bipolar electrode 11, between the bipolar electrode 11 and the positive terminal electrode 12, and between the bipolar electrode 11 and the negative terminal electrode 13. The separator 14 is located between the opposing positive electrode active material layer 16 and negative electrode active material layer 17. The separator 14 is, for example, sheet-shaped. When viewed from the Z-axis direction, the separator 14 is, for example, rectangular. When viewed from the Z-axis direction, the outer edge of the separator 14 is located outside the outer edge of the positive electrode active material layer 16 and the outer edge of the negative electrode active material layer 17, respectively. The separator 14 is a component that allows charge carriers such as lithium ions to pass through. The separator 14 isolates each of the adjacent electrodes 11, 12, and 13. This prevents electrical short circuits caused by contact between the electrodes 11, 12, and 13.

[0024] The current collector 15 has the function of maintaining the flow of current in the positive electrode active material layer 16 and the negative electrode active material layer 17 during the discharge or charging of the energy storage device 1. The current collector 15 is, for example, a chemically inert electrical conductor. The material of the current collector 15 is, for example, a metal material, a conductive resin material, a conductive inorganic material, etc. The conductive resin material is, for example, a conductive polymer material, or a non-conductive polymer material to which a conductive filler has been added. If the current collector 15 has multiple layers, the material of each layer may be any of the materials described above. A coating layer may be formed on the surface of the current collector 15. The coating layer may be formed by known methods such as plating or spray coating.

[0025] The current collector 15 may be, for example, a plate, foil, sheet, film, or mesh. The current collector 15 may be, for example, aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 15 may be an alloy foil or clad foil of the above metals. If the current collector 15 is foil-shaped, its thickness is, for example, 1 μm or more and 100 μm or less. The current collector 15 may include, for example, aluminum foil and copper plating formed on one side of the aluminum foil. The current collector 15 may be integrated by bonding.

[0026] The positive electrode active material layer 16 contains a positive electrode active material capable of intercepting and releasing charge carriers such as lithium ions. The positive electrode active material is, for example, a composite oxide, metallic lithium, and sulfur. The composite oxide contains, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. The composite oxide is olivine-type lithium iron phosphate (LiFePO4), LiCoO2, LiNiMnCoO2, etc.

[0027] The negative electrode active material layer 17 contains a negative electrode active material capable of intercepting and releasing charge carriers such as lithium ions. Examples of negative electrode active materials include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, soft carbon, metallic compounds, elements or compounds thereof that can alloy with lithium, and boron-doped carbon. Examples of elements that can alloy with lithium include silicon or tin.

[0028] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 may contain a binder and a conductive additive in addition to the active material. The binder has the function of connecting the active material or conductive additive to each other and maintaining the conductive network in the electrode. Examples of binders include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as polyacrylic acid and polymethacrylic acid; styrene-butadiene rubber; alginates such as carboxymethylcellulose, sodium alginate, and ammonium alginate; water-soluble cellulose ester crosslinked products; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. The conductive additive is a conductive material that has the function of increasing electrical conductivity. Examples of conductive additives include acetylene black, carbon black, and graphite. Examples of viscosity-adjusting solvents include N-methyl-2-pyrrolidone.

[0029] Conventional methods such as roll coating, die coating, dip coating, doctor blade coating, spray coating, and curtain coating are used to form the positive electrode active material layer 16 on surface 15a and the negative electrode active material layer 17 on surface 15b. Specifically, an active material, solvent, and optionally a binder and conductive additive are mixed to produce a slurry-like active material layer forming composition. This active material layer forming composition is then applied to surface 15a or surface 15b and dried. Examples of solvents include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. The dried material may be compressed to increase electrode density.

[0030] The separator 14 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. The material of the separator 14 is, for example, polypropylene, polyethylene, polyolefin, polyester, etc. The separator 14 may have a single-layer structure or a multi-layer structure. If the separator 14 has a multi-layer structure, it may include, for example, a base layer and a pair of adhesive layers, and may be bonded and fixed to the positive electrode active material layer 16 and the negative electrode active material layer 17 by the pair of adhesive layers. The separator 14 may also include a ceramic layer that serves as a heat-resistant layer. The separator 14 may be reinforced with a vinylidene fluoride resin compound.

[0031] The electrolyte impregnated into the separator 14 is, for example, a liquid containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte salt of the electrolyte is, for example, a known lithium salt such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, LiN(CF3SO2)2, etc. The non-aqueous solvent is a cyclic carbonate, a cyclic ester, a linear carbonate, a linear ester, an ether, etc. Two or more of these known solvent materials may be used in combination.

[0032] The sealing body 20 is a member for sealing each internal space S of the laminate 10. The sealing body 20 is provided on the side surface 10c of the laminate 10. The sealing body 20 has, for example, a rectangular cylindrical shape. The sealing body 20 has electrical insulating properties.

[0033] The sealing body 20 includes a sealing body 40 and a frame 50. The sealing body 40 includes a sealing member 41, a spacer 42, a welded portion 43 formed by welding the sealing member 41 and the spacer 42 together, a side wall portion 44 provided to cover a part of the welded portion 43, and an overhang portion 45 provided integrally with the side wall portion 44. The sealing member 41 and the spacer 42, stacked in the Z-axis direction, form the welded portion 43 by welding their outer edges together. The side wall portion 44, the overhang portion 45, and the frame 50 are integrally formed, for example, by injection molding. The side wall portion 44 and the overhang portion 45 are welded to the welded portion 43. The side wall portion 44, the overhang portion 45, and the frame 50 are integrally formed from the same material.

[0034] The sealing member 41 has, for example, a rectangular frame shape. The sealing member 41 covers the peripheral edge of each current collector 15. The sealing member 41 is provided on both surfaces 15a and 15b of each current collector 15. The portions of the sealing member 41 provided on both surfaces of each current collector are welded together at the points where they are located outside the outer edge of the current collector 15 when viewed from the Z-axis direction. That is, the peripheral edge of each current collector 15 is covered by the sealing member 41 from surface 15a to surface 15b, as shown in Figure 2. When viewed from the Z-axis direction, the sealing member 41 surrounds the positive electrode active material layer 16 and the negative electrode active material layer 17 in a frame shape. On the surface of the current collector 15, the inner edge of the sealing member 41 is separated from the positive electrode active material layer 16 and the negative electrode active material layer 17. The outer edge of the sealing member 41 is located outside the outer edge of the current collector 15 when viewed from the Z-axis direction. In other words, the sealing member 41 has an inner portion that overlaps with the current collector 15 when viewed from the Z-axis direction, and an outer portion that does not overlap with the current collector 15. The sealing member 41 is welded to the current collector 15 at its inner portion.

[0035] The spacer 42 has, for example, a rectangular frame shape. The spacer 42 is provided between adjacent sealing members 41. The spacer 42 is sandwiched between adjacent sealing members 41. The inner edge of the spacer 42 may include a portion located outside the inner edge of the sealing member 41 when viewed from the Z-axis direction, and may also include a portion located inside the inner edge of the sealing member 41 when viewed from the Z-axis direction. In other words, the inner edge of the spacer 42 may include a portion that is further away from the positive electrode active material layer 16 or the negative electrode active material layer 17 than the inner edge of the sealing member 41. The outer edge of the spacer 42 substantially coincides with the outer edge of the sealing member 41 when viewed from the Z-axis direction. That is, the spacer 42 has a portion located outside the outer edge of the current collector 15 when viewed from the Z-axis direction.

[0036] The peripheral edge of the separator 14 is located between the sealing member 41 and the spacer 42, which are provided on the surface 15b of the current collector 15. The peripheral edge of the separator 14 may be fixed to the sealing member 41 or the spacer 42.

[0037] The welded portion 43 is formed by welding the outer edges of each sealing member 41 and each spacer 42. The welded portion 43 is formed by welding the regions of each sealing member 41 and each spacer 42 that are located outside the outer edge of the current collector 15. The welded portion 43 has, for example, a rectangular cylindrical shape. The inner edge of the welded portion 43 may be located outside the outer edge of the current collector 15 when viewed from the Z-axis direction. In other words, the inner edge of the welded portion 43 may be separated from the outer edge of the current collector 15.

[0038] The materials of the sealing member 41 and the spacer 42 are, for example, acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene. Both the sealing member 41 and the spacer 42 have electrolyte resistance. The materials of the sealing member 41 and the spacer 42 may be the same or different. In this embodiment, the material of the sealing member 41 is, for example, acid-modified polyethylene or acid-modified polypropylene. In this embodiment, the material of the spacer 42 is, for example, polyethylene or polypropylene. Acid-modified polyethylene and acid-modified polypropylene are easier to bond to metals than un-acid-modified polyethylene and un-acid-modified polypropylene. When the current collector 15 is made of metal, the bonding strength of the sealing member 41 to the current collector 15 can be improved by composing the sealing member 41 of acid-modified polyethylene or acid-modified polypropylene.

[0039] The side wall portion 44 is provided on the side surface 43c of the welded portion 43 that intersects in the X-axis direction. The side wall portion 44 is provided on a part of the side surface 43c of the welded portion 43. The side wall portion 44 is, for example, rectangular plate-shaped. That is, the length of the side wall portion 44 in the Z-axis direction is approximately the same as the length of the welded portion 43 in the Z-axis direction, and the length of the side wall portion 44 in the Y-axis direction is smaller than the length of the side surface 43c in the Y-axis direction. The side wall portion 44 has a surface 44c that faces away from the welded portion 43. The surface 44c intersects in the X-axis direction. The surface 44c is a part of the side surface 40c of the sealing body 40.

[0040] The overhang portions 45 are provided at each end of the side wall portion 44 in the Z-axis direction. That is, one end of each overhang portion 45 is connected to the end of the side wall portion 44 in the Z-axis direction. The overhang portions 45 are provided so as to cover both ends of the welded portion 43 in the Z-axis direction. The overhang portions 45 are provided so as to cover the outer surface 41a of the sealing member 41 provided on the positive terminal electrode 12. The overhang portions 45 are provided so as to cover the outer surface 41b of the sealing member 41 provided on the negative terminal electrode 13. The overhang portions 45 have, for example, a rectangular plate shape. When viewed from the Z-axis direction, one end of the overhang portion 45 in the X-axis direction may be located inside the side surface 10c of the laminate 10. When viewed from the Z-axis direction, one end of the overhang portion 45 in the X-axis direction may be located between the side surface 10c of the laminate 10 and the inner edge of the spacer 42.

[0041] As shown in Figures 2 and 3, the sealing body 40 of the sealing body 20 has an injection port 40a formed therein. The injection port 40a communicates with the internal space S of the laminate 10. In this embodiment, the sealing body 40 includes a plurality of injection ports 40a. Specifically, the sealing body 40 has a plurality of injection port rows 40A, 40B, and 40C. Each of the injection port rows 40A, 40B, and 40C includes a plurality of injection ports 40a that are positioned at different locations in the Z-axis direction and aligned in the Y-axis direction. Each of the injection port rows 40A, 40B, and 40C includes, for example, 10 injection ports 40a. The injection port row 40B is adjacent to the injection port row 40A in the Z-axis direction. The injection port row 40C is adjacent to the injection port row 40B in the Z-axis direction. The injection port row 40C is located on the opposite side of the injection port row 40A from the injection port row 40B.

[0042] The nth (n is a natural number) injection port 40a in injection port row 40A, the nth injection port 40a in injection port row 40B, and the nth injection port 40a in injection port row 40C are aligned in the Z-axis direction at the same position in the Y-axis direction. Each injection port 40a in injection port row 40A communicates with the internal space S from the 1st to the 10th layer. Each injection port 40a in injection port row 40B communicates with the internal space S from the 11th to the 20th layer. Each injection port 40a in injection port row 40C communicates with the internal space S from the 21st to the 30th layer.

[0043] In each of the injection port rows 40A, 40B, and 40C, two injection ports 40a that communicate with two adjacent internal spaces S in the Z-axis direction are separated from each other in the Y-axis direction. Specifically, when viewed from the X-axis direction, the injection port 40a that communicates with one internal space S and the injection port 40a that communicates with the other internal space S adjacent to that internal space S are formed at different positions in the Y-axis direction. In each of the injection port rows 40A, 40B, and 40C, the multiple injection ports 40a are arranged diagonally with respect to the Y-axis direction.

[0044] The injection port 40a functions as a path for injecting electrolyte into the internal space S. The injection port 40a includes communication holes 42a and 44a. The injection port 40a is composed of communication holes 42a and 44a. Communication hole 42a is formed in the spacer 42 and the welded portion 43. Communication hole 42a penetrates the spacer 42 and the welded portion 43. Communication hole 42a opens at the outer edge of the welded portion 43 and the inner edge of the spacer 42, respectively. Communication hole 42a communicates with the internal space S. When viewed from the X-axis direction, communication hole 42a has, for example, a rectangular shape. Communication hole 44a is formed in the side wall portion 44. Communication hole 44a penetrates the side wall portion 44. Communication hole 44a opens at the surface 44c of the side wall portion 44. The communication hole 44a communicates with the communication hole 42a. When viewed from the X-axis direction, the communication hole 4a has, for example, a rectangular shape.

[0045] The sealing body 20 has a plurality of frame bodies 50. The frame bodies 50 are provided on the side surface 40c of the sealing body 40. The plurality of frame bodies 50 are arranged in the Y-axis direction. Adjacent frame bodies 50 in the Y-axis direction may be spaced apart from each other. When viewed from the X-axis direction (the direction intersecting the side surface 40c of the sealing body 40), one frame body 50 surrounds each of the three liquid injection ports 40a arranged in the Z-axis direction. Specifically, the nth frame body 50 surrounds the nth liquid injection port 40a of the liquid injection port row 40A, the nth liquid injection port 40a of the liquid injection port row 40B, and the nth liquid injection port 40a of the liquid injection port row 40C.

[0046] The sealing member 30 is, for example, in the form of a sheet or plate. The sealing member 30 is attached to the multiple frames 50 so as to cover each of the openings of the multiple frames 50 when viewed from the X-axis direction. The sealing member 30 is, for example, a laminate sheet. The laminate sheet is composed of, for example, a metal layer and a resin layer. The material of the metal layer of the laminate sheet is, for example, aluminum. The sealing member 30 is welded to the ends of the multiple frames 50. This seals the multiple liquid injection ports 40a. Note that the sealing member 30 is not shown in Figure 3.

[0047] Next, the manufacturing method of the energy storage device 1 will be described. First, the laminate 10 and the sealant 20 are prepared (preparation step). Specifically, as shown in Figure 4, electrodes 11, 12, and 13, each provided with a sealing member 41, are laminated (laminated step). In the laminate step, spacers 42 are placed between adjacent sealing members 41. Communication holes 42a are formed in the spacers 42. In the laminate step, separators 14 are placed between adjacent electrodes 11, between adjacent electrodes 11 and electrode 12, and between adjacent electrodes 11 and electrode 13.

[0048] Next, as shown in Figure 5, the liquid inlet forming member 8 is inserted into the communication hole 42a of the spacer 42. The liquid inlet forming member 8 is, for example, plate-shaped. The liquid inlet forming member 8 extends from the outside of the spacer 42 to the internal space S. Subsequently, with the liquid inlet forming member 8 inserted into the communication hole 42a, the peripheral edges of each seal member 41 and each spacer 42 are welded to each other (welding process). Specifically, the outer surfaces of each seal member 41 and each spacer 42 are melted by a heating device. The heating device is, for example, an infrared heater. The heating device irradiates the outer surfaces of each seal member 41 and each spacer 42 with infrared rays. As a result, the outer edges of each seal member 41 and each spacer 42 melt. As the melted outer edges of each seal member 41 and each spacer 42 solidify, a welded portion 43 is formed.

[0049] Next, as shown in Figure 6, the side wall portion 44, the overhang portion 45, and the frame 50 are formed, for example, by injection molding. Specifically, first, the area of ​​the side surface 43c of the welded portion 43 in which the multiple communication holes 42a are formed is covered by, for example, a mold. Subsequently, with the liquid injection port forming member 8 inserted into the communication holes 42a, resin is injected into the molding space of the mold.

[0050] Next, as shown in Figure 7, the liquid injection port forming member 8 is removed from the communication hole 42a. This forms a communication hole 44a in the side wall portion 44. In other words, a liquid injection port 40a is formed. This provides a sealant 20 on the side surface 10c of the laminate 10. In other words, a module body 60 having the laminate 10 and the sealant 20 is prepared.

[0051] Next, electrolyte is injected into the internal space S of the laminate 10 (injection step). Specifically, first, a nozzle 9 is pressed against a frame 50. In this embodiment, one nozzle 9 is pressed against one frame 50. The nozzle 9 has a support member 91 and a sealing member 92. The sealing member 92 is provided on the surface of the support member 91. The sealing member 92 is, for example, an elastic material. The sealing member 92 is, for example, a packing. When the surface of the sealing member 92 is pressed against the frame 50, at least a part of the frame 50 bites into the sealing member 92. The nozzle 9 has a plurality of injection ports 9a. The injection ports 9a penetrate the nozzle 9. Next, electrolyte is injected into the internal space S through the injection ports 9a and 40a. In this embodiment, electrolyte is injected into multiple internal spaces S simultaneously.

[0052] Next, the liquid injection port 40a is sealed (sealing step). Specifically, as shown in Figure 8, the sealing member 30 is welded to the frame 50. In this embodiment, one sealing member 30 is welded to multiple frame 50s. This manufactures the energy storage device 1 shown in Figure 1.

[0053] The sealing process will now be described in more detail. As shown in Figure 9, the frame 50 prepared in the preparation process has, for example, a rectangular frame shape when viewed from the X-axis direction. The frame 50 includes four outer surfaces 50a. The frame 50 includes a pair of edges (first edges) 51, a pair of edges 52, and a plurality of edges (second edges) 53. The edges 51 are located at both ends of the frame 50 in the Z-axis direction. The edges 51 extend along the Y-axis direction. The edges 51 intersect in the Z-axis direction. The edges 51 include an outer surface (first outer surface) 51a. The outer surface 51a of the edges 51 is the outer surface 50a of the frame 50 that intersects in the Z-axis direction. In other words, the edges 51 include the outer surface 50a of the frame 50 that intersects in the Z-axis direction.

[0054] The edges 52 are located at both ends of the frame 50 in the Y-axis direction. The edges 52 extend along the Z-axis direction. The edges 52 intersect in the Y-axis direction. The edges 52 include an outer surface 52a. The outer surface 52a of the edges 52 is the outer surface 50a of the frame 50 that intersects in the Y-axis direction. In other words, the edges 52 include the outer surface 50a of the frame 50 that intersects in the Y-axis direction. The pair of edges 51 and the pair of edges 52 constitute the outer frame of the frame 50.

[0055] The edge portion 53 is located inside both ends of the sealing body 40 in the Z-axis direction. The edge portion 53 is located between a pair of edge portions 51. The edge portion 53 is located between a pair of edge portions 52. The edge portion 53 extends along the Y-axis direction. The edge portion 53 intersects in the Z-axis direction. When viewed from the X-axis direction, the edge portion 53 is located on the opposite side of the edge portion 51 from the injection port 40a of the injection port row 40A. The edge portion 53 is located on the opposite side of the edge portion 51 from the injection port 40a of the injection port row 40C. The edge portion 53 is located between the injection port 40a of the injection port row 40A and the injection port 40a of the injection port row 40B, and between the injection port 40a of the injection port row 40B and the injection port 40a of the injection port row 40C. When viewed from the X-axis direction, each injection port 40a is surrounded by its respective sides 51, 52, and 53. Each injection port 40a is isolated by its respective sides 51, 52, and 53.

[0056] As shown in Figures 10 and 11, the frame 50 protrudes from the side surface 40c (the surface 44c of the side wall portion 44) of the sealing body 40. The base end 50b of the frame 50 coincides with the side surface 40c in the X-axis direction. The tip 50c of the frame 50 is a plane that intersects in the X-axis direction. That is, the tip 50c of the frame 50 has a predetermined area. The outer surface 51a of the edge portion 51 is formed flush with the outer surface 45a of the overhang portion 45. That is, the outer surface 51a and the outer surface 45a are located on the same plane. The outer surface 45a is the outer surface (second outer surface) 40b of the sealing body 40 that intersects in the Z-axis direction.

[0057] The width (thickness) of each side 51, 52, and 53 of the frame 50 decreases from the base end 50b of the frame 50 to the tip end 50c of the frame 50. The width D1 of the side 51 in the Z-axis direction decreases from the base end 50b of the frame 50 to the tip end 50c of the frame 50. The width of the tip of the side 51 in the Z-axis direction is smaller than the width of the base end of the side 51 in the Z-axis direction. The outer surface 51a of the side 51 is a plane parallel to the XY plane. The inner surface 51b of the side 51 is a plane inclined with respect to the XY plane. The line of intersection between the inner surface 51b and the XY plane is a straight line parallel to the Y-axis direction. The inner surface 51b of the side 51 approaches the outer surface 51a of the side 51 as it moves from the base end 50b of the frame 50 to the tip end 50c.

[0058] The rate of decrease in the width D1 of the edge 51 at the tip 50c side of the frame 50 is greater than the rate of decrease in the width D1 of the edge 51 at the base 50b side of the frame 50. Specifically, the edge 51 includes the tip 51c. The tip 51c is a chamfer (C-chamfer or R-chamfer) formed at the tip of the edge 51. At the tip 50c side of the frame 50, the width D1 of the edge 51 decreases in stages. Note that in other figures, the illustration of the tip 51c may be omitted.

[0059] The width D2 of the edge 52 in the Y-axis direction decreases from the base end 50b of the frame 50 to the tip end 50c of the frame 50. The width of the tip end of the edge 52 in the Y-axis direction is smaller than the width of the base end of the edge 52 in the Y-axis direction. The outer surface 52a of the edge 52 is a plane parallel to the XZ plane. The inner surface 52b of the edge 52 is a plane inclined with respect to the XZ plane. The line of intersection between the inner surface 52b and the XZ plane is a straight line parallel to the Z-axis direction. The inner surface 52b of the edge 52 approaches the outer surface 52a of the edge 52 as it moves from the base end 50b of the frame 50 to the tip end 50c.

[0060] The rate of decrease in the width D2 of the edge 52 at the tip 50c side of the frame 50 is greater than the rate of decrease in the width D2 of the edge 52 at the base 50b side of the frame 50. Specifically, the edge 52 includes the tip 52c. The tip 52c is a chamfer (C-chamfer or R-chamfer) formed at the tip of the edge 52. At the tip 50c side of the frame 50, the width D2 of the edge 52 decreases in stages. Note that in other figures, the illustration of the tip 52c may be omitted.

[0061] The width D3 of the edge 53 in the Z-axis direction decreases from the base end 50b of the frame 50 to the tip end 50c of the frame 50. The width of the tip end of the edge 53 in the Z-axis direction is smaller than the width of the base end of the edge 53 in the Z-axis direction. Each side surface 53a of the edge 53 is a plane inclined with respect to the XY plane. The line of intersection between each side surface 53b and the XY plane is a straight line parallel to the Y-axis direction. The sides 53a of the edge 53 approach each other as the frame 50 moves from the base end 50b to the tip end 50c.

[0062] The rate of decrease in the width D3 of the edge 53 at the tip 50c side of the frame 50 is greater than the rate of decrease in the width D3 of the edge 53 at the base 50b side of the frame 50. Specifically, the edge 53 includes the tip 53c. The tip 53c is a chamfer (C-chamfer or R-chamfer) formed at the tip of the edge 53. At the tip 50c side of the frame 50, the width D3 of the edge 53 decreases in stages. Note that in other figures, the illustration of the tip 53c may be omitted.

[0063] The frame 50 is symmetrical with respect to the XY plane. The frame 50 is symmetrical with respect to the XZ plane. The inclination angle of the inner surface 51b of edge 51 with respect to the XY plane, the inclination angle of the inner surface 52b of edge 52 with respect to the XZ plane, and the inclination angle of the side surface 53a of edge 53 with respect to the XY plane are all the same. At the same position in the X-axis direction, the width D1 of edge 51 and the width D2 of edge 52 are the same. At the same position in the X-axis direction, the width D1 of edge 51 and the width D2 of edge 52 are each smaller than the width D3 of edge 53. At the tip 50c of the frame 50, the width D1 of edge 51, the width D2 of edge 52, and the width D3 of edge 53 are all the same. At the base end 50b of the frame 50, the width D1 of edge 51 and the width D2 of edge 52 are each smaller than the width D3 of edge 53.

[0064] As shown in Figures 12 and 13, in the sealing process, the sealing member 30 is welded to the frame 50. Specifically, first, the frame 50 and the sealing member 30 are heated to a predetermined temperature. The frame 50 and the sealing member 30 are heated, for example, by an infrared heater. Subsequently, the sealing member 30 is welded to the frame 50 so that the tip 50c of the frame 50 is deformed while the tip 50c of the frame 50 is pressed by the sealing member 30. As a result, the tip 50c of the frame 50 is crushed, and burrs 50d are formed at the tips of each side portion 51, 52, 53. The burrs 50d protrude from each side portion 51, 52, 53 in the width direction of each side portion 51, 52, 53. Note that in other figures, the illustration of the burrs 50d may be omitted.

[0065] As explained above, in the sealing step of the manufacturing method for the energy storage device 1, the sealing member 30 is welded to the frame 50 so that the tip 50c of the frame 50 deforms as the tip 50c of the frame 50 is pressed by the sealing member 30. Furthermore, in the preparation step, the frame 50 is formed such that the widths D1, D2, D3 of the sides 51, 52, 53 of the frame 50 surrounding the liquid injection port 40a decrease from the base end 50b of the frame 50 to the tip 50c of the frame 50. As a result, the width of the tips of the sides 51, 52, 53 is smaller than the width of the base ends of the sides 51, 52, 53, thus suppressing a decrease in the surface pressure from the sealing member 30 that the tip 50c of the frame 50 receives. In addition, the width of the base ends of the sides 51, 52, 53 is larger than the width of the tips of the sides 51, 52, 53, thus suppressing a decrease in the strength of the frame 50. Therefore, it becomes easier to control the welding of the sealing member 30 to the frame 50. Thus, according to the manufacturing method of the energy storage device 1, sealing defects between the frame 50 and the sealing member 30 can be suppressed. The widths (thicknesses) D1, D2, D3 of the edges 51, 52, 53 of the frame 50 affect the surface pressure or strength of the frame 50 required to ensure sufficient sealing performance. If the widths D1, D2, D3 of the edges 51, 52, 53 are made too large or too small, it may become difficult to control the sealing between the frame 50 and the sealing member 30. According to the manufacturing method of the energy storage device 1, as described above, sealing defects between the frame 50 and the sealing member 30 can be suppressed. Furthermore, in the preparation process, the frame 50 is formed such that the widths D1, D2, D3 of the sides 51, 52, 53 of the frame 50 decrease from the base end 50b of the frame 50 to the tip end 50c of the frame 50. Therefore, in the liquid injection process, the strength of the frame 50 can be ensured while ensuring the sealing performance between the frame 50 and the sealing member 92 of the nozzle 9.

[0066] In the preparation step, the frame 50 is formed such that the outer surface 50a (outer surface 51a of the edge portion 51) of the frame 50 intersecting the stacking direction (Z-axis direction) of each electrode 11, 12, and 13 is flush with the outer surface 40b (outer surface 45a of the overhang portion 45) of the sealing body 40 intersecting in the Z-axis direction. Because the width of the tip of the edge portion 51 is smaller than the width of the base end of the edge portion 51, the amount of deformation of the tip of the edge portion 51 during the sealing step is relatively small. As a result, the amount of burrs 50d generated by the deformation of the tip of the edge portion 51 is reduced, and consequently, the amount of burrs 50d protruding from the outer surface 50a of the frame 50 is reduced. Therefore, the enlargement of the energy storage device 1 in the Z-axis direction is suppressed.

[0067] The frame 50 includes a side portion 51 that includes the outer surface 50a of the frame 50, and a side portion 53 that, when viewed from the X-axis direction, is located on the opposite side of the side portion 51 from the liquid injection port 40a and is located inside the ends of the sealing body 40 in the Z-axis direction. In the preparation step, the frame 50 is formed such that the width D1 of the side portion 51 is smaller than the width D3 of the side portion 53. Because the width D1 of the side portion 51 is smaller than the width D3 of the side portion 53, the amount of deformation of the side portion 51 during the sealing step is reduced. As a result, the amount of burrs 50d generated by the deformation of the side portion 51 is reduced, and consequently, the amount of burrs 50d protruding from the outer surface 50a of the frame 50 is reduced. Therefore, the enlargement of the energy storage device 1 in the Z-axis direction is further suppressed. Also, because the width D1 of the side portion 51 is smaller than the width D3 of the side portion 53, the space between the side portion 51 and the side portion 53 of the frame 50 is relatively wide. This improves the degree of freedom in arranging the injection ports 40a in injection port row 40A or injection ports 40a in injection port row 40C.

[0068] In the preparation process, the frame 50 is formed such that the rate of decrease in the widths D1, D2, D3 of the edges 51, 52, 53 of the frame 50 at the tip 50c side is greater than the rate of decrease in the widths D1, D2, D3 of the edges 51, 52, 53 of the frame 50 at the base end 50b side. This ensures a uniform distribution of surface pressure from the sealing member 30 on the tip 50c of the frame 50. Specifically, even if the tip 50c of the frame 50 is pressed against the sealing member 30 which is inclined with respect to the frame 50 (YZ plane), the stress concentration at the tip 50c of the frame 50 is mitigated. Consequently, the control of welding the sealing member 30 to the frame 50 becomes easier, resulting in even more precise sealing of the liquid injection port 40a.

[0069] Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiments described above.

[0070] As shown in Figure 14, the sealing member 30 may include a main body portion 31 and a protruding portion 32. Both ends of the main body portion 31 in the Z-axis direction substantially coincide with both ends of the frame 50 in the Z-axis direction. The protruding portions 32 are provided at each end of the main body portion 31 in the Z-axis direction. When viewed from the X-axis direction, the protruding portions 32 protrude beyond the outer surface 51a of the frame 50. In the sealing process, the main body portion 31 of the sealing member 30 may be welded to the tip of the frame 50 such that the protruding portions 32 of the sealing member 30 protrude beyond the outer surface 51a of the frame 50. When the main body portion 31 is welded to the tip of the frame 50, burrs 50d generated by the deformation of the tip of the edge portion 51 of the frame 50 may protrude beyond the outer surface 51a of the frame 50. Next, in the sealing process, as shown in Figure 15, the protruding portion 32 of the sealing member 30 that protrudes beyond the outer surface 51a of the frame 50 may be welded to the outer surface 51a of the frame 50. Specifically, in the sealing process, the protruding portion 32 may be bent toward the outer surface 51a of the frame 50, and then the protruding portion 32 may be welded to the outer surface 51a. This makes it possible to crush the burr 50d that protrudes beyond the outer surface 51a of the frame 50, and to reduce the thickness of the burr 50d in the Z-axis direction. Therefore, the enlargement of the energy storage device 1 in the Z-axis direction is further suppressed.

[0071] In this embodiment, an example is shown where the rate of decrease in width D1, D2, D3 of each side 51, 52, 53 at the tip 50c side of the frame 50 is greater than the rate of decrease in width D1, D2, D3 of each side 51, 52, 53 at the base 50b side of the frame 50. However, the rate of decrease in width D1, D2, D3 of each side 51, 52, 53 may be constant from the base 50b side of the frame 50 to the tip 50c side of the frame 50. Each side 51, 52, 53 does not necessarily include the tip portions 51c, 52c, 53c.

[0072] Although an example of the frame 50 being formed by injection molding has been shown, the frame 50 may also be formed by, for example, hot plate welding.

[0073] In the sealing process, an example was shown in which the frame 50 and the sealing member 30 are heated by an infrared heater or the like. However, in the sealing process, the frame 50 and the sealing member 30 may be welded together using a hot plate.

[0074] The gist of this disclosure is as follows: [1] to [5]. [1] A method for manufacturing an energy storage device, comprising: a preparation step of preparing a module body having a laminate including a plurality of stacked electrodes and a sealing body provided on the side of the laminate; and a sealing step of sealing a liquid injection port formed in the sealing body and communicating with the internal space of the laminate, wherein the sealing body comprises a sealing body including the liquid injection port and a frame body including a side portion that protrudes from the side of the sealing body and is arranged to surround the liquid injection port when viewed from a direction intersecting the side, the preparation step of forming the frame body such that the width of the side portion of the frame body surrounding the liquid injection port decreases from the base end of the frame body to the tip of the frame body, and the sealing step of welding the sealing member to the frame body while pressing the tip of the frame body with a sealing member such that the tip of the frame body deforms. [2] The method for manufacturing an energy storage device according to [1], wherein in the preparation step, the frame is formed such that the first outer surface of the frame intersecting the stacking direction of the plurality of electrodes is flush with the second outer surface of the sealing body intersecting the stacking direction. [3] The method for manufacturing an energy storage device according to [1] or [2], wherein the frame includes a first side portion that intersects the stacking direction of the plurality of electrodes with respect to the first outer surface of the frame, and a second side portion that, when viewed from a direction intersecting the side surface, is located on the opposite side from the liquid injection port and is located inside the ends of the sealing body in the stacking direction, and in the preparation step, the frame is formed such that the width of the first side portion is smaller than the width of the second side portion. [4] The method for manufacturing an energy storage device according to any one of [1] to [3], wherein in the sealing step, when viewed from a direction intersecting the side surface, one end of the sealing member in the stacking direction of the plurality of electrodes protrudes beyond the first outer surface of the frame that intersects the stacking direction, the sealing member is welded to the tip of the frame, and the protruding portion of the sealing member that protrudes beyond the first outer surface of the frame is welded to the first outer surface of the frame. [5] The method for manufacturing an energy storage device according to any one of [1] to [4], wherein in the preparation step, the frame is formed such that the rate of reduction in the width of the side of the frame at the tip side of the frame is greater than the rate of reduction in the width of the side of the frame at the base end side of the frame. [Explanation of symbols]

[0075] 1...Energy storage device, 10...Laminate, 11...Bipolar electrode, 12...Positive terminal electrode, 13...Negative terminal electrode, 20...Sealing body, 30...Sealing member, 32...Protruding part, 40...Sealing body, 40a...Injection port, 40b...Outer surface (second outer surface), 40c...Side, 50...Frame, 50a...Outer surface (first outer surface), 50b...Base end, 50c...Tip, 51, 52, 53...Edges, 60...Module body, D1, D2, D3...Width, S...Internal space.

Claims

1. Preparation steps include preparing a module body having a laminate containing multiple stacked electrodes and a sealing body provided on the side surface of the laminate, The sealing step includes sealing an injection port formed in the sealing body and communicating with the internal space of the laminate, The sealing body comprises a sealing body including the liquid injection port, and a frame including a side portion that protrudes from the side of the sealing body and is arranged to surround the liquid injection port when viewed from a direction intersecting the side. In the preparation step, the frame is formed such that the width of the side portion of the frame surrounding the liquid injection port decreases from the base end to the tip of the frame. A method for manufacturing an energy storage device, wherein in the sealing step, the sealing member is welded to the frame body while pressing the tip of the frame body with the sealing member, so as to deform the tip of the frame body.

2. The method for manufacturing an energy storage device according to claim 1, wherein in the preparation step, the frame is formed such that the first outer surface of the frame intersecting the stacking direction of the plurality of electrodes is flush with the second outer surface of the sealing body intersecting the stacking direction.

3. The frame includes a first side portion that includes a first outer surface of the frame intersecting the stacking direction of the plurality of electrodes, and a second side portion that, when viewed from a direction intersecting the side surface, is located on the opposite side from the first side portion with respect to the liquid injection port and is located inside the ends of the sealing body in the stacking direction. The method for manufacturing an energy storage device according to claim 1 or 2, wherein in the preparation step, the frame is formed such that the width of the first side is smaller than the width of the second side.

4. The method for manufacturing an energy storage device according to claim 1 or 2, wherein in the sealing step, when viewed from a direction intersecting the side surface, one end of the sealing member in the stacking direction of the plurality of electrodes protrudes beyond the first outer surface of the frame that intersects the stacking direction, the sealing member is welded to the tip of the frame, and the protruding portion of the sealing member that protrudes beyond the first outer surface is welded to the first outer surface.

5. The method for manufacturing an energy storage device according to claim 1 or 2, wherein in the preparation step, the frame is formed such that the rate of reduction in the width of the side portion of the frame at the tip end of the frame is greater than the rate of reduction in the width of the side portion of the frame at the base end of the frame.

Images