Electric power storage module manufacturing method

Abstract

Provided is an electric power storage module manufacturing method for manufacturing an electric power storage module provided with: an electrode laminate configured by stacking a plurality of current-collector-including electrodes along a first direction; a sealing body in which a plurality of seal materials respectively provided to the plurality of electrodes are stacked in the first direction, whereby the sealing body is provided so as to surround the electrode laminate; and a plurality of terminals that are joined to the current collectors of each of the plurality of electrodes and are led out to the outside of the sealing body, the terminals extending along a direction intersecting the first direction, wherein the electric power storage module manufacturing method comprises a terminal-joining step for joining the terminals to the current collectors at peripheral edge parts of the current collectors, and an inspection step for applying a tensile load to the terminals joined to the current collector, the tensile load being applied along the extension direction of the terminals.

Description

Energy storage module manufacturing method

[0001] The present disclosure relates to a method for manufacturing an electricity storage module.

[0002] Patent Document 1 describes a bipolar secondary battery. This bipolar secondary battery has a battery element formed by stacking unit cells. Each unit cell includes a positive electrode, a negative electrode, a separator, and an insulating member. The bipolar secondary battery has a voltage detection terminal disposed on the outer periphery of the battery element between one of the two surfaces of the positive electrode current collector that does not contact the insulating member and one of the two surfaces of the negative electrode current collector that does not contact the insulating member, for detecting the voltage of the unit cell. The bipolar secondary battery has an adhesive layer that bonds either the positive electrode current collector or the negative electrode current collector to the voltage detection terminal.

[0003] Japanese Patent Application Laid-Open No. 2020-061221

[0004] In a storage module such as the bipolar secondary battery described in Patent Document 1, the terminals and the current collectors must be joined with sufficient bonding strength to prevent terminals such as the voltage detection terminals from peeling off.

[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing an electricity storage module that can ensure the bonding strength between the terminal and the current collector.

[0006] The method for manufacturing an energy storage module according to the present disclosure is a method for manufacturing an energy storage module including: an electrode stack formed by stacking a plurality of electrodes, each including a current collector, along a first direction; a sealing body provided so as to surround the electrode stack by stacking a plurality of sealing materials provided on each of the plurality of electrodes along the first direction; and a plurality of terminals joined to the current collectors of the plurality of electrodes, drawn out to the outside of the sealing body, and extending along a direction intersecting the first direction, the method including a terminal joining step of joining the terminals to the current collector at a peripheral portion thereof; and an inspection step of applying a tensile load to the terminals joined to the current collector in the extension direction of the terminals, the inspection step including a first confirmation step of confirming whether the tensile load reaches the inspection load; and a second confirmation step of confirming whether the time taken for the tensile load to reach the inspection load is equal to or shorter than a reference time, or whether the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a reference distance.

[0007] In this energy storage module manufacturing method, a terminal joining step of joining terminals to current collectors of electrodes and an inspection step of applying a tensile load to the terminals in the extension direction of the terminals to units including the electrodes and terminals formed in the terminal joining step are performed during manufacturing of the energy storage module. In the inspection step, a first inspection step is performed to check whether the tensile load applied to the terminals reaches the inspection load. This makes it possible to detect units in which the bonding strength between the current collectors and the terminals does not reach the inspection load.

[0008] Here, if the tensile load reaches the test load even though plastic deformation occurs at the joint between the current collector and the terminal during the tensile test, the time required to reach the test load or the tensile stroke will be greater than when no plastic deformation occurs. Therefore, this energy storage module manufacturing method checks whether the time required for the tensile load to reach the test load is equal to or shorter than a reference time, or whether the tensile stroke required for the tensile load to reach the test load is equal to or shorter than a reference distance. This allows units whose time or stroke is longer than the reference time or distance to be detected as units whose bond strength has decreased due to plastic deformation caused by the tensile test. Therefore, this energy storage module manufacturing method ensures the bond strength between the terminal and the current collector.

[0009] The energy storage module manufacturing method according to the present disclosure may further include a sealing material joining process in which, for units including electrodes and terminals formed in the joining process, the time is equal to or shorter than a reference time or the stroke is equal to or shorter than a reference distance, a sealing material is arranged so as to overlap the current collector and the terminal when viewed from a direction intersecting the joining surface of the terminal on the current collector, and the sealing material is joined to the current collector and the terminal.

[0010] In the energy storage module manufacturing method according to the present disclosure, in the inspection process, a tensile load may be applied to the terminal, and the tensile load may be confirmed in a first confirmation process. If it is confirmed in a second confirmation process that the time has exceeded a reference time or that the stroke has exceeded a reference distance, the application of the tensile load to the terminal may be stopped.

[0011] According to the present disclosure, it is possible to provide a method for manufacturing an electricity storage module that can ensure the bonding strength between the terminal and the current collector.

[0012] FIG. 1 is a schematic plan view of an energy storage module according to one embodiment. FIG. 2 is a schematic side view showing an enlarged portion of the energy storage module shown in FIG. 1. FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a flowchart showing one step of a method for manufacturing an energy storage module according to this embodiment. FIG. 5 is a schematic view showing one step of the method for manufacturing an energy storage module shown in FIG. 4. FIG. 5(a) is a cross-sectional view, and FIG. 5(b) is a plan view. FIG. 6 is a flowchart showing each step of step S102. FIG. 7 is a schematic view showing step S102. FIG. 7(a) is a cross-sectional view, and FIG. 7(b) is a plan view. FIG. 8 is a graph showing the relationship between tensile load and time or stroke. FIG. 9 is a schematic view showing step S103. FIG. 9(a) is a plan view, and FIG. 9(b) is a cross-sectional view. FIG. 10 is a flowchart showing step S102 according to a modified example.

[0013] An embodiment of the present disclosure will be described below with reference to the drawings. In the description of each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate descriptions may be omitted. In addition, each drawing may show a Cartesian coordinate system consisting of an X-axis, a Y-axis, and a Z-axis.

[0014] Fig. 1 is a schematic plan view of an energy storage module according to one embodiment. Fig. 2 is a schematic side view showing an enlarged portion of the energy storage module shown in Fig. 1. Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 2. The liquid injection port shown in Figs. 1 and 2 and the sealing member shown in Fig. 1 are omitted from Fig. 3.

[0015] 1 to 3 is mounted on, for example, a forklift, a hybrid vehicle, or an electric vehicle. The power storage module 1 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage module 1 may also be, for example, an electric double layer capacitor. In this embodiment, the power storage module 1 is a lithium-ion secondary battery.

[0016] The energy storage module 1 includes an electrode stack 10, a sealing body 20, a sealing member 30, and a plurality of detection lines (a plurality of terminals) 60. The electrode stack 10 is configured by stacking a plurality of electrodes along the Z-axis direction. The electrode stack 10 has, for example, a rectangular parallelepiped shape.

[0017] The sealing body 20 has a liquid injection port 50 formed therein. The sealing body 20 is provided on the peripheral edge of the electrode stack 10. The sealing body 20 seals the side surface of the electrode stack 10. The sealing body 20 has, for example, a rectangular cylindrical shape. The sealing body 20 has electrical insulation properties.

[0018] The liquid inlet portion 50 is provided in a region of the sealing body 20 where a liquid inlet 20a (described later) is formed. The liquid inlet portion 50 is provided on a side surface 20c of the sealing body 20. The width of the liquid inlet portion 50 in the X-axis direction is smaller than the width of the sealing body 20 in the X-axis direction. Both ends of the liquid inlet portion 50 in the X-axis direction are located inside both ends of the sealing body 20 in the X-axis direction. The liquid inlet portion 50 includes a side wall portion 51, an overhang portion 52, an overhang portion 53, a frame portion 54, and a thin-walled portion 55.

[0019] The sidewall portion 51 is provided on the side surface 20c of the sealing body 20. The sidewall portion 51 has, for example, a rectangular plate shape. The overhang portion 52 is provided on one end surface of the sealing body 20 in the Z-axis direction. The overhang portion 52 has, for example, a rectangular plate shape. The overhang portion 53 is provided on the other end surface of the sealing body 20 in the Z-axis direction. The overhang portion 53 has, for example, a rectangular plate shape.

[0020] The liquid inlet portion 50 includes multiple frame portions 54. The frame portions 54 protrude from the side surfaces of the sidewall portions 51. When viewed from the Y-axis direction, the frame portions 54 surround each of the liquid inlets 20a lined up in the Z-axis direction. Thin-walled portions 55 are provided on the side surfaces of the sidewall portions 51 on both sides of the sidewall portions 51 in the X-axis direction. The thin-walled portions 55 extend along the Z-axis direction. The thin-walled portions 55 reach both ends of the sidewall portions 51 in the Z-axis direction. The thickness of the thin-walled portions 55 is smaller than the thickness of the sidewall portions 51. The sidewall portions 51, the overhanging portions 52 and 53, the frame portions 54, and the thin-walled portions 55 are each a partial region of the liquid inlet portion 50 integrated from the same material. The liquid inlet portion 50 is formed, for example, by injection molding.

[0021] The sealing body 20 includes a plurality of liquid injection ports 20a. The liquid injection ports 20a communicate with a plurality of internal spaces S of the electrode stack 10. The liquid injection ports 20a function as paths for injecting the electrolyte into the internal spaces S. The sealing body 20 has a plurality of liquid injection port rows. The plurality of liquid injection port rows are aligned in the Z-axis direction. Each liquid injection port row includes a plurality of liquid injection ports 20a aligned in the X-axis direction. Each liquid injection port row includes, for example, ten liquid injection ports 20a. When viewed from the Y-axis direction, in each liquid injection port row, the plurality of liquid injection ports 20a are aligned diagonally with respect to the X-axis direction. In each liquid injection port row, the liquid injection ports 20a are spaced apart from each other in the X-axis direction.

[0022] The sealing member 30 has, for example, a plate shape. When viewed from the X-axis direction, the sealing member 30 overlaps with the multiple frame portions 54. The sealing member 30 is, for example, a laminate sheet or the like. The sealing member 30 includes, for example, a metal layer and a resin layer. The material of the metal layer is, for example, aluminum. The sealing member 30 is welded to the tips of the multiple frame portions 54. This seals the multiple liquid injection ports 20a. Note that the sealing member 30 is not shown in FIG. 2.

[0023] The multiple detection wires 60 are located adjacent to the multiple frame portions 54 when viewed from the Y-axis direction. The detection wires 60 are used to detect the battery state of the energy storage module 1. In this embodiment, the voltage between adjacent electrodes of the energy storage module 1 is detected by an external device via the detection wires 60. That is, the detection wires 60 are, for example, voltage detection wires (i.e., include terminals for voltage detection). The detection wires 60 protrude from the side wall portion 51. Each detection wire 60 is joined to a respective current collector 15, which will be described later.

[0024] The energy storage module 1 has a plurality of detection line arrays 61. Each detection line array 61 has a plurality of detection lines 60 lined up in the Z-axis direction. That is, the plurality of detection lines 60 constituting one detection line array 61 overlap one another when viewed in the Z-axis direction. The plurality of detection line arrays 61 are lined up along the X-axis direction at predetermined intervals. The positions of the detection lines 60 in the Z-axis direction are shifted from one another. In this embodiment, the detection line arrays 61 are positioned closer to the negative terminal electrode 13 (described later) (lower side in FIG. 2 ) as they move away from the frame portion 54 in the X-axis direction.

[0025] When focusing on a pair of adjacent detection line arrays 61 in the X-axis direction, for example, one detection line 60 of one detection line array 61 is located closer to the positive electrode terminal electrode 12 (upper side in FIG. 2 ), which will be described later, than another detection line 60 of another detection line array 61 that is located on the opposite side of the frame portion 54 from the one detection line array 61. Note that the one detection line 60 is the Nth (N is a natural number) detection line of the one detection line array 61 when counted from the positive electrode terminal electrode 12 side, and the other detection line 60 is the Nth (N is a natural number) detection line of the other detection line array 61 when counted from the positive electrode terminal electrode 12 side.

[0026] The electrode stack 10 has a plurality of bipolar electrodes 11, a positive terminal electrode 12, a negative terminal electrode 13, and a plurality of separators 14. The plurality of bipolar electrodes 11, the positive terminal electrodes 12, the negative terminal electrodes 13, and the plurality of separators 14 are stacked along the Z-axis direction (first direction). That is, the electrode stack includes a plurality of electrodes (bipolar electrodes 11, positive terminal electrodes 12, negative terminal electrodes 13) stacked along the Z-axis direction.

[0027] The bipolar electrode 11 includes a current collector 15, a first active material layer 16, and a second active material layer 17. When viewed from the Z-axis direction, the current collector 15 has, for example, a rectangular shape. The current collector 15 includes a surface 15a and a surface 15b opposite to the surface 15a.

[0028] The first active material layer 16 is provided on the surface 15a. The first active material layer 16 is, for example, a positive electrode active material layer. When viewed from the Z-axis direction, the first active material layer 16 has, for example, a rectangular shape. The surface 15a includes an unformed region where the first active material layer 16 is not provided. When viewed from the Z-axis direction, the unformed region surrounds the first active material layer 16.

[0029] The second active material layer 17 is provided on the surface 15b. The polarity of the second active material layer 17 is different from the polarity of the first active material layer 16. The second active material layer 17 is, for example, a negative electrode active material layer. When viewed from the Z-axis direction, the second active material layer 17 has, for example, a rectangular shape. The surface 15b includes an unformed region where the second active material layer 17 is not provided. When viewed from the Z-axis direction, the unformed region surrounds the second active material layer 17. When viewed from the Z-axis direction, the area of ​​the second active material layer 17 is larger than the area of ​​the first active material layer 16. When viewed from the Z-axis direction, the outer edge of the second active material layer 17 is located outside the outer edge of the first active material layer 16.

[0030] The multiple bipolar electrodes 11 are stacked such that the first active material layer 16 of one bipolar electrode 11 faces the second active material layer 17 of another bipolar electrode 11. In other words, the multiple bipolar electrodes 11 are stacked such that, of adjacent bipolar electrodes 11, 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.

[0031] The positive terminal electrode 12 is disposed on one side of the plurality of bipolar electrodes 11 in the Z-axis direction. The positive terminal electrode 12 includes a current collector 15 and a first active material layer 16. The positive terminal electrode 12 differs from the bipolar electrode 11 primarily in that it does not include a second active material layer 17. The other configuration of the positive terminal electrode 12 may be the same as that of the bipolar electrode 11. The first active material layer 16 of the positive terminal electrode 12 faces the second active material layer 17 of the bipolar electrode 11. That is, the positive terminal electrode 12 is stacked such 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.

[0032] The negative electrode terminal electrode 13 is disposed on the other side of the plurality of bipolar electrodes 11 in the Z-axis direction. The negative electrode terminal electrode 13 includes a current collector 15 and a second active material layer 17. The negative electrode terminal electrode 13 differs from the bipolar electrode 11 mainly in that it does not include a first active material layer 16. The other configuration of the negative electrode terminal electrode 13 may be the same as that of the bipolar electrode 11. The second active material layer 17 of the negative electrode terminal electrode 13 faces the first active material layer 16 of the bipolar electrode 11. That is, the negative electrode terminal electrode 13 is stacked such that the surface 15b of the current collector 15 of the negative electrode terminal electrode 13 faces the surface 15a of the current collector 15 of the bipolar electrode 11 adjacent to the negative electrode terminal electrode 13.

[0033] The outer edges of the current collectors 15 of each electrode form the side surfaces of the electrode stack 10. Internal spaces S for accommodating an electrolyte are 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.

[0034] Separators 14 are disposed 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 separators 14 are disposed between the opposing first and second active material layers 16 and 17. The separators 14 are, for example, sheet-shaped. When viewed from the Z-axis direction, the outer edges of the separator 14 are located further outward than the outer edges of the first and second active material layers 16 and 17. The separators 14 allow charge carriers such as lithium ions to pass through. The separators 14 separate adjacent electrodes, thereby preventing electrical shorts due to contact between the electrodes. The separators 14 absorb and retain the electrolyte.

[0035] The current collector 15 has the function of maintaining the flow of current in the first active material layer 16 and the second active material layer 17 during discharging or charging of the energy storage module 1. The current collector 15 is, for example, a chemically inactive 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, etc. When the current collector 15 has multiple layers, the material of each layer may be any of the materials described above. A coating layer is formed on the surface of the current collector 15. The coating layer may be formed by a known method such as plating or spray coating.

[0036] The current collector 15 has, for example, a plate, foil, sheet, film, or mesh shape. The current collector 15 may be, for example, an 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. When the current collector 15 is foil-shaped, the thickness of the current collector 15 is, for example, 1 μm or more and 100 μm or less. The current collector 15 may be a laminate having multiple metal layers. The current collector 15 may be, for example, a laminate in which an aluminum layer and a copper layer are integrated. The current collector 15 may include, for example, an aluminum foil and copper plating formed on one side of the aluminum foil. The current collector 15 may include multiple metal foils bonded together with a conductive adhesive.

[0037] The first active material layer 16 includes a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The positive electrode active material is, for example, a composite oxide, metallic lithium, or sulfur. The composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. The composite oxide is, for example, olivine-type lithium iron phosphate (LiFePO ４ ), LiCoO ２ , LiNiMnCoO ２ etc.

[0038] The second active material layer 17 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the negative electrode active material include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, soft carbon, metal compounds, elements or compounds thereof that can be alloyed with lithium, and boron-doped carbon. Examples of the elements that can be alloyed with lithium include silicon and tin.

[0039] Each of the first active material layer 16 and the second active material layer 17 may contain a binder and a conductive additive in addition to the active material. The binder functions to bind the active material or conductive additive together and maintain the conductive network in the electrode. Examples of binders include fluorine-containing resins 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; carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders may be used alone or in combination. The conductive additive is a conductive material that enhances electrical conductivity. Examples of conductive additives include acetylene black, carbon black, and graphite. Examples of viscosity-adjusting solvents include N-methyl-2-pyrrolidone.

[0040] Formation of the first active material layer 16 on the surface 15a and the second active material layer 17 on the surface 15b can be achieved by conventional methods such as roll coating, die coating, dip coating, doctor blade coating, spray coating, and curtain coating. Specifically, an active material, a solvent, and, if necessary, a binder and a conductive additive are mixed to produce a slurry-like active material layer-forming composition, which is then applied to the surface 15a or the surface 15b and dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. The dried electrode may be compressed to increase electrode density.

[0041] The electrolyte solution is accommodated in the internal space S. The separator 14 is impregnated with the electrolyte solution. The electrolyte solution 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 solution is, for example, LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ ) ２ The non-aqueous solvent is a cyclic carbonate, a cyclic ester, a chain carbonate, a chain ester, an ether, etc. Two or more of these known solvent materials may be used in combination.

[0042] The sealing body 20 has a sealing material 41, a spacer 42, and a welded portion 43. The sealing material 41 has, for example, a rectangular frame shape. The sealing material 41 is provided on the peripheral portion 15c of each current collector 15 and covers the peripheral portion 15c. The sealing material 41 is provided on the surface 15a and the surface 15b of each current collector 15. The sealing material 41 is formed in a frame shape so as to surround the first active material layer 16 and the second active material layer 17 when viewed from the Z-axis direction. The inner edge of the sealing material 41 is separated from the first active material layer 16 and the second active material layer 17. The sealing material 41 is welded to the current collector 15.

[0043] The spacer 42 has, for example, a rectangular frame shape. The spacer 42 is provided between adjacent sealing materials 41. The spacer 42 is sandwiched between adjacent sealing materials 41. The inner peripheral portion of the spacer 42 overlaps with the second active material layer 17 when viewed from the Z-axis direction. The inner peripheral portion of the spacer 42 is located between the surface 15a of the current collector 15 and the second active material layer 17. The welded portion 43 is formed by welding and integrating the outer edges of each sealing material 41 and each spacer 42. The welded portion 43 has, for example, a rectangular cylindrical shape.

[0044] In this way, in the energy storage module 1, the sealing material 41 provided on each electrode is stacked in multiple layers along the Z-axis direction via spacers 42, surrounding the electrode stack 10, and a sealing body 20 is formed to seal the internal space S formed between adjacent electrodes in the Z-axis direction.

[0045] The sealant 41 and the spacer 42 are made of, for example, acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene. The sealant 41 and the spacer 42 are both electrolyte-resistant. The sealant 41 and the spacer 42 may be made of the same material or different materials. In this embodiment, the sealant 41 is made of, for example, acid-modified polyethylene or acid-modified polypropylene. In this embodiment, the spacer 42 is made of, for example, polyethylene or polypropylene. Acid-modified polyethylene and acid-modified polypropylene are more easily bonded to metal than non-acid-modified polyethylene and non-acid-modified polypropylene. When the current collector 15 is made of metal, the bonding strength of the sealant 41 to the current collector 15 can be improved by forming the sealant 41 from acid-modified polyethylene or acid-modified polypropylene.

[0046] The detection wires 60 are bonded to the surfaces 15b of the current collectors 15 and are electrically connected to the surfaces 15b. The detection wires 60 are located between the surfaces 15b of the current collectors 15 and the sealing material 41. The detection wires 60 pass through the sealing body 20 and are drawn out to the outside of the sealing body 20. The detection wires 60 are formed of, for example, a metal. The detection wires 60 are, for example, stainless steel foil. The detection wires 60 extend along a direction (the Y-axis direction in the illustrated example) that intersects with the Z-axis direction (first direction), which is the stacking direction of the electrodes in the electrode stack 10.

[0047] Next, a description will be given of a method for manufacturing an energy storage module according to this embodiment. In this embodiment, the above-described energy storage module 1 is manufactured. FIG. 4 is a flowchart showing one step of the method for manufacturing an energy storage module according to this embodiment. FIG. 5 is a schematic diagram showing one step of the method for manufacturing an energy storage module shown in FIG. 4. Note that the Cartesian coordinate system shown in FIG. 5 and subsequent figures is the same as the Cartesian coordinate system shown in FIGS. 1 to 3 for ease of understanding, but the directions during manufacturing do not need to match the directions in the manufactured energy storage module 1.

[0048] 4 and 5 , in the method for manufacturing an energy storage module according to this embodiment, first, a detection wire 60 is joined to a current collector 15 at a peripheral portion 15 c of the electrode, thereby forming a first electrode unit U1 (unit) consisting of the electrode and the detection wire 60 (step S101: terminal joining step). In the illustrated example, in step S101, a bipolar electrode 11 is prepared, and the detection wire 60 is joined (welded) to a surface 15 b at the peripheral portion 15 c of the current collector 15 of the bipolar electrode 11 by, for example, ultrasonic joining, thereby forming the first electrode unit U1 including the bipolar electrode 11.

[0049] In this embodiment, the surface 15b has a rectangular shape including four sides. In step S101, the detection wire 60 is joined to a first side 151 of the four sides of the surface 15b. In step S101, the detection wire 60 is also joined to the positive terminal electrode 12 and the negative terminal electrode 13 using a similar method, thereby forming a first electrode unit U1 including each of the positive terminal electrode 12 and the negative terminal electrode 13.

[0050] Next, a tensile test is performed on the detection wire 60 joined to the current collector 15 (step S102: inspection step). Step S102 will be described in detail. FIG. 6 is a flowchart showing each step of step S102. FIG. 7 is a schematic diagram showing step S102. As shown in FIGS. 6 and 7 , in step S102, a tensile load is applied to the detection wire 60 joined to the current collector 15 along the extension direction DP of the detection wire 60 (in the illustrated example, this is the Y-axis direction, or the shear direction of the detection wire 60), thereby performing a tensile test on the joint P between the current collector 15 and the detection wire 60.

[0051] In particular, in step S102, first, it is confirmed whether the tensile load reaches a predetermined inspection load (step S201: first confirmation step). As a result of the confirmation in step S201, if the tensile load does not reach the inspection load, for example, if the detection wire 60 falls off the current collector 15 before the tensile load reaches the inspection load, the first electrode unit U1 is rejected as a defective product.

[0052] On the other hand, as a result of checking in step S201, among the first electrode units U1 whose tensile load has reached the inspection load, there may be some in which, for example, the bond strength of the joint P between the current collector 15 and the detection wire 60 is insufficient, and when a tensile load is applied, plastic deformation (damage) occurs at the joint P, resulting in a longer time until the inspection load is reached or a larger tensile stroke.

[0053] Graph G1 in FIG. 8 shows a case where no plastic deformation occurs at the joint P and the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a predetermined reference distance (a non-defective product). Graph G2 shows a case where plastic deformation occurs at the joint P, resulting in a tensile stroke longer than the reference distance. As shown in graph G2, the first electrode unit U1 whose tensile stroke is longer than the reference distance is not rejected as a defective product in step S201 because the tensile load reaches the inspection load. However, because the joint strength of the first electrode unit U1 at the joint P is lower than the required strength due to the tensile test, if the first electrode unit U1 is sent to a subsequent process in this state, there is a risk of the detection wire 60 falling off. A similar phenomenon can occur with respect to the time until the inspection load is reached.

[0054] Therefore, in the subsequent step S202, after step S201, a check is made to see whether the time until the tensile load applied to the joint P reaches the inspection load is equal to or shorter than a reference time, or whether the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a reference distance (step S202: second check step). As a result of the check in step S202, a first electrode unit U1 whose time until the tensile load reaches the inspection load is longer than the reference time, or whose tensile stroke until the tensile load reaches the inspection load is longer than the reference distance, is rejected as a defective product. That is, only first electrode units U1 whose time until the tensile load reaches the inspection load is equal to or shorter than the reference time, or whose tensile stroke until the tensile load reaches the inspection load is equal to or shorter than the reference distance, are subjected to the subsequent steps (good products).

[0055] 4 and 9 , a sealant 41 is bonded to the first electrode unit that has undergone the tensile test in step S102 (step S103: sealant bonding step). More specifically, in step S103, the sealant 41 is placed on the surface 15b and the detection line 60 in the peripheral portion 15c of the current collector 15 of the first electrode unit U1, thereby forming the second electrode unit U2 (step S102: second step). More specifically, in step S102, a sealant 71, which is the basis for the sealant 41, is placed so as to overlap the current collector 15 and the detection line 60 when viewed from a direction intersecting the surface 15b, which is the bonding surface of the detection line 60 on the current collector 15 (the Z-axis direction in the illustrated example). Here, the sealant 71 is placed on the surface 15b side, and a sealant 71 is also placed on the surface 15a side. Then, a sealant 71 is welded to the surface 15 b of the current collector 15 of the second electrode unit U 2 and the detection line 60 on the surface 15 b , and also to the surface 15 a of the current collector 15 .

[0056] As a result, welding of the sealant 71 is completed at the first side portion 151 (and the same portion on the surface 15a) where the detection line 60 is provided on the surface 15b of the current collector 15. Thereafter, welding of the sealant 71 is performed at the three second side portions 152 (and the same portions on the surface 15a) where the detection line 60 is not provided on the surface 15b of the current collector 15. As a result, the frame-shaped sealant 71 is welded to the current collector 15 over its entirety, and the pair of sealants 71 form the sealant 41, and a third electrode unit including the sealant 41 is configured.

[0057] 4 , in the next step, a plurality of third electrode units configured as described above are stacked along the Z-axis direction via separators 14 and spacers 42 (step S104), and a plurality of seal materials 41 (of the plurality of third electrode units) stacked on one another are integrated to form the electrode stack 10 and the sealed body 20 (step S105). In step S105, the seal materials 41 and the plurality of spacers 42 are welded to one another to form welded portions 43, thereby forming the sealed body 20.

[0058] Thereafter, subsequent processes such as a process of forming a liquid injection port 50 in the sealing body 20 and a process of injecting the electrolyte into the internal space S using the liquid injection port 50 are carried out, and the energy storage module 1 is manufactured.

[0059] As described above, in the energy storage module manufacturing method according to this embodiment, when manufacturing the energy storage module 1, step S101 of joining the detection wire 60 to the current collector 15 of the electrode and step S102 of applying a tensile load to the detection wire 60 along the extension direction of the detection wire 60 to the first electrode unit U1 including the electrode and the detection wire 60 configured in step S101 are performed. In step S102, step S201 of checking whether the tensile load applied to the detection wire 60 reaches the inspection load is performed. This makes it possible to detect a first electrode unit U1 in which the bonding strength between the current collector 15 and the detection wire 60 does not reach the inspection load.

[0060] Here, if the tensile load reaches the test load even when plastic deformation occurs at the joint P between the current collector 15 and the detection wire 60 during the tensile test, the time required to reach the test load or the tensile stroke is longer than when no plastic deformation occurs. Therefore, step S202 is performed to check whether the time required for the tensile load to reach the test load is equal to or shorter than a reference time or whether the tensile stroke required for the tensile load to reach the test load is equal to or shorter than a reference distance. This allows a first electrode unit U1 whose time or stroke is longer than the reference time or distance to be detected as a first electrode unit U1 whose bond strength has decreased due to plastic deformation caused by the tensile test. Therefore, the energy storage module manufacturing method according to this embodiment ensures the bond strength between the detection wire 60 and the current collector 15. As a result, it is possible to prevent first electrode units U1 with reduced bond strength from being sent to subsequent processes, thereby improving reliability.

[0061] Furthermore, the energy storage module manufacturing method according to the present embodiment further includes, after step S102, step S103, in which, for a first electrode unit U1 including the electrode formed in step S101 and the detection wire 60, the time until the tensile load reaches the inspection load is equal to or shorter than a reference time, or the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a reference distance, a sealant 71 is disposed so as to overlap the current collector 15 and the detection wire 60 as viewed from the Y-axis direction intersecting the joint surface (surface 15b) of the detection wire 60 on the current collector 15, and the sealant 71 is joined to the current collector 15 and the detection wire 60. By providing the sealant 41 after the tensile test in this manner, it is possible to prevent the sealant 41, which is provided so as to cover the joint P between the current collector 15 and the detection wire 60, from affecting the tensile test.

[0062] The above embodiment has described one aspect of the energy storage module manufacturing method according to the present disclosure. Therefore, the energy storage module manufacturing method according to the present disclosure is not limited to the above embodiment and can be modified as desired.

[0063] For example, in the above embodiment, as an example of step S102, after checking in step S201 whether the tensile load applied to the detection line 60 reaches the inspection load, it is checked in step S202 whether the time until the tensile load reaches the inspection load is equal to or shorter than a reference time or whether the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a reference distance. However, steps S201 and S202 may be performed simultaneously, and if it is confirmed that the time or stroke until the tensile load reaches the inspection load has exceeded the reference distance, the application of the tensile load to the detection line 60 may be stopped. This modification will be described in more detail.

[0064] 10 is a flowchart showing step S102 according to a modified example. As shown in FIG. 10 , in this example, first, a tensile load is applied to the detection line 60 along the extension direction DP of the detection line 60 (step S301, inspection step). Then, a step of checking whether the tensile load reaches a predetermined inspection load (step S302, inspection step, first confirmation step) and a step of checking whether the time it takes for the tensile load to reach the inspection load is equal to or shorter than a reference time or whether the tensile stroke until the tensile load reaches the inspection load is equal to or shorter than a reference distance are simultaneously performed (step S302, inspection step, second confirmation step).

[0065] That is, in step S302, a tensile load is applied to the detection line 60 while checking the tensile load (first confirmation step), and a confirmation is made as to whether the time until the tensile load reaches the inspection load (here, the time from when the tensile load started to be applied) exceeds a reference time (second confirmation step), or whether the tensile stroke until the tensile load reaches the inspection load (here, the tensile stroke from when the tensile load started to be applied) exceeds a reference distance (second confirmation step). Thereafter, based on the confirmation made in step S302, it is determined whether the time has exceeded the reference time or whether the stroke has exceeded the reference distance (step S303).

[0066] If the result of the determination in step S303 indicates that the time has exceeded the reference time or that the stroke has exceeded the reference distance (step S303: YES), the application of the tensile load to the detection line 60 is stopped (step S304). On the other hand, if the result of the determination in step S303 indicates that the time has not exceeded the reference time or that the stroke has not exceeded the reference distance, the process proceeds to step S302, and confirmation is repeated while the tensile load is continuously applied.

[0067] In this manner, in this modified example, the tensile load is applied to the detection wire 60 and checked, and if it is confirmed that the time taken for the tensile load to reach the inspection load exceeds the reference time, or if it is confirmed that the tensile stroke required for the tensile load to reach the inspection load exceeds the reference distance, application of the tensile load to the detection wire 60 is stopped. This makes it possible to detect as a defective first electrode unit U1 in which the joint P between the detection wire 60 and the current collector 15 has undergone plastic deformation even before the tensile load reaches the inspection load.

[0068] 1...storage module, 10...electrode laminate, 15...current collector, 15b...surface, 15c...periphery, 20...sealing body, 41, 71...sealing material, 60...detection line (terminal), U1...first electrode unit (unit), P...joint.

Claims

1. A method for manufacturing an energy storage module comprising: an electrode stack formed by stacking a plurality of electrodes, each including a current collector, along a first direction; a sealing body provided so as to surround the electrode stack by stacking a plurality of sealing materials provided on each of the plurality of electrodes along the first direction; and a plurality of terminals joined to the current collectors of the plurality of electrodes, drawn to the outside of the sealing body, and extending along a direction intersecting the first direction, the method comprising: a terminal joining step of joining the terminals to the current collectors at peripheral portions of the current collectors; and an inspection step of applying a tensile load to the terminals joined to the current collectors in the extension direction of the terminals, wherein the inspection step includes: a first confirmation step of confirming whether the tensile load reaches an inspection load; and a second confirmation step of confirming whether the time taken for the tensile load to reach the inspection load is within a reference time, or whether the tensile stroke until the tensile load reaches the inspection load is within a reference distance.

2. The method for manufacturing a storage module according to claim 1, further comprising a sealing material joining process for arranging the sealing material so as to overlap the current collector and the terminal when viewed from a direction intersecting the joining surface of the terminal on the current collector, in a unit including the electrode and the terminal formed in the joining process, where the time is less than or equal to the reference time or the stroke is less than or equal to the reference distance, and joining the sealing material to the current collector and the terminal.

3. The method for manufacturing an energy storage module according to claim 1 or 2, wherein in the inspection step, while the tensile load is being applied to the terminal, the tensile load is checked in the first checking step, and when it is confirmed in the second checking step that the time has exceeded the reference time or that the stroke has exceeded the reference distance, application of the tensile load to the terminal is stopped.

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