Method for manufacturing power storage device

Abstract

This method for manufacturing a power storage device comprises: a step (S10) for preparing a module body comprising a laminate including a plurality of electrodes laminated in a first direction, and a sealing body for sealing a side surface of the laminate along the first direction; and a step (S20) for sealing a communication hole formed in the sealing body and communicating with an internal space of the laminate. The step (S20) for sealing the communication hole includes a preliminary heating step (S21) for moving a heating body toward the module body along a second direction to a first position to bring the heating body into contact with a frame part of the module body, and a welding step (S23) for moving the heating body toward the module body to a second position closer to a sealing body part than the first position, and welding a sealing material to the frame part. In the welding step (S23), the sealing material is sandwiched between the frame part and the heating body.

Description

Method for manufacturing an electricity storage device

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

[0002] Patent Document 1 discloses a method for manufacturing an electricity storage device. In this method, a pressure adjustment valve is attached to a frame-shaped protrusion surrounding a liquid inlet provided on a battery module. The protrusion and the pressure adjustment valve are welded together to seal the liquid inlet.

[0003] Japanese Patent Application Laid-Open No. 2020-102360

[0004] The resin protrusion (frame) surrounding the fill port of the battery module can be permeated with the electrolyte by coming into contact with the electrolyte during the fill process, etc. If an attempt is made to seal each cell of the battery module by welding a sealant to the frame in such a state, the electrolyte in the resin forming the frame may evaporate due to the heat of welding, resulting in a risk of poor sealing.

[0005] The present disclosure provides a method for manufacturing an electricity storage device that can suppress the occurrence of sealing defects.

[0006] A method for manufacturing an energy storage device according to one aspect of the present disclosure includes the steps of: preparing a module main body including a stack including a plurality of electrodes stacked in a first direction and a sealing body that seals a side surface of the stack along the first direction; and sealing a communication hole formed in the sealing body and communicating with an internal space of the stack. The sealing body includes a seal main body portion having the communication hole and a frame portion that surrounds the communication hole when viewed from a second direction intersecting the first direction and protrudes further in the second direction than the seal main body portion. The step of sealing the communication hole includes a preheating step of moving a heating element along the second direction toward the module main body to a first position to bring the heating element into contact with the frame portion of the module main body; a separating step of moving the heating element that is in contact with the frame portion along the second direction away from the module main body to a retracted position to separate the heating element from the frame portion; and a welding step of, after the separating step, moving the heating element along the second direction toward the module main body to a second position that is closer to the seal main body portion than the first position and welding the sealing material to the frame portion. In the welding step, the sealing material is sandwiched between the frame and the heating body, and the heating body is moved to a second position to weld the sealing material to the frame.

[0007] In the manufacturing method of the above-described energy storage device, before the sealing material is welded to the frame, a heating body is brought into contact with the tip of the frame in a preheating step, thereby heating the tip of the frame and vaporizing the electrolyte that has permeated the tip of the frame. Therefore, when the welding step in which the sealing material is welded to the frame by the heating body is performed, the electrolyte that has permeated the frame has already been removed. Therefore, the occurrence of sealing defects can be suppressed.

[0008] In one example, the heater may be heated to a temperature above the melting point of the material forming the frame.

[0009] In one example, in the preheating step, the heating element can be pressed into the frame of the module body by a first pressing amount along the second direction, and in the welding step, the heating element can be pressed into the frame pressed into the first pressing amount along the second direction by a second pressing amount smaller than the first pressing amount.

[0010] In one example, in the step of sealing the communication holes, the steps from the preheating step to the welding step may be performed in a reduced pressure environment.

[0011] According to the present disclosure, it is possible to provide a method for manufacturing an electricity storage device that can suppress the occurrence of sealing defects.

[0012] FIG. 1 is a schematic plan view of an example of an energy storage device. FIG. 2 is a schematic view showing one side of a module main body constituting the example of the energy storage device. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a flow diagram showing an example of a method for manufacturing an energy storage device. FIG. 5 is a diagram showing a schematic view of each step in the example of the manufacturing method. FIG. 6 is a diagram showing a schematic view of each step in the example of the manufacturing method.

[0013] An embodiment will be described below with reference to the drawings. In the description of the drawings, identical or equivalent elements are denoted by the same reference numerals, and redundant description may be omitted. In the description, a Cartesian coordinate system defined by the X-axis, Y-axis, and Z-axis shown in the drawings may be referenced.

[0014] FIG. 1 is a schematic plan view showing a power storage device according to this embodiment. FIG. 2 is a schematic view of a module main body constituting the power storage device as seen from the Y direction. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. The power storage device 1 is a power storage device used in batteries for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage device 1 may also be an electric double layer capacitor. Here, the case where the power storage device 1 is a lithium-ion secondary battery is shown.

[0015] The energy storage device 1 includes a module body 1A and a sealing material 54. The module body 1A has a rectangular shape when viewed in the Z-axis direction (first direction) and has four outer surfaces 20s extending in the Z-axis direction. The outer surfaces 20s are composed of outer surfaces 20sA and 20sB facing each other in the Y-axis direction (second direction) and outer surfaces 20sC and 20sD facing each other in the X-axis direction (third direction). Both end surfaces of the module body 1A in the Z-axis direction are composed of a positive terminal electrode 12 and a negative terminal electrode 13, as described below, and are used for extracting power. A liquid injection frame 50 is provided on the outer surface 20sA of the module body 1A, and is used when injecting an electrolyte into the module body 1A.

[0016] 2 and 3 , the module main body 1A includes an electrode stack 10 and a sealing body 29 that surrounds the electrode stack 10 when viewed in the Z-axis direction. The electrode stack 10 includes multiple electrodes stacked along the Z-axis direction, which is the stacking direction of the electrodes and the thickness direction of the energy storage device 1. The multiple electrodes include multiple bipolar electrodes 11, a positive terminal electrode 12, and a negative terminal electrode 13. A separator 14 is interposed between adjacent electrodes. A pair of electrodes adjacent in the stacking direction forms one cell.

[0017] The bipolar electrode 11 includes a current collector 15, a positive electrode active material layer 16 provided on one surface of the current collector 15, and a negative electrode active material layer 17 provided on the other surface of the current collector 15. The current collector 15 is rectangular and sheet-shaped when viewed from the Z-axis direction. The active material layers (positive electrode active material layer 16, negative electrode active material layer 17) are provided in the center of the current collector 15 when viewed from the Z-axis direction, and the peripheral portion 15c of the current collector 15 is a so-called uncoated portion where no active material layer is provided. The positive electrode active material layer 16 is provided on a first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on a second surface 15b of the current collector 15, which is the surface opposite to the first surface 15a. The first surface 15a of the current collector 15 faces the negative side in the Z-axis direction, and the second surface 15b of the current collector 15 faces the positive side in the Z-axis direction. The multiple bipolar electrodes 11 are stacked so that the positive electrode active material layer 16 of one bipolar electrode 11 and the negative electrode active material layer 17 of the other bipolar electrode 11 adjacent in the stacking direction face each other with the separator 14 interposed therebetween.

[0018] The positive terminal electrode 12 has a current collector 15 and a positive electrode active material layer 16 provided on a first surface 15a of the current collector 15. No active material layer is provided on a second surface 15b of the current collector 15 of the positive terminal electrode 12. In other words, the second surface 15b of the current collector 15 of the positive terminal electrode 12 constitutes the positive electrode terminal surface of the energy storage device 1. The positive terminal electrode 12 is laminated on the bipolar electrode 11 at the positive end of the electrode laminate 10 in the Z-axis direction. The positive terminal electrode 12 is laminated on the bipolar electrode 11 so that the positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11 with the separator 14 interposed therebetween.

[0019] The negative electrode terminal electrode 13 has a current collector 15 and a negative electrode active material layer 17 provided on a second surface 15b of the current collector 15. No active material layer is provided on a first surface 15a of the current collector 15 of the negative electrode terminal electrode 13. In other words, the first surface 15a of the current collector 15 of the negative electrode terminal electrode 13 constitutes the negative electrode terminal surface of the energy storage device 1. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 at the negative end of the electrode laminate 10 in the Z-axis direction. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 so that the negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11 with the separator 14 interposed therebetween. In this embodiment, the current collectors of the bipolar electrode 11, the positive terminal electrode 12, and the negative terminal electrode 13 are designated by the same reference numeral 15, but the current collectors of the bipolar electrode 11, the positive terminal electrode 12, and the negative terminal electrode 13 may be the same as or different from one another.

[0020] The separators 14 are disposed between adjacent bipolar electrodes 11, between the positive terminal electrode 12 and the bipolar electrode 11, and between the negative terminal electrode 13 and the bipolar electrode 11. The separators 14 are interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, and separate the positive electrode active material layer 16 from the negative electrode active material layer 17. The separators 14 allow charge carriers such as lithium ions to pass through while preventing short circuits due to contact between adjacent electrodes.

[0021] The current collector 15 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charge of the lithium ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. Examples of conductive resin materials include resins obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed. The current collector 15 may have multiple layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material or conductive resin material.

[0022] A coating layer may be 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. The current collector 15 may be, for example, in the form of a plate, foil (e.g., metal foil), film, or mesh. Examples of metal foil include aluminum foil, copper foil, nickel foil, titanium foil, and 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 in the form of a foil, the thickness of the current collector 15 may be, for example, 1 μm to 100 μm. In this embodiment, the current collector 15 is an aluminum foil, or a foil formed by bonding and integrating aluminum foil and copper foil.

[0023] The positive electrode active material layer 16 contains a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanion compounds. The positive electrode active material may be any material that can be used in lithium ion secondary batteries. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains an olivine-type lithium iron phosphate (LiFePO ) as a composite oxide. ４ )

[0024] The negative electrode active material layer 17 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be a simple substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element or a compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (non-graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 17 includes graphite as a carbon-based material.

[0025] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter sometimes simply referred to as "active material layer") may further contain, as necessary, a conductive additive to enhance electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conductive polymer, electrolyte solution, etc.), an electrolyte supporting salt (lithium salt) to enhance ionic conductivity, etc. The conductive additive is added to enhance the conductivity of each electrode (bipolar electrode 11, positive terminal electrode 12, negative terminal electrode 13). Examples of the conductive additive include acetylene black, carbon black, graphite, carbon nanotubes, etc.

[0026] 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 acrylic acid and methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders may be used alone or in combination. Examples of solvents that may be used include water and N-methyl-2-pyrrolidone (NMP).

[0027] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte. Examples of materials for the separator 14 include polypropylene, polyethylene, polyolefin, and polyester. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may include, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The separator 14 may be composed of an electrolyte such as a polymer electrolyte or an inorganic electrolyte. Examples of the electrolyte impregnated in the separator 14 include a liquid electrolyte (electrolytic solution) containing a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent, and a polymer gel electrolyte containing an electrolyte retained in a polymer matrix.

[0028] When the separator 14 is impregnated with an electrolyte solution, the electrolyte salt is LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO ３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ ) ２ Known lithium salts such as those listed above may be used. Furthermore, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers may be used as the nonaqueous solvent. Two or more of these known solvent materials may be used in combination.

[0029] The seal 29 includes a seal main body 20 and a liquid injection frame 50 provided in a portion of the seal main body 20. The seal main body 20 is formed in a frame shape around the periphery of the electrode stack 10 so as to surround the periphery of the electrode stack 10 when viewed in the Z-axis direction. The seal main body 20 can be joined to the first surface 15a and the second surface 15b of each current collector 15 at the peripheral edge 15c of the current collector 15. The seal main body 20 can form an internal space S between adjacent current collectors 15 in the Z-axis direction and seal each of the internal spaces S. In other words, the seal main body 20 seals each cell formed by a pair of electrodes adjacent in the stacking direction. In this embodiment, each internal space S can contain an electrolyte (not shown). In other words, the seal main body 20 cooperates with adjacent current collectors 15 in the Z-axis direction to define an internal space S in which the electrolyte is contained. The seal body 20 can prevent the electrolyte solution contained in the internal space S from leaking out to the outside.

[0030] The seal body 20 can prevent air, moisture, and the like from entering and leaving between the outside of the electrode stack 10 and the internal space S. The seal body 20 can prevent, for example, gas generated in each electrode due to a charge / discharge reaction or the like from leaking to the outside of the module body 1A. The edge of the separator 14 is joined to the seal body 20. The seal body 20 includes an insulating material. Examples of materials for the seal body 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile-styrene resin.

[0031] An example of the seal main body 20 includes a plurality of seal materials 21, a pair of end seal materials 24, and a plurality of spacers 22. The seal materials 21, the end seal materials 24, and the spacers 22 may be frame-shaped members formed in a sheet shape. The seal main body 20 also has a welded end portion 23. The seal material 21 is frame-shaped when viewed from the Z-axis direction and is provided along the peripheral edge portion 15c of the current collector 15. The seal material 21 is provided so as to extend from the first surface 15a of the current collector 15, passing through the end face, to the second surface 15b, and covers the peripheral edge portion 15c. That is, on the first surface 15a and the second surface 15b of the current collector 15, the seal material 21 has an inner portion overlapping the current collector 15 and an outer portion located outside the edge of the current collector 15, as viewed from the Z direction. The outer portions of a pair of adjacent seal materials 21 sandwiching the current collector 15 are connected to each other. The seal material 21 can be welded to at least one of the first surface 15 a and the second surface 15 b of the current collector 15. In this embodiment, the seal material 21 is welded to both the first surface 15 a and the second surface 15 b of the current collector 15.

[0032] The end seal material 24 has a frame shape when viewed in the Z-axis direction and is provided along the peripheral edge 15c of the current collector 15 that constitutes the positive terminal electrode 12 and the negative terminal electrode 13, respectively. Therefore, the end seal material 24 is arranged to sandwich the plurality of seal materials 21 in the Z-axis direction. The end seal material 24 can be welded to at least one of the first surface 15a and the second surface 15b of the current collector 15. The end seal material 24 of this embodiment is welded to both the first surface 15a and the second surface 15b of the current collector 15. The end seal material 24 may be configured by further laminating a gas barrier layer made of a resin having lower gas permeability than the resin layer on a resin layer bonded to the current collector 15.

[0033] The spacer 22 has a frame shape when viewed from the Z-axis direction, and is arranged along the peripheral edge 15c of the current collector 15. The spacer 22 is arranged so as to be interposed between the seal materials 21 adjacent to each other in the Z-axis direction. The spacer 22 is also arranged so as to be interposed between the seal materials 21 and the end seal materials 24 adjacent to each other in the Z-axis direction. The spacer 22 can maintain the distance between the current collectors 15 adjacent to each other in the Z-axis direction. In other words, the spacer 22, the seal materials 21, and the end seal materials 24 define an internal space S between the adjacent current collectors 15.

[0034] The welded end portion 23 is formed by welding together and integrating the ends of the multiple seal materials 21, the pair of end seal materials 24, and the multiple spacers 22 on the opposite side to the internal space S. When viewed from the Z-axis direction, the welded end portion 23 has a frame shape that surrounds the electrode stack 10. The side of the welded end portion 23 on the opposite side to the internal space S extends along the Z-axis direction and forms the outer surface 20s of the seal main body 20. In other words, the seal main body 20 includes the outer surface 20s on the opposite side to the internal space S. The outer surface 20s may be formed as a flat surface.

[0035] The seal main body 20 has a plurality of communication holes 27 that communicate with each of the plurality of internal spaces S. As an example, the communication holes 27 are configured by cutting out a portion of the frame-shaped spacer 22 in a plan view. The communication holes 27 are through holes that penetrate the welded end portion 23. Each communication hole 27 has one opening in the internal space S and the other opening on the outer surface 20s of the seal main body 20. In the illustrated example, an opening is formed on the outer surface 20sA.

[0036] The liquid filling frame 50 is formed so as to overlap the region of the outer surface 20sA in which the communication holes 27 are formed. The liquid filling frame 50 is joined to the welding end portion 23. For example, the liquid filling frame 50 is formed by injection molding. The liquid filling frame is integrally joined to the welding end portion 23 by the heat generated during injection molding. One example of the liquid filling frame 50 includes a main body portion 51, a protruding frame portion 53 (frame portion), and an overhang portion 55.

[0037] The main body 51 partially covers the outer surface 20sA. For example, the main body 51 covers the outer surface 20sA so as to include the region where the plurality of communication holes 27 are formed on the outer surface 20sA. As described above, the plurality of communication holes 27 are respectively connected to the plurality of internal spaces S. In the example shown in FIG. 2 , 30 communication holes 27 corresponding to the 30 internal spaces formed between the current collectors 15 are discretely arranged in the X-axis direction and the Z-axis direction. More specifically, the communication holes 27 corresponding to the internal spaces of the first to tenth layers, with the positive terminal electrode 12 as the base end, are arranged at equal intervals along the X-axis direction, and the communication holes 27 corresponding to the internal spaces of the eleventh to twentieth layers and the communication holes 27 corresponding to the internal spaces of the twenty-first to thirtieth layers are arranged in order below the internal spaces of the first to tenth layers in the Z-axis direction. The main body 51 extends in a rectangular shape along the X-axis direction and the Z-axis direction to cover the area in which the 30 communication holes 27 are formed.

[0038] The main body 51 is formed in the shape of a rectangular plate having a predetermined thickness in the Y-axis direction. The main body 51 has a liquid injection port 52 that opens at a position corresponding to the communication hole 27. In other words, the communication hole 27 and the liquid injection port 52 are in communication with each other.

[0039] The protruding frame portion 53 protrudes along the Y-axis direction from the main body portion 51 as a base end. When viewed from the Y-axis direction, the protruding frame portion 53 surrounds each of the liquid inlet ports 52 (communication holes 27) and functions as a partition wall that separates each of the liquid inlet ports 52. In the example of Fig. 2, ten protruding frame portions 53 are arranged in the X-axis direction, each having three spaces formed therein to separate the three liquid inlet ports 52 aligned in the Z-axis direction.

[0040] As an example, the protruding frame portions 53 are used when injecting the electrolyte solution into each of the internal spaces S. For example, when injecting the electrolyte solution, a nozzle of a liquid injection device is brought into close contact with the top surface of the protruding frame portions 53, and the electrolyte solution is introduced from the nozzle into the space of each of the protruding frame portions 53. This allows the electrolyte solution to be injected into the internal spaces S through the liquid injection ports 52 and the communication holes 27. After the electrolyte solution is injected, a sealant 54 for sealing the internal spaces S of each cell is provided on the protruding frame portions 53. The sealant 54 is a sheet-like or plate-like member. For example, the sealant 54 is a rectangular sheet having a size sufficient to collectively cover the multiple protruding frame portions 53 provided on the liquid injection frame 50. The sealant 54 has a resin layer on at least one outer surface, which is made of the same material as the protruding frame portions 53. For example, the sealant 54 may be a resin sheet or a laminate sheet in which a metal layer is laminated on a resin layer.

[0041] In one example, the main body 51 includes a terminal 58 for voltage detection. The terminal 58 is formed in the main body 51 at a position shifted toward the positive side in the X-axis direction relative to the multiple protruding frame portions 53. For example, the terminal 58 is provided adjacent to the protruding frame portion 53 formed at the end on the positive side in the X-axis direction, with the flat surface 51a interposed therebetween. In one example, the terminal 58 is provided at the end on the positive side in the X-axis direction of the main body 51. The terminal 58 provides multiple terminals 58a electrically connected to the multiple current collectors 15, respectively. One end of the terminal 58a is connected to the corresponding current collector 15, and the other end of the terminal 58a is exposed from the main body 51. The terminal 58a may be, for example, a metal pin, as long as it is electrically connected to the current collector 15.

[0042] The overhang portions 55 are provided on both end edges of the main body 51 in the Z-axis direction. The overhang portions 55 partially cover both end edges of the welded end 23 in the Z-axis direction. For example, the overhang portions 55 partially cover the end seal material 24 joined to the positive terminal electrode 12. In the illustrated example, the end edge 55a of the overhang portion 55 extends from the end edge of the welded end 23 to a position outside the inner edge 22a of the spacer 22 and the inner edge 21a of the seal material 21 when viewed in the Z-axis direction, but this is not limited to this. The overhang portions 55 may be formed in the shape of a rectangular plate having the same length as the main body 51 in the X-axis direction.

[0043] Next, a description will be given of a method for manufacturing the energy storage device 1. Fig. 4 is a flow diagram showing a method for manufacturing the energy storage device 1. Fig. 5 is a diagram schematically showing each step in an example of the manufacturing method.

[0044] In one example manufacturing method, first, a module main body 1A is prepared (preparation step S10). The manufacturing method of the module main body 1A is not particularly limited. As an example, electrodes to which a sealing material 21 or an end sealing material 24 is attached are stacked. Spacers 22 are disposed between the sealing materials 21 attached to adjacent electrodes in the stacking direction, and between the sealing material 21 and the end sealing material 24. Separators 14 are also disposed between adjacent electrodes in the stacking direction. The spacers 22 are provided with cutouts for forming communication holes 27. A plate for forming a liquid injection port is placed in the cutouts of the spacers, and the peripheral edges of the sealing materials 21, end sealing materials 24, and spacers 22 adjacent in the stacking direction are welded together. The module main body 1A is then placed in an injection mold, and a liquid injection frame 50 is formed in a part of the sealing main body 20 by injection molding. The plate is pulled out of the communication hole 27 to form a liquid injection port 52. This completes the preparation of the module main body 1A. The electrolyte solution is poured into the internal space S of the prepared module body 1A through the pouring port 52. When the electrolyte solution is poured into the module body 1A, the electrolyte solution may permeate the pouring frame 50. For example, the electrolyte solution may be poured in a state in which the module body 1A is upright so that the pouring port 52 faces upward.

[0045] Next, each cell formed in the module main body 1A is sealed (sealing step S20). In the sealing step S20, a sealant 54 is welded to the protruding frame portion 53 surrounding the communication hole 27 (liquid inlet 52). That is, by attaching the sealant 54 to the protruding frame portion 53, the cell space including the liquid inlet 52, the communication hole 27, and the internal space S is sealed. Note that in the sealing step S20, the steps from the preheating step to the welding step, which will be described later, can be performed in a reduced pressure environment, such as in a reduced pressure chamber.

[0046] In an example of the sealing step S20, first, the protruding frame portion 53 of the liquid filling frame 50 is heated, and the electrolyte that has permeated the protruding frame portion 53 is vaporized (preheating step S21). In other words, the electrolyte that has permeated the protruding frame portion 53 is removed. In an example of the preheating step S21, the protruding frame portion 53 is heated by a hot plate welding device 91. The hot plate welding device 91 has a hot plate 91a (heating element), which is a plate that can be heated to any temperature using a heat source such as a heater. In an example of the hot plate 91a, the hot plate 91a has a flat contact surface 91b that contacts the target. For example, the hot plate 91a may be supported by a moving mechanism that can reciprocate in one direction. The hot plate 91a shown in FIG. 5 is arranged to be reciprocally movable along the Y-axis direction of the module main body 1A. In this example, since the Y-axis direction of the module main body 1A is vertical, the hot plate 91a is reciprocally movable along the vertical direction. For example, the hot plate 91a may reciprocate between a standby position ((a) in FIG. 5 ) where it does not contact the protruding frame 53 of the module body 1A and any set position (e.g., first position P1 and second position P2) closer to the module body 1A than the standby position. This set position is vertically lower than the reference position P0 where the moving hot plate 91a starts to contact the protruding frame 53. The contact surface 91b of the hot plate 91a is set to be perpendicular to the vertical direction (i.e., coincident with the horizontal plane). However, the contact surface 91b does not have to be completely perpendicular to the vertical direction. That is, the contact surface 91b may be slightly inclined according to its parallelism with the horizontal plane.

[0047] In the preheating step S21, the hot plate 91a is moved along the Y-axis direction toward the module main body 1A to a first position P1. At this time, the hot plate 91a may be heated to a temperature higher than the melting point of the material constituting the protruding frame 53. The first position P1 is a position where the entire tip of the protruding frame 53 abuts against the hot plate 91a. For example, the length of the protruding frame 53 along the Y-axis direction varies depending on the flatness of the tip surface of the protruding frame 53. Even if the tip surface of the protruding frame 53 is aligned with the XZ plane, the distance between the tip surface (XZ plane) of the protruding frame 53 and the abutment surface 91b of the hot plate 91a varies depending on the parallelism between the workpiece and the equipment, i.e., the parallelism between the tip surface of the protruding frame 53 and the abutment surface 91b of the hot plate 91a. Therefore, the first position P1 is determined taking into consideration the flatness of the tip surface of the protruding frame 53 and the parallelism between the tip surface of the protruding frame and the contact surface 91b of the hot plate. In the preheating step S21, the contact surface 91b of the hot plate 91a is moved to the first position P1, so that the heated contact surface 91b contacts the entire tip of the protruding frame 53 on the module main body 1A. By contacting the hot plate 91a, the tip of the protruding frame 53 is pressed into the main body 51 in a heated state by a first predetermined amount (first pressing amount L1) from the reference position P0 to the first position P1 (see FIG. 5B). This melts and deforms the tip of the protruding frame 53. Furthermore, the heat of the hot plate 91a raises the temperature of the portion of the protruding frame 53 near the tip, even in the undeformed region. Therefore, the electrolyte that has permeated the tip region of the protruding frame 53 evaporates, and the electrolyte is removed from the tip of the protruding frame 53. A release sheet may be disposed between the contact surface 91b of the heat plate 91a and the protruding frame 53 to prevent the protruding frame 53 from adhering to the contact surface 91b.

[0048] Next, the hot plate 91a is separated from the protruding frame 53 (separating step S22). The hot plate 91a may move from the first position P1 along the Y-axis direction to a standby position (retracted position). In this state, the tip of the protruding frame 53 is deformed into a shape corresponding to the contact surface 91b of the hot plate 91a ((a) in FIG. 6). Therefore, the tip of each part of the protruding frame 53, which had unevenness before the hot plate 91a contacted, becomes flat along the XZ plane and is aligned at the first position P1. In other words, the flatness of the tip surface of the protruding frame 53 is ensured, and the parallelism between the tip surface (XZ plane) of the protruding frame 53 and the hot plate 91a is also ensured.

[0049] Next, the sealing material 54 is welded to the protruding frame portion 53, whose tip end surface is aligned at the first position P1, to seal the communication hole 27 (liquid inlet 52) ​​surrounded by the protruding frame portion 53 (welding step S23). In the welding step S23, the hot plate 91a (second heating element) is moved along the Y-axis direction toward the module main body 1A to a second position P2, which is closer to the sealing main body 20 than the first position P1. The sealing material 54 is disposed between the protruding frame portion 53 and the hot plate 91a. When the hot plate 91a is at the second position P2, the sealing material 54 is sandwiched between the protruding frame portion 53 and the hot plate 91a (see (b) in FIG. 6 ). Furthermore, the tip of the protruding frame portion 53, while heated, is pressed toward the main body 51 by a second predetermined amount (second pressing amount L2) from the first position P1 to the second position P2. This causes the sealing material 54 to be welded to the protruding frame portion 53. Thereafter, the heat plate 91a is separated from the protruding frame portion 53 ((c) in FIG. 6). In one example, the second pushing amount L2 is smaller than the first pushing amount L1.

[0050] For example, the sealant 54 may be disposed on the tip of the protruding frame portion 53 after the separating step S22 and before the welding step S23. As described above, the sealant 54 has a resin layer made of the same material as the material of the protruding frame portion 53 on at least one outer surface. In the welding step S23, the sealant 54 is disposed so that the resin layer of the sealant 54 faces the protruding frame portion 53. A release sheet may be disposed between the contact surface 91b of the hot plate 91a and the sealant 54 to prevent the sealant 54 from adhering to the contact surface 91b.

[0051] As described above, the manufacturing method of the energy storage device 1 in one example includes a preparation step S10 of preparing a module main body 1A including an electrode stack 10 including a plurality of electrodes stacked in the Z-axis direction and a sealing body 29 that seals the side surface of the electrode stack 10, and a sealing step S20 of sealing a liquid filling port 52 that is formed in the sealing body 29 and communicates with the internal space S of the electrode stack 10. The sealing body 29 includes a sealing main body 20 having the liquid filling port 52, and a protruding frame portion 53 that surrounds the liquid filling port 52 when viewed from the Y-axis direction that intersects the Z-axis direction and protrudes from the sealing main body 20 in the Y-axis direction. The sealing process S20 includes a preheating process S21 in which the hot plate 91a is moved along the Y-axis direction toward the module body 1A to a first position P1 to bring the hot plate 91a into contact with the protruding frame portion 53 of the module body 1A, a separating process S22 in which the hot plate 91a, which is in contact with the protruding frame portion 53, is moved along the second direction away from the module body 1A to a retracted position to separate the hot plate 91a from the protruding frame portion 53, and a welding process S23 in which, after the separating process S22, the hot plate 91a is moved along the Y-axis direction toward the module body 1A to a second position P2 that is closer to the sealing body 20 than the first position P1. In the welding process S23, the sealing material 54 is welded to the protruding frame portion 53 by sandwiching the sealing material 54 between the protruding frame portion 53 and the hot plate 91a.

[0052] In the manufacturing method of the energy storage device described above, after the electrolyte is injected into the internal space S of the module body 1A, initial charging, aging, inspection, and the like are performed, and then the filling port 52 is sealed. In this case, the electrolyte may permeate the resin protruding frame portion 53 surrounding the filling port 52 of the module body 1A. For example, if an attempt is made to weld the sealing material 54 to the protruding frame portion 53 without performing the preheating step S21, it is conceivable that the electrolyte permeating the protruding frame portion 53 will evaporate, causing air bubbles to form in the protruding frame portion 53. If air bubbles form in the welding area between the sealing material 54 and the protruding frame portion 53, it is conceivable that the sealing material 54 and the protruding frame portion 53 will not be properly welded.

[0053] In the manufacturing method according to the present embodiment, before the sealing material 54 is welded to the protruding frame portion 53, a hot plate 91a is brought into contact with the tip of the protruding frame portion 53, thereby heating the tip of the protruding frame portion 53 and vaporizing the electrolyte that has permeated the tip of the protruding frame portion 53. Therefore, when the sealing material 54 is welded to the protruding frame portion 53 by the hot plate 91a, the electrolyte that has permeated the protruding frame portion 53 has already been removed. This prevents air bubbles from being generated in the protruding frame portion 53, thereby preventing poor sealing in the protruding frame portion 53.

[0054] In one example, the heater may be heated to a temperature higher than the melting point of the material forming the protruding frame portion 53 .

[0055] Considering the flatness of the tip surface of the protruding frame portion 53 and the parallelism of the contact surface 91b, properly welding the sealant 54 to the protruding frame portion 53 requires pushing the hot plate 91a to the second position P2. In this case, for example, if the sealant 54 is to be welded to the protruding frame portion 53 without the preheating step S21, the time the hot plate 91a and the protruding frame portion 53 are in contact will be longer, increasing the amount of air expansion due to heat. Furthermore, because the hot plate 91a is pushed in by a large amount at one time, the internal volume decreases significantly due to the pushing of the hot plate 91a. This increases the internal pressure of the module body 1A. In this case, holes may form in the molten resin, or the sealant 54 may bulge outward and become thinner due to the internal pressure when the hot plate 91a separates.

[0056] In the manufacturing method according to the present embodiment, in the preheating step S21, the tip of the protruding frame portion 53 is melted, and the protruding frame portion 53 is pressed by the hot plate 91a so that the length of the protruding frame portion 53 in the Y-axis direction is aligned with the first position P1. Therefore, in the welding step S23, the time that the hot plate 91a and the protruding frame portion 53 are in contact can be shortened, and the amount of pressing by the hot plate 91a can be reduced. This suppresses an increase in the internal pressure of the module main body 1A.

[0057] In one example, in the preheating step S21, the hot plate 91a may be pressed into the protruding frame portion 53 of the module main body 1A by a first pressing amount L1 along the Y-axis direction. In the welding step S23, the hot plate 91a may be pressed into the protruding frame portion 53 pressed into the protruding frame portion 53 by the first pressing amount L1 along the Y-axis direction by a second pressing amount L2, which is smaller than the first pressing amount L1, in the preheating step S21. In this configuration, the tip position of the protruding frame portion 53 is aligned with the first position P1 in the preheating step S21, thereby reducing the second pressing amount L2 in the welding step S23. By reducing the pressing amount when welding the sealing material, the time during which the hot plate 91a is in contact with the protruding frame portion 53 is shortened, thereby reducing the degree of volume reduction of the internal space due to expansion and pressing of air inside the cell caused by the heat of the hot plate 91a. That is, the increase in the internal pressure of each cell during sealing is suppressed, and the occurrence of sealing failure is effectively suppressed.

[0058] In one example, in the process of sealing the communication hole 27, the steps from the preheating step S21 to the welding step S23 may be performed in a reduced pressure environment. This configuration suppresses an increase in the internal pressure of the module main body 1A. Furthermore, since the module main body 1A taken out into the atmosphere after sealing is completed can be restrained by atmospheric pressure, a restraining member for restraining the module is not required.

[0059] In one example, the contact surface 91b of the heat plate 91a may be a flat surface. In this configuration, the welding surface between the protruding frame portion and the sealing material 54 is formed flat, so that stress concentration in the sealing material 54 is suppressed.

[0060] Although examples of the embodiments of the present disclosure have been described above with reference to the drawings, the present disclosure is not limited to the above embodiments.

[0061] For example, the example is shown in which the same hot plate is used as the heating body in the preheating step S21 and the welding step S23, but different hot plates may be used as the heating body in the preheating step S21 and the welding step S23.In addition, in the above embodiment, the same hot plate is used in the preheating step S21 and the welding step S23, so the position control of the hot plate can be performed with high precision.

[0062] REFERENCE SIGNS LIST 1 Energy storage device 1A Module body 10 Electrode laminate (laminated body) 11 Bipolar electrode (electrode) 12 Positive electrode terminal electrode (electrode) 13 Negative electrode terminal electrode (electrode) 20 Sealing body 27 Communication hole 29 Sealing body 50 Liquid filling frame 53 Protruding frame portion (frame portion) 54 Sealing material 91a Heat plate (heating body) S Internal space

Claims

1. A method for manufacturing a module comprising the steps of: preparing a module body including a stack including a plurality of electrodes stacked in a first direction; and a sealing body that seals a side surface of the stack along the first direction; and sealing a communication hole formed in the sealing body and communicating with an internal space of the stack, wherein the sealing body includes a sealing body portion having the communication hole, and a frame portion that surrounds the communication hole when viewed from a second direction intersecting the first direction and protrudes in the second direction beyond the sealing body portion, and the step of sealing the communication hole includes: a preheating step of moving a heating element along the second direction toward the module body to a first position to bring the heating element into contact with the frame portion of the module body; and a separating step of moving the heating element that is in contact with the frame portion along the second direction away from the module body to a retracted position to separate the heating element from the frame portion. a welding step of moving the heating element toward the module body in the second direction to a second position closer to the sealing body than the first position after the separating step, and welding the sealing material to the frame portion, wherein in the welding step, the heating element is moved to the second position with the sealing material sandwiched between the frame portion and the heating element, thereby welding the sealing material to the frame portion.

2. The method for manufacturing an electric storage device according to claim 1, wherein the heater is heated to a temperature higher than the melting point of the material forming the frame.

3. A method for manufacturing an energy storage device as described in claim 2, wherein in the preheating step, the heating element is pressed into the frame portion of the module main body by a first pressing amount along the second direction, and in the welding step, the heating element is pressed into the frame portion pressed into the first pressing amount in the preheating step by a second pressing amount along the second direction, the second pressing amount being smaller than the first pressing amount.

4. The method for manufacturing an electric storage device according to any one of claims 1 to 3, wherein in the step of sealing the communication holes, the steps from the preheating step to the welding step are carried out in a reduced pressure environment.

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