Method for producing power storage device

Abstract

This method for producing a power storage device includes temporary sealing steps (S21, S24), removal steps (S23, S26), and a main sealing step (S27). In the temporary sealing steps (S21, S24), a heat plate is pressed against a protruding frame part (53) via a sealing material (54), and the sealing material (54) is joined to the protruding frame part (53) in a state in which the protruding frame part (53) and the sealing material (54) are incompatible. In the removal steps (S23, S26), the sealing material (54) joined to the protruding frame part (53) in a non-compatible state is removed. In the main sealing step (S27), the heat plate is pressed against the protruding frame part (53) via the sealing material (54) after removal of the sealing material (54), and the sealing material (54) is joined to the protruding frame part (53) while the protruding frame part (53) and the sealing material (54) are in a compatible state.

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 energy storage device. In this method, an electrolyte solution is injected into the inside of the outer case through a through-hole provided in the outer case. After the electrolyte solution is injected, a first sealing film is further welded to the upper surface of a base film welded to an adhesive surface surrounding the through-hole, temporarily sealing the through-hole. Then, after a gas exhaust hole is formed in the first sealing film, a second sealing film is welded to the upper surface of the first sealing film, thereby sealing the through-hole.

[0003] JP 2009-181906 A

[0004] In sealing the electricity storage device after injecting the electrolyte solution, taking into consideration the generation of gas in the process up to the final sealing, for example, temporary sealing and final sealing may be performed multiple times. If holes are formed in the temporary sealing film attached in the first temporary sealing to discharge gas and a new sealing film is attached on top of that temporary sealing film, for example, it becomes difficult to wipe off the electrolyte solution that has seeped in between the laminated sealing films. The electrolyte solution remaining between the laminated sealing films is undesirable because it can cause sealing defects.

[0005] The present disclosure provides a method for manufacturing an electricity storage device that can properly seal a liquid filling port after injection of an electrolyte solution.

[0006] A method for manufacturing an energy storage device according to one aspect of the present disclosure includes: a preparation step 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 a sealing step of sealing a communication hole formed in the sealing body and communicating with an internal space of the stack. The sealing body includes a sealing main body portion having a communication hole and a frame portion protruding from the sealing main body portion in a second direction intersecting the first direction so as to surround the communication hole. The sealing step includes a temporary sealing step of pressing a first heating body against the frame portion via a temporary sealing material to bond the temporary sealing material to the frame portion in a state where the frame portion and the temporary sealing material are incompatible with each other; a removal step of removing the temporary sealing material bonded to the frame portion in a state where the temporary sealing material is incompatible with each other; and a final sealing step of pressing a second heating body against the frame portion via a final sealing material after the temporary sealing material has been removed, to bond the final sealing material to the frame portion in a state where the frame portion and the final sealing material are compatible with each other.

[0007] In the above-described method for manufacturing an energy storage device, after the temporary sealing material is removed, the permanent sealing material is bonded to the frame in a compatible state. Therefore, multiple sealing materials are not stacked, and the electrolyte does not get between the sealing materials. Therefore, the frame serving as a liquid injection port can be properly sealed. Note that, in the temporary sealing step, the frame and the temporary sealing material are bonded in an incompatible state, so the temporary sealing material can be easily removed from the frame. Furthermore, in the permanent sealing step, the frame and the permanent sealing material are bonded in a compatible state, so the communication holes can be properly sealed.

[0008] In one example, the temporary sealing material may include a first temporary sealing material having a melting point lower than that of the frame portion on a surface facing the frame portion. The temporary sealing step may include a first temporary sealing step of heating at a temperature lower than the melting point of the frame portion and higher than the melting point of the first temporary sealing material to bond the first temporary sealing material to the frame portion in a state in which the frame portion and the first temporary sealing material are incompatible with each other.

[0009] In one example, the temporary sealing material may include a second temporary sealing material having a melting point higher than that of the frame portion on a surface facing the frame portion. The temporary sealing step may include a second temporary sealing step of heating at a temperature higher than the melting point of the frame portion and lower than the melting point of the second temporary sealing material to bond the second temporary sealing material to the frame portion in a state in which the frame portion and the second temporary sealing material are incompatible with each other.

[0010] In one example, the temporary sealing step may include a step of pressing the first heating element against the frame portion before pressing the first heating element against the frame portion via the temporary sealing material.

[0011] According to the present disclosure, it is possible to provide a method for manufacturing an electricity storage device that can properly seal the injection hole after injection of the electrolyte solution.

[0012] FIG. 1 is a schematic diagram of an example energy storage device. FIG. 2 is a schematic plan view of an example energy storage module. FIG. 3 is a schematic diagram showing one side of a module main body constituting an example energy storage module. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a flow diagram showing an example method for manufacturing an energy storage device. FIG. 6 is a schematic diagram showing each step in an example manufacturing method. FIG. 7 is a schematic diagram showing each step in an example manufacturing method. FIG. 8 is a schematic diagram showing each step in an example manufacturing method. FIG. 9 is a schematic diagram showing each step in an example manufacturing method. FIG. 10 is a schematic diagram showing each step in an example manufacturing method. FIG. 11 is a schematic diagram showing each step in an example manufacturing method. FIG. 12 is a schematic diagram showing each step in an example manufacturing method. FIG. 13 is a schematic diagram showing each step in an example 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, reference may be made to an orthogonal coordinate system defined by mutually intersecting X-, Y-, and Z-axes shown in the drawings.

[0014] FIG. 1 is a schematic diagram showing a state in which a plurality of energy storage modules 2 according to this embodiment are unitized in a battery manufacturing process (so-called an energy storage device 1 in process). FIG. 2 is a schematic plan view of an example energy storage module 2. FIG. 3 is a schematic view of a module main body 2A constituting the energy storage module 2, viewed from the Y direction. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. The energy storage module 2 is used, for example, in batteries for various vehicles, such as forklifts, hybrid vehicles, and electric vehicles. The energy storage module 2 is, for example, a secondary battery, such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 2 may also be an electric double layer capacitor. Here, a case is shown in which the energy storage module 2 is a lithium-ion secondary battery.

[0015] The energy storage device 1 in the process includes a plurality of energy storage modules 2, a plurality of current-carrying plates P, and a pair of restraint plates 5, 5. The plurality of energy storage modules 2 and the plurality of current-carrying plates P are alternately stacked in the Z-axis direction. In the example of FIG. 1 , four energy storage modules 2 and five current-carrying plates P are stacked. The five current-carrying plates P are respectively arranged between the energy storage modules 2 and on the end faces of the energy storage modules 2 at both ends in the stacking direction. The current-carrying plates P electrically connect the energy storage modules 2 to each other and can be used as terminals for extracting power from the energy storage device 1. For example, conductive members (bus bars) functioning as positive and negative terminals of the energy storage device 1 may be connected to the current-carrying plates P arranged at both ends in the stacking direction.

[0016] The pair of restraint plates 5 apply a restraint load to the stacked energy storage modules 2 and current-carrying plates P in the stacking direction. The pair of restraint plates 5 are arranged to sandwich the stacked energy storage modules and current-carrying plates P in the stacking direction. The restraint plates 5 are formed of, for example, metal plates. The pair of restraint plates 5 may be fastened to each other by fastening members (not shown) formed of, for example, bolts and nuts. An insulating plate 6 may be arranged between the current-carrying plates P and the restraint plates 5, which are arranged at both ends in the stacking direction.

[0017] The energy storage module 2 includes a module main body 2A and a sealing material 54. The module main body 2A 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 configured with 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 main body 2A in the Z-axis direction are configured with 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 main body 2A and is used when injecting an electrolyte into the module main body 2A.

[0018] 3 and 4 , the module main body 2A includes an electrode stack 10 and a sealing body 29 that surrounds the electrode stack 10 when viewed from 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 )

[0026] 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.

[0027] 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.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 from leaking to the outside of the module body 2A. 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 connected to the plurality of internal spaces S. In the example shown in FIG. 3 , 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.

[0040] 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.

[0041] 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 separating each of the liquid inlet ports 52. In the example of Fig. 3, 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.

[0042] 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 makes it possible to inject the electrolyte solution into the internal spaces S through the liquid injection port 52 and the communication hole 27. After the electrolyte solution has been injected, a sealant 54 for sealing the internal space S of each cell is provided on the protruding frame portions 53.

[0043] 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.

[0044] 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.

[0045] Next, a description will be given of a method for manufacturing the energy storage device 1. Fig. 5 is a flow diagram showing a method for manufacturing the energy storage device 1. Figs. 6 to 13 are diagrams schematically showing each step in an example of the manufacturing method.

[0046] In one example manufacturing method, first, a module main body 2A is prepared (preparation step S10). The manufacturing method of the module main body 2A is not particularly limited. As an example, electrodes to which a sealing material 21 or an edge 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 edge 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, edge sealing materials 24, and spacers 22 adjacent in the stacking direction are welded together. The module main body 2A is then placed in an injection mold, and a liquid injection frame 50 is formed in a portion of the sealing main body 20 by injection molding. The plate is removed from the communication hole 27 to form a liquid injection port 52. This completes the preparation of the module main body 2A. The electrolyte is poured into the internal space S of the prepared module body 2A through the pouring port 52. For example, the electrolyte may be poured in while the module body 2A is in an upright position so that the pouring port 52 faces upward.

[0047] Next, each cell formed in the module main body 2A is sealed (sealing step S20). In the sealing step S20, a sealant 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 of each cell, including the liquid inlet 52, the communication hole 27, and the internal space S, is sealed.

[0048] In an example of the sealing step S20, first, the protruding frame portion 53 of the liquid filling frame 50 is temporarily sealed in a reduced-pressure environment (first temporary sealing step S21 (temporary sealing step)). In an example of the first temporary sealing step S21, the protruding frame portion 53 is temporarily sealed by a hot plate welding device 91. The hot plate welding device 91 has a hot plate 91a (first heating element) that is a plate that can be heated to a desired temperature by 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 is brought into contact with an object. 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. 6 is arranged to be reciprocable along the Y-axis direction of the module main body 2A. In this example, since the Y-axis direction of the module main body 2A is aligned with the vertical direction, the hot plate 91a is reciprocable along the vertical direction. The contact surface 91b of the hot plate 91a is set to be perpendicular to the vertical direction (i.e., coincident with a horizontal plane).

[0049] In the first temporary sealing step S21, the hot plate 91a is moved along the Y-axis direction toward the module main body 2A. The hot plate 91a moves to a position where it contacts the entire tip of the protruding frame portion 53. For example, the length of the protruding frame portion 53 along the Y-axis direction varies depending on the flatness L1 of the tip surface of the protruding frame portion 53. Therefore, the movement distance of the hot plate 91a may be determined taking into consideration the flatness L1 of the tip surface of the protruding frame portion 53. In FIG. 6, the flatness L1 is shown as the maximum value of the variation in the tip position of the protruding frame portion 53.

[0050] A sealing material 54 (first temporary sealing material) is disposed between the protruding frame portion 53 and the hot plate 91a, and as the hot plate 91a moves, the sealing material 54 is sandwiched between the protruding frame portion 53 and the hot plate 91a. The sealing material 54 is a sheet-like or plate-like member. For example, the sealing material 54 is a rectangular sheet having a size that allows the sealing material 54 to collectively cover the multiple protruding frame portions 53 provided on the liquid filling frame 50.

[0051] The sealing material 54 has a resin layer 54a (low-melting-point sealing material) on its inner surface facing the protruding frame portion 53. The resin layer 54a may be made of a material compatible with the resin of the protruding frame portion 53. For example, if the protruding frame portion 53 is made of polyethylene, the resin layer 54a may also be made of polyethylene. In this case, the resin layer 54a may be made of a resin material with a relatively low melting point, such as low-density polyethylene, so that the melting point of the resin layer 54a is lower than that of the protruding frame portion 53, and the protruding frame portion 53 may be made of high-density polyethylene, which has a relatively high melting point. The thickness of the resin layer 54a may be designed to be greater than the flatness L1 shown in FIG. 6.

[0052] Furthermore, the sealing material 54 has a surface layer made of a material with a higher melting point than the resin layer 54a on the surface opposite the side of the resin layer 54a facing the protruding frame portion 53. The surface layer may be made of a resin material. In this embodiment, the sealing material 54 has a resin layer 54b as the surface layer. The melting point of the resin layer 54b may be higher than the melting point of the protruding frame portion 53. For example, if the resin layer 54a is made of low-density polyethylene with a relatively low melting point, the resin layer 54b may be made of polypropylene with a relatively high melting point. In one example, the protruding frame portion 53 may be made of polyethylene with a melting point of approximately 130°C, the resin layer 54a may be made of polyethylene with a melting point of approximately 110°C, and the resin layer 54b may be made of polypropylene with a melting point of approximately 160°C. The sealing material 54 may also be a laminate sheet including a metal layer. That is, the surface layer of the sealing material 54 may be a laminate sheet in which a metal layer and a resin layer are laminated.

[0053] In the first temporary sealing step S21, the hot plate 91a is heated to a first temperature (e.g., approximately 120°C) that is lower than the melting point of the material constituting the protruding frame portion 53 but higher than the melting point of the material constituting the resin layer 54a of the sealing material 54. The sealing material 54 is arranged so that the resin layer 54a faces the protruding frame portion 53 and the resin layer 54b faces the hot plate 91a. The hot plate 91a, heated to the first temperature, presses the sealing material 54 against the tip of the protruding frame portion 53, thereby sandwiching the sealing material 54 between the protruding frame portion 53 and the hot plate 91a with the resin layer 54a molten. Because the protruding frame portion 53 does not melt, the sealing material 54 is not fused to the protruding frame portion 53 but is instead bonded to the protruding frame portion 53 in an incompatible state. Because the sealing material 54 bonded to the protruding frame portion 53 is incompatible with the protruding frame portion 53, it is releasable from the protruding frame portion 53. In this embodiment, the first temporary sealing step S21 is a temporary sealing step using a sealing material melting method. Note that variations in the tip position of the protruding frame portion 53 due to flatness are absorbed by the thickness of the resin layer 54a. After the sealing material 54 is pressed into the protruding frame portion 53 by the hot plate 91a, the hot plate 91a returns to its standby position.

[0054] The temporarily sealed module bodies 2A are stacked alternately with the current-carrying plates P and are restrained by a pair of restraining plates 5 (see FIG. 7). Then, in the same environment, preliminary charging or the like may be performed to check whether or not a short circuit has occurred in the module bodies 2A.

[0055] Next, while the multiple module bodies 2A remain restrained by the restraint plates 5, initial charging, aging, etc. are performed on each module body 2A (first processing step S22). In the first processing step S22, initial charging, aging, etc. are performed in a state in which a hole H is opened in the sealant 54 that seals the protruding frame portion 53 of the liquid filling frame 50 (see FIG. 8). The hole H connects the internal space S with the outside of the module body 2A. Gas generated in the internal space S due to aging is released to the outside of the module body 2A through the hole H.

[0056] After the first processing step S22 is completed, the sealant 54 is removed from the protruding frame portion 53 (first removal step S23). As described above, the temporarily sealed sealant 54 is releasably bonded to the protruding frame portion 53. Therefore, when the sealant 54 is peeled off, the end face of the protruding frame portion 53 is exposed (see FIG. 9 ).

[0057] Next, in a reduced pressure environment, the protruding frame portion 53 of the liquid filling frame 50 is temporarily sealed (second temporary sealing step S24 (temporary sealing step)). In an example of the second temporary sealing step S24, the protruding frame portion 53 is temporarily sealed by a hot plate welding device 92. The hot plate welding device 92 has a hot plate 92a (second heating element) that is a plate that can be heated to a desired temperature by a heat source such as a heater. In an example of the hot plate 92a, the hot plate 92a has a flat contact surface 92b that is brought into contact with an object. In the present embodiment, the length of the hot plate 92a in the Z axis direction may be equal to or greater than the length of the stacked module bodies 2A in the Z axis direction so that the protruding frame portions 53 of the module bodies 2A restrained by the restraint plate 5 are temporarily sealed collectively.

[0058] The hot plate 92a may be supported by a moving mechanism that can reciprocate along one direction. The hot plate 92a shown in Figure 10 is arranged to be able to reciprocate along the Y-axis direction of the module body 2A. In this example, since the Y-axis direction of the module body 2A is aligned with the vertical direction, the hot plate 92a can reciprocate along the vertical direction. The contact surface 92b of the hot plate 92a is set to be perpendicular to the vertical direction.

[0059] In the second temporary sealing process S24, the hot plate 92a is moved along the Y-axis toward the multiple module bodies 2A. The hot plate 92a moves to a position where it abuts the entire tips of the multiple protruding frame portions 53. When multiple module bodies 2A are stacked, stacking tolerances may occur. For example, in the example of FIG. 7, the leftmost module body 2A is shifted upward, and the second module body 2A from the right is shifted downward. The movement distance of the hot plate 92a may be determined taking into consideration the stacking tolerance L2 of the module bodies 2A and the flatness of the tip surfaces of each protruding frame portion 53. The tolerance L2 is shown as the maximum variation in the stacking position of the module bodies 2A in the Y-axis direction. Note that, as shown in FIG. 10, the difference between the position closest to the hot plate 92a and the position farthest from the hot plate 92a on the protruding frame portions 53 of the multiple module bodies 2A can be expressed as the sum of the flatness L1 of the protruding frame portion 53 and the stacking tolerance L2 of the module bodies 2A.

[0060] A sealant 56 (second temporary sealant) is disposed between the hot plate 92a and each protruding frame portion 53. As the hot plate 92a moves, the sealant 56 is sandwiched between the protruding frame portion 53 and the hot plate 92a. In this embodiment, the sealant 56 is composed of a single layer of a resin layer 54b (high-melting-point sealant). When the same sealant 54 as the first temporary sealant is used as the second temporary sealant, the sealant 54 is disposed so that the resin layer 54b (high-melting-point sealant) faces the protruding frame portion 53 and the resin layer 54a faces the hot plate. In this case, a release sheet may be disposed between the hot plate 92a and the sealant 54 to prevent the sealant 54 from adhering to the hot plate 92a.

[0061] The hot plate 92a is heated to a second temperature (e.g., approximately 140°C) that is higher than the melting point of the material constituting the protruding frame portion 53 but lower than the melting point of the material constituting the resin layer 54b of the sealing material 56. The hot plate 92a presses the sealing material 56 against the protruding frame portion 53, thereby sandwiching the sealing material 56 between the protruding frame portion 53 and the hot plate 92a with the leading end of the protruding frame portion 53 melted (see FIG. 11 ). Because the resin layer 54b does not melt, the sealing material 56 is not fused to the protruding frame portion 53 but is instead bonded to the protruding frame portion 53 in an incompatible state. Because the sealing material 56 bonded to the protruding frame portion 53 is incompatible with the protruding frame portion 53, it can be peeled from the protruding frame portion 53. In this embodiment, the second temporary sealing step S24 is a temporary sealing step using a frame melting method. Incidentally, variations in the position of the tip of the protruding frame portion 53 due to the tolerance of the stacking of modules and the flatness of the protruding frame portion 53 are eliminated by the hot plate 92a pressing the molten protruding frame portion 53. After the hot plate 92a presses the sealing material 56 into the protruding frame portion 53, the hot plate 92a returns to the standby position.

[0062] After the plurality of module bodies 2A are temporarily sealed in the second temporary sealing step S24, the plurality of module bodies 2A are inspected for self-discharge characteristics (second processing step S25). In the self-discharge characteristic inspection, the temporarily sealed plurality of module bodies 2A are left in a predetermined environment for a certain period of time. This causes self-discharge in the module bodies 2A. During the self-discharge characteristic inspection, air permeates into the internal space S of the module bodies 2A, causing the internal space S to regain pressure compared to the state before the inspection began. Therefore, the sealing material 56 is subsequently removed from the protruding frame portion 53 of the liquid filling frame 50 (second removal step S26 (removal step)). As described above, the temporarily sealed sealing material 56 is releasably bonded to the protruding frame portion 53. Therefore, when the sealing material 56 is removed, the end surface of the protruding frame portion 53 is exposed (see FIG. 12 ).

[0063] Next, a sealant is attached to the protruding frame portion 53 of the liquid filling frame 50 in a reduced pressure environment, thereby performing a final seal (final seal step S27). In the final seal step S27, the protruding frame portion 53 and the sealant are welded together by a hot plate welding device 92. The hot plate 92a of the hot plate welding device 92 is moved along the Y-axis direction toward the multiple module bodies 2A. The hot plate 92a moves to a position where it abuts against the entire tips of the multiple protruding frame portions 53. In the final seal step S27, the tip positions of the multiple protruding frame portions 53 are aligned, so the movement distance of the hot plate 92a can be easily set.

[0064] A sealant 54 (main sealant) is disposed between the hot plate 92a and each protruding frame portion 53. As the hot plate 92a moves, the sealant 54 is sandwiched between the protruding frame portion 53 and the hot plate 92a ( FIG. 13 ). The hot plate 92a is heated to a temperature (e.g., approximately 140°C) higher than the melting point of the material constituting the protruding frame portion 53 and the material constituting the resin layer 54a of the sealant 54. The sealant 54 is disposed so that the resin layer 54a faces the protruding frame portion 53 and the resin layer 54b faces the hot plate 92a. When the hot plate 92a presses the sealant 54 against the protruding frame portion 53, the resin layer 54a melts, and the sealant 54 is sandwiched between the protruding frame portion 53 and the hot plate 92a with the leading edge of the protruding frame portion 53 melted. As a result, the sealing material 54 is joined (i.e., welded) to the protruding frame portion 53 with the resin layer 54a and the tip of the protruding frame portion being compatible with each other. After the sealing material 54 is pressed into the protruding frame portion 53 by the hot plate 92a, the hot plate 92a returns to the standby position. The energy storage modules 2 manufactured in this manner are released from the restraint by the restraining plate 5 and are sealed with laminate packs, thereby forming an energy storage device as a product.

[0065] As described above, the exemplary manufacturing method for a power storage device includes a preparation step S10 and a sealing step S20. The preparation step S10 prepares a module main body 2A 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 along the Z-axis direction. The sealing step S20 seals the communication holes 27 that are formed in the sealing body 29 and communicate with the internal space S of the electrode stack 10. The sealing body 29 includes a sealing main body portion 20 having the communication holes 27 and a protruding frame portion 53 that protrudes from the sealing main body portion 20 in the Y-axis direction so as to surround the communication holes 27. The sealing step S20 includes a temporary sealing step, a removal step, and a main sealing step. In the temporary sealing process, hot plates 91a and 92a are pressed against the protruding frame portion 53 via the temporary sealing material (sealing materials 54 and 56), and the temporary sealing material is bonded to the protruding frame portion 53 while the protruding frame portion 53 and the temporary sealing material are incompatible with each other. In the removal process, the temporary sealing material bonded to the protruding frame portion 53 while incompatible with each other is removed. In the main sealing process, after the temporary sealing material is removed, hot plate 92a is pressed against the protruding frame portion 53 via the main sealing material (sealing material 54), and the main sealing material is bonded to the protruding frame portion 53 while the protruding frame portion 53 and the main sealing material are incompatible with each other.

[0066] In the manufacturing method of the energy storage device described above, after the temporary sealing materials 54, 56 are removed, another sealing material 54 serving as a permanent sealing material is bonded to the protruding frame portion 53 in a compatible state. Therefore, multiple sealing materials 54, 56 are not stacked, and an event in which the electrolyte solution enters between the sealing materials does not occur. Therefore, the liquid filling hole 52 can be properly sealed. Note that in the temporary sealing step, the protruding frame portion 53 and the sealing material 54 are bonded in an incompatible state, so the sealing material 54 can be easily removed from the protruding frame portion 53. Furthermore, in the permanent sealing step, the protruding frame portion 53 and the sealing material 54 are bonded in a compatible state, so the communication hole 27 can be properly sealed.

[0067] When multiple sealing materials are stacked, there is a risk of wrinkles occurring in the sealing materials due to welding between the stacked sealing materials. Furthermore, overlapping multiple sealing materials may make image inspection of the welding portion between the sealing material and the protruding frame portion 53 difficult. Furthermore, if any sealing material with gas vent holes remains, there is a risk that the intermediate layer of the sealing material may be exposed to the electrolyte. The above manufacturing method does not involve stacking multiple sealing materials, so these risks do not occur.

[0068] In one example, the sealing material 54 may include a resin layer 54a (first temporary sealing material) having a melting point lower than that of the protruding frame portion 53 on the surface facing the protruding frame portion 53. The temporary sealing step may include a first temporary sealing step S21 in which the sealing material 54 is bonded to the protruding frame portion 53 while the protruding frame portion 53 and the resin layer 54a are incompatible with each other by heating at a temperature lower than that of the protruding frame portion 53 and higher than that of the resin layer 54a. In the first temporary sealing step S21, the protruding frame portion 53 does not melt, thereby suppressing deformation of the protruding frame portion 53. Furthermore, since the protruding frame portion 53 and the resin layer 54a are incompatible with each other, the sealing material 54 is easily peeled off.

[0069] In one example, the sealing material 56 may include, on a surface facing the protruding frame portion 53, a resin layer 54b (second temporary sealing material) having a melting point higher than that of the protruding frame portion 53. The temporary sealing step may include a second temporary sealing step S24 in which the sealing material 56 is bonded to the protruding frame portion 53 in a state in which the protruding frame portion 53 and the resin layer 54b are incompatible with each other by heating at a temperature higher than the melting point of the protruding frame portion 53 and lower than the melting point of the resin layer 54b. In the second temporary sealing step S24, the sealing material 56 is easily peeled off because the protruding frame portion 53 and the resin layer 54b are incompatible with each other.

[0070] Thus, the method for temporarily sealing the protruding frame portion 53 includes a first temporary sealing step S21 in which the protruding frame portion 53 is sealed by melting the sealing material 54 without melting the protruding frame portion 53, and a second temporary sealing step S24 in which the protruding frame portion 53 is sealed by melting the sealing material 54 without melting the sealing material 56. In the second temporary sealing step S24, the protruding frame portions 53 of the stacked module bodies 2A are temporarily sealed together. In this case, due to stacking tolerances of the module bodies 2A, some module bodies 2A are closer to the hot plate 92a and others are farther from the hot plate 92a. If the protruding frame portion 53 is not melted, the presence of the protruding frame portion 53 of the module body 2A closest to the hot plate 92a may prevent the hot plate 92a from being sufficiently pushed in to reach the module body 2A farther from the hot plate 92a. However, in the second temporary sealing step S24 according to the above embodiment, the protruding frame portion 53 is melted, allowing the hot plate 92a to be sufficiently pushed in.

[0071] Furthermore, in the second temporary sealing step S24, temporary sealing is performed by the frame melting method while the multiple module bodies 2A are stacked, so that the leading edge positions of the protruding frame portions 53 of the multiple stacked module bodies 2A can be aligned. As a result, the amount of depression of the protruding frame portions 53 in the main sealing step, which is performed while the modules are stacked, can be reduced, and an increase in internal pressure in each module in the main sealing step can be suppressed, allowing each module to be properly sealed with high precision.

[0072] Furthermore, since temporary sealing is performed using a sealing material melting method in the first temporary sealing step S21, there is no need to ensure a sufficient amount of melted frame portion for the first temporary sealing step, and the protruding length of the protruding frame portion 53 formed by injection molding can be shortened, allowing the protruding frame portion 53 to be formed accurately into the desired shape.

[0073] 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.

[0074] For example, although the example has been shown in which the first temporary sealing step S21 involves temporary sealing in which the temporary sealing material is melted without melting the protruding frame portion 53 (temporary sealing by a sealant melting method), and the second temporary sealing step S24 involves temporary sealing in which the protruding frame portion 53 is melted without melting the temporary sealing material (temporary sealing by a frame melting method), it is also possible to perform temporary sealing in which the protruding frame portion 53 is melted without melting the temporary sealing material (temporary sealing by a frame melting method) in the first temporary sealing step S21, and then perform temporary sealing in which the temporary sealing material is melted without melting the protruding frame portion 53 in the second temporary sealing step S24. That is, it is also possible to melt the protruding frame portion 53 in the first temporary sealing step S21 to bond the temporary sealing material and the protruding frame portion 53, peel the temporary sealing material from the protruding frame portion 53 after the first processing step S22, and melt the temporary sealing material to bond the temporary sealing material and the protruding frame portion 53 in the second temporary sealing step S24.

[0075] In both the first temporary sealing step S21 and the second temporary sealing step S24, temporary sealing may be performed by the frame melting method. Similarly, in both the first temporary sealing step S21 and the second temporary sealing step S24, temporary sealing may be performed by the sealant melting method.

[0076] Although the temporary sealing step is performed twice, that is, the first temporary sealing step S21 and the second temporary sealing step S24, the temporary sealing step may be performed only once. That is, after the first temporary sealing step S21, the temporary sealing material may be peeled off and the final sealing may be performed using the final sealing material. In this case, the first temporary sealing step S21 may be a temporary sealing step using a sealing material melting method or a temporary sealing step using a frame melting method.

[0077] As the temporary sealing step, a third temporary sealing step may be performed after the first temporary sealing step S21 and the second temporary sealing step S24. In this case, after the third temporary sealing step is performed, the temporary sealing material may be peeled off and final sealing may be performed using a final sealing material. The third temporary sealing step may be a temporary sealing step using a sealing material melting method or a temporary sealing step using a frame melting method.

[0078] Although an example in which the same sealing material is used in the first temporary sealing step S21, the second temporary sealing step S24, and the final sealing step S27 has been described, this is not limiting. Different sealing materials may be used in the first temporary sealing step S21, the second temporary sealing step S24, and the final sealing step S27. If melting of the protruding frame portion 53 is not desired during temporary sealing, the sealing material may be formed of a material having a melting point lower than that of the material of the protruding frame portion 53. If melting of the protruding frame portion 53 is desired during temporary sealing, the sealing material may be formed of a material having a melting point higher than that of the material of the protruding frame portion 53, or a material with a different component that is incompatible with the material of the protruding frame portion 53. If final sealing of the protruding frame portion 53 is desired, the sealing material may be formed of a material that can be welded to the protruding frame portion 53.

[0079] Although an example has been shown in which the hot plate welding device 91 and the hot plate welding device 92 are used in the first temporary sealing process S21 and the second temporary sealing process S24, for example, the hot plate welding device 92 may be used in either process.

[0080] The sealing step S20 may include a preheating step. In this preheating step, before pressing the hot plate 91a against the protruding frame portion 53 via the sealing material 54, the hot plate 91a is pressed against the protruding frame portion 53 without the sealing material 54, and then the hot plate 91a is separated from the protruding frame portion 53. In the preheating step, the hot plate 91a may be heated to a temperature higher than the melting point of the material constituting the protruding frame portion 53. In the preheating step, the hot plate 91a may be pressed against the protruding frame portion 53 with a release sheet disposed between the hot plate 91a and the protruding frame portion 53 to facilitate separation of the hot plate 91a from the molten tip of the protruding frame portion 53. In the preheating step, the hot plate 91a is pressed against the protruding frame portion 53, melting the tip of the protruding frame portion 53 and aligning the tip position of the protruding frame portion 53. The preheating step eliminates variations in the position of the tip of the protruding frame portion 53 and also ensures parallelism between the heating body (hot plate 91 a) and the protruding frame portion 53. Therefore, it is possible to prevent defective sealing in the temporary sealing step and the main sealing step, which are performed immediately after the preheating step.

[0081] The sealing step S20 may also include another preheating step. This preheating step may involve pressing a hot plate 92a against the protruding frame portion 53 immediately before a main sealing step S27 in which a hot plate 92a is pressed against the protruding frame portion 53 via the sealing material 54 to bond the sealing material 54 and the protruding frame portion 53 in a compatible state. This preheating step may involve pressing the hot plate 92a against the protruding frame portion 53 immediately before a temporary sealing step by a frame melting method in which a hot plate 92a is pressed against the protruding frame portion 53 via the sealing material 56 (temporary sealing material) to melt only the protruding frame portion 53 and bond the protruding frame portion 53 to the temporary sealing material.

[0082] The protruding frame portion 53 surrounding the liquid filling port 52 may be permeated with electrolyte by contacting the electrolyte during a liquid filling process or the like. For example, if the module main body 2A is left for a long time during testing for aging, self-discharge characteristics, or the like, electrolyte may permeate the tip of the protruding frame portion 53. In such a state, when attempting to weld the sealing material 54 to the protruding frame portion 53, the electrolyte in the resin forming the protruding frame portion 53 may evaporate due to the heat of welding, resulting in a sealing defect. If the protruding frame portion 53 is heated by a hot plate during a preheating process, for example, immediately before the second temporary sealing process S24 or the main sealing process S27, the tip of the protruding frame portion 53 is heated, and the electrolyte permeating the tip of the protruding frame portion 53 evaporates. Therefore, by the process of welding the sealing material 54 to the protruding frame portion 53 using a hot plate, the electrolyte that has permeated the protruding frame portion 53 has already been removed. This prevents sealing defects from occurring.

[0083] An embodiment of the present disclosure can be expressed as follows: [1] A method for manufacturing an energy storage device, comprising: a preparation step 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; a sealing step of sealing a communication hole formed in the sealing body and communicating with an internal space of the stack, the sealing body including a sealing main body portion having the communication hole and a frame portion that protrudes from the sealing main body portion in a second direction intersecting the first direction so as to surround the communication hole; a temporary sealing step of pressing a first heating body against the frame portion via a temporary sealing material to bond the temporary sealing material to the frame portion in a state where the frame portion and the temporary sealing material are incompatible with each other; a removal step of removing the temporary sealing material bonded to the frame portion in an incompatible state; and a final sealing step of pressing a second heating body against the frame portion via a final sealing material after the temporary sealing material has been removed, and bonding the final sealing material to the frame portion in a state where the frame portion and the temporary sealing material are compatible with each other. [2] The method for manufacturing an electric storage device according to [1], wherein the temporary sealing material includes a first temporary sealing material having a melting point lower than that of the frame portion, and the temporary sealing step includes a first temporary sealing step of heating at a temperature lower than the melting point of the frame portion and higher than the melting point of the first temporary sealing material, thereby joining the first temporary sealing material to the frame portion in a state where the frame portion and the first temporary sealing material are incompatible. [3] The method for manufacturing an electric storage device according to [1] or [2], wherein the temporary sealing material includes a second temporary sealing material having a melting point higher than that of the frame portion, and the temporary sealing step includes a second temporary sealing step of heating at a temperature higher than the melting point of the frame portion and lower than the melting point of the second temporary sealing material, thereby joining the second temporary sealing material to the frame portion in a state where the frame portion and the second temporary sealing material are incompatible. [4] The method for manufacturing an electric storage device according to any one of [1] to [3], wherein the temporary sealing step includes a step of pressing the first heating body against the frame portion before pressing the first heating body against the frame portion via the temporary sealing material.

[0084] 2 Energy storage module (energy storage device) 2A Module body 10 Electrode stack (stack) 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 (frame) 54 Sealing material S Internal space

Claims

1. A method for manufacturing an energy storage device, comprising: a preparation step 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; a sealing step of sealing communication holes formed in the sealing body and communicating with an internal space of the stack, wherein the sealing body includes a sealing main body portion having the communication holes and a frame portion that protrudes from the sealing main body portion in a second direction that intersects with the first direction so as to surround the communication holes; and the sealing step comprises: a temporary sealing step of pressing a first heating body against the frame portion via a temporary sealing material, and joining the temporary sealing material to the frame portion in a state where the frame portion and the temporary sealing material are incompatible; a removal step of removing the temporary sealing material joined to the frame portion in an incompatible state; and a final sealing step of pressing a second heating body against the frame portion via a final sealing material, after the temporary sealing material has been removed, and joining the frame portion to the frame portion in a state where the frame portion and the final sealing material are compatible with each other.

2. A method for manufacturing an energy storage device as described in claim 1, wherein the temporary sealing material includes a first temporary sealing material on a surface facing the frame portion, the first temporary sealing material having a melting point lower than that of the frame portion, and the temporary sealing process includes a first temporary sealing process in which the first temporary sealing material is joined to the frame portion in a state in which the frame portion and the first temporary sealing material are incompatible by heating at a temperature lower than the melting point of the frame portion and higher than the melting point of the first temporary sealing material.

3. A method for manufacturing an energy storage device as described in claim 1 or 2, wherein the temporary sealing material includes a second temporary sealing material having a melting point higher than the melting point of the frame portion on a surface facing the frame portion, and the temporary sealing process includes a second temporary sealing process in which the second temporary sealing material is joined to the frame portion in a state in which the frame portion and the second temporary sealing material are incompatible by heating at a temperature higher than the melting point of the frame portion and lower than the melting point of the second temporary sealing material.

4. The method for manufacturing an energy storage device according to claim 1, wherein the temporary sealing step includes a step of pressing the first heating element against the frame portion before pressing the first heating element against the frame portion via the temporary sealing material.

Images