Power storage module production method

Abstract

A power storage module production method according to the present invention includes a step (S10) for preparing a module (1A) to be inspected and an inspection step (S20) for inspecting the airtightness of the module (1A) to be inspected. The inspection step (S20) includes a step (S201) for placing the module (1A) to be inspected in a vacuum chamber (CH), a step (S202) for reducing the pressure inside the vacuum chamber CH, and, after step (S202) or during step (S202), a step (S203, S204) for determining the airtightness of each of a plurality of power storage cells (C) on the basis of the deformation state of each of a plurality of frame sealing parts (41) of a film (40) of the module (1A) to be inspected.

Description

Energy storage module manufacturing method

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

[0002] Patent Document 1 describes a method for inspecting the airtightness of a battery. In a battery inspected by this inspection method, a cell, which is a power generating element, has a multilayer structure in which a separator is sandwiched between a positive electrode layer and a negative electrode layer, and is sealed in an outer container. The outer container that houses such a cell is generally made of a flexible sheet-like outer container having a resin layer on both sides of a metal foil such as aluminum. The outer container is then placed in a vacuum atmosphere, or its opening is sealed while the container is evacuated.

[0003] In the inspection method described in Patent Document 1, the above-mentioned battery is first placed in a battery holder inside a vacuum chamber. Then, a vacuum pump is operated to evacuate the vacuum chamber. When the battery is placed inside the vacuum chamber and the pressure is gradually reduced, the outer container expands outward, and this change is detected by a micrometer. The pressure inside the vacuum chamber is then measured when the outer container begins to expand.

[0004] Japanese Patent Application Laid-Open No. 2004-327097

[0005] In the inspection method of Patent Document 1, in a battery in which multiple stacked electrodes are housed in a single outer container, and the interior of the outer container forms a single cell space, expansion of the outer container is detected to determine whether the battery is airtight. In contrast, in a battery constructed by stacking multiple airtightly sealed cells, such as a bipolar battery, in which the volume of the internal space of each cell is much smaller than the volume of the cell space in Patent Document 1, it is difficult to inspect the airtightness of each cell (internal space) based on deformation of the battery cell, as in the inspection method of Patent Document 1.

[0006] An object of the present disclosure is to provide a method for manufacturing an energy storage module that is capable of inspecting the airtightness of energy storage cells.

[0007] The method for manufacturing an energy storage module according to the present disclosure includes a preparation step of preparing an inspection module having a stack in which a plurality of energy storage cells, each having a reduced-pressure internal space, are stacked along a first direction, a sealing body provided on the stack so as to seal the internal space of the energy storage cell, a frame member provided on an outer surface of the sealing body along the first direction, and a film provided on a surface opposite to the outer surface of the frame member, and an inspection step of inspecting the inspection module after the preparation step, wherein the sealing body has a plurality of communication holes formed therein that communicate with the internal spaces of the plurality of energy storage cells and open to the outer surface, When viewed from a second direction intersecting the outer surface, the member includes a plurality of frame portions that surround each of the openings of the plurality of communicating holes, and the length in the first direction of the space surrounded by the frame portions is greater than the thickness in the first direction of the storage cell, and the film includes a plurality of frame sealing portions for sealing the space surrounded by each of the plurality of frame portions, and the inspection process includes a first step of placing the module to be inspected in a vacuum chamber, a second step of reducing the pressure inside the vacuum chamber after the first step, and a third step of determining the airtightness of each of the plurality of storage cells based on the deformation state of each of the plurality of frame sealing portions of the film after or during the second step.

[0008] In this manufacturing method, after preparing a module to be inspected, an inspection process is performed to inspect the module for airtightness. The module to be inspected includes a reduced-pressure internal space and a plurality of stacked energy storage cells. The internal space is connected to a space enclosed by a frame portion of a frame member provided on the outer surface of the sealing body through a communication hole in the sealing body. The internal space is sealed by providing a film, including a plurality of frame sealing portions, on the frame member for sealing the spaces enclosed by the plurality of frame portions. In the inspection process, the module to be inspected is placed in a vacuum chamber, and then the vacuum chamber is depressurized. Then, the airtightness of each of the plurality of energy storage cells is determined based on the deformation state of each of the frame sealing portions of the film. This makes it possible to inspect the airtightness of each energy storage cell. In particular, the length of the frame portion of the frame member in the stacking direction (first direction) of the energy storage cells is greater than the thickness of the energy storage cells in the same direction. Therefore, the frame sealing portions of the film that seal the frame portions also have a constant length greater than the thickness of the energy storage cells, making deformation thereof easy to detect. Therefore, even if the storage cell is thin, deformation of the frame sealing portion can be easily detected, and the airtightness of the storage cell can be reliably inspected.

[0009] In the energy storage module manufacturing method according to the present disclosure, before the second step, each of the plurality of frame sealing portions of the film may be convex facing inward, and in the third step, when or during the depressurization of the vacuum chamber to the threshold value in the second step, if one of the plurality of frame sealing portions is detected to have deformed so as to be convex facing outward, it may be determined that the energy storage cell corresponding to that frame sealing portion has an airtight leak. In this case, it is possible to reliably determine whether or not the energy storage cell has an airtight leak.

[0010] In the energy storage module manufacturing method according to the present disclosure, each of the plurality of frame sealing portions may have a flexible portion that is relatively more flexible than other portions. In this case, the frame sealing portion is more likely to deform at the flexible portion. This makes it possible to more easily detect deformation of the frame sealing portion and more reliably inspect the airtightness of the energy storage cells. Note that the energy storage cell corresponding to the frame sealing portion is a single energy storage cell that includes an internal space that is connected to a space surrounded by a frame sealed by one frame sealing portion via a communication hole in the sealing body.

[0011] In the energy storage module manufacturing method according to the present disclosure, the film may be made of resin. In this case, the frame sealing portion is more easily deformed than when the frame sealing portion is made of, for example, a laminate film including a metal layer, and therefore deformation of the frame sealing portion can be more easily detected, enabling more reliable inspection of the airtightness of the energy storage cells.

[0012] The energy storage module manufacturing method according to the present disclosure may include an exterior packaging step of sealing the inspected module with an exterior packaging film after the inspection step. In this case, it is possible to obtain an energy storage module with improved airtightness.

[0013] According to the present disclosure, it is possible to provide a method for manufacturing an energy storage module that is capable of inspecting the airtightness of energy storage cells.

[0014] FIG. 1 is a schematic cross-sectional view showing an energy storage module according to this embodiment. FIG. 2 is a schematic cross-sectional view of the energy storage module shown in FIG. 1. FIG. 3 is a schematic cross-sectional view showing an enlarged portion of FIG. 2. FIG. 4 is a partial schematic side view of a frame member seen from the outer surface side where the opening of the communication hole in the sealing body is provided. FIG. 5 is a schematic side view showing the relationship between the opening of the communication hole and the frame member. FIG. 6 is a flowchart showing main steps of a method for manufacturing an energy storage module according to this embodiment. FIG. 7 is a schematic side view showing one step shown in FIG. 6. FIG. 8 is a flowchart showing each step of the airtightness inspection shown in FIG. 6. FIG. 9 is a schematic view showing one step of the flowchart shown in FIG. 8. FIG. 10 is a schematic view showing one step of the flowchart shown in FIG. 8. FIG. 11 is a schematic cross-sectional view showing a film according to a modified example.

[0015] Hereinafter, an energy storage module and an energy storage module manufacturing method according to one embodiment will be described with reference to the drawings. In the description of each drawing, the same or corresponding elements are denoted by the same reference numerals, and duplicated descriptions may be omitted. In addition, each drawing may show an orthogonal coordinate system that defines a first direction D1, a second direction D2 perpendicular to the first direction D1, and a third direction D3 perpendicular to the first direction D1 and the second direction D2.

[0016] Fig. 1 is a schematic cross-sectional view showing an energy storage module according to this embodiment. The packaged module 100 shown in Fig. 1 is configured by sealing an energy storage module 1 with an exterior film 90. The exterior film 90 includes a first film portion 91 provided on one side of the energy storage module 1 in the first direction D1, and a second film portion 92 provided on the other side of the energy storage module 1 in the first direction D1.

[0017] The exterior film 90 is formed, for example, by a laminate film configured by sequentially stacking a first resin layer 93, a metal layer 94, and a second resin layer 95. The metal layer 94 is, for example, aluminum foil. One end of the first film portion 91 and one end of the second film portion 92 are airtightly joined to each other on a side surface of the energy storage module 1 along the first direction D1 to form a sealing portion 90p. In the sealing portion 90p, the first resin layer 93 of the first film portion 91 and the first resin layer 93 of the second film portion 92 are joined. Note that the first film portion 91 and the second film portion 92 are joined in a state where insulation is ensured.

[0018] The first film portion 91 has an opening on one end surface of the energy storage module 1 in the first direction D1 (a second surface 15b of a current collector 15 of a positive terminal electrode 13, which will be described later). A conductive member 97 is interposed between the first film portion 91 and the one end surface of the energy storage module 1 so as to cover the opening. The conductive member 97 is electrically connected to the current collector 15 of the positive terminal electrode 13. The area of ​​the conductive member 97 exposed from the first film portion 91 serves as a terminal surface of the packaged module 100. The conductive member 97 is made of a metal foil with good conductivity, such as aluminum foil or stainless steel foil. The first film portion 91 and the conductive member 97 are hermetically joined via an insulating resin material, ensuring their mutual insulation.

[0019] The second film portion 92 has an opening on the other end surface of the energy storage module 1 in the first direction D1 (a first surface 15a of a current collector 15 of a negative terminal electrode 12, which will be described later). A conductive member 98 is interposed between the second film portion 92 and the other end surface of the energy storage module 1 so as to cover the opening. The conductive member 98 is electrically connected to the current collector 15 of the negative terminal electrode 12. The area of ​​the conductive member 98 exposed from the second film portion 92 serves as a terminal surface of the packaged module 100. The conductive member 98 is made of a metal foil with good conductivity, such as aluminum foil or stainless steel foil. The second film portion 92 and the conductive member 98 are hermetically joined via an insulating resin material, ensuring their mutual insulation.

[0020] Fig. 2 is a schematic cross-sectional view of the energy storage module shown in Fig. 1. Fig. 3 is a schematic cross-sectional view showing an enlarged portion of Fig. 2. The energy storage module 1 shown in Figs. 2 and 3 is used, for example, as a battery for various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The energy storage module 1 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the energy storage module 1 is a lithium-ion secondary battery will be illustrated as an example.

[0021] The energy storage module 1 includes an electrode stack (stack) 10, a sealing body 20, a frame member 30, and a film 40. The electrode stack 10 includes a plurality of electrodes stacked along a first direction D1. The plurality of electrodes includes a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13. Separators 14 are interposed between adjacent electrodes.

[0022] The bipolar electrode 11 includes a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 has, for example, a rectangular sheet shape. The current collector 15 includes a first surface 15a and a second surface 15b. As an example, the first surface 15a is a surface that intersects with the first direction D1, and the second surface 15b is a surface that intersects with the first direction D1 and is opposite to the first surface 15a. Here, the first surface 15a of the current collector 15 faces one side of the first direction D1 (the direction from the positive electrode terminal electrode 13 to the negative electrode terminal electrode 12 in FIG. 2), and the second surface 15b of the current collector 15 faces the other side of the first direction (the direction from the negative electrode terminal electrode 12 to the positive electrode terminal electrode 13 in FIG. 2).

[0023] The positive electrode active material layer 16 is provided on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the second surface 15b of the current collector 15. The peripheral portion surrounding the positive electrode active material layer 16 on the first surface 15a of the current collector 15 and the peripheral portion surrounding the negative electrode active material layer 17 on the second surface 15b of the current collector 15 are each an unformed region (uncoated region) where no active material layer is provided. The multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 and the negative electrode active material layer 17 of another bipolar electrode 11 face each other via the separator 14. The positive electrode active material layer 16 and the negative electrode active material layer 17 of each bipolar electrode 11 may have grooves formed therein to improve liquid injection and gas escape properties.

[0024] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the first direction D1. In a plan view viewed from the first direction D1, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17. In other words, when viewed from the first direction D1, the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16.

[0025] The negative electrode terminal electrode 12 has a current collector 15 and a negative electrode active material layer 17 provided on a second surface 15b of the current collector 15. The negative electrode terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a first surface 15a of the current collector 15. In other words, no active material layer is provided on the first surface 15a of the current collector 15 of the negative electrode terminal electrode 12, and the first surface 15a forms the negative electrode terminal surface of the energy storage module 1. The negative electrode terminal electrode 12 is stacked on the bipolar electrode 11 at one end of the electrode stack 10 in the first direction D1. The negative electrode terminal electrode 12 is stacked on the bipolar electrode 11 via a separator 14 so that the negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0026] The positive terminal electrode 13 has a current collector 15 and a positive electrode active material layer 16 provided on a first surface 15a of the current collector 15. The positive terminal electrode 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a second surface 15b, which is the surface opposite to the first surface 15a of the current collector 15. In other words, no active material layer is provided on the second surface 15b of the current collector 15 of the positive terminal electrode 13, and this second surface 15b constitutes a positive electrode terminal surface of the energy storage module 1. The positive terminal electrode 13 is stacked on the bipolar electrode 11 at one end of the electrode stack 10 in the first direction D1. The positive terminal electrode 13 is stacked on the bipolar electrode 11 such 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.

[0027] In this embodiment, the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 are denoted by the same reference numeral 15, but the materials constituting the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 may be the same as or different from one another.

[0028] The separators 14 are respectively disposed between the bipolar electrodes 11 adjacent to each other in the first direction D1, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive terminal electrode 13 and the bipolar electrode 11. That is, the separators 14 are interposed between the positive electrode surface of the current collector 15 on which the positive electrode active material layer 16 is provided and the negative electrode surface on which the negative electrode active material layer 17 is provided. The separators 14 are members that allow charge carriers such as lithium ions to pass through, and by isolating the positive electrode surface from the negative electrode surface, they prevent short circuits due to contact between adjacent electrodes.

[0029] 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 and / or conductive resin material.

[0030] 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, film, or mesh. Examples of metal foils include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The current collector 15 may be an alloy foil of the above metals or a foil formed by integrating multiple metal foils. 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 200 μm. The current collector 15 may be a foil formed by integrating aluminum foil and copper foil by bonding them together with a conductive adhesive, or a foil formed by vapor-depositing a copper layer on one side of aluminum foil.

[0031] 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 )

[0032] 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.

[0033] 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 a conductive additive, a binder, an electrolyte, an electrolyte supporting salt, etc., as necessary. The conductive additive is added to enhance electrical conductivity. Examples of the conductive additive include acetylene black, carbon black, and graphite. The electrolyte supporting salt is added to enhance ionic conductivity.

[0034] 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; carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Examples of solvents for binders include water and N-methyl-2-pyrrolidone.

[0035] 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 multi-layer structure. The multi-layer 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 electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0036] The electrolyte salt of the electrolyte solution 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.

[0037] The sealing body 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the Z direction. For example, the sealing body 20 is formed as a rectangular tubular member on the peripheral portion of the electrode stack 10 so as to surround four side surfaces of the electrode stack 10, which is a substantially rectangular parallelepiped. The sealing body 20 can be joined (welded) to each of the first surface 15a and the second surface 15b of the current collector 15 at the peripheral portion 15c of each current collector 15. The sealing body 20 insulates adjacent current collectors 15 in the first direction D1 and forms an internal space S in cooperation with the adjacent current collectors 15. The sealing body 20 seals each of the internal spaces S. An electrolyte is accommodated in each internal space S. The sealing body 20 can prevent the electrolyte accommodated in the internal space S from leaking out to the outside. Furthermore, the sealing body 20 can prevent air, moisture, and the like from entering the internal space S from the outside of the electrode stack 10 .

[0038] The sealing body 20 includes an insulating material, and examples of the material for the sealing body 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile-styrene resin.

[0039] The sealing body 20 includes a plurality of resin sealants 21 and a plurality of resin spacers 22. The sealants 21 are provided on each of the plurality of electrodes. More specifically, the sealants 21 are provided on the peripheral edge portions 15c of the current collectors 15. Therefore, the plurality of sealants 21 are stacked along the first direction D1. The sealants 21 provided on the peripheral edge portions 15c of the current collectors 15 are formed in a frame shape that follows the outline of the current collectors 15 when viewed from the first direction D1. Here, because the current collectors 15 are rectangular in plan view, the sealants 21 also have a rectangular frame shape when viewed from the first direction D1. The sealants 21 include an inner portion that overlaps the peripheral edge portions 15c of the current collectors 15 when viewed from the first direction D1, and an outer portion that extends beyond the edge of the current collectors 15. The sealing material 21 is formed by joining together and integrating an outer portion of a first resin member joined to the first surface 15 a of the current collector 15 and a second resin member joined to the second surface 15 b of the current collector 15. In other words, the sealing material 21 covers the peripheral portion 15 c of the current collector 15.

[0040] In this embodiment, the sealing materials provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the negative terminal electrode 12, and the current collector 15 of the positive terminal electrode 13 are each given the same reference numeral as a sealing material 21. However, the sealing material provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the negative terminal electrode 12, and the sealing material provided on the current collector 15 of the positive terminal electrode 13 may be the same as or different from one another.

[0041] The spacer 22 is formed in a generally frame-like shape so as to surround the positive electrode active material layer 16 when viewed from the first direction D1. The spacer 22 has an inner portion overlapping the current collector 15 and an outer portion extending beyond the edge of the current collector 15 when viewed from the first direction D1. The spacer 22 is disposed so as to be interposed between the sealing materials 21 provided on the electrodes adjacent to each other in the first direction D1. As a result, the spacer 22, together with the pair of sealing materials 21 adjacent to each other in the first direction D1, maintains the spacing between the current collectors 15 adjacent to each other in the first direction D1. An internal space S is defined by the pair of current collectors 15 adjacent to each other in the first direction D1, the spacer 22, and the pair of sealing materials 21 adjacent to the spacer 22.

[0042] The end of the separator 14 may be held by being sandwiched between the sealant 21 and the spacer 22. The end of the separator 14 may be fixed by being welded to at least one of the sealant 21 and the spacer 22.

[0043] The outer ends of the multiple sealants 21 and the outer ends of the multiple spacers 22 are welded together and integrated to form a welded portion 23. That is, the sealing body 20 includes the welded portion 23 formed by welding the multiple sealants 21 and the multiple spacers 22 together. When viewed from the first direction D1, the welded portion 23 has a frame shape (here, a rectangular frame shape) surrounding the electrode stack 10 and forms the outer periphery of the sealing body 20. Therefore, the outer surface 23s of the welded portion 23 forms the outer surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer surfaces 23s extending along the first direction D1. The spacers 22 do not need to be welded to the sealing material 21, at least in the inner portion of the sealing material 21 adjacent to the first direction D1.

[0044] Conductive members 97, 98 (see FIG. 1 ) are laminated on the second surface 15 b of the current collector 15 of the negative terminal electrode 12 and on the exposed portions of the first surface 15 a of the current collector 15 of the positive terminal electrode 13 that are not covered by the sealing body 20 (i.e., portions where the sealing material 21 is not provided when viewed from the first direction D1). The conductive members 97, 98 can each be used to extract current from the energy storage module 1. When a battery pack is formed using multiple packaged modules 100 by stacking multiple packaged modules 100 in the first direction D1 and connecting them in series, the multiple packaged modules 100 are electrically connected by placing a conductive plate, conductive adhesive, or the like between two packaged modules 100 adjacent to each other in the first direction D1. That is, the conductive members 97, 98 can be used to electrically connect the multiple energy storage modules 1.

[0045] When viewed from the first direction D1, the inner edge 22 e of the spacer 22 is located between the outer edge 17 e of the negative electrode active material layer 17 and the outer edge 16 e of the positive electrode active material layer 16. As a result, the spacer 22 includes a portion that overlaps with the negative electrode active material layer 17 when viewed from the first direction D1.

[0046] The spacers 22 may be configured not to contact the current collectors 15 of the adjacent bipolar electrodes 11. In other words, a minute gap may be provided between the spacers 22 and the first surfaces 15 a of the current collectors 15 of the adjacent bipolar electrodes.

[0047] Here, the sealing body 20 has a plurality of communication holes 31 that communicate with each of the plurality of internal spaces S. One communication hole 31 is connected to one internal space S. The communication hole 31 communicates the internal space S with the outside of the energy storage module 1. The communication hole 31 is formed as a through-hole that penetrates the sealing body 20, for example, by cutting out a part of the spacer 22. One opening 31A of the communication hole 31 is provided on one outer side surface 23s of the sealing body 20, and the other opening 31B is provided on the surface of the sealing body 20 that faces the internal space S. In the energy storage module 1, one energy storage cell C is formed by a pair of current collectors 15 adjacent to each other along the first direction D1. The energy storage cell C includes the current collectors 15 of a pair of electrodes adjacent to each other in the first direction, the internal space S between the pair of current collectors 15, and a part of the sealing body 20 that seals the internal space S. Therefore, the electrode stack 10 includes a plurality of storage cells C arranged along the first direction D1. Each of the plurality of communication holes 31 communicates with the internal space S of one of the storage cells C.

[0048] The frame member 30 is provided on an outer surface 23s of the sealing body 20 along the first direction D1. In the present embodiment, the frame member 30 is provided on one of the four outer surfaces 23s of the sealing body 20, the outer surface 23s on which the opening 31A of the communication hole 31 is provided. A film 40 is provided on the surface of the frame member 30 opposite the outer surface 23s to prevent electrolytes, such as electrolytic solution, contained in the energy storage cells C from leaking out of the energy storage module 1. The film 40 is, for example, a resin sheet member, and is joined to the frame member 30 to seal the internal space S of each energy storage cell C.

[0049] Fig. 4 is a partial schematic side view of the frame member from the outer surface side where the openings of the communication holes are provided in the sealing body. Fig. 5 is a schematic side view showing the relationship between the openings of the communication holes and the frame member. Fig. 5(a) is a side view in which the frame member 30 is omitted, and Fig. 5(b) is a side view including the frame member 30. The film 40 is omitted in Figs. 4 and 5.

[0050] 3 to 5 , in the energy storage module 1, the openings 31A of a predetermined number (three in this example) of the communication holes 31 that communicate with different energy storage cells C are arranged in positions that overlap when viewed from the first direction D1. The openings 31A of a group (three in this example) of communication holes 31 arranged along the first direction D1 are arranged along the third direction D3. Here, the openings 31A of the communication holes 31 that communicate with energy storage cells C adjacent in the first direction D1 may be arranged adjacent to each other in the third direction.

[0051] The frame member 30 is configured such that, when viewed from the second direction D2 intersecting the outer surface 23s, a plurality of portions 30p including a group (three in this example) of frame portions 30f surrounding the respective openings 31A of the group of communication holes 31 are arranged along the third direction D3. That is, when viewed from the second direction D2 intersecting the outer surface 23s, the frame member 30 includes a plurality of frame portions 30f surrounding the respective openings 31A of the plurality of communication holes 31. The space 33 surrounded by the frame portions 30f communicates with the internal space S of the energy storage cell C via the communication holes 31. However, the length Ts of the space 33 in the first direction D1 is greater than the thickness Tc of the energy storage cell C in the first direction D1. In this embodiment, the length Ts corresponds to the thickness Tc of the plurality of energy storage cells C.

[0052] Note that the portions 30p each including a group of frame portions 30f arranged along the first direction D1 may be integrated with one another. Furthermore, the group of frame portions 30f included in one portion 30p may be configured to have different lengths Ts in the first direction D1. In this embodiment, the length Ts of the space 33 enclosed by the shortest frame portion 30f in the first direction D1 is set to be greater than the thickness Tc of the storage cell C.

[0053] As described above, the film 40 is bonded to the surface of the frame member 30 opposite the outer surface 23s (i.e., the top surface of the frame portion 30f) and seals each of the multiple spaces 33 (i.e., the internal space S and the communication holes 31). That is, the film 40 includes multiple frame sealing portions 41 for sealing the spaces 33 enclosed by each of the multiple frame portions 30f. The film 40 includes the same number of frame sealing portions 41 as the number of frame portions 30f (i.e., the number of openings 31A of the communication holes 31). As described above, the frame member 30 may include multiple frame portions 30f having different lengths in the first direction D1. In this case, the film 40 also includes multiple frame sealing portions 41 having different widths depending on the lengths of the frame portions 30f in the first direction D1. The film 40 may be composed of a single sheet member. That is, the multiple spaces 33 may be sealed collectively by the film 40 made of a single sheet member.

[0054] Before the film 40 is installed, the frame member 30 can be used as a liquid injection frame when injecting electrolyte into each internal space S of the energy storage cell C by pressing a nozzle of an electrolyte injection device against the frame member 30.

[0055] Next, an example of a method for manufacturing the above-described energy storage module 1 will be described. Fig. 6 is a flowchart showing the main steps of the energy storage module manufacturing method according to this embodiment. Fig. 7 is a schematic side view showing one step shown in Fig. 6. As shown in Figs. 6 and 7, in this manufacturing method, first, a module to be inspected 1A is prepared (step S10, preparation step). The module to be inspected 1A is similar to the energy storage module 1 described above.

[0056] In the module 1A to be inspected (i.e., the energy storage module 1), a film 40 is provided on the frame member 30 in a decompressed chamber to seal the internal space S. Each of the multiple internal spaces S of the module 1A to be inspected is sealed in a state where the pressure is reduced below atmospheric pressure. Therefore, when the module 1A to be inspected sealed in a decompressed chamber is placed at atmospheric pressure, each of the frame sealing portions 41 may be recessed so as to protrude inward due to the difference in pressure between the internal space S and atmospheric pressure. On the other hand, if a pinhole is formed in any of the frame sealing portions 41, there is a risk that the pressure in the energy storage cell C including the internal space S sealed by that frame sealing portion 41 will return to normal during a predetermined characteristic inspection after the decompressed sealing.

[0057] Therefore, in the next step, an airtightness test is performed to detect the storage cells C whose pressure has been restored (step S20, test step). Fig. 8 is a flowchart showing the steps of the airtightness test shown in Fig. 6. Figs. 9 and 10 are schematic diagrams showing one step of the flowchart shown in Fig. 8. As shown in Figs. 8 and 9, in the airtightness test, first, the module 1A to be tested is placed in a vacuum chamber CH (step S201, first step).

[0058] A detection device D is disposed outside the vacuum chamber CH for detecting the deformation state of each of the frame sealing portions 41 of the film 40 of the module 1A to be inspected. The detection device D is, for example, a laser displacement meter. In this case, the detection device D can detect the deformation state of the frame sealing portion 41 by irradiating laser light L into the vacuum chamber CH through a light-transmitting window W provided in the vacuum chamber CH and receiving reflected light of the laser light L through the window W. In step S201, the module 1A to be inspected is disposed in the vacuum chamber CH so that the film 40 faces the detection device D via the window W of the vacuum chamber CH.

[0059] In the next step, the vacuum chamber CH is evacuated to reduce the pressure therein (step S202, second step), whereby the pressure in the vacuum chamber CH is gradually reduced from atmospheric pressure.

[0060] 8 and 10 , after or during step S202, a detection device D is used to detect the deformation state of each of the frame sealing portions 41 of the film 40 (step S203, third step). More specifically, in step S202, the vacuum chamber CH is depressurized until it reaches a predetermined threshold (specified value). Therefore, if there is a storage cell C whose internal pressure is higher than the threshold due to the pressure recovery, the frame sealing portion 41 corresponding to that storage cell C will deform from an inwardly convex state to an outwardly convex state (it will bulge so that the curvature is reversed) at the point in time when the internal pressure of the vacuum chamber CH becomes lower than the internal pressure of that storage cell C before it reached the threshold.

[0061] In step S203, a detection device D is used to detect the deformation state of the frame sealing portion 41. As an example, if the detection device D is a laser displacement meter, the deformation state (displacement) of the frame sealing portion 41 can be detected as a numerical value or an image by scanning a laser beam L over the plurality of frame sealing portions 41. Step S203 may be performed during the course of step S202, i.e., while the vacuum chamber CH is being depressurized, or may be performed after step S202 is completed and the internal pressure of the vacuum chamber CH has reached a predetermined threshold value.

[0062] In the next step, the airtightness of the energy storage cell C is determined (step S204, third step). That is, in step S204, if a frame sealing portion 41 is found to be deformed to a certain degree or more based on the detection result of the deformation state of the frame sealing portion 41 by the detection device D in step S203, it is determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41. In this embodiment, if the detection device D detects a frame sealing portion 41 that has deformed so as to be convex outward, it can be determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41.

[0063] As described above, in steps S203 and S204, after step S202 or during step S202, an airtightness determination is performed on each of the multiple storage cells C based on the deformation state of each of the multiple frame sealing portions 41 of the film 40. More specifically, before step S202, each of the multiple frame sealing portions 41 of the film 40 is convex facing inward, and in steps S203 and S204, if a frame sealing portion 41 among the multiple frame sealing portions 41 that has deformed to become convex facing outward is detected when or while the pressure is reduced to the threshold value in step S202, it is determined that there is an airtight leak in the storage cell C corresponding to that frame sealing portion 41.

[0064] Thereafter, if no leaking energy storage cell C is detected in steps S203 and S204, an exterior film 90 (and conductive members 97, 98) is provided on the module 1A to be inspected (step S30, exterior packaging step), as shown in Fig. 6. That is, in step S30, the module 1A to be inspected that has been inspected in step S20 is sealed with an exterior film, thereby forming an exterior-packaged module 100 from the module 1A to be inspected (energy storage module 1).

[0065] As described above, in the energy storage module manufacturing method according to this embodiment, after preparing the module 1A to be inspected, an inspection step (step S20) is performed to inspect the airtightness of the module 1A to be inspected. The module 1A to be inspected includes a reduced-pressure internal space S and has a plurality of stacked energy storage cells C. The internal space S is in communication with a space 33 enclosed by a frame portion 30f of a frame member 30 provided on an outer surface 23s of the sealing body 20 via a communication hole 31 in the sealing body 20.

[0066] The internal space S is sealed by providing the frame member 30 with a film 40 including a plurality of frame sealing portions 41 for sealing the space 33 enclosed by each of the plurality of frame portions 30f. In the inspection process, the module 1A to be inspected is placed in a vacuum chamber CH (step S201), and then the pressure inside the vacuum chamber CH is reduced (step S202). Then, the airtightness of each of the plurality of storage cells C is determined based on the deformation state of each of the plurality of frame sealing portions 40f of the film 40 (steps S203 and S204). This makes it possible to inspect the airtightness of each storage cell C.

[0067] In particular, the length Ts of the frame portion 30f of the frame member 30 in the stacking direction (first direction D1) of the energy storage cells C is greater than the thickness Tc of the energy storage cells C in the same direction. Therefore, the frame sealing portion 41 that seals the frame portion 30f of the film 40 also has a length Ts that is greater than the thickness Tc of the energy storage cells C, making it easy to detect deformation thereof. Therefore, even if the energy storage cells C are thin, deformation of the frame sealing portion 41 can be easily detected, and the airtightness of the energy storage cells C can be reliably inspected.

[0068] In the energy storage module manufacturing method according to this embodiment, before step S202, each of the multiple frame sealing portions 41 of the film 40 is convex facing inward. Furthermore, in steps S203 and S204, when the pressure inside the vacuum chamber CH is reduced to the threshold value in step S202, or while the pressure is being reduced to the threshold value, if one of the multiple frame sealing portions 41 is detected to have deformed so as to be convex facing outward, it is determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41. This makes it possible to reliably determine whether there is an airtight leak in the energy storage cell C.

[0069] In the energy storage module manufacturing method according to this embodiment, the film 40 is a resin sheet member. In this case, the frame sealing portion 41 is more easily deformed than when it is configured of, for example, a laminate film including a metal layer. Therefore, deformation of the frame sealing portion 41 can be more easily detected, and the airtightness of the energy storage cells C can be more reliably inspected.

[0070] The energy storage module manufacturing method according to this embodiment includes an exterior packaging step (S30) in which the inspected module 1A that has been inspected in the inspection step (step S20) is sealed with an exterior packaging film 90. This makes it possible to obtain an exterior-packaged module 100 with improved airtightness.

[0071] The above embodiment has been described as an example of the method for manufacturing an electric storage module according to the present invention. Therefore, the method for manufacturing an electric storage module according to the present invention is not limited to the above embodiment and can be modified as desired.

[0072] For example, in the energy storage module manufacturing method according to the above embodiment, as shown in FIG. 11 , each of the frame sealing portions 41 may be formed with a flexible portion 42 that is relatively more flexible than other portions. The flexible portion 42 is, for example, a recess formed by embossing at a position of the film 40 corresponding to each of the frame sealing portions 41. That is, the flexible portion 42 is further recessed so as to be convex inward at the time of step S201. In this case, when the vacuum chamber CH is depressurized in step S202, the frame sealing portion 41 is more likely to deform so that the flexible portion 42 is convex outward. This makes it possible to more easily detect deformation of the frame sealing portion 41 and more reliably inspect the airtightness of the energy storage cells C.

[0073] In the above embodiment, an example has been described in which, in steps S203 and S204, deformation of the frame sealing portion 41 that has deformed to be convex outward is detected to determine the airtightness of the energy storage cell C. However, in steps S203 and S204, it is sufficient to detect the state of deformation of the frame sealing portion 41 to determine the airtightness of the energy storage cell C, and the airtightness of the energy storage cell C may also be determined by detecting a state in which the frame sealing portion 41 has deformed from an inwardly convex state to a flat state or by detecting the amount of depression in the inwardly convex state.

[0074] Furthermore, the film 40 is not limited to being made of resin, and may be made of a material containing both resin and a material other than resin. Furthermore, in the energy storage module manufacturing method according to the above embodiment, the energy storage module 1 is exemplified as the module to be inspected 1A, but the module to be inspected 1A may be an energy storage module different from the energy storage module 1.

[0075] The following additional notes will be made regarding the above embodiment.

[0076] The energy storage module manufacturing method according to the appendix includes: [1] a preparation step of preparing an inspected module including: a stack of a plurality of energy storage cells stacked along a first direction, each of the energy storage cells having a reduced-pressure internal space; a sealing body provided on the stack so as to seal the internal space of the energy storage cell; a frame member provided on an outer surface of the sealing body along the first direction; and a film provided on a surface of the frame member opposite the outer surface; and an inspection step of performing an airtightness inspection of the inspected module after the preparation step, wherein the sealing body has a plurality of communication holes formed therein that communicate with the internal spaces of the plurality of energy storage cells and that open to the outer surface, and the frame member has a width that is greater than or equal to the width of the outer surface when viewed from a second direction intersecting the outer surface. the film includes a plurality of frame portions surrounding each of the openings of the plurality of communication holes, the thickness in the first direction of the space surrounded by the frame portions being greater than the thickness in the first direction of the storage cells, the film includes a plurality of frame sealing portions for sealing the spaces surrounded by each of the plurality of frame portions, and the inspection process includes a first process of placing the module to be inspected in a vacuum chamber, a second process of reducing the pressure inside the vacuum chamber after the first process, and a third process of determining the airtightness of each of the plurality of storage cells based on the deformation state of each of the plurality of frame sealing portions of the film after the second process or during the second process.

[0077] The energy storage module manufacturing method according to the appendix may be [2] "the energy storage module manufacturing method described in [1] above, in which, before the second step, each of the plurality of frame sealing portions of the film is convex facing inward, and in the third step, when the pressure inside the vacuum chamber is reduced to a threshold value in the second step or while the pressure is being reduced to the threshold value, if one of the plurality of frame sealing portions is detected to have deformed so as to be convex facing outward, it is determined that there is an airtight leak in the energy storage cell corresponding to the frame sealing portion."

[0078] The storage module manufacturing method according to the appendix may be [3] "the storage module manufacturing method described in [1] or [2] above, in which each of the plurality of frame sealing portions has a flexible portion that is relatively more flexible than other portions."

[0079] The method for manufacturing an electric storage module according to the appendix may be [4] "the method for manufacturing an electric storage module according to any one of [1] to [3] above, in which the film is made of resin."

[0080] The storage module manufacturing method according to the appendix may be [5] "the storage module manufacturing method according to any one of [1] to [4], including an exterior packaging process of sealing the inspected module that has been inspected in the inspection process with an exterior packaging film."

[0081] 1A Module to be inspected 10 Electrode laminate (laminate) 20 Sealing body 30 Frame member 30f Frame portion 31 Communication hole 31A Opening 33 Space 40 Film 41 Frame sealing portion 42 Flexible portion

Claims

1. A method for manufacturing an inspection module, comprising: a preparation step of preparing an inspection module having a stack of a plurality of storage cells, each of which has a reduced pressure internal space, stacked along a first direction, a sealing body provided on the stack so as to seal the internal space of the storage cell, a frame member provided on an outer surface of the sealing body along the first direction, and a film provided on a surface of the frame member opposite the outer surface; and an inspection step of performing an airtight inspection of the inspection module after the preparation step, wherein the sealing body has a plurality of communication holes formed therein, the communication holes communicating with the internal spaces of each of the plurality of storage cells and opening to the outer surface, the frame member includes a plurality of frame portions surrounding each of the openings of the communication holes when viewed from a second direction intersecting the outer surface, the length in the first direction of the space surrounded by the frame portions is greater than the thickness in the first direction of the storage cell, and the film includes a plurality of frame sealing portions for sealing the spaces surrounded by each of the plurality of frame portions, and the inspection step includes: a first step of placing the inspection module in a vacuum chamber; a second step of reducing the pressure inside the vacuum chamber after the first step; and a third step of determining airtightness of each of the plurality of storage cells based on the deformation state of each of the plurality of frame sealing portions of the film after or during the second step.

2. The method for manufacturing a storage module as described in claim 1, wherein prior to the second step, each of the multiple frame sealing portions of the film is convex facing inward, and in the third step, when the pressure inside the vacuum chamber is reduced to a threshold value in the second step or while the pressure is being reduced to the threshold value, if one of the multiple frame sealing portions is detected to have deformed to become convex facing outward, it is determined that there is an air leak in the storage cell corresponding to that frame sealing portion.

3. The method for manufacturing an energy storage module according to claim 1, wherein each of the plurality of frame sealing portions is formed with a flexible portion that is relatively more flexible than other portions.

4. The method for producing a storage module according to claim 1, wherein the film is made of resin.

5. The method for producing an energy storage module according to any one of claims 1 to 4, further comprising an exterior packaging process for sealing the inspected module, which has been inspected in the inspection process, with an exterior packaging film.

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