Power storage device

Abstract

To provide a power storage device capable of suppressing deformation of a collector.SOLUTION: A power storage device 1 comprises: a lamination body; and a sealing body 3 for sealing a side surface of the lamination body. The sealing body 3 includes: a seal part 35 that is melted to a front surface 24a of a collector 24; a seal part 36 that is melted to a surface 24b of the collector 24; a spacer 34 that is nipped by the seal part 35 and the seal part 36; and a melting part 32 that is formed by a melting of an external edge part of each of seal part 33 and the spacer 34 positioned to the side outer than an outer edge 24c of the collector 24. The spacer 34 contains a liquid injection port 34a communicated to an inner space S. The melting part 32 contains a liquid injection port 32a communicated to the liquid injection port 34a. A thickness T1 of the spacer 34 is larger than a thickness T2 of the seal part 35 and a thickness T3 of the seal part 36.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Conventionally, there has been known an electricity storage device that includes a stack including a plurality of electrodes and a seal for sealing the side surface of the stack (see, for example, Patent Document 1). In such an electricity storage device, the seal has a member including a seal welded to one surface of the current collector of the electrode. A liquid injection port for injecting an electrolyte solution into the internal space is formed in the seal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-200955 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described energy storage device, the seal portion may be required to have a relatively large thickness in order to form a liquid injection port in the seal portion. However, if the seal portion is too thick, there is a risk that the current collector may be deformed due to thermal contraction of the seal portion when the seal portion is welded to one surface of the current collector.

[0005] An object of the present invention is to provide an electricity storage device capable of suppressing deformation of a current collector. [Means for solving the problem]

[0006] The electricity storage device of the present invention includes a laminate including a first electrode and a second electrode stacked in a stacking direction, and a sealing body for sealing a side surface of the laminate, wherein the first electrode has a first current collector including a first surface and a positive electrode active material layer provided on the first surface, the second electrode has a second current collector including a second surface opposing the first surface and a negative electrode active material layer provided on the second surface, and the sealing body includes a first sealing part including a first sealing part welded to the first surface so as to surround the positive electrode active material layer when viewed from the stacking direction, and a second sealing part welded to the second surface so as to surround the negative electrode active material layer when viewed from the stacking direction. The battery has a second seal portion, a spacer sandwiched between the first seal portion and the second seal portion, and a welded portion formed by welding the outer edge portions of the first seal portion, the second seal portion, and the spacer, which are located outside the outer edges of the first current collector and the second current collector when viewed from the stacking direction, wherein the spacer includes a first fill port formed by the first electrode, the second electrode, and the sealing body and communicating with an internal space that contains an electrolyte, the welded portion includes a second fill port that communicates with the first fill port, and the thickness of the spacer is greater than the thickness of the first seal portion and the thickness of the second seal portion.

[0007] In this electricity storage device, a first seal portion is welded to the first surface of the first current collector, and a second seal portion is welded to the second surface of the second current collector. Moreover, welded portions are formed by welding the outer edges of the first seal portion, the second seal portion, and the spacer. This allows the internal space to be reliably sealed. Furthermore, the thickness of the spacer is greater than the thicknesses of the first seal portion and the second seal portion, and the first liquid inlet is formed in the spacer. This allows the thickness of the first seal portion or the second seal portion to be sufficiently small while ensuring a sufficient thickness for the spacer to form the first liquid inlet. Therefore, this electricity storage device can suppress deformation of the current collector caused by welding the first seal portion to the first surface or the second seal portion to the second surface.

[0008] The width of the second liquid inlet may be smaller than the width of the first liquid inlet, thereby making it possible to prevent the electrolyte contained in the internal space from flowing back to the outside.

[0009] The energy storage device may further include a separator provided between the positive electrode active material layer and the negative electrode active material layer, a peripheral edge of the separator being located between the spacer and the second seal portion, and a first region of the internal space between the separator and the first electrode having a larger volume than a second region between the separator and the second electrode. In this case, the first liquid injection port communicates with the first region having a larger volume, thereby achieving smooth liquid injection.

[0010] When viewed from the stacking direction, the area of ​​the positive electrode active material layer may be smaller than the area of ​​the negative electrode active material layer, which allows the volume of the first region to be larger than the volume of the second region, thereby achieving smooth injection as described above.

[0011] The thickness of the positive electrode active material layer may be greater than the thickness of the negative electrode active material layer, which allows the volume of the first region to be greater than the volume of the second region, thereby achieving smooth injection as described above.

[0012] The positive electrode active material layer may include a groove extending in the direction in which the first liquid pouring port and the internal space are aligned, thereby preventing the positive electrode active material layer from interfering with the flow of the electrolyte, thereby achieving smooth liquid pouring.

[0013] The spacers may include a first spacer and a second spacer, each formed in a frame shape and stacked in the stacking direction, which makes it easy to adjust the thickness of the spacers and facilitates manufacturing of the energy storage device.

[0014] The energy storage device may further include a separator disposed between the positive electrode active material layer and the negative electrode active material layer, the first liquid injection port being formed in the first spacer, and the peripheral edge of the separator being welded to the second spacer. This allows the peripheral edge of the separator to be more securely fixed than when the peripheral edge of the separator is welded to the first spacer, for example. This makes it possible to suppress short circuits between the first electrode and the second electrode.

[0015] When viewed from the stacking direction, the inner edge of the second spacer may be located more inward than the inner edge of the first spacer. This ensures that the second spacer has a sufficient area for welding the separator. This allows the periphery of the separator to be more securely fixed, and more reliably prevents short circuits between the first electrode and the second electrode.

[0016] The spacer may further include a third spacer stacked on the opposite side of the first spacer with respect to the second spacer, and the first liquid injection port may be formed in each of the first spacer and the third spacer. This allows liquid injection from both sides of the separator in the stacking direction, thereby achieving smooth liquid injection. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an electricity storage device capable of suppressing deformation of a current collector. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view of the electricity storage device according to the first embodiment. [Figure 2] FIG. 2 is a partially enlarged view of FIG. [Figure 3] FIG. 3 is a side view of the power storage device shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 6] FIG. 6 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 7] FIG. 7 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 8] FIG. 8 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 9]FIG. 9 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 10] FIG. 10 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 11] FIG. 11 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 12] FIG. 12 is a partially enlarged cross-sectional view of the electricity storage device according to the second embodiment. [Figure 13] FIG. 13 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 14] FIG. 14 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 15] FIG. 15 is a partially enlarged cross-sectional view of the electricity storage device according to the third embodiment. [Figure 16] FIG. 16 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. [Figure 17] FIG. 17 is a diagram showing steps of a method for manufacturing the electricity storage device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0020] [First embodiment] The power storage device 1 according to the first embodiment shown in Fig. 1 is a power storage module used in batteries for, for example, forklifts, hybrid vehicles, electric vehicles, etc. The power storage device 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. In this embodiment, the power storage device 1 is a lithium-ion secondary battery.

[0021] 1, the energy storage device 1 includes a laminate 2 and a sealing body 3. The laminate 2 includes a plurality of bipolar electrodes 21 stacked in a stacking direction D, a positive terminal electrode 22, and a negative terminal electrode 23. The bipolar electrode 21 includes a current collector 24, a positive electrode active material layer 25, and a negative electrode active material layer 26.

[0022] When viewed from the stacking direction D, the current collector 24 has, for example, a rectangular shape. The current collector 24 includes a surface 24a and a surface 24b opposite to the surface 24a. The current collector 24 has a first layer 241 and a second layer 242 stacked in the stacking direction D. The first layer 241 and the second layer 242 are electrically connected. The surface 24a of the current collector 24 is the surface of the first layer 241. The surface 24b of the current collector 24 is the surface of the second layer 242.

[0023] The positive electrode active material layer 25 is provided on the surface 24a. When viewed from the stacking direction D, the positive electrode active material layer 25 has, for example, a rectangular shape. The surface 24a includes an uncoated region where the positive electrode active material layer 25 is not provided. When viewed from the stacking direction D, the uncoated region surrounds the positive electrode active material layer 25. The negative electrode active material layer 26 is provided on the surface 24b. When viewed from the stacking direction D, the negative electrode active material layer 26 has, for example, a rectangular shape. When viewed from the stacking direction D, the surface 24b includes an uncoated region where the negative electrode active material layer 26 is not provided. When viewed from the stacking direction D, the uncoated region surrounds the negative electrode active material layer 26. The multiple bipolar electrodes 21 are stacked such that the positive electrode active material layer 25 of one bipolar electrode 21 and the negative electrode active material layer 26 of another bipolar electrode 21 face each other. That is, the multiple bipolar electrodes 21 are stacked such that the surface 24a of the current collector 24 of one bipolar electrode 21 faces the surface 24b of the current collector 24 of the other bipolar electrode 21 among the adjacent bipolar electrodes 21.

[0024] The positive terminal electrode 22 is disposed on one side of the plurality of bipolar electrodes 21 in the stacking direction D. The positive terminal electrode 22 has a current collector 24 and a positive electrode active material layer 25. The positive terminal electrode 22 differs from the bipolar electrodes 21 in that it does not have a negative electrode active material layer 26. The other configuration of the positive terminal electrode 22 is the same as that of the bipolar electrodes 21. The positive terminal electrode 22 is disposed such that the positive electrode active material layer 25 of the positive terminal electrode 22 faces the negative electrode active material layer 26 of the bipolar electrode 21. That is, the positive terminal electrode 22 is stacked such that the surface 24a of the current collector 24 of the positive terminal electrode 22 faces the surface 24b of the current collector 24 of the bipolar electrode 21 adjacent to the positive terminal electrode 22.

[0025] The negative terminal electrode 23 is disposed on the other side of the plurality of bipolar electrodes 21 in the stacking direction D. The negative terminal electrode 23 has a current collector 24 and a negative electrode active material layer 26. The negative terminal electrode 23 differs from the bipolar electrodes 21 in that it does not have a positive electrode active material layer 25. The other configuration of the negative terminal electrode 23 is the same as that of the bipolar electrode 21. The negative terminal electrode 23 is disposed such that the negative electrode active material layer 26 of the negative terminal electrode 23 faces the positive electrode active material layer 25 of the bipolar electrode 21. That is, the negative terminal electrode 23 is stacked such that the surface 24b of the current collector 24 of the negative terminal electrode 23 faces the surface 24a of the current collector 24 of the bipolar electrode 21 adjacent to the negative terminal electrode 23. Between each bipolar electrode 21, between the bipolar electrode 21 and the positive terminal electrode 22, and between the bipolar electrode 21 and the negative terminal electrode 23, an internal space S containing an electrolyte is formed.

[0026] The laminate 2 includes a plurality of separators 27. The separators 27 are disposed between the bipolar electrodes 21, between the bipolar electrodes 21 and the positive terminal electrode 22, and between the bipolar electrodes 21 and the negative terminal electrode 23. The separators 27 are positioned between the opposing positive electrode active material layers 25 and negative electrode active material layers 26. The separators 27 are, for example, sheet-shaped. When viewed from the stacking direction D, the separators 27 are, for example, rectangular. When viewed from the stacking direction D, the outer edges of the separators 27 are positioned outside the outer edges of the positive electrode active material layers 25 and the negative electrode active material layers 26. The separators 27 are a member that allows charge carriers such as lithium ions to pass through. The separators 27 isolate the adjacent electrodes 21, 22, and 23. This prevents electrical short circuits due to contact between the electrodes 21, 22, and 23.

[0027] The current collector 24 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer 25 and the negative electrode active material layer 26 during discharge or charge of the lithium-ion secondary battery. The material of the current collector 24 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. Examples of conductive resin materials include resins in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material. The current collector 24 may include one or more layers containing the above-mentioned metal material or conductive resin material. A coating layer may be formed on the surface of the current collector 24 by a known method such as plating or spray coating.

[0028] The current collector 24 may be, for example, plate-shaped, foil-shaped, sheet-shaped, film-shaped, mesh-shaped, or the like. When the current collector 24 is a metal foil, the current collector 24 may be, for example, an aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 24 may be an alloy foil or clad foil of any of the above metals. When the current collector 24 is foil-shaped, the thickness of the current collector 24 may be in the range of 1 μm to 100 μm. The current collector 24 may be integrated by, for example, copper plating one side of an aluminum foil. The current collector 24 may be integrated by bonding. In this embodiment, the first layer 241 of the current collector 24 contains aluminum, for example, aluminum foil. In this embodiment, the second layer 242 of the current collector 24 contains copper, for example, copper foil.

[0029] The positive electrode active material layer 25 includes a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include composite oxides, metallic lithium, and sulfur. The composite oxides include at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. Examples of the composite oxides include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2.

[0030] The negative electrode active material layer 26 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the negative electrode active material include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, soft carbon, and other carbons, metal compounds, elements or compounds thereof that can be alloyed with lithium, and boron-doped carbon. Examples of elements that can be alloyed with lithium include silicon and tin.

[0031] In addition to the active material, each of the positive electrode active material layer 25 and the negative electrode active material layer 26 may contain a binder and a conductive additive. The binder serves to connect the active material or conductive additive to each other and maintain the conductive network within the electrode. Examples of binders include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as polyacrylic acid and polymethacrylic acid; styrene-butadiene rubber; carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders may be used alone or in combination. The conductive additive is, for example, a conductive material such as acetylene black, carbon black, or graphite, and can enhance electrical conductivity. Examples of viscosity-adjusting solvents include N-methyl-2-pyrrolidone.

[0032] Formation of the positive electrode active material layer 25 on the surface 24a and the negative electrode active material layer 26 on the surface 24b can be achieved by conventional methods such as roll coating, die coating, dip coating, doctor blade coating, spray coating, and curtain coating. Specifically, an active material, a solvent, and, if necessary, a binder and a conductive additive are mixed to produce a slurry-like active material layer-forming composition. The active material layer-forming composition is then applied to the surface 24a or the surface 24b and dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. The dried electrode may be compressed to increase electrode density.

[0033] The separator 27 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. The separator 27 may be made of, for example, polypropylene, polyethylene, polyolefin, polyester, or the like. The separator 27 may have a single-layer structure or a multi-layer structure. When the separator 27 has a multi-layer structure, the separator 27 may include, for example, a substrate layer and a pair of adhesive layers, and may be bonded and fixed to the positive electrode active material layer 25 and the negative electrode active material layer 26 by the pair of adhesive layers. The separator 27 may also include a ceramic layer that serves as a heat-resistant layer. The separator 27 may also be reinforced with a vinylidene fluoride resin compound.

[0034] The electrolyte solution impregnated in the separator 27 may be, for example, a liquid containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte salt of the electrolyte solution. Known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as the non-aqueous solvent. Two or more of these known solvent materials may be used in combination.

[0035] The sealing body 3 is a member that seals the internal space S. The sealing body 3 is provided on the side surface of the stacked body 2. The sealing body 3 seals the side surface of the stacked body 2. The sealing body 3 has, for example, a rectangular cylindrical shape. The sealing body 3 has electrical insulation properties. Below, with reference to FIG. 2, a description will be given focusing on a pair of adjacent electrodes (for example, a pair of bipolar electrodes 21).

[0036] 2, the sealing body 3 has a main body portion 31 and a welding portion 32. The main body portion 31 is provided on the outer edge of the laminate 2. The main body portion 31 is composed of multiple independent members. The main body portion 31 has multiple sealing portions 33 and multiple spacers 34. The sealing portion 33 has a sealing portion 35 provided on the surface 24a of the current collector 24, a sealing portion 36 provided on the surface 24b of the current collector 24, and a sealing portion 37 provided on the side surface of the current collector 24.

[0037] Each of the sealing portions 35, 36 has, for example, a rectangular frame shape when viewed from the stacking direction. The sealing portion 35 surrounds the positive electrode active material layer 25 and the negative electrode active material layer 26 when viewed from the stacking direction D. An inner edge 35d of the sealing portion 35 is spaced apart from the positive electrode active material layer 25. An outer edge 35c of the sealing portion 35 substantially coincides with the outer edge 24c of the current collector 24 when viewed from the stacking direction D. The sealing portion 35 is welded to the surface 24a. The sealing portion 36 surrounds the positive electrode active material layer 25 and the negative electrode active material layer 26 when viewed from the stacking direction D. An inner edge 36d of the sealing portion 36 is spaced apart from the negative electrode active material layer 26. The inner edge 36d of the sealing portion 36 substantially coincides with the inner edge 35d of the sealing portion 35 when viewed from the stacking direction D. An outer edge 36c of the sealing portion 36 substantially coincides with the outer edge 24c of the current collector 24 when viewed from the stacking direction D. The sealing portion 36 is welded to the surface 24b.

[0038] The seal portion 37 is provided on the side surface of the current collector 24. The seal portion 37 covers the side surface of the current collector 24. The seal portion 37 is welded to the side surface of the current collector 24. The seal portion 37 seals between the first layer 241 and the second layer 242. The seal portion 37 is connected to the outer edge 35c of the seal portion 35 and the outer edge 36c of the seal portion 36. The seal portions 35, 36, and 37 are partial regions of the seal section 33 that are integrally formed from the same material.

[0039] Hereinafter, of a pair of adjacent bipolar electrodes 21, one bipolar electrode 21 (for example, the upper bipolar electrode 21 shown in FIG. 2) will be referred to as the first electrode 21, and the other bipolar electrode 21 (for example, the lower bipolar electrode 21 shown in FIG. 2) will be referred to as the second electrode 21. Furthermore, the current collector 24 of the first electrode 21 will be referred to as the first current collector 24, and the current collector 24 of the second electrode 21 will be referred to as the second current collector 24. Furthermore, the surface 24a of the first current collector 24 will be referred to as the first surface 24a, and the surface 24b of the second current collector 24 will be referred to as the second surface 24b. Furthermore, the seal portion 33 provided on the first current collector 24 will be referred to as the first seal portion 33, and the seal portion 33 provided on the second current collector 24 will be referred to as the second seal portion 33. In addition, the seal portion 35 of the first seal portion 33 that is welded to the first surface 24a of the first current collector 24 is referred to as the first seal portion 35, and the seal portion 36 of the second seal portion 33 that is welded to the second surface 24b of the second current collector 24 is referred to as the second seal portion 36.

[0040] The spacer 34, together with the first electrode 21, the first seal portion 33, the second electrode 21, and the second seal portion 33, forms an internal space S for accommodating the electrolyte. The spacer 34 has, for example, a rectangular frame shape (see FIG. 4 ) with a portion cut out for a liquid filling port 34a (described later). The spacer 34 is a separate member from the first seal portion 33 and the second seal portion 33. The spacer 34 is provided between the first seal portion 33 and the second seal portion 33. The spacer 34 is sandwiched between the first seal portion 35 and the second seal portion 36. The spacer 34 is in contact with both the first seal portion 35 and the second seal portion 36. The spacer 34 is not welded to either the first seal portion 35 or the second seal portion 36. When viewed from the stacking direction, the inner edge 34d of the spacer 34 is located on the opposite side of the positive electrode active material layer 25 or the negative electrode active material layer 26 with respect to the inner edge 35d of the first seal portion 35 and the inner edge 36d of the second seal portion 36. That is, the inner edge 34d of the spacer 34 is located farther from the positive electrode active material layer 25 or the negative electrode active material layer 26 than the inner edge 35d of the first seal portion 35 and the inner edge 36d of the second seal portion 36. When viewed from the stacking direction, the outer edge 34c of the spacer 34 approximately coincides with the outer edge 33c of the first seal portion 33 and the outer edge 33c of the second seal portion 33.

[0041] The thickness T1 of the spacer 34 is greater than the thickness T2 of the first seal portion 35 and the thickness T3 of the second seal portion 36. The thickness T1 of the spacer 34 is, for example, at least twice the thickness T2 of the first seal portion 35 or the thickness T3 of the second seal portion 36. The thickness T1 of the spacer 34 is smaller than the thickness T4 of the first seal portion 33 or the second seal portion 33. In other words, the thickness T1 of the spacer 34 is smaller than the sum of the thickness of the first layer 241 of the current collector 24, the thickness of the second layer 242 of the current collector 24, the thickness of the seal portion 35, and the thickness of the seal portion 36. The thickness T2 of the first seal portion 35 and the thickness T3 of the second seal portion 36 may be the same or different.

[0042] A peripheral edge portion 27a of the separator 27 is located between the spacer 34 and the second seal portion 36. The peripheral edge portion 27a of the separator 27 is sandwiched between the spacer 34 and the second seal portion 36, excluding a liquid inlet 34a described below. The separator 27 divides the internal space S into a first region S1 and a second region S2. The first region S1 is a region of the internal space S between the separator 27 and the first electrode 21. The second region S2 is a region of the internal space S between the separator 27 and the second electrode 21.

[0043] The volume of the first region S1 is larger than the volume of the second region S2. Specifically, when viewed from the stacking direction D, the area of ​​the positive electrode active material layer 25 is smaller than the area of ​​the negative electrode active material layer 26. When viewed from the stacking direction D, the outer edge of the positive electrode active material layer 25 is located more inward than the outer edge of the negative electrode active material layer 26. In addition, the thickness of the positive electrode active material layer 25 is larger than the thickness of the negative electrode active material layer 26. Furthermore, as described above, the peripheral portion 27a of the separator 27 is located between the spacer 34 and the second seal portion 36. With this configuration, the volume of the first region S1 is larger than the volume of the second region S2.

[0044] As shown in FIGS. 2 and 3, the spacer 34 includes a liquid inlet (first liquid inlet) 34a. The liquid inlet 34a penetrates the spacer 34. The liquid inlet 34a opens at each of an outer edge 34c and an inner edge 34d of the spacer 34. The liquid inlet 34a opens at both ends of the spacer 34 in the stacking direction D. The liquid inlet 34a communicates with the internal space S. The liquid inlet 34a functions as a path for injecting the electrolyte into the internal space S. The liquid inlets 34a of the multiple spacers 34 are formed at different positions from each other. The liquid inlets 34a are aligned obliquely with respect to the stacking direction D. The liquid inlets 34a adjacent to each other in the stacking direction D do not overlap with each other in the stacking direction D. The liquid inlet 34a has, for example, a rectangular shape when viewed from a direction intersecting the outer surface 32b of the welded portion 32.

[0045] The welded portion 32 is provided on the outside of the main body portion 31. The welded portion 32 has, for example, a rectangular cylindrical shape. The welded portion 32 extends to both ends of the stack 2 in the stacking direction D. The welded portion 32 is integrally formed. The welded portion 32 is formed by melting the outer edge portions of each seal portion 33 and each spacer 34 and then solidifying and welding them together. More specifically, the welded portion 32 is formed by welding the outer edge portions of each seal portion 33 and each spacer 34 that are located outside the outer edge 24c of the current collector 24 (the outer edge 35c of the seal portion 35 and the outer edge 36c of the seal portion 36) when viewed from the stacking direction D. The welded portion 32 is formed by welding a portion of the region of each seal portion 33 and each spacer 34 that is located outside the outer edge 24c of the current collector 24. The welded portion 32 does not extend to the outer edge 24c of each current collector 24. In this way, the welded portion 32 is formed by integrating the seal portions 33 and the spacers 34 by welding.

[0046] The welded portion 32 includes a plurality of liquid inlets (second liquid inlets) 32a. The liquid inlets 32a penetrate the welded portion 32. The liquid inlets 32a open to the outer surface 32b of the welded portion 32. The liquid inlets 32a communicate with the liquid inlets 34a. The liquid inlets 32a function as a path for injecting the electrolyte into the internal space S via the liquid inlets 34a. The liquid inlets 32a are arranged diagonally with respect to the stacking direction D. The liquid inlets 32a adjacent to each other in the stacking direction D do not overlap with each other in the stacking direction D. When viewed from a direction intersecting the outer surface 32b of the welded portion 32, the liquid inlets 32a have, for example, a rectangular shape.

[0047] When viewed from a direction intersecting the outer side surface 32b, the area of ​​the liquid inlet 32a is smaller than the area of ​​the liquid inlet 34a. When viewed from a direction intersecting the outer side surface 32b, the liquid inlet 32a is located inside the liquid inlet 34a. The width W1 of the liquid inlet 32a in the stacking direction D is smaller than the width W2 of the liquid inlet 34a in the stacking direction D. When viewed from a direction intersecting the outer side surface 32b, the width W3 of the liquid inlet 32a in the direction intersecting the stacking direction D is smaller than the width W4 of the liquid inlet 34a in the direction intersecting the stacking direction D.

[0048] A frame portion 38 that surrounds the liquid pouring port 32a is formed on the outer side surface 32b. The frame portion 38 protrudes from the outer side surface 32b. When viewed from a direction intersecting the outer side surface 32b, the frame portion 38 has, for example, a rectangular frame shape. When viewed from a direction intersecting the outer side surface 32b, the inner edge of the frame portion 38 is located outward from the liquid pouring port 32a and the liquid pouring port 34a. The area inside the frame portion 38 communicates with the liquid pouring port 34a via the liquid pouring port 32a.

[0049] The seal portion 33 and the spacer 34 are each made of a material such as acid-modified polyethylene (acid-modified PE), acid-modified polypropylene (acid-modified PP), polyethylene, or polypropylene. The seal portion 33 and the spacer 34 are each electrolyte-resistant. The seal portion 33 and the spacer 34 may be made of the same material or different materials. In this embodiment, the seal portion 33 is made of, for example, acid-modified polyethylene or acid-modified polypropylene. In this embodiment, the spacer 34 is made of, for example, polyethylene or polypropylene.

[0050] Acid-modified polyethylene and acid-modified polypropylene are more easily bonded to metal than non-acid-modified polyethylene and non-acid-modified polypropylene. When the current collector 24 is made of metal, the bonding strength of the seal portions 35, 36 to the current collector 24 can be improved by forming the seal portions 35, 36 from acid-modified polyethylene or acid-modified polypropylene.

[0051] As shown in FIG. 4, the positive electrode active material layer 25 includes a plurality of grooves 25a. Each groove 25a extends in the direction in which the liquid inlet 32a, the liquid inlet 34a, and the internal space S are aligned. Each groove 25a reaches both ends of the positive electrode active material layer 25 in the extension direction of the groove 25a. Each groove 25a reaches the first surface 24a of the first current collector 24. That is, the first surface 24a of the first current collector 24 is exposed to each groove 25a. Each groove 25a is part of the first region S1. The electrolyte solution injected through the liquid inlet 32a, 34a can move through the region of the first region S1 between the positive electrode active material layer 25 and the spacer 34 and each groove 25a.

[0052] Next, a method for manufacturing the electricity storage device 1 will be described. First, as shown in Fig. 5, the bipolar electrode 21, the sealing member 41, and the sealing member 42 are prepared. Next, the sealing member 41 is placed on the surface 24a of the current collector 24, and the sealing member 42 is placed on the surface 24b of the current collector 24. The sealing members 41 and 42 are placed so as to protrude beyond the outer edge 24c of the current collector 24.

[0053] Next, as shown in FIG. 6 , the surfaces of the seal members 41 and 42 are heated by a heater 5. The heater 5 is, for example, an impulse sealer. The heater 5 heats the seal members 41 and 42 while sandwiching the current collector 24 between the seal members 41 and 42. As a result, the portion of the seal member 41 that overlaps the surface 24a is welded to the surface 24a, forming a sealed portion 35. The portion of the seal member 42 that overlaps the surface 24b is welded to the surface 24b, forming a sealed portion 36. Furthermore, the portions of the seal member 41 located outside the outer edge 24c of the current collector 24 and the portions of the seal member 42 located outside the outer edge 24c of the current collector 24 are melted to form a sealed portion 37. In other words, a sealed portion 33 is formed on the bipolar electrode 21. Similarly, a sealed portion 33 is formed on the positive terminal electrode 22 and the negative terminal electrode 23.

[0054] Next, as shown in FIG. 7, the electrodes 21, 22, 23 with the seal portions 33 formed thereon and the spacers 34 are stacked. The spacers 34 are disposed between the seal portions 33. Next, the liquid inlet forming member 6 is inserted into the liquid inlet 34a of the spacer 34. The liquid inlet forming member 6 has, for example, a plate shape. The liquid inlet forming member 6 extends from the outside of the spacer 34 to the internal space S. The width of the liquid inlet forming member 6 is smaller than the width of the liquid inlet 34a. In other words, a clearance exists between the liquid inlet forming member 6 and the liquid inlet 34a.

[0055] Next, as shown in FIG. 8 , the outer surfaces of the seal portions 33 and the spacers 34 are melted by a heating device 7. Specifically, the heating device 7 is, for example, an infrared heater. The heating device 7 irradiates the outer surfaces of the seal portions 33 and the spacers 34 with infrared rays. When the outer surfaces of the seal portions 33 and the spacers 34 are irradiated with infrared rays, heat is generated from the seal portions 33 and the spacers 34. The heat of the seal portions 33 and the spacers 34 is controlled to a temperature equal to or higher than their melting points. As a result, the outer edge portions of the seal portions 33 and the spacers 34 located outside the outer edge 24c of the current collector 24 melt. When the outer edge portions of the seal portions 33 and the spacers 34 melt, the molten liquid portions penetrate between the liquid inlet 34a and the liquid inlet-forming member 6. The melted outer edge portions of the seal portions 33 and the spacers 34 solidify to form the welded portions 32.

[0056] 9, each liquid pouring port-forming member 6 is pulled out from the liquid pouring port 34a. This forms the liquid pouring port 32a in the welded portion 32. Next, a frame portion 38 is formed on the outer surface 32b of the welded portion 32 by, for example, injection molding.

[0057] Next, as shown in FIG. 10 , the electrolyte is injected into each internal space S through each liquid filling port 32a and each liquid filling port 34a. Specifically, the equipment-side nozzle 8 is pressed against the frame portion 38. The equipment-side nozzle 8 has a support member 81 and a seal member 82. The seal member 82 is provided on the surface of the support member 81. The seal member 82 is, for example, an elastic body. The seal member 82 is, for example, a packing. The equipment-side nozzle 8 is formed with a plurality of liquid filling ports 8a. Each liquid filling port 8a corresponds to each liquid filling port 32a and each liquid filling port 34a. The surface of the seal member 82 is pressed against the frame portion 38. When the surface of the seal member 82 is pressed against the frame portion 38, at least a portion of the frame portion 38 is embedded in the seal member 82. Next, the electrolyte is injected into the internal space S using the equipment-side nozzle 8.

[0058] Next, as shown in Fig. 11, each liquid filling port 32a is sealed. Specifically, the sealing material 9 is joined to the frame portion 38 to seal the liquid filling port 32a surrounded by the frame portion 38. In this way, the energy storage device 1 shown in Fig. 1 is manufactured. Note that the frame portion 38 and the sealing material 9 are not shown in Fig. 1.

[0059] As described above, in the electricity storage device 1, the seal portion 35 is welded to the surface 24a of the current collector 24, and the seal portion 36 is welded to the surface 24b of the current collector 24. Moreover, the welded portion 32 is formed by welding each seal portion 33 and the outer edge of each spacer 34. This allows the internal space S to be reliably sealed. Furthermore, the thickness T1 of the spacer 34 is greater than the thickness T2 of the seal portion 35 and the thickness T3 of the seal portion 36, and the liquid inlet 34a is formed in the spacer 34. This allows the thickness of the seal portion 35 or the seal portion 36 to be sufficiently small while ensuring that the spacer 34 is thick enough to form the liquid inlet 34a. Therefore, the electricity storage device 1 can suppress deformation (e.g., wrinkles) of the current collector 24 due to welding of the seal portion 35 to the surface 24a or deformation of the current collector 24 due to welding of the seal portion 36 to the surface 24b.

[0060] The width of the liquid filling port 32a is smaller than the width of the liquid filling port 34a, which makes it possible to prevent the electrolyte contained in the internal space S from flowing back to the outside.

[0061] The peripheral edge 27a of the separator 27 is located between the spacer 34 and the seal portion 36. The volume of the first region S1 of the internal space S is larger than the volume of the second region S2 of the internal space S. As a result, the liquid pouring port 34a communicates with the first region S1, which has a larger volume, and therefore, smooth liquid pouring can be achieved.

[0062] When viewed from the stacking direction D, the area of ​​the positive electrode active material layer 25 is smaller than the area of ​​the negative electrode active material layer 26. This allows the volume of the first region S1 to be larger than the volume of the second region S2, thereby achieving smooth injection as described above.

[0063] The thickness of the positive electrode active material layer 25 is greater than the thickness of the negative electrode active material layer 26. This allows the volume of the first region S1 to be greater than the volume of the second region S2, thereby realizing smooth injection as described above.

[0064] The positive electrode active material layer 25 includes a groove 25a extending in the direction in which the injection port 34a and the internal space S are aligned. This prevents the flow of the electrolyte from being obstructed by the positive electrode active material layer 25, thereby achieving smooth injection. Furthermore, because the groove 25a reaches the surface 24a of the current collector 24, gases and the like generated during the formation of the positive electrode active material layer 25 on the surface 24a can be efficiently discharged from between the surface 24a and the positive electrode active material layer 25.

[0065] The current collector 24 has a first layer 241 and a second layer 242. The seal portion 33 includes a seal portion 35 welded to the surface 24a, a seal portion 36 welded to the surface 24b, and a seal portion 37 welded to a side surface of the current collector 24. This prevents the electrolyte from entering between the seal portion 35 and the surface 24a of the first layer 241 and between the seal portion 37 and the side surface of the first layer 241 and then contacting the second layer 242. Similarly, it prevents the electrolyte from entering between the seal portion 36 and the surface 24b of the second layer 242 and between the seal portion 37 and the side surface of the second layer 242 and then contacting the first layer 241.

[0066] [Second embodiment] The energy storage device of the second embodiment differs from the energy storage device 1 of the first embodiment mainly in that it includes a spacer 34A instead of the spacer 34. As shown in Fig. 12, the spacer 34A is provided between the first seal portion 33 and the second seal portion 33. The spacer 34A includes a first spacer 341 and a second spacer 342. The first spacer 341 and the second spacer 342 are separate members.

[0067] The first spacer 341 has, for example, a rectangular frame shape. The first spacer 341 is in contact with the first seal portion 35 of the first seal unit 33. The first spacer 341 is not welded to the first seal portion 35. When viewed from the stacking direction D, an inner edge 341d of the first spacer 341 is located on the opposite side of the positive electrode active material layer 25 from the inner edge 35d of the first seal portion 35. That is, the inner edge 341d of the first spacer 341 is located farther from the positive electrode active material layer 25 than the inner edge 35d of the first seal portion 35. The first spacer 341 includes a liquid inlet (first liquid inlet) 34a. That is, the liquid inlet 34a is formed in the first spacer 341. The liquid inlet 34a penetrates the first spacer 341. The liquid inlet 34a opens at both the outer edge and the inner edge 341d of the first spacer 341. The liquid injection port 34a is formed by cutting out the entire first spacer 341 in the stacking direction D.

[0068] The second spacer 342 has, for example, a rectangular frame shape. The second spacer 342 is provided between the first spacer 341 and the second seal portion 33. The second spacer 342 is in contact with the first spacer 341. The second spacer 342 is in contact with the second seal portion 36 of the second seal portion 33. The second spacer 342 is not welded to the second seal portion 36. When viewed from the stacking direction D, the inner edge 342d of the second spacer 342 is located on the opposite side of the negative electrode active material layer 26 from the inner edge 36d of the second seal portion 36. That is, the inner edge 342d of the second spacer 342 is located farther from the negative electrode active material layer 26 than the inner edge 36d of the second seal portion 36. When viewed from the stacking direction D, the inner edge 342d of the second spacer 342 approximately coincides with the inner edge 341d of the first spacer 341. The second spacer 342 does not include a liquid injection hole. That is, the second spacer 342 has a frame shape that is continuously connected in the circumferential direction.

[0069] The thickness T11 of the first spacer 341 is greater than the thickness T2 of the first seal portion 35 and the thickness T3 of the second seal portion 36. The thickness T12 of the second spacer 342 is greater than the thickness T2 of the first seal portion 35 and the thickness T3 of the second seal portion 36. The thickness T11 of the first spacer 341 and the thickness T12 of the second spacer 342 are the same. That is, the thickness T11 of the first spacer 341 and the thickness T12 of the second spacer 342 are each approximately half the thickness T1 of the spacer 34A. The thickness T11 of the first spacer 341 and the thickness T12 of the second spacer 342 may be different. The thickness T11 of the first spacer 341 may be greater than the thickness T12 of the second spacer 342. The thickness T11 of the first spacer 341 may be smaller than the thickness T12 of the second spacer 342. The thickness T11 of the first spacer 341 may be equal to or smaller than the thickness T2 of the first seal portion 35 or the thickness T3 of the second seal portion 36. The thickness T12 of the second spacer 342 may be equal to or smaller than the thickness T2 of the first seal portion 35 or the thickness T3 of the second seal portion 36.

[0070] The peripheral edge portion 27a of the separator 27 is located between the first spacer 341 and the second spacer 342. The peripheral edge portion 27a of the separator 27 is welded to the second spacer 342. The peripheral edge portion 27a of the separator 27 is welded to the surface of the second spacer 342 that faces the first spacer 341. The peripheral edge portion 27a of the separator 27 is welded to the second spacer 342 around the entire periphery of the second spacer 342. In other words, the portion of the separator 27 that is welded to the second spacer 342 has a rectangular frame shape when viewed from the stacking direction D.

[0071] Next, a method for manufacturing the electricity storage device according to the second embodiment will be described. First, as in the first embodiment, a seal portion 33 is formed on each of the electrodes 21, 22, 23 (see FIGS. 5 and 6). Next, as shown in FIG. 13, the peripheral portion 27a of the separator 27 is welded to the second spacer 342. Specifically, after the peripheral portion 27a of the separator 27 is disposed on one side of the second spacer 342, the peripheral portion 27a of the separator 27 and the second spacer 342 are heated.

[0072] Next, as shown in FIG. 14 , the electrodes 21, 22, and 23 with the seal portions 33 formed thereon, the second spacer 342 with the separator 27 welded thereto, and the first spacer 341 are stacked together. The first spacer 341 is disposed on one side of the second spacer 342 to which the peripheral edge portion 27a of the separator 27 is welded. The first spacer 341 and the second spacer 342 are disposed between the seal portions 33. Next, as in the first embodiment, the liquid inlet forming member 6 is inserted into the liquid inlet 34a. Next, as in the first embodiment, the formation of the weld portions, the injection of the electrolyte, the sealing of the liquid inlet, and the like are performed. In this way, the electricity storage device of the second embodiment is manufactured.

[0073] As described above, the spacer 34A includes a first spacer 341 and a second spacer 342, each of which is formed in a frame shape and stacked in the stacking direction D. This makes it easy to adjust the thickness of the spacer 34A, facilitating the manufacture of the electricity storage device. Furthermore, because the spacer 34A includes multiple spacers, the thickness of each spacer 341, 342 is smaller than the distance between adjacent seal portions 33, making it possible to make the spacers thinner than when a single spacer is used. This makes it easy to wind, for example, precursors of the spacers 341, 342 into a roll. This makes it easy to handle the precursors of the spacers 341, 342, facilitating the manufacture of the electricity storage device.

[0074] A peripheral edge portion 27a of the separator 27 is welded to the second spacer 342. When the separator 27 is welded to the first spacer 341, the separator 27 is not welded to the first spacer 341 in a region of the first spacer 341 where the liquid inlet 34a is formed, and therefore the separator 27 may not be sufficiently fixed. According to the configuration of the energy storage device of the second embodiment, the peripheral edge portion 27a of the separator 27 is welded to the second spacer 342 where the liquid inlet 34a is not formed, and therefore the peripheral edge portion 27a of the separator 27 can be more reliably fixed. Therefore, short circuits between the electrodes 21, 22, and 23 can be suppressed.

[0075] When the separator 27 is welded to the first sealed portion 35 or the second sealed portion 36, the separator 27 may be welded to the first sealed portion 35 or the second sealed portion 36 after the first sealed portion 35 or the second sealed portion 36 is welded to the current collector 24. In such a case, the first sealed portion 35 or the second sealed portion 36 is heated multiple times, which may reduce the welding strength of the first sealed portion 35 or the second sealed portion 36 to the current collector 24. According to the configuration of the electricity storage device of the second embodiment, the peripheral edge portion 27a of the separator 27 is welded to the second spacer 342, which prevents a reduction in the welding strength of the first sealed portion 35 or the second sealed portion 36 to the current collector 24.

[0076] [Third embodiment] The electricity storage device of the third embodiment differs from the electricity storage device of the second embodiment mainly in that it includes a spacer 34B instead of the spacer 34A. As shown in Fig. 15, the spacer 34B is provided between the first seal portion 33 and the second seal portion 33. The spacer 34B includes a first spacer 341, a second spacer 342, and a third spacer 343. The first spacer 341, the second spacer 342, and the third spacer 343 are each separate members.

[0077] The thickness T11 of the first spacer 341 is approximately one-third the thickness T1 of the spacer 34B. The rest of the first spacer 341 is the same as the first spacer 341 of the second embodiment. The second spacer 342 is disposed between the first spacer 341 and the third spacer 343. The thickness T12 of the second spacer 342 is the same as the thickness T11 of the first spacer 341. That is, the thickness T12 of the second spacer 342 is approximately one-third the thickness T1 of the spacer 34B. When viewed from the stacking direction D, the inner edge 342d of the second spacer 342 is located more inward than the inner edge 341d of the first spacer 341. When viewed from the stacking direction D, the inner edge 342d of the second spacer 342 is located more inward than the inner edge 35d of the first seal portion 35 or the inner edge 36d of the second seal portion 36. The width of the side of the second spacer 342 is greater than the width of the side of the first spacer 341. Other points of the second spacer 342 are the same as those of the second spacer 342 of the second embodiment.

[0078] The third spacer 343 is stacked on the second spacer 342 on the opposite side of the first spacer 341. The third spacer 343 has, for example, a rectangular frame shape. The thickness T13 of the third spacer 343 is the same as the thickness T11 of the first spacer 341. That is, the thickness T13 of the third spacer 343 is approximately one-third the thickness T1 of the spacer 34B. The third spacer 343 is in contact with the second seal portion 36 of the second seal unit 33. The third spacer 343 is not welded to the second seal portion 36. When viewed from the stacking direction D, the inner edge 343d of the third spacer 343 is located on the opposite side of the negative electrode active material layer 26 with respect to the inner edge 36d of the second seal portion 36. When viewed from the stacking direction D, the inner edge 343d of the third spacer 343 approximately coincides with the inner edge 341d of the first spacer 341.

[0079] The third spacer 343 includes a liquid inlet (first liquid inlet) 34a. That is, the liquid inlet 34a is also formed in the third spacer 343. The liquid inlet 34a penetrates the third spacer 343. The liquid inlet 34a opens at each of the outer edge and inner edge 343d of the third spacer 343. The liquid inlet 34a opens at both ends of the third spacer 343 in the stacking direction D.

[0080] The thickness T11 of the first spacer 341, the thickness T12 of the second spacer 342, and the thickness T13 of the third spacer 343 are each greater than the thickness T2 of the first seal portion 35 and the thickness T3 of the second seal portion 36, respectively. The thickness T11 of the first spacer 341, the thickness T12 of the second spacer 342, and the thickness T13 of the third spacer 343 may be different from each other, as in the energy storage device of the second embodiment. The thickness T13 of the third spacer 343 may be equal to or less than the thickness T2 of the first seal portion 35 or the thickness T3 of the second seal portion 36.

[0081] The peripheral edge portion 27a of the separator 27 is welded to the second spacer 342. The peripheral edge portion 27a of the separator 27 is welded to a surface of the second spacer 342 facing the first spacer 341. The peripheral edge portion 27a of the separator 27 is welded to a portion of the second spacer 342 that is more inward than the first spacer 341. The peripheral edge portion 27a of the separator 27 is welded to the second spacer 342 around the entire periphery of the second spacer 342. In other words, the portion of the separator 27 welded to the second spacer 342 has a rectangular frame shape when viewed from the stacking direction D. The peripheral edge portion 27a of the separator 27 may extend between the first spacer 341 and the second spacer 342.

[0082] Next, a method for manufacturing the electricity storage device according to the third embodiment will be described. First, as in the first embodiment, a seal portion 33 is formed on each of the electrodes 21, 22, 23 (see FIGS. 5 and 6). Next, as shown in FIG. 16, the peripheral portion 27a of the separator 27 is welded to the second spacer 342. Specifically, after the peripheral portion 27a of the separator 27 is disposed on one side of the second spacer 342, the peripheral portion 27a of the separator 27 and the second spacer 342 are heated.

[0083] Next, as shown in FIG. 17 , the electrodes 21, 22, and 23 with the seal portions 33 formed thereon, the second spacer 342 with the separator 27 welded thereto, the first spacer 341, and the third spacer 343 are stacked. The first spacer 341 is disposed on one side of the second spacer 342 to which the peripheral edge portion 27a of the separator 27 is welded. The third spacer 343 is disposed on the opposite side of the second spacer 342 from the first spacer 341. The first spacer 341, the second spacer 342, and the third spacer 343 are disposed between the seal portions 33. Next, as in the first embodiment, the liquid inlet forming member 6 is inserted into the liquid inlet 34a. Next, as in the first embodiment, the formation of the weld portions, the injection of the electrolyte, the sealing of the liquid inlet, and the like are performed. This completes the manufacture of the electricity storage device of the third embodiment.

[0084] As described above, when viewed from the stacking direction D, the inner edge 342d of the second spacer 342 is located more inward than the inner edge 341d of the first spacer 341. This ensures a sufficient area of ​​the second spacer 342 for welding the separator 27. This makes it possible to more reliably fix the peripheral edge 27a of the separator 27, and more reliably prevent short circuits between the electrodes 21, 22, and 23.

[0085] The spacer 34B includes a third spacer 343 stacked on the opposite side of the first spacer 341 with respect to the second spacer 342. The liquid pouring port 34a is formed in each of the first spacer 341 and the third spacer 343. This allows liquid to be poured from both sides of the separator 27 in the stacking direction D. This allows for smooth liquid pouring.

[0086] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0087] In each embodiment, the description has been given focusing on a pair of bipolar electrodes 21, but attention may also be paid to the positive terminal electrode 22 and the bipolar electrode 21 adjacent to the positive terminal electrode 22. In this case, the first electrode is the positive terminal electrode 22, and the second electrode is the bipolar electrode 21 adjacent to the positive terminal electrode 22. Similarly, attention may also be paid to the negative terminal electrode 23 and the bipolar electrode 21 adjacent to the negative terminal electrode 23. In this case, the first electrode is the bipolar electrode 21 adjacent to the negative terminal electrode 23, and the second electrode is the negative terminal electrode 23.

[0088] In each embodiment, an example has been shown in which the current collector 24 has the first layer 241 and the second layer 242, but the current collector 24 may have only one layer.

[0089] In the first embodiment, an example is shown in which the peripheral edge portion 27a of the separator 27 is sandwiched between the spacer 34 and the second seal portion 36, but the peripheral edge portion 27a of the separator 27 may be welded to the second seal portion 36.

[0090] In the second and third embodiments, an example has been described in which the peripheral edge portion 27a of the separator 27 is welded to a surface of the second spacer 342 facing the first spacer 341. However, the peripheral edge portion 27a of the separator 27 may be welded to a surface of the second spacer 342 opposite to the first spacer 341. Furthermore, in the second and third embodiments, an example has been described in which the peripheral edge portion 27a of the separator 27 is welded to the second spacer 342 around the entire periphery of the second spacer 342. However, the peripheral edge portion 27a of the separator 27 may be welded to the second spacer 342 at predetermined intervals in the circumferential direction of the second spacer 342. In other words, the peripheral edge portion 27a of the separator 27 may be partially welded to the second spacer 342. Even in this case, the separator 27 can be welded to the second spacer 342 at intervals that are independent of the width of the liquid injection port 34a, thereby reliably fixing the peripheral edge portion 27a of the separator 27. In the second and third embodiments, the separator 27 does not have to be welded to the spacers 34A, 34B. In the second and third embodiments, the peripheral edge 27a of the separator 27 may be welded to the first seal portion 35 or the second seal portion 36. In the second and third embodiments, the separator 27 does not have to be welded.

[0091] The gist of the present invention is as follows [1] to

[10] . [1] A laminate including a first electrode and a second electrode stacked in a stacking direction, and a sealing body for sealing a side surface of the laminate, wherein the first electrode has a first current collector including a first surface and a positive electrode active material layer provided on the first surface, the second electrode has a second current collector including a second surface facing the first surface and a negative electrode active material layer provided on the second surface, and the sealing body includes a first sealing part including a first sealing part welded to the first surface so as to surround the positive electrode active material layer when viewed from the stacking direction, and a second sealing part including a second sealing part welded to the second surface so as to surround the negative electrode active material layer when viewed from the stacking direction, and an electricity storage device comprising: a spacer sandwiched between the first seal portion and the second seal portion; and a welded portion formed by welding outer edge portions of the first seal portion, the second seal portion, and the spacer, the outer edge portions being located outside outer edges of the first current collector and the second current collector when viewed from the stacking direction, wherein the spacer includes a first fill port that is formed by the first electrode, the second electrode, and the sealing body and that communicates with an internal space that contains an electrolyte solution, the welded portion includes a second fill port that communicates with the first fill port, and the thickness of the spacer is greater than the thickness of each of the first seal portion and the second seal portion. [2] The electricity storage device according to [1], wherein the width of the second liquid inlet is smaller than the width of the first liquid inlet. [3] The energy storage device according to [1] or [2], further comprising a separator provided between the positive electrode active material layer and the negative electrode active material layer, wherein a peripheral edge portion of the separator is located between the spacer and the second seal portion, and wherein a volume of a first region of the internal space between the separator and the first electrode is larger than a volume of a second region of the internal space between the separator and the second electrode. [4] The power storage device according to [3], wherein the area of ​​the positive electrode active material layer is smaller than the area of ​​the negative electrode active material layer when viewed from the stacking direction. [5] The electricity storage device according to [3] or [4], wherein the thickness of the positive electrode active material layer is greater than the thickness of the negative electrode active material layer. [6] The electricity storage device according to any one of [1] to [5], wherein the positive electrode active material layer includes a groove extending in a direction in which the first liquid injection port and the internal space are aligned. [7] The power storage device according to [1], wherein the spacers include a first spacer and a second spacer, each of which is formed in a frame shape and stacked in the stacking direction. [8] The energy storage device according to [7], further comprising a separator provided between the positive electrode active material layer and the negative electrode active material layer, wherein the first liquid injection port is formed in the first spacer, and a peripheral portion of the separator is welded to the second spacer. [9] The power storage device according to [8], wherein an inner edge of the second spacer is located more inward than an inner edge of the first spacer when viewed from the stacking direction.

[10] The energy storage device according to any one of [7] to [9], wherein the spacer further includes a third spacer stacked on the opposite side of the second spacer from the first spacer, and the first liquid injection port is formed in each of the first spacer and the third spacer. [Explanation of symbols]

[0092] 1...electricity storage device, 2...laminated body, 3...sealing body, 21...bipolar electrode, 24...current collector, 24a, 24b...surface, 25...positive electrode active material layer, 25a...groove, 26...negative electrode active material layer, 27...separator, 27a...periphery, 32...welded portion, 34...spacer, 32a, 34a...filling port, 33...seal portion, 35, 36...sealed portion, 341...first spacer, 342...second spacer, 343...third spacer, S...internal space, S1...first region, S2...second region.

Claims

1. a stacked body including a first electrode and a second electrode stacked in a stacking direction; a sealant for sealing a side surface of the stack; the first electrode has a first current collector including a first surface and a positive electrode active material layer provided on the first surface; the second electrode includes a second current collector including a second surface facing the first surface, and a negative electrode active material layer provided on the second surface; the sealing body includes a first sealing portion including a first sealing part welded to the first surface so as to surround the positive electrode active material layer when viewed from the stacking direction; a second sealing portion including a second sealing part welded to the second surface so as to surround the negative electrode active material layer when viewed from the stacking direction; a spacer sandwiched between the first seal portion and the second seal portion; a welded portion formed by welding outer edge portions of the first seal portion, the second seal portion, and the spacer, which are located outside outer edges of the first current collector and the second current collector when viewed from the stacking direction, the spacer includes a first filling port formed by the first electrode, the second electrode, and the sealing body and communicating with an internal space in which an electrolyte is accommodated, the welded portion includes a second liquid inlet communicating with the first liquid inlet, The thickness of the spacer is greater than the thickness of each of the first seal portion and the second seal portion.

2. The power storage device according to claim 1 , wherein a width of the second liquid inlet is smaller than a width of the first liquid inlet.

3. further comprising a separator provided between the positive electrode active material layer and the negative electrode active material layer; a peripheral edge portion of the separator is located between the spacer and the second seal portion; 3 . The power storage device according to claim 1 , wherein a volume of a first region between the separator and the first electrode in the internal space is larger than a volume of a second region between the separator and the second electrode.

4. The power storage device according to claim 3 , wherein an area of ​​the positive electrode active material layer is smaller than an area of ​​the negative electrode active material layer when viewed from the stacking direction.

5. The power storage device according to claim 3 , wherein the thickness of the positive electrode active material layer is greater than the thickness of the negative electrode active material layer.

6. The power storage device according to claim 1 , wherein the positive electrode active material layer includes a groove extending in a direction in which the first liquid injection port and the internal space are aligned.

7. The power storage device according to claim 1 , wherein the spacers include a first spacer and a second spacer, each of which is formed in a frame shape and which are stacked in the stacking direction.

8. further comprising a separator provided between the positive electrode active material layer and the negative electrode active material layer; the first liquid injection port is formed in the first spacer, The power storage device according to claim 7 , wherein a peripheral edge portion of the separator is welded to the second spacer.

9. The power storage device according to claim 8 , wherein an inner edge of the second spacer is located more inward than an inner edge of the first spacer when viewed from the stacking direction.

10. the spacer further includes a third spacer stacked on the second spacer on an opposite side to the first spacer, The power storage device according to claim 8 , wherein the first liquid injection port is formed in each of the first spacer and the third spacer.

Images