Battery

Abstract

To provide a battery in which ability of an electrolytic solution to permeate into an active material layer is improved.SOLUTION: A battery includes: an electrode stack that includes a stack of electrodes, each electrode including a current collector and an active material layer 16a divided with grooves 16b in between; a sealing body 12 that forms, between the current collectors 15, internal spaces V where an electrolytic solution is contained and that seals the internal spaces V; and injection ports P that are formed in the sealing body 12 and that communicate the internal spaces V with the outside. The internal spaces V are formed by the grooves 16b, and uncoated regions 150 where the active material layers are not provided around the active material layers 16. Internal regions sealed by the sealing body 12 have a polygonal shape when viewed from a stacking direction of the electrode stack. The grooves 16b extend between the active material layers from the side of the injection ports P toward the opposite direction thereof. A cross-sectional area [a] of regions of the uncoated regions 150 that face surfaces where the injection ports P are formed is larger than a cross-sectional area [d] of the grooves 16b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] 2. Description of the Related Art A known conventional method for manufacturing a battery includes a step of injecting an electrolyte solution into a space between electrodes disposed opposite each other with a separator sandwiched therebetween (see, for example, Patent Document 1).

[0003] Patent Document 2 also discloses a manufacturing method for a bipolar type electricity storage device, which includes a first depressurization step of depressurizing the internal space to a first pressure when permeating an electrolyte into the internal space of a battery, a first liquid injection step of injecting a predetermined amount of electrolyte from a holder that holds a preset amount of electrolyte into the internal space depressurized in the first depressurization step through an injection port, a second depressurization step of depressurizing the internal space into which the predetermined amount of electrolyte has been injected through the holder and the injection port to a second pressure to cause a portion of the electrolyte to flow back from the internal space to the holder, and a second liquid injection step of setting the inside of the holder that holds the backflowed electrolyte to a pressure higher than the second pressure and injecting the electrolyte from the holder through the injection port into the internal space, wherein the second depressurization step includes an initial depressurization step of depressurizing the internal space at a depressurization rate slower than that of the first depressurization step S20. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-191450 A [Patent Document 2] JP 2022-188536 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the past, in order to improve the battery capacity, it was considered to reduce the volume (width) of the uncoated region on the current collector where the active material layer is not formed. However, if the width of the uncoated region is made too small, there is a problem that the circulation of the electrolyte in the grooves provided in the active material layer is deteriorated.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a battery in which the impregnation of an active material layer with an electrolyte solution is improved. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> an electrode laminate including electrodes stacked together, the electrodes including a current collector and an active material layer provided on one or both surfaces of the current collector and divided into a plurality of regions by providing grooves between the active material layers; a seal that forms an internal space between adjacent current collectors in which an electrolyte is contained and seals the internal space; a liquid injection port formed in the sealing body and communicating the internal space with the outside; the internal space is formed by the groove and an uncoated region around the active material layer where the active material layer is not provided, an internal region sealed by the sealing body has a polygonal shape when viewed from a stacking direction of the electrode stack, When a surface of the sealing body on the side on which the liquid injection hole is formed, facing the internal space, is defined as a liquid injection hole side surface, When the surface facing the edge on which the liquid injection port is formed is defined as the liquid injection port side surface, the groove extends between the active material layers from the liquid inlet side surface side toward a direction opposite to the liquid inlet side surface, a cross-sectional area [a] of the uncoated region facing the liquid inlet side surface, taken in a cross section perpendicular to the direction in which the liquid inlet side surface extends, is larger than a cross-sectional area [d] of the groove, taken in a cross section perpendicular to the direction in which the groove extends. <2> an internal region sealed by the sealing body has a rectangular shape when viewed from a stacking direction of the electrode stack, The liquid injection port is provided only in the sealing body in a region facing one side of the rectangular shape. <1> 2. The battery according to claim 1 . <3> The ratio ([d] / [a]) of the cross-sectional area [d] of the groove to the cross-sectional area [a] of the uncoated region is 0.1 or more and 0.9 or less. <1> or <2> 2. The battery according to claim 1 . <4> The cross-sectional area [d] of the groove is 0.4 mm 2 More than 2.0mm 2 Below is the <1> ~ <3> 13. The battery according to any one of claims 1 to 12. <5> When viewed from the stacking direction of the electrode stack, the area of ​​the electrode stack is 0.5 m 2 That's all. <1> ~ <4> 13. The battery according to any one of claims 1 to 12. Effect of the Invention

[0008] According to the present disclosure, a battery is provided in which the impregnation of an electrolyte into an active material layer is improved. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of a bipolar electricity storage device according to an embodiment. [Diagram 2] 2 is a schematic cross-sectional view showing the internal configuration of the electricity storage module shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view perpendicular to the stacking direction of the electricity storage module shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a battery according to an embodiment of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0011] Fig. 1 is a schematic cross-sectional view showing the configuration of a bipolar type energy storage device according to one embodiment. The bipolar type energy storage device 1 (hereinafter also simply referred to as "energy storage device 1") shown in Fig. 1 is a device used in batteries of various vehicles such as forklifts, hybrid cars, and electric cars. The energy 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 energy storage device 1 is a lithium-ion secondary battery. The energy storage device 1 includes a module stack 2 and a binding member 3 that applies a binding load to the module stack 2 in the stacking direction of the module stack 2.

[0012] The module stack 2 includes a power storage module 4 and a conductive plate 5 stacked on the power storage module 4. The module stack 2 includes a plurality (three here) of power storage modules 4 and a plurality (four here) of conductive plates 5. The power storage module 4 is a bipolar battery and has a rectangular shape when viewed in the stacking direction.

[0013] The adjacent energy storage modules 4 in the stacking direction are electrically connected to each other via a conductive plate 5. The conductive plates 5 are respectively arranged between the adjacent energy storage modules 4 in the stacking direction and on the outside of the energy storage module 4 located at the stacking end. A positive electrode terminal 6 is connected to one of the conductive plates 5 arranged on the outside of the energy storage module 4 located at the stacking end. A negative electrode terminal 7 is connected to the other conductive plate 5 arranged on the outside of the energy storage module 4 located at the stacking end. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out, for example, from the edge of the conductive plate 5 in a direction intersecting with the stacking direction. The positive electrode terminal 6 and the negative electrode terminal 7 charge and discharge the energy storage device 1.

[0014] A plurality of flow paths 5a for circulating a coolant such as air are provided inside the conductive plate 5. The flow paths 5a extend, for example, along a direction intersecting (orthogonal to) the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. The conductive plate 5 not only functions as a connection member for electrically connecting the power storage modules 4 to each other, but also functions as a heat sink for radiating heat generated in the power storage modules 4 by circulating a coolant through these flow paths 5a.

[0015] The restraining member 3 is composed of a pair of end plates 8 that sandwich the module stack 2 in the stacking direction, and fastening bolts 9 and nuts 10 that fasten the end plates 8 together. An electrically insulating film F is provided on the surface of the end plate 8 facing the module stack 2, and the film F provides insulation between the end plate 8 and the conductive plate 5.

[0016] Next, the configuration of the electricity storage module 4 will be described in detail. Fig. 2 is a schematic cross-sectional view showing the internal configuration of the electricity storage module shown in Fig. 1. As shown in Fig. 2, the electricity storage module 4 includes an electrode stack 11 and a resin sealing body 12 that seals the electrode stack 11. The electricity storage module 4 is formed in, for example, a rectangular parallelepiped shape.

[0017] The electrode laminate 11 includes a plurality of electrodes laminated in a lamination direction D via separators 13, and current collectors (metal plates 20A, 20B) located at the stacking ends of the electrode laminate 11. The plurality of electrodes include a negative terminal electrode 18, a positive terminal electrode 19, and a plurality of bipolar electrodes 14 laminated between the negative terminal electrode 18 and the positive terminal electrode 19. The laminate of the plurality of bipolar electrodes 14 is provided between the negative terminal electrode 18 and the positive terminal electrode 19.

[0018] The bipolar electrode 14 has a metal plate 15 as a current collector, including one surface 15a and another surface 15b provided on the opposite side of the one surface 15a, a positive electrode 16 provided on the one surface 15a, and a negative electrode 17 provided on the other surface 15b. The one surface 15a faces one side of the stacking direction D, for example, facing upward in the direction of gravity. The other surface 15b faces the other side of the stacking direction D, for example, facing downward in the direction of gravity. The positive electrode 16 is a positive electrode active material layer formed by coating the metal plate 15 with a positive electrode active material. The negative electrode 17 is a negative electrode active material layer formed by coating the metal plate 15 with a negative electrode active material. In the electrode stack 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to one side of the stacking direction D across the separator 13. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another adjacent bipolar electrode 14 on the other side in the lamination direction D, with the separator 13 interposed therebetween.

[0019] The negative electrode terminal electrode 18 has a metal plate 15 and a negative electrode 17 provided on the other surface 15b of the metal plate 15. The negative electrode terminal electrode 18 is arranged on one end side of the stacking direction D so that the other surface 15b faces the center side of the stacking direction D in the electrode stack 11. A metal plate 20A is further laminated on one surface 15a of the metal plate 15 of the negative electrode terminal electrode 18, and is electrically connected to one conductive plate 5 adjacent to the electricity storage module 4 via this metal plate 20A. The negative electrode 17 provided on the other surface 15b of the metal plate 15 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end of the stacking direction D via the separator 13.

[0020] The positive terminal electrode 19 has a metal plate 15 and a positive electrode 16 provided on one surface 15a of the metal plate 15. The positive terminal electrode 19 is disposed on the other end side of the stacking direction D such that the one surface 15a faces the center side of the stacking direction D in the electrode stack 11. A metal plate 20B is further laminated on the other surface 15b of the metal plate 15 of the positive terminal electrode 19, and is electrically connected to the other conductive plate 5 adjacent to the power storage module 4 via the metal plate 20B. The positive electrode 16 provided on the one surface 15a of the metal plate 15 of the positive terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end of the stacking direction D via the separator 13.

[0021] The metal plate 15 is made of a metal such as Al, SUS, Ni, Cu, etc. Each metal plate 15 is one of the metal plates included in the electrode stack 11. The edge portion 15c of the metal plate 15 has a rectangular frame shape and forms a part of an uncoated region 15d (see FIG. 3) where the positive electrode active material and the negative electrode active material are not coated. Examples of the positive electrode active material constituting the positive electrode 16 include oxide active materials. Examples of the oxide active material include LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., rock salt layered active materials, LiMn2O4, Li(Ni 0.5 Mn 1.5 Examples of the negative electrode active material constituting the negative electrode 17 include a spinel type active material such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4, and an olivine type active material such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4. Examples of the negative electrode active material constituting the negative electrode 17 include a carbon active material, an oxide active material, and a metal active material. In this embodiment, the formation area of ​​the negative electrode 17 on the other surface 15b of the metal plate 15 is slightly larger than the formation area of ​​the positive electrode 16 on one surface 15a of the metal plate 15. The electrode laminate 11 has a plurality of stacked metal plates 15, 20A, and 20B.

[0022] The separator 13 is a member for preventing short circuits between the metal plates 15, and is formed, for example, in a sheet shape. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, methylcellulose, or the like. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 is not limited to a sheet shape, and a bag-shaped one may be used.

[0023] The metal plates 20A and 20B are substantially the same member as the metal plate 15, and are made of metals such as Al, SUS, Ni, and Cu. Both of the metal plates 20A and 20B are one of the metal plates included in the electrode laminate 11. The metal plates 20A and 20B form uncoated electrodes in which neither the positive electrode active material layer nor the negative electrode active material layer is coated on the one surface 20a nor the other surface 20b. In other words, the metal plates 20A and 20B are uncoated electrodes in which no active material layer is provided on both surfaces.

[0024] The metal plate 20A places the negative terminal electrode 18 between the metal plate 20A and the bipolar electrode 14 along the stacking direction D. The other side 20b of the metal plate 20A and one side 15a of the metal plate 15 of the negative terminal electrode 18 are electrically connected by direct contact without any interposition therebetween. The metal plate 20B places the positive terminal electrode 19 between the metal plate 20B and the bipolar electrode 14 along the stacking direction D. The one side 20a of the metal plate 20B and the other side 15b of the metal plate 15 of the positive terminal electrode 19 are electrically connected by direct contact without any interposition therebetween.

[0025] In the electrode laminate 11, a central region of the electrode laminate 11 (a region where active material layers are arranged in the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19) bulges out in the stacking direction D compared to the surrounding regions. Therefore, the metal plates 20A, 20B bend in a direction in which the central regions of the metal plates 20A, 20B move away from each other. The central regions of one surface 20a of the metal plate 20A and the other surface 20b of the metal plate 20B come into contact with the conductive plate 5.

[0026] The sealing body 12 is formed of, for example, an insulating resin into a generally rectangular tubular shape. The sealing body 12 is formed into, for example, a rectangular tubular shape having a pair of short side portions 12a and a pair of long side portions 12b (see FIG. 3). The sealing body 12 is provided so as to surround the side surface 11a of the electrode stack 11. The sealing body 12 holds an edge portion 15c on the side surface 11a.

[0027] The sealing body 12 has a plurality of frame-shaped first sealing portions 21 (resin portions) provided on the edge portions of the metal plates included in the electrode laminate 11 (i.e., the edge portion 15c of the metal plate 15 and the edge portions 20c of the metal plates 20A and 20B), and second sealing portions 22 surrounding the first sealing portions 21 from the outside along the side surface 11a and joined to each of the first sealing portions 21. The first sealing portions 21 and the second sealing portions 22 are, for example, insulating resin, and examples of the resin constituent material include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

[0028] The first sealing portion 21 is provided continuously around the entire periphery of the edge portion 15c of the metal plate 15 and the edge portions 20c of the metal plates 20A and 20B, and forms a rectangular frame shape when viewed from the stacking direction D. The first sealing portion 21 and the metal plate 15, and the first sealing portion 21 and the metal plates 20A and 20B are hermetically joined, respectively. The first sealing portion 21 extends outward beyond the edge portion 15c of the metal plate 15 or the edge portions 20c of the metal plates 20A and 20B when viewed from the stacking direction D. The first sealing portion 21 includes an outer portion 21a that protrudes outward beyond the edge of the metal plate 15 or the metal plates 20A and 20B, and an inner portion 21b that is located inside the edge of the metal plate 15 or the metal plates 20A and 20B. A welding layer 23 is formed on the tip portion (outer edge portion) of the outer portion 21a of the first sealing portion 21.

[0029] The multiple first sealing portions 21 include multiple first sealing portions 21A provided on the bipolar electrode 14 and the positive terminal electrode 19, a first sealing portion 21B provided on the negative terminal electrode 18, a first sealing portion 21C provided on the metal plate 20A, and first sealing portions 21D and 21E provided on the metal plate 20B.

[0030] The first sealing portion 21A is joined to one surface 15a of the metal plate 15 of the bipolar electrode 14 and the positive terminal electrode 19. The inner portion 21b of the first sealing portion 21A is located between the edge portions 15c of the metal plates 15 adjacent to each other in the stacking direction D. The region where the edge portions 15c on the one surface 15a of the metal plate 15 overlap with the first sealing portion 21A becomes a bonding region between the metal plate 15 and the first sealing portion 21A.

[0031] In this embodiment, the first sealing portion 21A is formed in a two-layer structure by folding one film in two. The outer edge of the first sealing portion 21A embedded in the second sealing portion 22 is a folded portion (bent portion) of the film. The first layer of film constituting the first sealing portion 21A is bonded to one surface 15a. The inner edge of the second layer of film is located outside the inner edge of the first layer of film, forming a step portion on which the separator 13 is placed. The inner edge of the second layer of film is located inside the edge of the metal plate 15.

[0032] The first sealing portion 21B is joined to one surface 15a of the metal plate 15 of the negative terminal electrode 18. The inner portion 21b of the first sealing portion 21B is located between the edge portion 15c of the metal plate 15 of the negative terminal electrode 18 and the edge portion 20c of the metal plate 20A, which are adjacent to each other in the stacking direction D. The area where the edge portion 15c on the one surface 15a of the metal plate 15 and the inner portion 21b of the first sealing portion 21B overlap is the bonding area between the metal plate 15 and the first sealing portion 21B. The first sealing portion 21B is also joined to the other surface 20b of the metal plate 20A. The area where the edge portion 20c on the other surface 20b of the metal plate 20A and the first sealing portion 21B overlap is the bonding area between the metal plate 20A and the first sealing portion 21B. In this embodiment, the first sealing portion 21B is also joined to an edge portion 20c on the other surface 20b of the metal plate 20A.

[0033] The first sealing portion 21C is joined to one surface 20a (outer surface) of the metal plate 20A. The area where the edge portion 20c on the one surface 20a of the metal plate 20A and the first sealing portion 21C overlap is the bonding area between the metal plate 20A and the first sealing portion 21C. The one surface 20a of the metal plate 20A has an exposed surface 20d exposed from the first sealing portion 21C. The conductive plate 5 is disposed in contact with the exposed surface 20d.

[0034] In this embodiment, the outer edges of the first sealing portions 21B and 21C embedded in the second sealing portion 22 are continuous with each other. That is, the first sealing portions 21B and 21C are formed by folding one film in two with the edge portion 20c of the metal plate 20A sandwiched therebetween. The outer edges of the first sealing portions 21B and 21C are folded back portions of the film. The films constituting the first sealing portions 21B and 21C are joined to the edge portion 20c on both the one surface 20a and the other surface 20b of the metal plate 20A.

[0035] The first sealing portion 21D is joined to one surface 20a of the metal plate 20B. The inner portion 21b of the first sealing portion 21D is located between the edge portion 15c of the metal plate 15 of the positive terminal electrode 19 and the edge portion 20c of the metal plate 20B, which are adjacent to each other in the stacking direction D. The region where the edge portion 20c on the one surface 20a of the metal plate 20B overlaps with the first sealing portion 21D becomes a bonding region between the metal plate 20B and the first sealing portion 21D.

[0036] The first sealing portion 21E is disposed at an edge portion 20c on the other surface 20b (outer surface) of the metal plate 20B. In this embodiment, the first sealing portion 21E is not joined to the metal plate 20B. The other surface 20b of the metal plate 20B has an exposed surface 20d exposed from the first sealing portion 21E. The conductive plate 5 is disposed in contact with the exposed surface 20d.

[0037] In this embodiment, the outer edges of the first sealing portions 21D and 21E embedded in the second sealing portion 22 are continuous with each other. That is, the first sealing portions 21D and 21E are formed by folding one film in two with the edge portion 20c of the metal plate 20B sandwiched therebetween. The outer edges of the first sealing portions 21D and 21E are folded back portions of the film. The films constituting the first sealing portions 21D and 21E are joined to the edge portion 20c on one surface 20a of the metal plate 20B.

[0038] A plurality of internal spaces V are provided in the electrode laminate 11. Each internal space V is provided between adjacent metal plates. The internal space V is a space between adjacent metal plates in the lamination direction D, which is partitioned airtight and liquidtight by the metal plates and the sealing body 12. The internal space V contains, for example, an electrolyte (not shown). The electrolyte contains, for example, a non-aqueous solvent and a supporting salt. Examples of the non-aqueous solvent include organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones. Examples of the supporting salt include lithium salts such as LiPF6. The electrolyte is impregnated into the separator 13, the positive electrode 16, and the negative electrode 17.

[0039] 3 is a cross-sectional view perpendicular to the stacking direction of the electricity storage module shown in FIG. 2. As shown in FIG. 3, a liquid inlet P is provided in one short side portion 12a of the sealing body 12. The liquid inlet P penetrates the sealing body 12 in the long side direction of the sealing body 12. The liquid inlet P communicates with the internal space V and the external space. The position at which the liquid inlet P is provided in one short side portion 12a of the sealing body 12 varies depending on the position of the corresponding internal space V in the stacking direction D (see FIG. 2). The liquid inlet P is provided offset in the short side direction of the sealing body 12 so that adjacent liquid inlet ports P do not overlap with each other in the stacking direction D (see FIG. 2). In the example of FIG. 3, the liquid inlet P is provided at one end of one short side portion 12a of the sealing body 12.

[0040] The shape of the internal region sealed by the sealing body 12 when viewed from the stacking direction (i.e., the shape of the interface between the internal space V and the sealing body 12 shown in FIG. 3) is rectangular. Note that the shape of the internal region sealed by the sealing body 12 is not limited to a rectangular shape, and may be a quadrangle, a polygonal shape other than a quadrangle, or the like. Furthermore, the corners of the polygonal shape may be rounded.

[0041] 3, in the internal region (rectangular region) sealed by the sealing body 12, the liquid injection port P is formed only in the sealing body 120 in a region facing one side of the rectangle. However, the liquid injection port P may be provided in multiple locations, and for example, the internal region sealed by the sealing body 12 may be polygonal, and two or more liquid injection ports P may be formed in total in the sealing body 120 in regions facing two or more sides of this polygonal shape.

[0042] The positive electrode 16 includes a plurality of divided regions 16a divided by grooves 16b on one surface 15a of the metal plate 15. When the surface of the sealing body 12 on the side where the liquid inlet P is formed on the internal space V side is defined as a liquid inlet side surface 150P, the grooves 16b extend from the liquid inlet side surface 150P side in the opposite direction to the liquid inlet side surface 150P (Y direction in FIG. 3). Therefore, in FIG. 3, the grooves 16b extend along the long side direction of the one surface 15a. The bottom surface of the grooves 16b is formed by the one surface 15a. The side of sealing body 12 on which liquid injection port P is formed refers to the side on which liquid injection port P is formed when electrode stack 11 is viewed from the stacking direction.

[0043] The divided regions 16a are spaced apart from one another in the short side direction of the one surface 15a. In this embodiment, the positive electrode 16 is divided into six divided regions 16a by five grooves 16b. The divided regions 16a each have a rectangular shape whose long side direction is the long side direction of the one surface 15a and whose short side direction is the short side direction of the one surface 15a.

[0044] The grooves 16b have, for example, the same shape as one another. In FIG. 3, the shape of the grooves 16b (shape in a cross section perpendicular to the direction in which the grooves 16b extend (Y direction in FIG. 3)) is rectangular. The shape of the grooves 16b is not particularly limited, and may be, for example, a square, rectangular, triangular, trapezoidal, or the like. In FIG. 3, the shape of the grooves 16d in the direction in which they extend (shape of the grooves 16d when viewed from above) is linear. The shape of the grooves 16d in the direction in which they extend is also not particularly limited, and may be, for example, a wavy, broken line, lattice, or the like.

[0045] Around the multiple divided regions 16a on one surface 15a of the metal plate 15, an uncoated region 150 where the positive electrode 16 is not formed is provided. The uncoated region 150 has an uncoated region 150A provided in a region facing the liquid inlet side surface 150P, an uncoated region 150B provided on the opposite side of the multiple divided regions 16a from the uncoated region 150A, and an uncoated region 150C provided in a region between the uncoated region 150A and the uncoated region 150B and outside the multiple divided regions 16a. An internal space V is formed by the groove 16b and the uncoated region 150.

[0046] Although not shown in the figure, the negative electrode 17 also includes a plurality of divided regions divided by grooves, similar to the positive electrode 16. The grooves of the negative electrode 17 are provided so as to overlap with the grooves 16b of the positive electrode 16 when viewed from the stacking direction D (see FIG. 2). In addition, an uncoated region is also provided around the negative electrode 17 which is divided into a plurality of divided regions.

[0047] When the electrolyte is injected into the internal space V, the gap formed by the combination of the grooves of the positive electrode 16 and the grooves of the negative electrode 17 functions as a flow path for the electrolyte, similar to the gap between the uncoated area 150 on one surface 15a and the uncoated area on the other surface 15b.

[0048] The uncoated region 150A provided in the region facing the inlet side surface 150P has a cross-sectional area [a] of the uncoated region 150A (cross-sectional area in a cross section perpendicular to the direction in which the inlet side surface 150P extends (X direction in Figure 3)) that is larger than the cross-sectional area [d] of the groove 16b (cross-sectional area in a cross section perpendicular to the direction in which the groove 16b extends (Y direction in Figure 3)).

[0049] Here, a conventional battery will be described. In conventional batteries, in order to improve the battery capacity, it has been considered to reduce the volume of the uncoated region on the current collector where the active material layer is not formed. However, there have been cases where the electrolyte solution is difficult to penetrate into the grooves provided between the multiple active material layers to allow the electrolyte solution to penetrate. This is because the volume of the uncoated region is reduced, making it difficult for the electrolyte solution to penetrate into the region of the internal space into which the electrolyte solution first penetrates from the inlet, in other words, the region of the uncoated region facing the side on which the inlet of the sealed body is formed. If the electrolyte solution is difficult to penetrate into the region of the uncoated region facing the side on which the inlet of the sealed body is formed, the electrolyte solution will also penetrate slower into the grooves that exist ahead in the direction of movement of the electrolyte solution, and as a result, it will take time for the electrolyte solution to spread throughout the entire internal space. In addition, as the region of the uncoated region facing the side on which the inlet of the sealed body is formed becomes narrower, the amount of electrolyte solution that can exist in that region will also decrease. Therefore, the electrolyte does not reach the grooves existing ahead of this region in the direction of electrolyte flow, and as a result, it takes time for the electrolyte to reach the entire internal space.

[0050] In contrast, in the embodiment of the present disclosure, the cross-sectional area of ​​the uncoated region 150A provided in the region facing the inlet side surface 150P is set to be larger than that of the conventional battery, and the cross-sectional area [a] of the uncoated region 150A is larger than the cross-sectional area [d] of the groove 16b. Therefore, the electrolyte is more likely to permeate into the uncoated region 150A, which is the region of the internal space into which the electrolyte first permeates from the inlet. In addition, the volume of the uncoated region 150A is increased, and the amount of electrolyte that can be present in the uncoated region 150A is also increased. Therefore, the electrolyte is more likely to permeate into the groove 16b that exists beyond the uncoated region 150A in the direction of movement of the electrolyte, and the electrolyte is more likely to permeate into the entire internal space V. As a result, the time required for the electrolyte to permeate the entire electrode stack 11 in the manufacture of the battery is shortened. In addition, the occurrence of defects in which the electrolyte does not permeate the entire active material layer after the injection of the electrolyte is completed is also suppressed.

[0051] The ratio ([d] / [a]) of the cross-sectional area [d] of the groove 16b to the cross-sectional area [a] of the uncoated region 150A is preferably 0.1 to 0.9, more preferably 0.2 to 0.8, and even more preferably 0.2 to 0.5. When [d] / [a] is equal to or greater than the lower limit and equal to or less than the upper limit, the electrolyte can easily spread throughout the entire internal space V when the electrolyte is injected.

[0052] The cross-sectional area [d] of the groove 16b is 0.4 mm 2 More than 2.0mm 2 Preferably, it is less than 0.5 mm. 2 More than 1.0mm 2 It is more preferable that the cross-sectional area [d] is equal to or greater than the above lower limit. When the electrolyte is injected, the electrolyte can easily spread throughout the entire internal space V. It is preferable that the cross-sectional area [d] is equal to or less than the above upper limit, since it is easy to improve the battery capacity.

[0053] The cross-sectional area [a] of the uncoated area 150A is 0.4 mm 2 Over 4.0mm 2 Preferably, it is 1.0 mm or less. 2 More than 3.0mm 2It is more preferable that the cross-sectional area [a] is equal to or larger than the lower limit, the electrolyte can be easily distributed throughout the entire internal space V when the electrolyte is injected. It is preferable that the cross-sectional area [a] is equal to or smaller than the upper limit, since it is easy to improve the battery capacity.

[0054] An example of a method for increasing the cross-sectional area [a] of the uncoated region 150A is to increase the width a of the uncoated region 150A. On the other hand, an example of a method for decreasing the cross-sectional area [d] of the groove 16b is to decrease the width d of the groove 16b.

[0055] The cross-sectional area [a] of the uncoated region facing the side surface of the inlet in a cross section perpendicular to the direction in which the side surface of the inlet extends refers to the area of ​​voids originating from "the side of the uncoated region that contacts the inlet" in a cross section obtained when a region of the uncoated region that includes the side that contacts the inlet is cut in a direction perpendicular to the side. Also, the cross-sectional area [d] of a groove in a cross section perpendicular to the direction in which the groove extends refers to the area of ​​voids "originating from any one groove" in a cross section obtained when the electrode laminate is cut in a direction perpendicular to the direction in which the groove extends.

[0056] The cross-sectional area [a] of the uncoated region 150A is measured by measuring the cross-sectional area of ​​the uncoated region 150A at any five points in a cross section perpendicular to the direction in which the inlet side surface 150P of the electrode laminate extends (the X direction in FIG. 3), and the arithmetic average value is defined as the cross-sectional area [a]. Here, the cross-sectional area of ​​the uncoated region 150A is a value calculated by the following formula (1). Formula (1): Cross-sectional area of ​​uncoated area 150A (mm 2 ) = Length of a in FIG. 3 (mm) × Thickness of divided region 16a (mm) The cross-sectional area [d] of the groove 16b is measured by measuring the cross-sectional area of ​​the groove 16b at any five points in a cross section perpendicular to the direction in which the groove 16b extends in the electrode laminate (Y direction in FIG. 3), and the arithmetic average value of the cross-sectional area [d] is defined as the cross-sectional area calculated by the following formula (2). Formula (2): Cross-sectional area of ​​groove 16b (mm 2) = Length of d in FIG. 3 (mm) × Thickness of division region 16a (mm)

[0057] The explanations for a and d in FIG. 3 are as follows. a: width of uncoated area 150A provided in the area facing liquid inlet side surface 150P (unit: mm) d: width of groove 16b (unit: mm)

[0058] In the above embodiment, the active material layers of both the positive electrode 16 and the negative electrode 17 have grooves. However, the present invention is not limited to this, and the grooves may be formed only in the positive electrode active material layer or only in the negative electrode active material layer. From the viewpoint of suppressing lithium precipitation, it is preferable that the grooves are formed only in the positive electrode active material layer.

[0059] The dimensions of the electrode stack in the battery according to the embodiment of the present disclosure are not particularly limited, but the area of ​​the electrode stack when viewed from the stacking direction of the electrode stack is, for example, 0.5 m 2 The upper limit of the area of ​​the electrode laminate is 4.0 m2 or more. 2 It can be as follows:

[0060] The configuration of the present disclosure is not limited to the above-described embodiment, and the configuration can be modified as appropriate as long as the problem can be solved.

[0061] Next, the effects of the battery according to the embodiment of the present disclosure were confirmed by a simulation experiment.

[0062] (Examples 1 to 3, Comparative Example 1) A simulation (CEA) was performed for an electrode laminate having the configuration shown in Fig. 3, which has an active material layer on one side of a metal plate serving as a current collector, the active material layer having divided regions divided by grooves, and an uncoated region where no active material layer is provided around the active material layer. The cross-sectional shape of the groove and the uncoated region was rectangular. However, the number of grooves was 14. Table 1 shows the "width" and "cross-sectional area" of the groove (groove 16b in FIG. 3), the uncoated region A (uncoated region 150A in FIG. 3) provided in the internal region sealed by the sealing body, facing the side of the sealing body on which the liquid injection port is formed, the uncoated region B (uncoated region 150B in FIG. 3) provided on the opposite side of the divided region of the active material layer from the uncoated region A, and the uncoated region C (uncoated region 150C in FIG. 3) provided in the region between the uncoated region A and the uncoated region B and outside the divided region of the active material layer.

[0063] In a simulation experiment, the time required for the electrolyte to completely permeate the entire electrode laminate (permeation time) was calculated. The results are shown in Table 1.

[0064] [Table 1]

[0065] As shown in Table 1, in Examples 1 to 3, which satisfy the requirement that the cross-sectional area [a] of the uncoated region A is larger than the cross-sectional area [d] of the groove, the time required for the electrolyte to completely permeate the entire electrode laminate can be shortened compared to Comparative Example 1, which does not satisfy this requirement. This shows that in Examples 1 to 3, batteries were obtained in which the electrolyte impregnation into the active material layer was improved. [Explanation of symbols]

[0066] 1 bipolar type electricity storage device, 11 electrode laminate, 12 sealing body, 13 separator, 14 bipolar electrode, 15 metal plate (current collector), 15a one side, 15b other side, 16 positive electrode, 17 negative electrode, D stacking direction, P liquid injection port, V internal space

Claims

1. an electrode laminate including electrodes stacked together, the electrodes including a current collector and an active material layer provided on one or both surfaces of the current collector and divided into a plurality of regions by providing grooves between the active material layers; a seal that forms an internal space between adjacent current collectors in which an electrolyte is contained and seals the internal space; a liquid injection port formed in the sealing body and communicating the internal space with the outside; the internal space is formed by the groove and an uncoated region around the active material layer where the active material layer is not provided, an internal region sealed by the sealing body has a polygonal shape when viewed from a stacking direction of the electrode stack, When a surface of the sealing body on the side on which the liquid injection hole is formed, facing the internal space, is defined as a liquid injection hole side surface, the groove extends between the active material layers from the liquid inlet side surface side toward a direction opposite to the liquid inlet side surface, a cross-sectional area [a] of the uncoated region facing the liquid inlet side surface, in a cross section perpendicular to the direction in which the liquid inlet side surface extends, is larger than a cross-sectional area [d] of the groove, in a cross section perpendicular to the direction in which the groove extends.

2. an internal region sealed by the sealing body has a rectangular shape when viewed from a stacking direction of the electrode stack, The battery according to claim 1 , wherein the liquid injection hole is provided only in the sealing body in an area facing one side of the rectangular shape.

3. 2. The battery according to claim 1, wherein a ratio ([d] / [a]) of the cross-sectional area [d] of the groove to the cross-sectional area [a] of the uncoated region is 0.1 or more and 0.9 or less.

4. The cross-sectional area [d] of the groove is 0.4 mm ２ More than 2.0 mm ２ 2. The battery of claim 1 , wherein:

5. When viewed from the stacking direction of the electrode stack, the area of ​​the electrode stack is 0.5 m ２ The battery according to claim 1 .

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