Power storage device

Abstract

To provide a power storage device which can determine whether there is an abnormality in the internal pressure, from the outside.SOLUTION: A power storage device 10 has an electrode laminate part 20 and a seal part 30. In the electrode laminate part 20, a plurality of bipolar electrodes 22, in which a positive electrode 27 is formed on one surface 25A of a collector 25 and a negative electrode 28 is formed on the other surface 25B, are laminated through a separator 24. The seal part 30 is arranged to surround the electrode laminate part 20, holds the collector 25, forms a space S between two bipolar electrodes 22 adjacent to each other through the separator 24, and seals the space S. A space S1, which is formed in an outmost end part of the bipolar electrode 22 in a lamination direction D, is narrower than another space S.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electricity storage device having a bipolar structure. [Background technology]

[0002] Patent Document 1 discloses an electricity storage device having a bipolar structure in which separators and current collectors, both sides of which are coated with positive and negative electrode active materials, are alternately stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-016904 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, in the electricity storage device having a bipolar structure described in Patent Document 1, the cells are overlapped with each other, so it is difficult to visually confirm whether the pressure inside each cell is negative.

[0005] In consideration of the above, an object of the present invention is to provide an electricity storage device that allows for determining from the outside whether or not there is an abnormality in the internal pressure. [Means for solving the problem]

[0006] The energy storage device of the present invention described in claim 1 comprises an electrode stacking portion in which multiple bipolar electrodes, each having a positive electrode formed on one side of a collector and a negative electrode formed on the other side, are stacked with a separator interposed therebetween, and a sealing portion arranged to surround the electrode stacking portion, holds the collector, forms a space between two adjacent bipolar electrodes with the separator interposed therebetween, and seals the space, wherein the space formed at the end portion in the stacking direction of the bipolar electrodes is narrower than the other spaces.

[0007] In the energy storage device according to the present invention described in claim 1, the space formed at the end of the bipolar electrodes in the stacking direction is narrower than the other spaces, so that when the pressure inside the battery rises, the space formed at the end is more likely to be affected than the other spaces. Therefore, by checking the internal pressure in the space formed at the end, it is possible to determine from the outside whether or not there is an abnormality in the internal pressure.

[0008] The energy storage device of the present invention as described in claim 2 has the configuration as described in claim 1, in which the sealing portion that forms the space formed at the end portion is formed longer inward than the sealing portions that form the other spaces.

[0009] In the energy storage device according to the present invention described in claim 2, the seal portion that forms the space at the end of the bipolar electrodes in the stacking direction is formed longer inward than the seal portions that form the other spaces, so that the space at the end can be narrowed by the seal portion. Therefore, by checking the internal pressure of the space at the end, it is possible to judge from the outside whether there is an abnormality in the internal pressure.

[0010] The energy storage device of the present invention described in claim 3 has the configuration described in claim 2, wherein the sealing portion includes a plurality of pairs of retaining seal materials that hold the current collectors of the stacked bipolar electrodes from both sides in the stacking direction, an outer periphery retaining seal portion that holds the outer periphery of the pair of retaining seal materials, and a spacer interposed between two pairs of adjacent retaining seal materials in the stacking direction of the bipolar electrodes, and the inner ends of the retaining seal materials and the spacer that form the space formed at least at the outermost end are positioned at the same position in a direction approximately perpendicular to the stacking direction.

[0011] In the energy storage device according to the present invention described in claim 3, the inner ends of the holding sealer and the spacer that form the space at least at the end of the bipolar electrodes in the stacking direction are at the same position in the direction substantially perpendicular to the stacking direction, so that the shape of the space at the end of the bipolar electrodes in the stacking direction can be prevented from becoming complicated.

[0012] The storage device of the present invention described in claim 4 has the configuration described in claim 1, wherein the sealing portion includes a plurality of pairs of holding seal materials that hold the current collectors of the bipolar electrodes stacked in multiple layers from both sides in the stacking direction, an outer periphery holding seal portion that holds the outer periphery of the pair of holding seal materials, and a spacer interposed between two pairs of holding seal materials adjacent to each other in the stacking direction of the bipolar electrodes, and the space is formed by being surrounded by the spacer, two holding seal materials located on both sides of the spacer in the stacking direction, a first current collector held by a pair of holding seal materials including one of the two holding seal materials, a second current collector held by a pair of holding seal materials including the other of the two holding seal materials, the positive electrode formed on one side of the first current collector, and the negative electrode formed on the other side of the second current collector, and at least one of the positive electrode and the negative electrode that form the space formed at the end is formed larger toward the outer periphery than the other positive electrode and the other negative electrode, respectively.

[0013] In the electricity storage device according to the present invention described in claim 4, at least one of the positive and negative electrodes forming a space at the end of the bipolar electrodes in the stacking direction is formed larger toward the outer periphery than the other positive and negative electrodes, respectively, so that the space at the end by at least one of the positive and negative electrodes can be narrowed without changing the shape of the seal portion. Therefore, by checking the internal pressure of the space formed at the end, it is possible to judge from the outside whether there is an abnormality in the internal pressure.

[0014] The storage device of the present invention described in claim 5 has the configuration described in claim 1, wherein the sealing portion includes a plurality of pairs of holding seal materials that hold the current collectors of the bipolar electrodes stacked in plurality from both sides in the stacking direction, an outer periphery holding seal portion that holds the outer periphery of the pair of holding seal materials, and a spacer interposed between two pairs of holding seal materials adjacent to each other in the stacking direction of the bipolar electrodes, and the space is formed by the spacer, two holding seal materials located on both sides of the spacer in the stacking direction, a first current collector held by a pair of holding seal materials including one of the two holding seal materials, a second current collector held by a pair of holding seal materials including the other of the two holding seal materials, the positive electrode formed on one side of the first current collector, and the negative electrode formed on the other side of the second current collector, and a member having electrolyte resistance is disposed at an outer periphery side end of at least one of the positive electrode and the negative electrode that form the space formed at the end.

[0015] In the electricity storage device according to the present invention described in claim 5, a member resistant to an electrolyte is disposed on the outer peripheral end of at least one of the positive electrode and the negative electrode that form the space formed at the end of the bipolar electrode in the stacking direction, so that the space formed at the end by the member can be narrowed without changing the shapes of the electrode stacking portion and the sealing portion. Therefore, by checking the internal pressure of the space formed at the end, it is possible to judge from the outside whether there is an abnormality in the internal pressure. Effect of the Invention

[0016] As described above, the electricity storage device according to the present invention has the excellent effect of making it possible to determine from the outside whether or not there is an abnormality in the internal pressure. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing the external appearance of a power storage device according to a first embodiment of the present invention before it is packed. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3]5 is a cross-sectional view corresponding to FIG. 2 of an electricity storage device according to a second embodiment of the present invention. FIG. [Figure 4] 5 is a cross-sectional view corresponding to FIG. 2 of an electricity storage device according to a third embodiment of the present invention. FIG. [Diagram 5] 10 is a cross-sectional view corresponding to FIG. 2 of an electricity storage device according to a fourth embodiment of the present invention. FIG. [Figure 6] FIG. 3 is a cross-sectional view corresponding to FIG. 2 of the electricity storage device of the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the electric storage device 10 according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the appearance of the electric storage device 10 according to the first embodiment of the present invention before packing, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicated descriptions are omitted. The electric storage device 10 according to the present embodiment is a bipolar type electric storage device, and is used, for example, in batteries for various vehicles such as forklifts, hybrid cars, and electric cars. The electric storage device 10 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The electric storage device 10 may be, for example, an electric double layer capacitor. In the present embodiment, the case where the electric storage device 10 is a lithium-ion secondary battery is illustrated.

[0019] 1, the electricity storage device 10 is formed in a substantially rectangular parallelepiped shape and includes a liquid filling port frame 12 in which a liquid filling port (not shown) through which an electrolyte solution described below is poured, and a substrate section 14 for detecting the voltage of each battery cell constituting the electricity storage device 10. The substrate section 14 includes an FPC (Flexible Printed Circuits) board 14A which is an example of a voltage detection circuit board including a circuit for detecting voltage, and both ends of the FPC board 14A in one direction are held by an FPC housing 14B. The electricity storage device 10 is housed in a battery case (not shown).

[0020] The electricity storage device 10 includes an electrode laminated section 20 and a sealing section 30 arranged to surround the electrode laminated section 20. As shown in Fig. 2, the electrode laminated section 20 is formed by laminating a plurality of bipolar electrodes 22 with separators 24 interposed therebetween. That is, the separators 24 are interposed between the bipolar electrodes 22 adjacent to each other in the lamination direction D (the vertical direction in Fig. 2). In this embodiment, at least three or more bipolar electrodes 22 are laminated. As shown in Fig. 1, the electrode laminated section 20 has, for example, a rectangular shape when viewed from the lamination direction.

[0021] The bipolar electrode 22 includes a current collector 25 and an electrode layer 26. The current collector 25 is formed in a rectangular sheet shape, and in this embodiment, has one surface 25A on the lower surface in the stacking direction D and another surface 25B on the upper surface. The current collector 25 is a chemically inactive electrical conductor for continuing to pass a current to the electrode layer 26, for example, during discharging or charging of the electricity storage device 10. In this embodiment, the current collector 25 is formed of a rectangular metal foil made of a metal such as Al, SUS, Ni, or Cu.

[0022] The electrode layer 26 is formed inside the periphery of the current collector 25, and is formed on at least one of the first surface 25A and the second surface 25B of the current collector 25. That is, the periphery 25C of the current collector 25 has a rectangular frame shape and is an uncoated region where the electrode layer 26 is not coated. In the following description, the periphery side (left side in the figure) of the electrode laminated portion 20 in Fig. 2 is referred to as the outside, and the inside (right side in the figure) of the electrode laminated portion 20 is referred to as the inside.

[0023] The electrode layer 26 includes at least one of a positive electrode 27 and a negative electrode 28. The positive electrode 27 is formed on one surface 25A of the current collector 25, and the negative electrode 28 is formed on the other surface 25B of the current collector 25. In the bipolar electrode 22A constituting the lowermost end of the electrode laminated portion 20 in the stacking direction D, the positive electrode 27 is not provided on the one surface 25A. In the bipolar electrode 22B constituting the uppermost end of the electrode laminated portion 20 in the stacking direction D, the negative electrode 28 is not provided on the other surface 25B.

[0024] The positive electrode 27 is a positive electrode active material layer formed by applying a positive electrode active material to one surface 25A of the current collector 25. Examples of the positive electrode active material constituting the positive electrode 27 include oxide active materials. Examples of the oxide active materials 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 active material include spinel-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, LiCuPO4, and olivine-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4. The positive electrode active material layer that forms the positive electrode 27 may contain a conductive material and a binder in addition to the positive electrode active material.

[0025] The negative electrode 28 is a negative electrode active material layer formed by applying a negative electrode active material to the other surface 25B of the current collector 25. Examples of the negative electrode active material constituting the negative electrode 28 include a carbon active material, an oxide active material, and a metal active material.

[0026] In the electrode stacking portion 20, the positive electrode 27 of one bipolar electrode 22 faces the negative electrode 28 of another adjacent bipolar electrode 22 on one side of the stacking direction D, with the separator 24 in between. In addition, in the electrode stacking portion 20, the negative electrode 28 of one bipolar electrode 22 faces the positive electrode 18 of another adjacent bipolar electrode 22 on the other side of the stacking direction D, with the separator 24 in between.

[0027] In this embodiment, the area on the other surface 25B of the current collector 25 where the negative electrode 28 is formed is slightly larger than the area on the one surface 25A of the current collector 25 where the positive electrode 27 is formed.

[0028] The separator 24 is disposed between the bipolar electrodes 22 adjacent to each other in the stacking direction D, and is interposed between the positive electrode 27 and the negative electrode 28. The separator 24 separates the positive electrode 27 and the negative electrode 28, thereby preventing short circuits caused by contact between the adjacent electrode layers 26, while allowing charge carriers such as lithium ions to pass through. The separator 24 is formed, for example, in a sheet shape. Examples of the separator 24 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 24 may be reinforced with a vinylidene fluoride resin compound. The separator 24 is not limited to a sheet shape, and may be a bag-shaped one.

[0029] The seal portion 30 is formed in a frame shape on the peripheral portion of the electrode laminate portion 20 so as to surround the electrode laminate portion 20, and includes a pair of holding seal materials 32, an outer peripheral portion holding seal portion 34, and a spacer 36. The pair of holding seal materials 32 hold an area including at least the outer peripheral side of the peripheral portion 25C of the one surface 25A and the other surface 25B of each current collector 25 from both sides in the stacking direction D. The pair of holding seal materials 32 include a first holding seal material 32A joined to the peripheral portion 25C of the one surface 25A of the current collector 25, and a second holding seal material 32B joined to the peripheral portion 25C of the other surface 25B of the current collector 25.

[0030] The first holding seal material 32A and the second holding seal material 32B are formed in a two-layer structure by folding one film in two, for example. That is, the peripheral side, which is the area not sandwiched between the current collector 25, is a folded-back portion (bent portion) of the film, and they are joined to each other at this peripheral portion. In addition, at least one of the surfaces of the first holding seal material 32A and the second holding seal material 32B opposite to the mutually opposing surfaces is joined to one surface 25A or the other surface 25B of the current collector 25.

[0031] In this embodiment, the pair of holding seal materials 32 is composed of one film, but the present invention is not limited to this, and may be composed of two films. That is, the first holding seal material 32A and the second holding seal material 32B may be formed separately. In this case, the peripheral side of the first holding seal material 32A and the second holding seal material 32B are joined.

[0032] The outer peripheral holding seal portion 34 holds the outer peripheral portions of the plurality of pairs of holding seal materials 32. Specifically, the outer peripheral holding seal portion 34 is a welding layer formed by integrating the plurality of pairs of holding seal materials 32 and the plurality of spacers 36 described later by welding the portions that overlap in the stacking direction of the plurality of pairs of holding seal materials 32 and the plurality of spacers 36 described later.

[0033] The spacer 36 is interposed between two pairs of adjacent holding seal materials 32 in the stacking direction D. That is, the spacer 36 is disposed between the first holding seal material 32A of one pair of adjacent holding seal materials 32 and the second holding seal material 32B of the other pair of adjacent holding seal materials 32. The spacer 36 maintains the gap between the pair of adjacent holding seal materials 32 in the stacking direction D. That is, the spacer 36 maintains the gap between the adjacent current collectors 25 in the stacking direction D at a desired distance.

[0034] The spacer 26 is formed in a frame shape and is disposed on the peripheral portion 25C of the current collector 25 when viewed from the stacking direction D. The spacer 36 is welded to at least one of the first holding seal material 32A and the second holding seal material 32B adjacent to each other in the stacking direction D, and in this embodiment, the inner side surface of the spacer 36 is formed longer than the inner side surfaces of the first holding seal material 32A and the second holding seal material 32B. In this embodiment, the peripheral portion of each separator 24 is fixed by being sandwiched between the spacer 36 and the second holding seal material 32B, as an example. The separator 24 may be joined to either the spacer 36 or the second holding seal material 32B.

[0035] The seal portion 30 is formed, for example, from an insulating resin, and examples of the resin material include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

[0036] In this embodiment, a plurality of spaces S are provided in the electricity storage device 10. Each space S is provided between adjacent bipolar electrodes 22 in the stacking direction D via a separator 24, and is a space airtightly and liquidtightly sealed by a seal portion 30. Specifically, as an example, a space S2 is defined by one surface 25A of a current collector 25 (first current collector) of an upper bipolar electrode 22-1 of adjacent bipolar electrodes 22-1 and 12-2 in the stacking direction D, an outer peripheral surface of a positive electrode 27, and an inner surface of a first holding seal material 32A, the other surface 25B of a current collector 25 (second current collector) of a lower bipolar electrode 22-2, an outer peripheral surface of a negative electrode 28, and an inner surface of a second holding seal material 32B, as well as an inner surface of a spacer 36 interposed between the bipolar electrodes 22-1 and 12-2, and an upper surface and a lower surface of the spacer 36 protruding from a pair of holding seal materials 32. The other spaces S of the space S2 are defined in the same manner.

[0037] Each space S 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 24, the positive electrode 27, and the negative electrode 28.

[0038] 1, the electricity storage device 10 is provided with a liquid filling port frame 12, and this liquid filling port frame 12 is provided with a plurality of liquid filling ports (not shown) that communicate each space S with the external space, lined up in the layer direction D. For example, the liquid filling ports are provided shifted in the short side direction of the seal portion 30 so that adjacent liquid filling ports do not overlap with each other in the stacking direction D (see FIG. 2).

[0039] In this embodiment, as shown in Fig. 2, the space S1 formed at the uppermost end (upper side in Fig. 2) as the most end in the stacking direction D is formed narrower than the other spaces S (including space S2). Specifically, the seal portion 30 forming the space S1 is formed longer inward than the seal portion 30 forming the other spaces S. More specifically, the inner surface of the first holding seal material 32A facing the space S1, the inner surface of the spacer 36 facing the space S1, and the inner surface of the second holding seal material 32B facing the space S1 are formed longer inward than the inner surfaces facing the other spaces S.

[0040] That is, when viewed from the stacking direction D, the width of the frame portion of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that form the space S1 is formed wider than the width of the frame portion of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that form the other space S. In other words, when viewed from the stacking direction D, the area of ​​the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that form the space S1 is formed wider than the area of ​​the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that form the other space S.

[0041] Next, the effects of the electricity storage device 10 in the first embodiment will be described.

[0042] Fig. 6 shows a cross-sectional view of a conventional electricity storage device 100 corresponding to Fig. 2. In Fig. 6, the same members as those in Fig. 2 are indicated by the same reference numerals and their explanation is omitted here, and only the different structure will be explained in detail.

[0043] 6, in the structure of the conventional energy storage device 100, the electrode stacking portion 20, the seal portion 30, and the spacer 36 in each bipolar electrode 22 stacked in the stacking direction D have the same shape. Therefore, the size of each space S formed inside the energy storage device 100 is uniform. In the structure of the conventional energy storage device 100, since each space S of the same size overlaps in the stacking direction D, it is difficult to visually confirm whether the pressure inside each space S is negative.

[0044] In contrast to the structure of the conventional energy storage device 100, in the energy storage device 10 of this embodiment, as shown in FIG. 2, the sealing portion 30 which forms the space S1 at the top end of the bipolar electrode 22 in the stacking direction D is formed longer inward than the sealing portions 30 which form other spaces S, so that the space S1 formed at the top end can be narrowed by the sealing portion 30 and the spacer 36.

[0045] As described above, in the present embodiment, the energy storage device 10 has a space S1 formed at the top end, which is the end of the bipolar electrodes 22 in the stacking direction D, which is narrower than the other spaces S. Therefore, when the pressure inside the energy storage device 10 rises, the space S1 formed at the top end is more likely to be affected than the other spaces S. This makes it possible to determine from the outside whether or not there is an abnormality in the internal pressure by checking the internal pressure of the space S1 formed at the top end. In other words, it is possible to determine whether or not there is an abnormality in the internal pressure of the energy storage device 10 by monitoring only the internal pressure of the space S1 formed at the top end, without monitoring the internal pressure of all the spaces S.

[0046] 1 and 2, in this embodiment, as an example, a change in the internal pressure of the space S1 can be detected by detecting the amount of swelling of the other surface 25B of the current collector 25 of the bipolar electrode 22B constituting the uppermost end of the electrode laminate 20 in the stacking direction D. Here, the sensor used for detection can be a known sensor such as a laser displacement sensor, but the type of sensor is not particularly limited.

[0047] 2, in the energy storage device 10 of the first embodiment, the inner surfaces of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that face the space S1 formed at the top end of the bipolar electrode 22 in the stacking direction D are formed longer inward than the inner surfaces that face other spaces S, but the present invention is not limited to this. It is sufficient that the inner surfaces of at least one of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B that face the space S1 formed at the top end of the bipolar electrode 22 in the stacking direction D are formed longer inward than the inner surfaces that face other spaces S.

[0048] Next, a description will be given of a power storage device 10A according to a second embodiment of the present invention. Fig. 3 is a cross-sectional view of the power storage device 10A according to the second embodiment of the present invention, corresponding to Fig. 2. Note that in the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals and will not be described again, and only the different structures will be described in detail.

[0049] In the first embodiment, the inner side surface of the spacer 36 is formed longer than the inner side surfaces of the first holding seal material 32A and the second holding seal material 32B. In contrast, in the energy storage device 10A of the second embodiment, as shown in Fig. 3, the inner side surface of the spacer 36 forming the space S1 formed at the uppermost end, which is the outermost end in the stacking direction D of the bipolar electrode 22, is formed to have the same length as the inner side surfaces of the first holding seal material 32A and the second holding seal material 32B. That is, the positions of the inner ends of the spacer 36, the first holding seal material 32A, and the second holding seal material 32B forming the space S1 in the direction approximately perpendicular to the stacking direction D are the same.

[0050] Next, the effects of the electricity storage device 10A in the second embodiment will be described.

[0051] The energy storage device 10A in the second embodiment can also provide the same effects as the energy storage device 10 in the first embodiment. Furthermore, in the energy storage device 10A in the second embodiment, the first holding seal material 32A, the second holding seal material 32B, and the inner end of the spacer 36, which form the space S1 at the uppermost end, which is the outermost end of the bipolar electrode 22 in the stacking direction D, are at the same position in the direction approximately perpendicular to the stacking direction D. This makes it possible to prevent the shape of the space S1 formed at the uppermost end of the bipolar electrode 22 in the stacking direction D from becoming complicated.

[0052] In the second embodiment, the lengths of the inner sides of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 are the same only in the space S1 formed at the top end, which is the end of the bipolar electrode 22 in the stacking direction D, but the present invention is not limited to this. Similarly, in spaces S other than the top end space S1, the lengths of the inner sides of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 may be the same. However, the lengths of the inner sides of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 in the top end space S1 are formed longer than those of the other spaces S.

[0053] Next, a description will be given of a power storage device 10B according to a third embodiment of the present invention. Fig. 4 is a cross-sectional view of a power storage device 10B according to the third embodiment of the present invention, corresponding to Fig. 2. Note that in the third embodiment, the same components as those in the first embodiment described above are indicated by the same reference numerals and will not be described again, and only different structures will be described in detail.

[0054] In the first embodiment, the seal portion 30 which forms the space S1 at the top end of the bipolar electrode 22 in the stacking direction D is formed longer inward than the seal portions 30 which form the other spaces S. In contrast, in the energy storage device 10B of the third embodiment, the seal portion 30 which forms the space S1 at the top end of the bipolar electrode 22 in the stacking direction D is formed to have the same inward length as the seal portions 30 which form the other spaces S.

[0055] 4, in the energy storage device 10B of the third embodiment, the positive electrode 27 and the negative electrode 28 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22 are formed larger toward the outer periphery than the positive electrode 27 and the negative electrode 28 forming the other spaces S. That is, when viewed from the stacking direction D, the area of ​​the positive electrode 27 and the negative electrode 28 forming the space S1 is formed larger than the area of ​​the positive electrode 27 and the negative electrode 28 forming the other spaces S.

[0056] Next, the effects of the power storage device 10B in the third embodiment will be described.

[0057] In the energy storage device 10B of the third embodiment, the positive electrodes 27 and negative electrodes 28 forming the space S1 at the top end of the bipolar electrodes 22 in the stacking direction D are formed larger toward the outer periphery than the positive electrodes 27 and negative electrodes 28 forming the other spaces S, respectively. Therefore, the space S1 formed at the top end of the bipolar electrodes 22 in the stacking direction D by the positive electrodes 27 and negative electrodes 28 can be narrowed without changing the shape of the seal portion 30. Therefore, similarly to the energy storage device 10 of the first embodiment described above, the presence or absence of an abnormality in the internal pressure can be determined from the outside by checking the internal pressure in the space S1 formed at the top end.

[0058] In the third embodiment, the positive electrode 27 and the negative electrode 28 forming the space S1 formed at the top end of the bipolar electrode 22 in the stacking direction D are formed larger toward the outer periphery than the positive electrode 27 and the negative electrode 28 forming the other spaces S, respectively, but the present invention is not limited to this. Only the positive electrode 27 forming the space S1 may be formed larger toward the outer periphery than the positive electrode 27 forming the other spaces S, or only the negative electrode 28 forming the space S1 may be formed larger toward the outer periphery than the negative electrode 28 forming the other spaces S.

[0059] Next, a power storage device 10C according to a fourth embodiment of the present invention will be described. Fig. 5 is a cross-sectional view of the power storage device 10C according to the fourth embodiment of the present invention, corresponding to Fig. 2. Note that in the fourth embodiment, configurations similar to those in the first embodiment described above are indicated by the same reference numerals and descriptions thereof will be omitted, and only different structures will be described in detail.

[0060] In the first embodiment, the seal portion 30 that forms the space S1 at the top end of the bipolar electrode 22 in the stacking direction D is formed longer inward than the seal portions 30 that form the other spaces S. In contrast, in the energy storage device 10B of the fourth embodiment, the seal portion 30 that forms the space S1 at the top end of the bipolar electrode 22 in the stacking direction D is formed to have the same inward length as the seal portions 30 that form the other spaces S.

[0061] 5, in the electricity storage device 10C of the fourth embodiment, a member 19 having electrolyte resistance is disposed at the outer peripheral end of the positive electrode 27 that forms a space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22. Examples of materials for the member 19 include polypropylene (PP), polyethylene (PE), perfluoroalkoxyalkane (PFA), and polytetrafluoroethylene (PTFT).

[0062] The member 19 may be provided on the entire outer peripheral end of the positive electrode 27, that is, so as to surround the positive electrode 27, or may be provided at a plurality of locations with gaps therebetween.

[0063] Next, the effects of the power storage device 10C in the fourth embodiment will be described.

[0064] In the electricity storage device 10C of the fourth embodiment, a member 19 having electrolyte resistance is disposed at an end portion on the outer circumferential side of the positive electrode 27 that defines a space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22. Therefore, the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22 can be narrowed by the member 19 without changing the shapes of the seal portion 30, the positive electrode 27, and the negative electrode 28. Therefore, similarly to the electricity storage device 10 of the first embodiment described above, the presence or absence of an abnormality in the internal pressure can be determined from the outside by checking the internal pressure in the space S1 formed at the uppermost end.

[0065] In the fourth embodiment, the member 19 is disposed only on the outer peripheral end of the positive electrode 27 that forms the space S1 formed at the top end of the bipolar electrode 22 in the stacking direction D, but the present invention is not limited to this. The member 19 may be disposed only on the outer peripheral end of the negative electrode 28 that forms the space S1, or the member 19 may be disposed on both ends of the positive electrode 27 and the negative electrode 28.

[0066] [remarks] In the above embodiment, the space S1 formed at the uppermost end of the bipolar electrode 22 in the stacking direction D is narrower than the other spaces S, but the present invention is not limited to this, and the space S formed at the lowermost end of the bipolar electrode 22 in the stacking direction D may be narrower than the other spaces S. In addition, both the spaces S1 formed at the uppermost end and the lowermost end of the bipolar electrode 22 in the stacking direction D may be narrower than the other spaces S.

[0067] In addition, in the above-described embodiment, a liquid battery in which an electrolyte is injected into the space S is used as an example, but the present invention is not limited to this, and can also be applied to an all-solid-state battery as long as it has a bipolar structure.

[0068] Furthermore, 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. [Explanation of symbols]

[0069] 10, 10A to 10C: Electric storage device; 20: Electrode laminate; 22, 22A, 22B bipolar electrodes, 24 separator, 25 current collector, 25A one surface, 25B other surface, 26 electrode layer, 27 positive electrode, 28 negative electrode, 29 member, 30 sealing portion, 32 pair of holding seal members, 34 outer peripheral holding seal member, 36 Spacer, S space, S1 space formed at the top end (space formed at the end)

Claims

1. an electrode laminated portion in which a plurality of bipolar electrodes, each of which has a positive electrode formed on one side of a current collector and a negative electrode formed on the other side, are laminated with a separator interposed therebetween; a seal portion that is disposed so as to surround the electrode laminate portion, holds the current collector, and forms a space between two adjacent bipolar electrodes via the separator and seals the space; The power storage device has a space formed at an end portion of the bipolar electrodes in a stacking direction, the space being narrower than the other spaces.

2. The power storage device according to claim 1 , wherein the seal portion that defines the space formed at the end portion is formed longer inward than the seal portions that define other spaces.

3. The sealing portion includes a plurality of pairs of holding seal materials that hold the current collectors of the bipolar electrodes stacked in a plurality of layers from both sides in the stacking direction, and an outer periphery holding seal portion that holds the outer periphery of the pair of holding seal materials; a spacer interposed between two of the pair of holding and sealing materials adjacent to each other in a stacking direction of the bipolar electrodes; The power storage device according to claim 2 , wherein at least inner ends of the holding sealer and the spacer that form the space formed at the outermost end are positioned at the same position in a direction substantially perpendicular to the stacking direction.

4. The sealing portion includes a plurality of pairs of holding seal materials that hold the current collectors of the bipolar electrodes stacked in a plurality of layers from both sides in the stacking direction, and an outer periphery holding seal portion that holds the outer periphery of the pair of holding seal materials; a spacer interposed between two of the pair of holding and sealing materials adjacent to each other in a stacking direction of the bipolar electrodes; the space is formed by being surrounded by the spacer, two holding seal materials located on both sides of the spacer in the stacking direction, a first current collector held by a pair of holding seal materials including one of the two holding seal materials, a second current collector held by a pair of holding seal materials including the other of the two holding seal materials, the positive electrode formed on one surface of the first current collector, and the negative electrode formed on the other surface of the second current collector; 2 . The power storage device according to claim 1 , wherein at least one of the positive electrode and the negative electrode forming the space formed at the outermost end is formed larger toward the outer periphery than the other positive electrode and the other negative electrode, respectively.

5. the sealing portion includes a plurality of pairs of holding seal materials that hold the current collectors of the bipolar electrodes stacked in a plurality of layers from both sides in the stacking direction, an outer peripheral holding seal portion that holds the outer peripheral portions of the pair of holding seal materials, and a spacer that is interposed between two pairs of holding seal materials adjacent to each other in the stacking direction of the bipolar electrodes, the space is formed by the spacer, two holding seal materials located on both sides of the spacer in the stacking direction, a first current collector held by a pair of holding seal materials including one of the two holding seal materials, a second current collector held by a pair of holding seal materials including the other of the two holding seal materials, the positive electrode formed on one surface of the first current collector, and the negative electrode formed on the other surface of the second current collector; 2 . The electricity storage device according to claim 1 , wherein an electrolyte-resistant member is disposed on an outer peripheral end of at least one of the positive electrode and the negative electrode that form the space formed at the outermost end.

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