Electricity storage device

Abstract

The utility model provides an electrical storage device capable of judging whether internal pressure is abnormal or not from the outside. A power storage device (10) is provided with an electrode laminated part (20) and a sealing part (30). The electrode laminated part (20) is formed by laminating a plurality of bipolar electrodes (22) with a separator (24) therebetween, wherein a positive electrode (27) is formed on one surface (25A) of a current collector (25) and a negative electrode (28) is formed on the other surface (25B) of the current collector (25). The sealing part (30) is disposed so as to surround the electrode laminated part (20), holds the current collector (25), forms a space (S) between two bipolar electrodes (22) adjacent to each other with a separator (24) therebetween, and seals the space (S). A space (S1) formed at the end of the bipolar electrode (22) in the stacking direction (D) is narrower than the other spaces (S).

Description

Technical Field

[0001] The utility model relates to an electric storage device with a bipolar structure. Background Art

[0002] Japanese Patent Application Laid-Open No. 2022-016904 discloses a power storage device having a bipolar structure in which current collectors and separators are alternately stacked on both sides of which positive and negative electrode active materials are coated respectively. Utility Model Content

[0003] However, in a power storage device having a bipolar structure as described in Japanese Patent Application Laid-Open No. 2022-016904, for example, since the batteries overlap each other, it is difficult to visually confirm whether the pressure inside each battery is negative.

[0004] The present invention has been made in consideration of the above-mentioned facts, and an object of the present invention is to provide a power storage device capable of judging from the outside whether or not there is an abnormality in the internal pressure.

[0005] The first mode of the utility model provides an electric storage device comprising: an electrode stack portion formed by stacking a plurality of bipolar electrodes with a positive electrode formed on one side of a current collector and a negative electrode formed on the other side thereof via a partition; and a sealing portion arranged in a manner to surround the electrode stack portion, hold the current collector, form a space between two adjacent bipolar electrodes via the partition and seal the space, wherein the space formed at the end portion in the stacking direction of the bipolar electrodes is narrower than the other spaces.

[0006] In the first embodiment of the power storage device of the present invention, since the space formed at the endmost portion in the stacking direction of the bipolar electrodes is narrower than other spaces, when the pressure inside the battery rises, the space formed at the endmost portion is more likely to be affected than other spaces. Therefore, by confirming the internal pressure of the space formed at the endmost portion, it is possible to determine from the outside whether the internal pressure is abnormal.

[0007] The power storage device of the present invention according to a second aspect is configured as the first aspect, wherein the sealing portion forming the space formed at the end portion is formed longer on an inner side than the sealing portions forming the other spaces.

[0008] In the power storage device of the utility model of the second aspect, since the sealing portion forming the space formed at the endmost portion in the stacking direction of the bipolar electrodes is formed longer on the inner side than the sealing portion forming other spaces, the space formed at the endmost portion can be narrowed by the sealing portion. Therefore, by confirming the internal pressure of the space formed at the endmost portion, it is possible to judge from the outside whether the internal pressure is abnormal.

[0009] The third embodiment of the utility model is a storage device in the second embodiment, wherein the sealing portion comprises: a plurality of pairs of retaining sealing materials for retaining the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; a peripheral retaining sealing portion for retaining the peripheral portion of the pair of retaining sealing materials; and a spacer sandwiched between two adjacent pairs of retaining sealing portions in the stacking direction of the bipolar electrodes, wherein at least the inner ends of the retaining sealing material and the spacer forming the space at the end portion are in the same position in a direction substantially orthogonal to the stacking direction.

[0010] In the power storage device of the utility model of the third aspect, the holding sealing material forming at least the space formed at the end portion in the stacking direction of the bipolar electrodes is located at the same position as the inner end of the spacer in the direction substantially orthogonal to the stacking direction. Therefore, it is possible to suppress the complication of the shape of the space formed at the end portion in the stacking direction of the bipolar electrodes.

[0011] The storage device of the utility model in the fourth mode is in the structure of the first mode, wherein the sealing portion has: a plurality of pairs of retaining seals for retaining the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; an outer peripheral retaining seal for retaining the outer peripheral portion of the pair of retaining seals; a spacer sandwiched between two adjacent pairs of retaining seals in the stacking direction of the bipolar electrodes, the space being formed by being surrounded by the spacer, two retaining seals located on both sides of the spacer in the stacking direction, a first collector retained in a pair of retaining seals including one of the two retaining seals, a second collector retained in a pair of retaining seals including the other of the two retaining seals, the positive electrode formed on one side of the first collector, and the negative electrode formed on the other side of the second collector, and at least one of the positive electrode and the negative electrode in the space formed at the end portion is formed to the outer peripheral side larger than the other positive electrode and the other negative electrode.

[0012] In the power storage device of the utility model of the fourth aspect, since at least one of the positive electrode and the negative electrode forming the space formed at the end in the stacking direction of the bipolar electrodes is formed larger toward the outer peripheral side than the other positive electrodes and the other negative electrodes, the space formed by at least one of the positive electrode and the negative electrode at the end can be narrowed without changing the shape of the sealing portion. Therefore, by confirming the internal pressure of the space formed at the end, it is possible to judge from the outside whether the internal pressure is abnormal.

[0013] The fifth embodiment of the utility model is a storage device in the first embodiment, wherein the sealing portion comprises: a plurality of pairs of retaining seals, which respectively retain the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; a peripheral retaining seal portion, which retains the peripheral portion of the pair of retaining seals; a spacer, which is interposed between two adjacent pairs of retaining seals in the stacking direction of the bipolar electrodes, the space being formed by the spacer, two retaining seals located on both sides of the spacer in the stacking direction, a first collector retained in a pair of retaining seals including one of the two retaining seals, a second collector retained in a pair of retaining seals including the other of the two retaining seals, the positive electrode formed on one side of the first collector, and the negative electrode formed on the other side of the second collector, and a component having electrolyte resistance is arranged at the end of the peripheral side of at least one of the positive electrode and the negative electrode forming the space formed at the endmost portion.

[0014] In the power storage device of the utility model of the fifth aspect, since a component having electrolyte resistance is arranged at the end of the outer peripheral side of at least one of the positive electrode and the negative electrode forming the space formed at the end in the stacking direction of the bipolar electrodes, the space formed by the component at the end can be narrowed without changing the shape of the electrode stacking part and the sealing part. Therefore, by confirming the internal pressure of the space formed at the end, it is possible to judge from the outside whether the internal pressure is abnormal.

[0015] As described above, the power storage device of the present invention has an excellent effect of being able to determine from the outside whether or not there is an abnormality in the internal pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a perspective view showing the appearance of the power storage device according to the first embodiment of the present invention before assembly.

[0017] Figure 2 for Figure 1 AA line cross-section diagram.

[0018] Figure 3 A power storage device according to a second embodiment of the present invention Figure 2 The corresponding cross-sectional view.

[0019] Figure 4 A power storage device according to a third embodiment of the present invention Figure 2 The corresponding cross-sectional view.

[0020] Figure 5 A power storage device according to a fourth embodiment of the present invention Figure 2 The corresponding cross-sectional view.

[0021] Figure 6 The prior art power storage device is Figure 2 The corresponding cross-sectional view. DETAILED DESCRIPTION

[0022] Hereinafter, a power storage device 10 according to a first embodiment of the present invention will be described with reference to the drawings. Figure 1 1 is a perspective view showing the appearance of the power storage device 10 according to the first embodiment of the present invention before assembly. Figure 2 yes Figure 1 AA line cross-sectional view. In the description of the drawings, the same or equivalent parts are marked with the same figure numbers, and their descriptions are omitted. The power storage device 10 of the present embodiment is a bipolar power storage device, for example, a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 10 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage device 10 can be, for example, a double-layer capacitor. In the present embodiment, the case where the power storage device 10 is a lithium-ion secondary battery is illustrated.

[0023] like Figure 1 As shown, the power storage device 10 is formed in a substantially rectangular parallelepiped shape and includes a liquid injection port frame 12 formed with a liquid injection port (not shown) for injecting an electrolyte described later and a substrate portion 14 for detecting the voltage of each battery cell constituting the power storage device 10. The substrate portion 14 includes an FPC (Flexible Printed Circuits) substrate 14A as an example of a voltage detection circuit substrate including a circuit for detecting voltage, and both ends of the FPC substrate 14A in one direction are held by an FPC case 14B. Although not shown in the figure, the power storage device 10 is housed in a battery case.

[0024] The power storage device 10 includes an electrode stack 20 and a sealing portion 30 disposed so as to surround the electrode stack 20. Figure 2 As shown in FIG. 1 , the electrode stacking unit 20 is formed by stacking a plurality of bipolar electrodes 22 with separators 24 interposed therebetween. Figure 2 A separator 24 is present between the bipolar electrodes 22 adjacent to each other in the vertical direction. In addition, in this embodiment, at least three bipolar electrodes 22 are stacked. Figure 1 As shown, the electrode stack 20 has, for example, a rectangular shape when viewed from the stacking direction.

[0025] 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 at the bottom in the stacking direction D and another surface 25B at the top. The current collector 25 is, for example, a chemically inactive electrical conductor for allowing current to continue to flow through the electrode layer 26 during the discharge or charge of the power 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, Cu, etc.

[0026] The electrode layer 26 is formed inside the periphery of the current collector 25, and is formed on at least one of the one surface 25A and the other surface 25B of the current collector 25. That is, the periphery 25C of the current collector 25 is in a rectangular frame shape, and becomes an uncoated area where the electrode layer 26 is not coated. Figure 2 In the following description, the peripheral side of the electrode stack portion 20 (the left side in the figure) is referred to as the outer side, and the inner side of the electrode stack portion 20 (the right side in the figure) is referred to as the inner side.

[0027] 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 side 25A of the current collector 25, and the negative electrode 28 is formed on the other side 25B of the current collector 25. In addition, in the bipolar electrode 22A constituting the end portion of the lower side of the electrode stack 20 in the stacking direction D, the positive electrode 27 is not provided on one side 25A. In addition, in the bipolar electrode 22B constituting the end portion of the upper side of the electrode stack 20 in the stacking direction D, the negative electrode 28 is not provided on the other side 25B.

[0028] The positive electrode 27 is a positive electrode active material layer formed by applying a positive electrode active material to one side 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 material include LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 Rock salt layered active materials, LiMn 2 O 4 、Li(Ni 0.5 Mn 1.5 ) 4 Spinel active materials, LiFePO 4 、LiMnPO 4 、LiNiPO 4 、LiCuPO 4The positive electrode active material layer forming the positive electrode 27 may contain a conductive material and a binder in addition to the positive electrode active material.

[0029] 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 carbon active materials, oxide active materials, and metal active materials.

[0030] In the electrode stack 20, the positive electrode 27 of one bipolar electrode 22 faces the negative electrode 28 of another bipolar electrode 22 adjacent to one side of the stacking direction D with the separator 24 interposed therebetween. In addition, in the electrode stack 20, the negative electrode 28 of one bipolar electrode 22 faces the positive electrode 18 of another bipolar electrode 22 adjacent to the other side of the stacking direction D with the separator 24 interposed therebetween.

[0031] In the present embodiment, the region where the negative electrode 28 is formed on the other surface 25B of the current collector 25 is slightly larger than the region where the positive electrode 27 is formed on the one surface 25A of the current collector 25 .

[0032] The separator 24 is arranged between the bipolar electrodes 22 adjacent to each other in the stacking direction D, and between the positive electrode 27 and the negative electrode 28. The separator 24 prevents a short circuit caused by the contact of the adjacent electrode layers 26 by isolating the positive electrode 27 from the negative electrode 28, while allowing charge carriers such as lithium ions to pass through. The separator 24 is formed in a sheet shape, for example. As the separator 24, a porous film composed of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven or non-woven fabric composed of polypropylene, methyl cellulose, etc., etc. can be exemplified. The separator 24 can be a separator reinforced with a vinylidene fluoride resin compound. In addition, the separator 24 is not limited to a sheet shape, and a bag-shaped separator can also be used.

[0033] The sealing portion 30 is formed in a frame shape at the peripheral portion of the electrode stack portion 20 in a manner of surrounding the electrode stack portion 20, and includes a pair of holding seals 32, a peripheral holding seal 34, and a spacer 36. The pair of holding seals 32 holds the peripheral portion 25C of one side 25A and the other side 25B of each collector 25 from both sides of the stacking direction D, at least including the peripheral side. The pair of holding seals 32 includes a first holding seal 32A bonded to the peripheral portion 25C of one side 25A of the collector 25, and a second holding seal 32B bonded to the peripheral portion 25C of the other side 25B of the collector 25.

[0034] As an example, the first holding seal material 32A and the second holding seal material 32B are formed with a two-layer structure formed by folding one film into two. That is, the peripheral side of the region not passing through the collector 25 becomes the folded back portion (bend portion) of the film, and the peripheral portion is mutually joined. In addition, at least one side of the surface on the opposite side of the mutually opposing surface of the first holding seal material 32A and the second holding seal material 32B is joined to one side 25A or the other side 25B of the collector 25.

[0035] In addition, in the present embodiment, a pair of holding seal materials 32 is composed of one film, but the utility model is not limited thereto and can also be composed of two films. That is, the first holding seal material 32A and the second holding seal material 32B can be formed separately. In this case, the first holding seal material 32A is joined to the peripheral edge side of the second holding seal material 32B.

[0036] The peripheral holding seal portion 34 holds the peripheral portions of the plurality of pairs of holding seal materials 32. Specifically, the peripheral holding seal portion 34 is a fusion layer formed by integrating the plurality of pairs of holding seal materials 32 and the plurality of spacers 36 described later by fusing overlapping portions of the plurality of pairs of holding seal materials 32 and the plurality of spacers 36 described later in the stacking direction.

[0037] The spacer 36 is disposed between two pairs of holding seals 32 adjacent to each other in the stacking direction D. That is, the spacer 36 is disposed between the first holding seal 32A of one pair of holding seals 32 and the second holding seal 32B of the other pair of holding seals 32 of the two adjacent pairs of holding seals 32. The spacer 36 is used to maintain a gap between the pair of holding seals 32 adjacent to each other in the stacking direction D. That is, the gap between the collectors 25 adjacent to each other in the stacking direction D is maintained at a desired distance by the spacer 36.

[0038] The spacer 36 is formed in a frame shape and is arranged on the peripheral portion 25C of the collector 25 when viewed from the stacking direction D. The spacer 36 is fused to at least one of the first holding seal material 32A and the second holding seal material 32B adjacent in the stacking direction D. In the present embodiment, the inner side surface of the spacer 36 is formed to be longer than the inner side surface of the first holding seal material 32A and the second holding seal material 32B. In addition, in the present embodiment, the peripheral portion of each separator 24 is fixed between the spacer 36 and the second holding seal material 32B as an example. In addition, the separator 24 can be bonded to either the spacer 36 or the second holding seal material 32B.

[0039] The sealing portion 30 is formed of, for example, an insulating resin, and examples of the constituent material of the resin include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

[0040] In the present embodiment, a plurality of spaces S are provided in the power storage device 10. Each space S is provided between the bipolar electrodes 22 adjacent in the stacking direction D via the partition 24, and is a space sealed airtightly and liquid-tightly by the sealing portion 30. Specifically, as an example, the space S2 is divided by one side 25A of the collector 25 (first collector) of the upper bipolar electrode 22-1, the outer peripheral surface of the positive electrode 27 and the inner side surface of the first holding seal 32A, the other side 25B of the collector 25 (second collector) of the lower bipolar electrode 22-2, the outer peripheral surface of the negative electrode 28 and the inner side surface of the second holding seal 32B, and the inner side surface of the spacer 36 between the bipolar electrodes 22-1 and 22-2, and the upper and lower surfaces of the spacer 36 protruding from the pair of holding seals 32. The other spaces S of the space S2 are divided in the same manner.

[0041] 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 LiPF 6 The electrolyte is impregnated into the separator 24, the positive electrode 27 and the negative electrode 28.

[0042] Here, if Figure 1 As shown, the power storage device 10 is provided with a liquid injection port frame 12, and a plurality of liquid injection ports (not shown) are arranged in parallel in the stacking direction D to connect each space S with the external space. Figure 2 ) are arranged in an offset manner in the short side direction of the sealing portion 30 so that adjacent injection ports do not overlap with each other.

[0043] In this embodiment, if Figure 2 As shown, the uppermost end ( Figure 2 The space S1 (in the upper side) is formed to be narrower than other spaces S (including space S2). Specifically, the sealing portion 30 forming the space S1 is formed longer on the inner side than the sealing portion 30 forming the other spaces S. More specifically, the inner side surface of the first holding sealing material 32A facing the space S1, the inner side surface of the spacer 36 facing the space S1, and the inner side surface of the second holding sealing material 32B facing the space S1 are formed longer on the inner side than the inner side surfaces facing the other spaces S.

[0044] That is, when viewed from the stacking direction D, the width of the frame portion of the first holding sealing material 32A, the spacer 36, and the second holding sealing material 32B forming the space S1 is formed to be wider than the width of the frame portion of the first holding sealing material 32A, the spacer 36, and the second holding sealing material 32B forming other spaces S. In other words, when viewed from the stacking direction D, the area of ​​the first holding sealing material 32A, the spacer 36, and the second holding sealing material 32B forming the space S1 is formed to be larger than the area of ​​the first holding sealing material 32A, the spacer 36, and the second holding sealing material 32B forming other spaces S.

[0045] Next, the effects of the power storage device 10 in the first embodiment will be described.

[0046] Here, Figure 6 The conventional power storage device 100 is shown in FIG. Figure 2 Corresponding cross-sectional view. In addition, Figure 6 In Figure 2 The same components are denoted by the same reference numerals, and description thereof is omitted here, and only different structures are described in detail.

[0047] like Figure 6 As shown in FIG. 1 , in the structure of the conventional power storage device 100, the electrode stacking portion 20, the sealing portion 30, and the spacer 36 in each bipolar electrode 22 stacked in the stacking direction D have the same shape. Therefore, the sizes of the spaces S formed inside the power storage device 100 are equal. In the structure of the conventional power storage device 100, since the spaces S of the same size overlap in the stacking direction D, it is difficult to visually confirm whether the pressure inside each space S is negative.

[0048] Compared with the structure of the conventional power storage device 100, the power storage device 10 in this embodiment is as follows: Figure 2 As shown, since the sealing portion 30 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22 is formed longer inward than the sealing portion 30 forming other spaces S, the space S1 formed at the uppermost end by the sealing portion 30 and the spacer 36 can be narrowed.

[0049] Thus, in the present embodiment, in the power storage device 10, the space S1 formed at the uppermost end, i.e., the end portion in the stacking direction D of the bipolar electrodes 22, is narrower than the other spaces S. Therefore, when the pressure inside the power storage device 10 rises, the space S1 formed at the uppermost end is more likely to be affected than the other spaces S. Thus, by confirming the internal pressure of the space S1 formed at the uppermost end, it is possible to determine from the outside whether the internal pressure is abnormal. That is, by monitoring the internal pressure of the entire space S only by monitoring the internal pressure of the space S1 formed at the uppermost end, it is possible to determine whether the internal pressure of the power storage device 10 is abnormal.

[0050] In addition, in this embodiment, as an example, Figure 1 and Figure 2 As shown, by detecting the expansion amount of the other surface 25B of the collector 25 of the bipolar electrode 22B constituting the uppermost end of the electrode stack 20 in the stacking direction D, the change in the internal pressure of the space S1 can be detected. Here, the sensor used for the detection can use a known sensor such as a laser displacement sensor, and the type of the sensor is not particularly limited.

[0051] In addition, in the power storage device 10 of the first embodiment, as Figure 2 As shown in the figure, the inner side surfaces of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B facing the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22 are formed longer on the inner side than the inner side surfaces facing other spaces S, but the present invention is not limited thereto. As long as the inner surface of any one or more of the first holding seal material 32A, the spacer 36, and the second holding seal material 32B facing the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22 is formed longer on the inner side than the inner surfaces facing other spaces S.

[0052] Next, a power storage device 10A according to a second embodiment of the present invention will be described. Figure 3 The power storage device 10A according to the second embodiment of the present invention is Figure 2 In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and their description is omitted, and only the different structures are described in detail.

[0053] In the first embodiment, the inner side surface of the spacer 36 is formed longer than the inner side surfaces of the first holding sealing material 32A and the second holding sealing material 32B. Figure 3 As shown in FIG. 1 , the inner side surface of the spacer 36 forming the space S1 formed at the uppermost 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 inner ends of the spacer 36, the first holding seal material 32A, and the second holding seal material 32B forming the space S1 are located at the same position in the direction substantially orthogonal to the stacking direction D.

[0054] Next, the effects of the power storage device 10A in the second embodiment will be described.

[0055] The power storage device 10A in the second embodiment can also obtain the same effects as those of the power storage device 10 in the first embodiment. Furthermore, in the power storage device 10A in the second embodiment, at least the first holding seal material 32A, the second holding seal material 32B, and the inner ends of the spacer 36 that form the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 are located at the same position in a direction substantially orthogonal to the stacking direction D. Therefore, it is possible to suppress the complication of the shape of the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22.

[0056] In addition, in the second embodiment, only in the space S1 formed at the uppermost end of the stacking direction D of the bipolar electrode 22, the lengths of the inner side surfaces of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 are set to the same length, but the utility model is not limited thereto. Similarly, in the space S other than the uppermost space S1, the lengths of the inner side surfaces of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 can be made to be the same length. However, the uppermost space S1 is formed so that the lengths of the inner side surfaces of the first holding seal material 32A, the second holding seal material 32B, and the spacer 36 are longer than those of other spaces S.

[0057] Next, a power storage device 10B according to a third embodiment of the present invention will be described. Figure 4 The power storage device 10B according to the third embodiment of the present invention is Figure 2 In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and their description is omitted, and only the different structures are described in detail.

[0058] In the first embodiment, the sealing portion 30 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 is formed longer on the inner side than the sealing portion 30 forming the other spaces S. On the other hand, in the power storage device 10B of the third embodiment, the sealing portion 30 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 is formed to have the same inner length as the sealing portion 30 forming the other spaces S.

[0059] like Figure 4 As shown, in the power 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 peripheral side 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.

[0060] Next, the effects of the power storage device 10B in the third embodiment will be described.

[0061] In the power 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 electrodes 22 are formed larger toward the outer peripheral side than the positive electrode 27 and the negative electrode 28 forming the other spaces S. Therefore, the space S1 formed by the positive electrode 27 and the negative electrode 28 at the uppermost end in the stacking direction D of the bipolar electrodes 22 can be narrowed without changing the shape of the sealing portion 30. Therefore, similarly to the power storage device 10 of the first embodiment, the presence or absence of abnormality in the internal pressure can be determined from the outside by checking the internal pressure of the space S1 formed at the uppermost end.

[0062] In addition, in 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 respectively formed larger toward the outer periphery than the positive electrode 27 and the negative electrode 28 forming the other spaces S, but the present invention is not limited thereto. 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.

[0063] Next, a power storage device 10C according to a fourth embodiment of the present invention will be described. Figure 5 A power storage device 10C according to a fourth embodiment of the present invention Figure 2 In the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and their description is omitted, and only the different structures are described in detail.

[0064] In the first embodiment, the sealing portion 30 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 is formed longer on the inner side than the sealing portion 30 forming the other spaces S. On the other hand, in the power storage device 10C of the fourth embodiment, the sealing portion 30 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 is formed to have the same inner length as the sealing portion 30 forming the other spaces S.

[0065] like Figure 5 As shown, in the power storage device 10C of the fourth embodiment, a member 29 having electrolyte resistance is arranged at the end portion on the outer peripheral side of the positive electrode 27 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22. Examples of the constituent material of the member 29 include polypropylene (PP), polyethylene (PE), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFT), and the like.

[0066] The member 29 may be provided at the end portion of the entire outer circumference of the positive electrode 27 , that is, provided so as to surround the positive electrode 27 , or may be provided at a plurality of locations with gaps therebetween.

[0067] Next, the effects of the power storage device 10C in the fourth embodiment will be described.

[0068] In the power storage device 10C of the fourth embodiment, a member 29 having electrolyte resistance is disposed at the end portion on the outer peripheral side of the positive electrode 27 that forms the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22. Therefore, the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrodes 22 can be narrowed by the member 29 without changing the shapes of the sealing portion 30, the positive electrode 27, and the negative electrode 28. Therefore, similarly to the power storage device 10 of the first embodiment, the presence or absence of abnormality in the internal pressure can be determined from the outside by checking the internal pressure of the space S1 formed at the uppermost end.

[0069] In the fourth embodiment, the component 29 is disposed only at the end portion of the outer periphery of the positive electrode 27 forming the space S1 formed at the uppermost end in the stacking direction D of the bipolar electrode 22, but the present invention is not limited thereto. The component 29 may be disposed only at the end portion of the outer periphery of the negative electrode 28 forming the space S1, or may be disposed at the ends of both the positive electrode 27 and the negative electrode 28.

[0070] In addition, in the above-described embodiment, the space S1 formed at the uppermost end of the bipolar electrode 22 in the stacking direction D is made narrower than the other spaces S, but the present invention is not limited thereto, and the space S formed at the lowermost end of the bipolar electrode 22 in the stacking direction D may be made narrower than the other spaces S. In addition, the space S1 formed at both the uppermost end and the lowermost end of the bipolar electrode 22 in the stacking direction D may be made narrower than the other spaces S.

[0071] In addition, in the above-described embodiment, a liquid-based battery in which an electrolyte is injected into the space S is taken as an example, but the present invention is not limited thereto, and can also be applied to an all-solid-state battery as long as it has a bipolar structure.

[0072] In addition, the configuration of the present disclosure is not limited to the above-described embodiment, and the configuration can be appropriately changed as long as the problem can be solved.

Claims

1. A power storage device, characterized in that: have: An electrode stacking portion formed by stacking a plurality of bipolar electrodes with a positive electrode formed on one side of a current collector and a negative electrode formed on the other side via a separator; a sealing portion arranged to surround the electrode stack, holding the current collector, forming a space between two adjacent bipolar electrodes sandwiching the separator, and sealing the space, The space formed at the end portion in the stacking direction of the bipolar electrodes is narrower than the other spaces.

2. The power storage device according to claim 1, characterized in that The seal portion forming the space formed at the end portion is formed longer on the inner side than the seal portions forming the other spaces.

3. The power storage device according to claim 2, characterized in that The sealing portion comprises: a plurality of pairs of holding seals for holding the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; a peripheral holding seal for holding the peripheral portions of the pair of holding seals; and a spacer sandwiched between two adjacent pairs of holding seals in the stacking direction of the bipolar electrodes. At least the inner ends of the holding sealing material and the spacer that form the space formed at the end portion are located at the same position in a direction substantially orthogonal to the stacking direction.

4. The power storage device according to claim 1, wherein: The sealing portion comprises: a plurality of pairs of holding seals for holding the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; a peripheral holding seal for holding the peripheral portions of the pair of holding seals; and a spacer sandwiched between two adjacent pairs of holding seals in the stacking direction of the bipolar electrodes. The space is formed by being surrounded by the spacer, two holding seals located on both sides of the spacer in the stacking direction, a first current collector held in a pair of holding seals including one of the two holding seals, a second current collector held in a pair of holding seals including the other of the two holding seals, 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. At least one of the positive electrode and the negative electrode forming the space formed at the end portion is formed toward the outer peripheral side more than the other positive electrodes and the other negative electrodes.

5. The power storage device according to claim 1, wherein: The sealing portion comprises: a plurality of pairs of holding sealing materials, which respectively hold the collectors of the plurality of stacked bipolar electrodes from both sides of the stacking direction; a peripheral holding sealing portion, which holds the peripheral portion of the pair of holding sealing materials; and a spacer, which is interposed between two of the pairs of holding sealing materials adjacent to each other in the stacking direction of the bipolar electrodes. The space is formed by the spacer, two holding seals located on both sides of the spacer in the stacking direction, a first current collector held in a pair of holding seals including one of the two holding seals, a second current collector held in a pair of holding seals including the other of the two holding seals, 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. A member having electrolyte resistance is disposed at an end portion on an outer peripheral side of at least one of the positive electrode and the negative electrode forming the space formed at the endmost portion.

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