Electric energy storage module

Abstract

A power storage module (4) includes: a laminate including a plurality of electrodes laminated along a first direction; a sealing body including a first sealing portion (21) joined to the edge portion of the electrodes, forming an internal space (V) between adjacent electrodes and sealing the internal space (V); and an electrolytic solution including an alkaline solution accommodated in the internal space (V). The electrodes include a plurality of bipolar electrodes (14) and a negative terminal electrode (18). The power storage module (4) has a remaining space (VA, VB) independent of the internal space (V) on a path of an alkali creep phenomenon in which the electrolytic solution reaches the outside from the internal space (V) along the negative terminal electrode (18).

Description

Technical Field

[0001] The present disclosure relates to an electricity storage module. Background Art

[0002] As a conventional electricity storage module, a bipolar battery having a bipolar electrode with a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface of the electrode plate is known (see Patent Document 1). The bipolar battery includes a laminate in which a plurality of bipolar electrodes are laminated with a separator interposed therebetween. On a side surface of the laminate, a sealing body is provided to seal between the bipolar electrodes adjacent in the lamination direction, and an electrolytic solution is stored in an internal space formed between the bipolar electrodes.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-204386 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In such an electricity storage module as described above, a negative terminal electrode including an electrode plate having a negative electrode formed on an inner surface is disposed at one end in the lamination direction of the laminate. The edge portion of the electrode plate of the negative terminal electrode is also sealed by the sealing body, but when the electrolytic solution includes an alkaline solution, due to a so-called alkali creep phenomenon, the electrolytic solution sometimes flows along the surface of the electrode plate of the negative terminal electrode and penetrates between the sealing body and the electrode plate and leaks to the outer surface side of the electrode plate. If the electrolytic solution leaks to the outer surface side and spreads, for example, corrosion of a conductive plate disposed adjacent to the negative terminal electrode, short circuit between the negative terminal electrode and a restraint member, etc. may occur, which is not preferable from the viewpoint of reliability.

[0008] An object of the present disclosure is to provide an electricity storage module in which reliability is improved.

[0009] Solutions for Solving the Problems

[0010] The energy storage module of the present disclosure includes: a laminate including a plurality of electrodes laminated along a first direction; a sealing body including a first sealing portion joined to the edge portion of the electrode, forming an internal space between adjacent electrodes and sealing the internal space; and an electrolytic solution including an alkaline solution stored in the internal space. In the energy storage module, the electrode includes a plurality of bipolar electrodes and a negative terminal electrode. The bipolar electrode includes: an electrode plate having a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a negative electrode provided on the second surface. The negative terminal electrode includes: an electrode plate having a third surface and a fourth surface opposite to the third surface, and a negative electrode provided on the fourth surface. The negative terminal electrode is disposed at one end in the first direction of the laminate such that the fourth surface faces the first surface of the electrode plate of the bipolar electrode. There is a remaining space independent of the internal space on the path where the electrolytic solution reaches the outside of the energy storage module from the internal space along the negative terminal electrode.

[0011] In this energy storage module, there is a remaining space independent of the internal space on the path of the alkali creep phenomenon of the electrolytic solution. Thus, it is possible to suppress moisture contained in the outside air from entering the gap between the electrode plate of the negative terminal electrode, which is the starting point of the leakage of the electrolytic solution, and the first sealing portion. Therefore, the influence of the external humidity, which is an accelerating condition for the alkali creep phenomenon, is suppressed, and thus it is possible to suppress the electrolytic solution from leaking to the outside of the energy storage module.

[0012] Alternatively, in the energy storage module of the present disclosure, the laminate has a metal plate disposed outside the electrode plate of the negative terminal electrode in the first direction, and a remaining space having airtightness with respect to the outside of the energy storage module is formed by the first sealing portion, the electrode plate of the negative terminal electrode, and the metal plate. In this configuration, a remaining space formed by the first sealing portion, the negative terminal electrode, and the metal plate is also formed on the movement path of the electrolytic solution. Therefore, it is possible to suppress the electrolytic solution from leaking to the outside of the energy storage module.

[0013] The energy storage module of the present disclosure includes: a laminate including a plurality of electrodes laminated along a first direction; a metal plate disposed at one end of the laminate in the first direction; a sealing body including a first sealing portion joined to the electrode, forming an internal space between adjacent electrodes and sealing the internal space; and an electrolytic solution including an alkaline solution stored in the internal space. The electrode includes a plurality of bipolar electrodes and a negative terminal electrode. The sealing body includes a first resin portion disposed between the negative terminal electrode and the metal plate. One surface of the first resin portion in the first direction is joined to the negative terminal electrode, and the other surface of the first resin portion in the first direction is joined to the metal plate.

[0014] In the power storage module of the present disclosure, the sealing body includes a first resin portion disposed between the negative terminal electrode and the metal plate. One surface of the first resin portion in the first direction is joined to the negative terminal electrode, and the other surface of the first resin portion in the first direction is joined to the metal plate. Thus, a remaining space is formed by the first resin portion, the negative terminal electrode, and the metal plate. This remaining space is located on the movement path of the electrolyte formed by the alkali creep phenomenon. Accordingly, it is possible to suppress moisture contained in the external air from entering the gap between the electrode plate of the negative terminal electrode, which is the starting point of electrolyte leakage, and the first sealing portion. Therefore, the influence of the external humidity, which is an accelerating condition for the alkali creep phenomenon, is suppressed, and thus it is possible to suppress the electrolyte from leaking to the outside of the power storage module.

[0015] Alternatively, in the power storage module of the present disclosure, the bipolar electrode includes: an electrode plate having a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a negative electrode provided on the second surface. The negative terminal electrode includes: an electrode plate having a third surface and a fourth surface opposite to the third surface, and a negative electrode provided on the fourth surface. The negative terminal electrode is disposed between the bipolar electrode and the metal plate at one end in the first direction of the laminate such that the fourth surface faces the first surface of the electrode plate of the bipolar electrode. The metal plate includes a fifth surface opposite to the third surface of the negative terminal electrode and a sixth surface opposite to the fifth surface, and is welded to the first resin portion at the peripheral portion of the fifth surface. In this configuration as well, a remaining space formed by the first resin portion, the negative terminal electrode, and the metal plate is formed on the movement path of the electrolyte. Therefore, it is possible to suppress the electrolyte from leaking to the outside of the power storage module.

[0016] Alternatively, in the power storage module of the present disclosure, the first sealing portion includes a first resin portion welded to the third surface of the negative terminal electrode. The metal plate includes a fifth surface opposite to the third surface of the negative terminal electrode and a sixth surface opposite to the fifth surface, and is welded to the first resin portion at the peripheral portion of the fifth surface. In this configuration as well, a remaining space formed by the first sealing portion, the negative terminal electrode, and the metal plate is formed on the movement path of the electrolyte. Therefore, it is possible to suppress the electrolyte from leaking to the outside of the power storage module.

[0017] Alternatively, in the power storage module of the present disclosure, a second sealing portion that is joined to the first sealing portion and the second resin portion so as to surround the plurality of first sealing portions and the second resin portion from the outside is further provided. The second sealing portion includes an overlapping portion that overlaps the metal plate and the second resin portion when viewed from the first direction, and is welded to the second resin portion at the overlapping portion. In this case, the internal space is reliably sealed by the second sealing portion. In addition, the deformation of the second resin portion is suppressed by the overlapping portion of the second sealing portion. As a result, the generation of a gap between the second resin portion and the sixth surface is suppressed. Accordingly, the leakage due to alkali creep is more reliably suppressed.

[0018] Alternatively, in the power storage module of the present disclosure, the metal plate includes: a welded portion, which is in a frame shape and is welded to the first resin portion; and a contacted portion, which is located on the third surface side closer to the negative terminal electrode than the welded portion inside the welded portion and contacts the third surface. In this case, the remaining space formed between the metal plate and the negative terminal electrode is restricted. Thereby, the influence of the humidity in the remaining space is suppressed.

[0019] Alternatively, in the power storage module of the present disclosure, the regions of the third surface, the fifth surface, and the sixth surface welded to the sealing body are roughened. According to this configuration, the bonding strength between the sealing body and the third surface, the fifth surface, and the sixth surface can be improved by the anchoring effect.

[0020] Alternatively, in the power storage module of the present disclosure, the metal plate is an electrode plate. In this case, there is no need to separately prepare a metal plate other than the electrode plate. Thereby, the above-described configuration can be achieved at low cost.

[0021] Advantages of the Invention

[0022] According to the present disclosure, a power storage module with improved reliability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic cross-sectional view showing an embodiment of a power storage device.

[0024] Figure 2 shows Figure 1 a schematic cross-sectional view of the internal structure of the power storage module shown.

[0025] Figure 3 is Figure 2 a partial enlarged view of

[0026] Figure 4 a partial enlarged cross-sectional view of a power storage module of a comparative example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Hereinafter, an embodiment of a power storage module will be described with reference to the drawings. In addition, in the description of the drawings, the same reference numerals are given to the same elements or corresponding elements to each other, and duplicate descriptions may be omitted sometimes.

[0028] Figure 1 is a schematic cross-sectional view showing an embodiment of a power storage device. Figure 1 The power storage device 1 shown is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes: a module laminate 2 including a plurality of stacked power storage modules 4, and a constraint member 3 that applies a constraint load to the module laminate 2 in its stacking direction.

[0029] The module laminate 2 includes a plurality (here, three) of power storage modules 4 and a plurality (here, four) of conductive plates 5. The power storage module 4 is a bipolar battery and has a rectangular shape when viewed in the stacking direction. The power storage module 4 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery, or an electric double layer capacitor. In the following description, a nickel-metal hydride secondary battery is exemplified.

[0030] The power storage modules 4 adjacent to each other in the stacking direction are electrically connected to each other via the conductive plates 5. The conductive plates 5 are respectively disposed between the power storage modules 4 adjacent to each other in the stacking direction and outside the power storage modules 4 located at the stacking ends. One conductive plate 5 disposed outside the power storage module 4 located at the stacking end is connected to the positive terminal 6. The other conductive plate 5 disposed outside the power storage module 4 located at the stacking end is connected to the negative terminal 7. The positive terminal 6 and the negative terminal 7 are led out, for example, from the edge portion of the conductive plate 5 in a direction intersecting the stacking direction. Charging and discharging of the power storage device 1 are performed through the positive terminal 6 and the negative terminal 7.

[0031] A plurality of flow paths 5a through which a refrigerant such as air flows are provided inside the conductive plate 5. The flow paths 5a extend, for example, in a direction intersecting (orthogonal to) the stacking direction and the lead-out directions of the positive terminal 6 and the negative terminal 7, respectively. In addition to having the function of a connection member for electrically connecting the power storage modules 4 to each other, the conductive plate 5 also has the function of a heat dissipation plate for dissipating the heat generated in the power storage module 4 by allowing the refrigerant to flow through these flow paths 5a. In addition, although in Figure 1 the example, when viewed in the stacking direction, the area of the conductive plate 5 is smaller than the area of the power storage module 4, from the viewpoint of improving the heat dissipation performance, the area of the conductive plate 5 may be the same as the area of the power storage module 4, or may be larger than the area of the power storage module 4.

[0032] The restraint member 3 includes a pair of end plates 8 sandwiching the module laminate 2 in the stacking direction, and fastening bolts 9 and nuts 10 for fastening the end plates 8 to each other. The end plates 8 are rectangular metal plates having an area that is one size larger than the areas of the power storage module 4 and the conductive plate 5 when viewed in the stacking direction. An electrically insulating film F is provided on the inner side surface (the surface on the module laminate 2 side) of the end plate 8. The end plate 8 and the conductive plate 5 are insulated by the film F.

[0033] At the edge portion of the end plate 8, insertion holes 8a are provided at positions outside the module laminate 2. The fastening bolt 9 passes through the insertion hole 8a of one end plate 8 toward the insertion hole 8a of the other end plate 8, and the nut 10 is screwed onto the top portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. Thus, the power storage module 4 and the conductive plate 5 are clamped by the end plates 8 to form the module laminate 2 into a unit, and a restraint load is applied to the module laminate 2 in the stacking direction.

[0034] Next, the configuration of the power storage module 4 will be described in detail. Figure 2 It shows Figure 1 a schematic cross-sectional view of the internal configuration of the power storage module shown. Figure 3 It is Figure 2 a partial enlarged view of. As Figure 2 , Figure 3 shown, the power storage module 4 includes an electrode laminate (laminate) 11 and a resin sealing body 12 that seals the electrode laminate 11. The electrode laminate 11 includes a plurality of electrodes (a plurality of bipolar electrodes 14, a single negative terminal electrode (electrode) 18, and a single positive terminal electrode 19) laminated along the lamination direction D (first direction) with a separator 13 interposed therebetween. Here, the lamination direction D of the electrode laminate 11 coincides with the lamination direction of the module laminate 2. The electrode laminate 11 has a side surface 11a extending in the lamination direction D.

[0035] The bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19 each include an electrode plate 15, and the electrode plate 15 has one surface 15a and the other surface 15b on the opposite side of the one surface 15a. One surface 15a of the bipolar electrode 14 is the first surface, and the other surface 15b of the bipolar electrode 14 is the second surface. One surface 15a of the negative terminal electrode 18 is the third surface, and the other surface 15b of the negative terminal electrode 18 is the fourth surface.

[0036] The bipolar electrode 14 includes an electrode plate 15, a positive electrode 16 provided on one surface 15a of the electrode plate 15, and a negative electrode 17 provided on the other surface 15b of the electrode plate 15. The positive electrode 16 is a positive electrode active material layer formed by applying a positive electrode active material to the electrode plate 15. The negative electrode 17 is a negative electrode active material layer formed by applying a negative electrode active material to the electrode plate 15. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent in the lamination direction D with a separator 13 interposed therebetween. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent in the lamination direction D with a separator 13 interposed therebetween.

[0037] The negative terminal electrode 18 includes an electrode plate 15 and a negative electrode 17 provided on the other surface 15b of the electrode plate 15. The negative terminal electrode 18 is disposed at one end in the stacking direction D such that its other surface 15b faces the inside (the center side in the stacking direction D) of the electrode laminate 11. The negative electrode 17 of the negative terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D with the separator 13 interposed therebetween. The positive terminal electrode 19 includes an electrode plate 15 and a positive electrode 16 provided on one surface 15a of the electrode plate 15. The positive terminal electrode 19 is disposed at the other end in the stacking direction D such that its one surface 15a faces the inside of the electrode laminate 11. The positive electrode 16 of the positive terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the stacking direction D with the separator 13 interposed therebetween.

[0038] One surface 15a of the electrode plate 15 of the negative terminal electrode 18 is a surface facing the outside of the electrode laminate 11. One surface 15a of the negative terminal electrode 18 is electrically connected to the conductive plate 5 via a metal plate 50 described later. Another conductive plate 5 adjacent to the power storage module 4 is in contact with the other surface 15b of the electrode plate 15 of the positive terminal electrode 19. The restraining load from the restraining member 3 is applied to the electrode laminate 11 from the negative terminal electrode 18 and the positive terminal electrode 19 via the conductive plate 5. That is, the conductive plate 5 is also a restraining member that applies a restraining load to the electrode laminate 11 along the stacking direction D.

[0039] The electrode plate 15 is made of a metal such as nickel or a nickel-plated steel sheet. As an example, the electrode plate 15 is a rectangular metal foil containing nickel. The edge portion 15c of the electrode plate 15 (the edge portions of the bipolar electrode 14, the negative terminal electrode 18, and the positive terminal electrode 19) has a rectangular frame shape and is an uncoated area where the positive electrode active material and the negative electrode active material are not coated. As the positive electrode active material constituting the positive electrode 16, nickel hydroxide can be cited, for example. As the negative electrode active material constituting the negative electrode 17, a hydrogen storage alloy can be cited, for example. In the present embodiment, the formation region of the negative electrode 17 on the other surface 15b of the electrode plate 15 is one size larger than the formation region of the positive electrode 16 on one surface 15a of the electrode plate 15.

[0040] The separator 13 is formed in a sheet shape, for example. As the separator 13, a porous membrane including a polyolefin resin such as polyethylene (PE) or polypropylene (PP), a woven fabric or a non-woven fabric including polypropylene, methylcellulose, etc. can be exemplified. The separator 13 may also be a separator reinforced with a vinylidene fluoride resin compound. In addition, the separator 13 is not limited to a sheet shape, and a bag-shaped separator may also be used.

[0041] The sealing body 12 is integrally formed in a rectangular cylindrical shape by an insulating resin, for example. The sealing body 12 is disposed on the side surface 11a of the electrode laminate 11 so as to surround the edge portion 15c. The sealing body 12 holds the edge portion 15c on the side surface 11a. The sealing body 12 has: a plurality of first sealing portions 21, which are welded to the edge portion 15c; and a single second sealing portion 22, which is joined to the first sealing portion 21 so as to surround the first sealing portion 21 from the outside along the side surface 11a.

[0042] The first sealing portion 21 is in a rectangular ring shape when viewed in the stacking direction D and is continuously provided on the entire circumference of the edge portion 15c. The first sealing portion 21 is welded to one surface 15a of the electrode plate 15 and is hermetically joined. The first sealing portion 21 is welded by ultrasonic waves or heat, for example. The first sealing portion 21 is a film having a predetermined thickness (the length in the stacking direction D). The end surface of the electrode plate 15 is exposed from the first sealing portion 21. A part of the inside of the first sealing portion 21 is located between the edge portions 15c of the electrode plates 15 adjacent to each other in the stacking direction D, and a part of the outside extends outward from the electrode plate 15. The outside part of the first sealing portion 21 is held by the second sealing portion 22. The first sealing portions 21 adjacent to each other along the stacking direction D are separated from each other. The first sealing portion 21 includes a first resin portion 21A welded to one surface 15a of the negative terminal electrode 18. Here, one of the first sealing portions 21 is the first resin portion 21A. In addition, it is also possible that the first sealing portion 21 is also welded to the other surface 15b side of the electrode plate 15 of the positive terminal electrode 19.

[0043] The second sealing portion 22 is disposed outside the electrode laminate 11 and the first sealing portion 21 and constitutes the outer wall (box body) of the power storage module 4. The second sealing portion 22 is formed by injection molding of resin, for example, and extends along the entire length of the electrode laminate 11 in the stacking direction D. The second sealing portion 22 is in a cylindrical (ring-shaped) form extending with the stacking direction D as the axis. The second sealing portion 22 is welded (joined) to the outer surface of the first sealing portion 21 by the heat during injection molding, for example.

[0044] The second sealing portion 22 and the first sealing portion 21 together seal between the bipolar electrodes 14 adjacent to each other in the stacking direction D, between the negative terminal electrode 18 and the bipolar electrode 14 adjacent to each other in the stacking direction D, and between the positive terminal electrode 19 and the bipolar electrode 14 adjacent to each other in the stacking direction D, respectively. Thereby, internally spaces V hermetically separated are respectively formed between the bipolar electrodes 14, between the negative terminal electrode 18 and the bipolar electrode 14, and between the positive terminal electrode 19 and the bipolar electrode 14. That is, the first sealing portion 21 and the second sealing portion 22 are used to form the internal space V between adjacent electrodes and seal the internal space V. An electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution is stored in the internal space V, for example. The electrolytic solution is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

[0045] Here, the power storage module 4 includes a metal plate 50 and a second resin portion 51. The metal plate 50 is provided at one end (the end on the negative terminal electrode 18 side) in the stacking direction D of the electrode laminate 11. The metal plate 50 includes one surface 50a and the other surface 50b opposite to the one surface 50a. One surface 50a of the metal plate 50 faces one surface 15a of the electrode plate 15 of the negative terminal electrode 18. The other surface 50b of the metal plate 50 is in contact with the conductive plate 5. The metal plate 50 is stacked together with the electrodes in the stacking direction D. Thereby, the negative terminal electrode 18 is arranged between the metal plate 50 and the bipolar electrode 14 in the stacking direction D. In other words, in the power storage module 4, the metal plate 50 is provided on the outer side of the negative terminal electrode 18. One surface 50a of the metal plate 50 is the fifth surface, and the other surface 50b of the metal plate 50 is the sixth surface.

[0046] The metal plate 50 is welded to the first resin portion 21A and contacts one surface 15a of the negative terminal electrode 18. More specifically, the metal plate 50 includes: a welded portion 52 which is rectangular ring-shaped, disposed on the first resin portion 21A and one surface 15a, and welded to the first resin portion 21A; and a contacted portion 53 which is rectangular-shaped, located inside the welded portion 52 on the side closer to one surface 15a of the negative terminal electrode 18 than the welded portion 52 (recessed toward one surface 15a of the negative terminal electrode 18 from the welded portion 52), and contacts one surface 15a. The welded portion 52 and the contacted portion 53 are continuous with each other. A remaining space VA equivalent to the thickness of the first resin portion 21A (length along the stacking direction D) can be formed between the metal plate 50 and the negative terminal electrode 18 (between one surface 50a of the metal plate 50 and one surface 15a of the electrode plate 15), but since the metal plate 50 is recessed toward the negative terminal electrode 18 at the contacted portion 53, this remaining space VA is restricted to be narrow. In addition, the metal plate 50 can be made of any metal, but as an example, it can be set as the same metal plate as the electrode plate 15. That is, as an example, the metal plate 50 is the electrode plate 15. In this case, the metal plate 50 is a metal foil without an active material layer formed thereon (uncoated foil).

[0047] When viewed from the stacking direction D, the second resin portion 51 has substantially the same shape as the first resin portion 21A. That is, the second resin portion 51 is rectangular ring-shaped and is a film with a prescribed thickness. The second resin portion 51 is disposed to extend from the peripheral portion of the other surface 50b of the metal plate 50 to the first resin portion 21A. The second resin portion 51 is welded to the other surface 50b and the first resin portion 21A. The second sealing portion 22 is joined to the first sealing portion 21 and the second resin portion 51 so as to surround the plurality of first sealing portions 21 and the second resin portion 51 from the outside. The second sealing portion 22 includes an overlapping portion 22A which overlaps with the metal plate 50 and the second resin portion 51 when viewed from the stacking direction D, and is welded to the second resin portion 51 at the overlapping portion 22A.

[0048] The first sealing portion 21 (the first resin portion 21A), the second sealing portion 22, and the second resin portion 51 are, for example, insulating resins and can be made of polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), or the like.

[0049] In addition, regions that are fused to the first resin portion 21A or the second resin portion 51 are formed on one surface 15a of the electrode plate 15, one surface 50a and the other surface 50b of the metal plate 50. Specifically, when viewed in the stacking direction D, a region A1 in one surface 15a of the electrode plate 15 that overlaps with the first resin portion 21A, and a region A2 in one surface 50a of the metal plate 50 that overlaps with the first resin portion 21A are regions fused to the first resin portion 21A. Further, when viewed in the stacking direction D, a region A3 in the other surface 50b of the metal plate 50 that overlaps with the second resin portion 51 is a region fused to the second resin portion 51. The regions A1 to A3 are rectangular rings. At least these regions A1 to A3 are roughened. Here, the entire one surface 15a of the electrode plate 15, one surface 50a and the other surface 50b of the metal plate 50 are roughened.

[0050] One surface 15a of the electrode plate 15, one surface 50a and the other surface 50b of the metal plate 50 are roughened, for example, by forming a plurality of protrusions through electrolytic plating treatment. Thereby, in the bonding interfaces of one surface 15a of the electrode plate 15, one surface 50a and the other surface 50b of the metal plate 50 with the first resin portion 21A or the second resin portion 51, the molten first resin portion 21A or the second resin portion 51 enters the recesses formed by the roughening, exerting an anchoring effect. Thereby, the bonding force between each other can be improved. The protrusions formed during roughening have, for example, a shape in which the tip becomes thicker from the base end side to the tip end side. Thereby, the cross-sectional shape between adjacent protrusions is an undercut shape, and it is easy to generate an anchoring effect.

[0051] Here, the power storage module 4 may further include a hydrophobic member 60. The hydrophobic member 60 can be disposed in regions that are not used for welding on one surface 15a and the other surface 15b of the electrode plate 15, one surface 50a and the other surface 50b of the metal plate 50. Here, the hydrophobic member 60 is disposed in a region A4 on the other surface 15b of the negative terminal electrode 18 that faces the first sealing portion 21, a region A5 on one surface 50a of the metal plate 50 that extends from the region A2 fused to the first resin portion 21A toward the inside of the one surface 50a, and a region A6 on the other surface 50b of the metal plate 50 that extends from the region A3 fused to the second resin portion 51 toward the inside of the other surface 50b. However, the hydrophobic member 60 only needs to be disposed in at least one of these regions A4 to A6. The region A4 faces the first sealing portion 21 of the bipolar electrode 14 adjacent to the negative terminal electrode 18. The region A5 is a region facing the remaining space VA. The region A6 is a region facing the outside of the power storage module 4.

[0052] The hydrophobic member 60 is formed in a film shape as an example. The hydrophobic member 60 can be formed by coating a fluorine-based resin material (for example, "OS-90HF" manufactured by Harves Co., Ltd.), fluororubber, a polymer having fluorine-based / methyl-based functional groups, or the like.

[0053] In addition, the power storage module 4 may further include a liquid absorption member 31. The liquid absorption member 31 is disposed on the other surface 50b of the metal plate 50. The liquid absorption member 31 is formed in a sheet shape from, for example, non-woven fabric. Examples of the material constituting the non-woven fabric include polyolefin. In order to improve water absorption, the non-woven fabric may be subjected to plasma treatment. The thickness (length in the stacking direction D) of the liquid absorption member 31 is, for example, on the order of several hundred μm. The liquid absorption member 31 is, for example, in a rectangular ring shape when viewed from the stacking direction D and surrounds the conductive plate 5.

[0054] Next, an example of a manufacturing method of the power storage device 1 will be described. In this method, first, the above-described power storage module 4 is manufactured. The manufacturing method of the power storage module 4 includes a primary molding process, a stacking process, a secondary molding process, and an injection process. In the primary molding process, a predetermined number of bipolar electrodes 14, a negative terminal electrode 18, and a positive terminal electrode 19 are prepared, and the first sealing portion 21 is welded to one surface 15a of the edge portion 15c of each electrode plate 15. In addition, a metal plate 50 is prepared, and the second resin portion 51 is welded to the other surface 50b thereof.

[0055] In the stacking process, the bipolar electrodes 14, the negative terminal electrode 18, and the positive terminal electrode 19 are stacked with the separator 13 interposed therebetween so that the first sealing portion 21 is disposed between the edge portions 15c of the electrode plates 15, thereby forming an electrode laminate 11. In addition, the metal plate 50 is disposed at one end of the electrode laminate 11 so that the second resin portion 51 is disposed on the first resin portion 21A. In the secondary molding process, after the electrode laminate 11 and the metal plate 50 are disposed in a mold (not shown) for injection molding, molten resin is injected into the mold to form the second sealing portion 22 so as to surround the first sealing portion 21 and the second resin portion 51. Thus, a sealing body 12 is formed on the side surface 11a of the electrode laminate 11. In the injection process, after the secondary molding process, an electrolytic solution is injected into the internal space V between the bipolar electrodes 14, 14. Thus, the power storage module 4 is obtained.

[0056] Next, the operation / effect of the power storage module 4 will be described. Figure 4 It is a partially enlarged cross-sectional view of a power storage module of a comparative example. In Figure 4In the example shown, the metal plate 50 is not provided. Therefore, for example, when a load is applied to the electrode plate 15 of the negative terminal electrode 18 as the internal pressure rises, the first resin portion 21A welded to the electrode plate 15 may be deformed. In this case, a gap may be generated between the first resin portion 21A and the electrode plate 15, and leakage of the electrolyte L may occur through this gap.

[0057] In the power storage module, due to the so-called alkali creep phenomenon, the electrolyte L sometimes flows along the electrode plate 15 of the negative terminal electrode 18 and leaks out to the side of one surface 15a of the electrode plate 15 through the gap between the first resin portion 21A and the electrode plate 15. In Figure 4 this, the movement path of the electrolyte L in the alkali creep phenomenon is shown by an arrow A. This alkali creep phenomenon may occur during charging, discharging, and no-load of the power storage device due to electrochemical factors and fluid phenomena. The alkali creep phenomenon occurs because there are respectively a negative electrode potential, moisture, and a channel for the electrolyte L.

[0058] In response to this, in the power storage module 4, an internal space V for storing the electrolyte is formed by the first sealing portion 21 between the electrodes of the electrode laminate 11. In addition, at one end of the electrode laminate 11, the negative terminal electrode 18 among the plurality of electrodes is arranged such that the other surface 15b of the electrode plate 15 faces the one surface 15a of the electrode plate 15 of the bipolar electrode 14. The first resin portion 21A, which is the first sealing portion 21, is welded to the one surface 15a of the negative terminal electrode 18 facing the outside of the electrode laminate 11. On the other hand, a metal plate 50 is provided at one end of the electrode laminate 11. As a result, the negative terminal electrode 18 is arranged between the bipolar electrode 14 among the electrodes and the metal plate 50. That is, the metal plate 50 is provided outside the negative terminal electrode 18. Further, the metal plate 50 is welded to the first resin portion 21A welded to the one surface 15a of the negative terminal electrode 18 at the peripheral portion of the one surface 50a of the metal plate 50 facing the one surface 15a of the negative terminal electrode 18.

[0059] By adopting such a configuration, the following effects can be obtained. That is, as the first effect, since the metal plate 50 having a higher rigidity than the first resin portion 21A is welded to the first resin portion 21A on one surface 15a of the negative terminal electrode 18, deformation of the first resin portion 21A that may cause the first resin portion 21A to be peeled off from one surface 15a of the negative terminal electrode 18 is suppressed. In addition, as the second effect, since the metal plate 50 is also provided outside the negative terminal electrode 18, intrusion of moisture from the outside into the internal space V is suppressed. Moreover, as the third effect, at least two-stage seals are formed on the path leading from the negative terminal electrode 18 to the outside of the power storage module, including the welded portion between one surface 15a of the negative terminal electrode 18 and the first resin portion 21A and the welded portion between one surface 50a of the metal plate 50 and the first resin portion 21A.

[0060] Through the first effect, a gap that may become a leakage path of the electrolyte due to alkali creep is suppressed from being generated between the first resin portion 21A and one surface 15a of the negative terminal electrode 18. In addition, through the second effect, the influence of the external humidity, which is an accelerating condition for alkali creep, is suppressed. Moreover, through the third effect, the leakage rate is reduced by the multi-stage seal. According to this power storage module 4, these effects can be obtained in combination, and as a result, leakage due to alkali creep is reliably suppressed, and the reliability is improved.

[0061] In addition, the power storage module 4 further includes a second resin portion 51, which is arranged to extend from the peripheral portion of the other surface 50b of the metal plate 50 to the first resin portion 21A and is welded to the other surface 50b and the first resin portion 21A. And the region A3 of the other surface 50b where the second resin portion 51 is welded is roughened. Therefore, on the path leading from the negative terminal electrode 18 to the outside, a seal is also formed by the welded portion (region A3) between the other surface 50b of the metal plate 50 and the second resin portion 51. As a result, the leakage rate is reliably reduced by more stages (three stages) of seals, and leakage due to alkali creep is more reliably suppressed.

[0062] In addition, the power storage module 4 further includes a second seal portion 22, which is joined to the first seal portion 21 and the second resin portion 51 so as to surround the plurality of first seal portions 21 and the second resin portion 51 from the outside. The second seal portion 22 includes an overlapping portion 22A that overlaps with the metal plate 50 and the second resin portion 51 when viewed from the stacking direction D, and the overlapping portion 22A is welded to the second resin portion 51. Therefore, the internal space V is reliably sealed by the second seal portion 22. In addition, deformation of the second resin portion 51 is suppressed by the overlapping portion 22A of the second seal portion 22, and as a result, a gap is suppressed from being generated between the second resin portion 51 and the other surface 50b of the metal plate 50. Thereby, leakage due to alkali creep is more reliably suppressed.

[0063] In addition, in the power storage module 4, the metal plate 50 includes: a welded portion 52, which is annular and welded to the first resin portion 21A; and a contacted portion 53, which is located on the inner side of the welded portion 52 and on the side of one surface 15a closer to the negative terminal electrode 18 than the welded portion 52, and contacts the one surface 15a. Therefore, the remaining space VA formed between the metal plate 50 and the negative terminal electrode 18 is restricted. Thereby, the influence of the humidity in the remaining space VA is suppressed.

[0064] In addition, in the power storage module 4, the metal plate 50 is the electrode plate 15. Therefore, there is no need to separately prepare the metal plate 50 in addition to the electrode plate 15. Thereby, the above-described configuration can be achieved at low cost.

[0065] In addition, in the power storage module 4, a hydrophobic member 60 is provided in a region A4 on the other surface 15b of the negative terminal electrode 18 that faces the first sealing portion 21, and in a region A5 on one surface 50a of the metal plate 50 that extends from a region A2 welded to the first resin portion 21A toward the inside of the one surface 50a. By providing the hydrophobic member 60 in the region A4, leakage of the electrolyte from the internal space V can be suppressed. In addition, by providing the hydrophobic member 60 in the region A5, leakage from the remaining space VA to the outside and intrusion of moisture from the outside into the remaining space VA are suppressed.

[0066] Moreover, in the power storage module 4, a hydrophobic member 60 is provided in a region A6 on the other surface 50b of the metal plate 50 that extends from a region A3 where the second resin portion 51 is welded toward the inside of the other surface 50b. Thereby, intrusion of moisture from the outside into the remaining space VA is reliably suppressed.

[0067] The above-described embodiment has been described with respect to one embodiment of the power storage module of the present disclosure. Therefore, the power storage module of the present disclosure is not limited to the above-described power storage module 4 and can be arbitrarily changed.

[0068] For example, in the power storage module 4, a sealant can be provided instead of the hydrophobic member 60. That is, a sealant can be provided in at least one of the regions A4, A5, and A6. The sealant is, for example, a cured product of a liquid sealant. In this case, formation of the sealant is easy. In addition, the liquid sealant is, for example, a polyolefin resin material such as polypropylene (PP), and an adhesive (tar pitch) mainly composed of blown asphalt. The tar pitch is, for example, obtained by dissolving blown asphalt and polybutene in toluene. Specifically, the sealant can be formed by applying a liquid sealant to at least one of the regions A4, A5, and A6 and curing the liquid sealant. When a sealant is provided instead of the hydrophobic member 60, the same effects as those of the hydrophobic member 60 can also be achieved.

[0069] Moreover, in the power storage module 4, both the hydrophobic member 60 and the seal member can be provided. That is, the hydrophobic member 60 can be provided in a part of the regions A4, A5, and A6, and the seal member can be provided in the remaining part. In this way, in the power storage module 4, the hydrophobic member 60 and the seal member can be used separately according to the characteristics required for each region or the state of each region.

[0070] Next, referring again to Figure 2 and Figure 3 , the remaining space of the power storage module 4 will be described in more detail. As Figure 2 and Figure 3 show, the power storage module 4 has a remaining space VA independent of the internal space V. The remaining space VA does not contain electrolyte during manufacturing. The remaining space VA is airtight with respect to the outside. The remaining space VA is formed by the metal plate 50, the electrode plate 15 of the negative terminal electrode 18, and the first resin portion 21A. One surface in the stacking direction D (the first direction) of the first resin portion 21A is joined to the electrode plate 15 of the negative terminal electrode 18, and the other surface in the stacking direction D of the first resin portion 21A is joined to one surface 50a of the metal plate 50. When viewed from the stacking direction D, the remaining space VA is formed so as to surround the periphery of the contacted portion 53. When viewed from a cross-section along the stacking direction D, the remaining space VA has a substantially triangular shape whose height (dimension along the stacking direction D) decreases as it goes from the first resin portion 21A side to the contacted portion 53 side. In addition, the power storage module 4 has a remaining space VB independent of the internal space V and the remaining space VA. In addition, the remaining space VB also does not contain electrolyte during manufacturing. The remaining space VB is formed by the electrode plate 15 of the negative terminal electrode 18, the first sealing portion 21 (the first resin portion 21A), and the second sealing portion 22. The remaining space VB is formed so as to surround the outside of the edge portion of the electrode plate 15 of the negative terminal electrode 18 joined by the first resin portion 21A. When viewed from a cross-section along the stacking direction D, the remaining space VB has a substantially rectangular shape.

[0071] Both the remaining space VA and the remaining space VB are provided on the moving path of the electrolyte formed by the alkali creep phenomenon from the internal space V along the negative terminal electrode 18 to the outside of the power storage module 4. As shown by the arrow B in Figure 3 , when the alkali creep phenomenon occurs in the power storage module 4, the assumed moving path of the electrolyte is a path including the gap between the first sealing portion 21 and the electrode plate 15 of the negative terminal electrode 18, the remaining space VB, the gap between the electrode plate 15 of the negative terminal electrode 18 and the first resin portion 21A, the remaining space VA, and the gap between the metal plate 50 and the second resin portion 51.

[0072] As described above, the power storage module 4 is formed by Figure 3On the movement path of the electrolyte formed by the alkali creep phenomenon shown by arrow B, there is a remaining space VB where the electrolyte was not contained during manufacturing. Thus, since there is the remaining space VB on the movement path of the electrolyte, it is possible to suppress moisture contained in the external air from entering the gap between the negative terminal electrode 18, which is the starting point of electrolyte leakage, and the electrode plate 15. As a result, the influence of the external humidity, which is an accelerating condition for the alkali creep phenomenon, is suppressed, so that electrolyte leakage to the outside of the power storage module 4 is suppressed, and the reliability of the power storage module 4 is improved.

[0073] In addition, the electrode laminate 11 has a metal plate 50 disposed outside the electrode plate 15 of the negative terminal electrode 18 in the first direction. A remaining space VA having airtightness with respect to the outside is formed by the first resin portion 21A, the electrode plate 15 of the negative terminal electrode 18, and the metal plate 50. Thus, since there is also the remaining space VA on the movement path of the electrolyte formed by the alkali creep phenomenon, it is possible to more reliably suppress moisture contained in the external air from entering the gap between the negative terminal electrode 18, which is the starting point of electrolyte leakage, and the electrode plate 15. As a result, electrolyte leakage to the outside of the power storage module 4 is suppressed, and the reliability of the power storage module 4 is further improved.

[0074] In addition, in the above-described embodiment, an example in which the electrode laminate 11 of the power storage module 4 has the metal plate 50 outside the negative terminal electrode 18 has been described. However, the electrode laminate 11 may not have the metal plate 50. In this case, the power storage module 4 may not have the remaining space VA.

[0075] In addition, in the above-described embodiment, an example in which the power storage module 4 has two remaining spaces VA and VB has been described. However, the power storage module 4 only needs to have at least one remaining space on the movement path of the electrolyte when the alkali creep phenomenon occurs, and the number thereof is not particularly limited.

[0076] In addition, in the above-described embodiment, an example in which the remaining spaces VA are formed by the metal plate 50, the electrode plate 15 of the negative terminal electrode 18, and the first resin portion 21A, and the remaining space VB is formed by the electrode plate 15 of the negative terminal electrode 18, the first sealing portion 21 (the first resin portion 21A), and the second sealing portion 22 has been described. However, the constituent elements of the power storage module 4 that form the remaining space are not particularly limited.

[0077] Explanation of Reference Signs

[0078] 4…Power storage module, 11…Electrode laminate (laminate), 14…Bipolar electrode, 15…Electrode plate, 15a, 50a…One surface, 15b, 50b…The other surface, 17…Negative electrode, 18…Negative terminal electrode, 21…First sealing portion, 21A…First resin portion, 22…Second sealing portion, 22A…Overlapping portion, 50…Metal plate, 51…Second resin portion, 52…Welded portion, 53…Contact portion, 60…Hydrophobic member, A1 to A6…Regions, VA, VB…Remaining space.

Claims

1. A power storage module, comprising: A laminate including a plurality of electrodes laminated along a first direction; A sealing body including a plurality of first sealing portions respectively welded to the edges of the plurality of electrodes, forming an internal space between adjacent ones of the electrodes and sealing the internal space; and An electrolytic solution including an alkaline solution accommodated in the internal space, The power storage module is characterized in that The electrodes include a plurality of bipolar electrodes and a negative terminal electrode, The bipolar electrode includes: an electrode plate having a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a negative electrode provided on the second surface, The negative terminal electrode includes: an electrode plate having a third surface and a fourth surface opposite to the third surface, and a negative electrode provided on the fourth surface, and the negative terminal electrode is arranged at one end of the laminate in the first direction with the fourth surface facing the first surface of the electrode plate of the bipolar electrode, On a path where the electrolytic solution reaches the outside of the power storage module from the internal space along the negative terminal electrode, there is a remaining space independent of the internal space, The laminate has a metal plate arranged outside the electrode plate of the negative terminal electrode in the first direction, The first sealing portion includes a first resin portion welded to the third surface of the electrode plate of the negative terminal electrode, The metal plate includes a fifth surface opposite to the third surface of the electrode plate of the negative terminal electrode, The first resin portion is welded to the peripheral portion of the fifth surface of the metal plate, The remaining space is formed by the first resin portion, the third surface of the electrode plate of the negative terminal electrode, and the metal plate, and has airtightness with respect to the outside of the power storage module.

2. A power storage module, characterized in that, Comprising: A laminate including a plurality of electrodes laminated along a first direction; A metal plate provided at one end of the laminate in the first direction; A sealing body including a plurality of first sealing portions respectively welded to the plurality of electrodes, forming an internal space between adjacent ones of the electrodes and sealing the internal space; and An electrolytic solution including an alkaline solution accommodated in the internal space, The electrodes include a plurality of bipolar electrodes and a negative terminal electrode, The sealing body includes a first resin portion disposed between the negative terminal electrode and the metal plate, One surface of the first resin portion in the first direction is welded to the negative terminal electrode, The other surface of the first resin portion in the first direction is welded to the metal plate, A remaining space independent of the internal space is formed by the negative terminal electrode, the metal plate, and the first resin portion.

3. The power storage module according to claim 2, wherein The bipolar electrode includes: an electrode plate having a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a negative electrode provided on the second surface, The above-mentioned negative electrode terminal electrode includes: an electrode plate having a third surface and a fourth surface on the opposite side of the third surface, and a negative electrode provided on the fourth surface. The negative electrode terminal electrode is disposed between the bipolar electrode and the metal plate at one end in the first direction of the laminate in such a manner that the fourth surface faces the first surface of the electrode plate of the bipolar electrode. The metal plate includes a fifth surface opposite to the third surface of the negative electrode terminal electrode, and is welded to the first resin portion at the peripheral portion of the fifth surface.

4. The power storage module according to claim 1, wherein the metal plate further includes a sixth surface opposite to the fifth surface, and further includes a second resin portion, which is disposed to extend from the peripheral portion of the sixth surface to the first resin portion and is welded to the sixth surface and the first resin portion.

5. The power storage module according to claim 3, wherein the metal plate further includes a sixth surface opposite to the fifth surface, and further includes a second resin portion, which is disposed to extend from the peripheral portion of the sixth surface to the first resin portion and is welded to the sixth surface and the first resin portion.

6. The power storage module according to claim 4, wherein it further includes a second sealing portion, which is joined to the first sealing portion and the second resin portion in such a manner as to surround the plurality of first sealing portions and the second resin portion from the outside, the second sealing portion includes an overlapping portion that overlaps the metal plate and the second resin portion when viewed from the first direction, and is welded to the second resin portion at the overlapping portion.

7. The power storage module according to claim 5, wherein it further includes a second sealing portion, which is joined to the first sealing portion and the second resin portion in such a manner as to surround the plurality of first sealing portions and the second resin portion from the outside, the second sealing portion includes an overlapping portion that overlaps the metal plate and the second resin portion when viewed from the first direction, and is welded to the second resin portion at the overlapping portion.

8. The power storage module according to any one of claims 1, 3 to 7, wherein the metal plate includes: a welded portion, which is in a frame shape and is welded to the first resin portion; and a contacted portion, which is located inside the welded portion on the side closer to the third surface of the negative electrode terminal electrode than the welded portion and contacts the third surface.

9. The power storage module according to any one of claims 1, 3 to 7, wherein the regions where the third surface and the fifth surface are welded to the sealing body are roughened.

10. The power storage module according to any one of claims 1, 3 to 7, wherein the metal plate is the electrode plate.

11. The power storage module according to any one of claims 1 to 7, wherein the metal plate has a region facing the outside of the power storage module.

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