JP2020030951A - Power storage module - Google Patents

Abstract

To provide a power storage module capable of inhibiting an electrolyte from leaking due to an alkali creep phenomenon.SOLUTION: A power storage module 4 includes an electrode laminate 11 including a laminate of a plurality of bipolar electrodes 14, and a negative electrode termination electrode 18 disposed at one end in a laminating direction D of the laminate, a sealing body 12 that is provided so as to surround a side surface 11a of the electrode laminate 11, forms an internal space V between adjacent electrodes, and seals the internal space V, and an electrolytic solution L containing an alkaline solution housed in the internal space V, and the electrode laminate 11 has a surplus space S on a path of an alkali creep phenomenon of the alkali solution from the internal space V to the outside of the negative electrode termination electrode 18, and a hygroscopic member 31 is disposed in the surplus space S.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power storage module.

  BACKGROUND ART As a conventional power storage module, a bipolar battery including a bipolar electrode in which a positive electrode is formed on one surface of an electrode plate and a negative electrode is formed on the other surface is known (see Patent Document 1). A bipolar battery includes a laminate formed by laminating a plurality of bipolar electrodes with a separator interposed therebetween. A sealing body that seals between the bipolar electrodes adjacent to each other in the stacking direction is provided on a side surface of the stacked body, and the electrolyte is contained in an internal space formed between the bipolar electrodes.

JP 2011-204386 A

  In the above-described power storage module, the negative terminal electrode is disposed at one end in the stacking direction of the stack. The negative electrode termination electrode is provided with only the negative electrode on one side of the electrode plate, and is disposed at one end in the stacking direction such that the negative electrode faces the center in the stacking direction. The edge of the electrode plate of the negative terminal electrode is also sealed by a sealing body like other bipolar electrodes. However, when the electrolytic solution is composed of an alkaline solution, the electrolytic solution is transmitted along the surface of the electrode plate of the negative electrode terminal electrode by a so-called alkaline creep phenomenon, passes between the sealing body and the electrode plate, and faces the outer surface of the electrode plate. May ooze into the surface. When the electrolyte leaks to the outer surface side and diffuses, for example, corrosion of a conductive plate disposed adjacent to the negative electrode termination electrode or a short circuit between the negative electrode termination electrode and the restraining member may occur, thereby lowering reliability. Can be a factor.

  The present invention has been made to solve the above problem, and an object of the present invention is to provide a power storage module that can suppress oozing of an electrolytic solution due to an alkaline creep phenomenon.

  An energy storage module according to one aspect of the present invention includes an electrode stack including a stacked body of a plurality of bipolar electrodes, and a negative electrode termination electrode disposed at one end in the stacking direction of the stacked body, and an electrode stacked body. A sealing body that is provided so as to surround the side surface of the electrode, forms an internal space between adjacent electrodes and seals the internal space, and an electrolytic solution containing an alkaline solution contained in the internal space. The laminate has an extra space on the path of the alkali creep phenomenon of the alkaline solution from the internal space to the outside of the negative electrode termination electrode, and a moisture absorbing member is arranged in the extra space.

  The alkali creep phenomenon occurs due to the existence of the paths of the negative electrode potential, moisture, and the electrolytic solution, respectively, and progresses with the passage of time. On the other hand, in this power storage module, by arranging the moisture absorbing member in the surplus space located on the path of the alkali creep of the alkali solution, moisture, which is a requirement for occurrence of the alkali creep phenomenon, is removed from the surplus space. Thereby, the traveling path of the alkaline creep phenomenon from the internal space to the outside of the negative electrode termination electrode can be blocked in the surplus space. Therefore, in this power storage module, oozing of the electrolyte due to the alkali creep phenomenon can be suppressed.

  Further, the electrode laminate has a metal plate disposed outside in the laminating direction with respect to the electrode plate of the negative electrode terminal electrode, and the first electrode surrounded by the sealing body, the electrode plate of the negative electrode terminal electrode, and the metal plate. It may have an extra space, and the first moisture absorbing member may be arranged in the first extra space. In this case, by disposing the first moisture absorbing member in the first surplus space, moisture, which is a requirement for the occurrence of the alkali creep phenomenon, is removed from the first surplus space. Thereby, the traveling path of the alkaline creep phenomenon from the internal space to the outside of the negative electrode termination electrode can be blocked in the first surplus space. Further, by disposing a relatively rigid metal plate with respect to the electrode plate, the expansion of the gap between the sealing body and the electrode plate is suppressed, and the generation of a traveling path of the alkali creep phenomenon is suppressed. You. Further, intrusion of moisture from the outside into the internal space between the electrodes is also suppressed.

  The sealing body includes a first sealing portion coupled to an edge of the electrode plate of the bipolar electrode, an edge of the electrode plate of the negative electrode termination electrode, and an edge of the metal plate, and a first sealing portion. A second sealing portion provided so as to surround from the outside, and the electrode laminate has a first sealing portion coupled to an edge portion of the electrode plate of the negative terminal electrode, and a second sealing portion provided at an edge portion of the metal plate. It has a second surplus space surrounded by the coupled first sealing portion, the second sealing portion, and the metal plate, and the second excess space may be provided with a second moisture absorbing member. . In this case, the traveling path of the alkali creep phenomenon from the internal space to the outside of the negative electrode termination electrode can be blocked stepwise in the first surplus space and the second surplus space. Therefore, the seepage of the electrolyte solution due to the alkali creep phenomenon can be more reliably suppressed.

  The electrode laminate further includes a first sealing portion coupled to an edge of the electrode plate of the negative electrode, a first sealing portion coupled to an edge of the electrode plate of the bipolar electrode, and a second sealing portion. A third excess space surrounded by the portion and the electrode plate of the negative electrode termination electrode, and a third moisture absorbing member may be arranged in the third excess space. In this case, the traveling path of the alkali creep phenomenon from the internal space to the outside of the negative electrode termination electrode can be blocked stepwise in the first extra space, the second extra space, and the third extra space. Therefore, the seepage of the electrolyte solution due to the alkali creep phenomenon can be more reliably suppressed.

  The surplus space may be a space surrounded by the sealing body and the electrode plate of the negative electrode terminal electrode. In this case, even in the configuration in which the metal plate is not provided, the traveling path of the alkali creep phenomenon from the internal space to the outside of the negative electrode termination electrode can be blocked in the surplus space.

  The metal plate may be formed of the same member as the electrode plate of the negative terminal electrode. In this case, the cost of the power storage module can be reduced by using common components.

  According to this power storage module, oozing of the electrolyte solution due to the alkali creep phenomenon can be suppressed.

1 is a schematic cross-sectional view illustrating a power storage device including a power storage module according to an embodiment. FIG. 2 is a schematic sectional view illustrating an internal configuration of the power storage module illustrated in FIG. 1. FIG. 3 is an enlarged sectional view of a main part of FIG. 2. FIG. 5 is an enlarged cross-sectional view of a main part of a power storage module according to a comparative example. It is a principal part expanded sectional view of the electric storage module which concerns on a modification.

  Hereinafter, preferred embodiments of a power storage module according to one aspect of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a power storage device. The power storage device 1 shown in FIG. 1 is used as a battery of various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The power storage device 1 includes a module stack 2 including a plurality of stacked power storage modules 4 and a restraining member 3 that applies a restraining load to the module stack 2 in the stacking direction of the module stack 2.

  The module stack 2 includes a plurality of (here, three) power storage modules 4 and a plurality of (here, four) conductive plates 5. The power storage module 4 is a bipolar battery, and has a rectangular shape when viewed from the stacking direction. The power storage module 4 is, for example, a secondary battery such as a nickel hydrogen 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.

  The power storage modules 4 adjacent to each other in the stacking direction are electrically connected via the conductive plate 5. The conductive plates 5 are arranged between the power storage modules 4 adjacent to each other in the stacking direction and outside the power storage module 4 located at the stacking end. A positive electrode terminal 6 is connected to one conductive plate 5 arranged outside the power storage module 4 located at the lamination end. The negative electrode terminal 7 is connected to the other conductive plate 5 disposed outside the power storage module 4 located at the lamination end. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out, for example, from the edge of the conductive plate 5 in a direction crossing the laminating direction. The power storage device 1 is charged and discharged by the positive terminal 6 and the negative terminal 7.

  Inside the conductive plate 5, a plurality of flow paths 5a for circulating a refrigerant such as air are provided. The flow path 5a extends, for example, along a direction that intersects (orthogonally) the laminating direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7, respectively. The conductive plate 5 functions not only as a connecting member for electrically connecting the power storage modules 4 to each other, but also as a heat radiating plate for radiating heat generated in the power storage module 4 by flowing a refrigerant through these flow paths 5a. Has both functions. In the example of FIG. 1, the area of the conductive plate 5 as viewed from the stacking direction is smaller than the area of the power storage module 4, but from the viewpoint of improving heat dissipation, the area of the conductive plate 5 is 4 may be the same as the area of the power storage module 4.

  The restraining member 3 includes a pair of end plates 8 sandwiching the module stack 2 in the stacking direction, and a fastening bolt 9 and a nut 10 for fastening the end plates 8 to each other. The end plate 8 is a rectangular metal plate having an area slightly larger than the areas of the power storage module 4 and the conductive plate 5 when viewed from the stacking direction. A film F having an electrical insulation property is provided on a surface of the end plate 8 on the module laminate 2 side. The film F insulates between the end plate 8 and the conductive plate 5.

  At the edge of the end plate 8, an insertion hole 8 a is provided at a position outside the module laminate 2. The fastening bolt 9 is passed from the insertion hole 8a of the one end plate 8 toward the insertion hole 8a of the other end plate 8, and is provided at the tip of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. , Nut 10 are screwed. As a result, the power storage module 4 and the conductive plate 5 are sandwiched by the end plates 8 to form a unit as the module stack 2, and a constraint load is applied to the module stack 2 in the stacking direction.

  Next, the configuration of the power storage module 4 will be described in detail. FIG. 2 is a schematic sectional view showing the internal configuration of the power storage module shown in FIG. FIG. 3 is an enlarged sectional view of a main part of FIG. As shown in FIGS. 2 and 3, the power storage module 4 includes an electrode stack 11 and a resin sealing body 12 that seals the electrode stack 11. The electrode stack 11 includes a plurality of electrodes stacked along the stacking direction D of the power storage module 4 with the separator 13 interposed therebetween. These electrodes include a stacked body of a plurality of bipolar electrodes 14, a negative terminal electrode 18, and a positive terminal electrode 19.

  The bipolar electrode 14 includes an electrode plate 15 including one surface 15a and the other surface 15b opposite to the one surface 15a, a positive electrode 16 provided on one surface 15a, and a negative electrode 17 provided on the other surface 15b. ing. 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 stack 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to one side in the stacking direction D with the separator 13 interposed therebetween. In the electrode stack 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent to the other in the stacking direction D with the separator 13 interposed therebetween.

  The negative terminal electrode 18 has the electrode plate 15 and the negative electrode 17 provided on the other surface 15 b of the electrode plate 15. The negative electrode terminating electrode 18 is arranged at one end in the stacking direction D such that the other surface 15b faces the center of the electrode stack 11 in the stacking direction D. A metal plate 20, which will be described later, is further laminated on one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and is electrically connected to one conductive plate 5 (see FIG. 1) adjacent to the power storage module 4 via the metal plate 20. Connected. The negative electrode 17 provided on the other surface 15 b of the electrode plate 15 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D via the separator 13.

  The positive electrode termination electrode 19 has an electrode plate 15 and a positive electrode 16 provided on one surface 15 a of the electrode plate 15. The positive electrode termination electrode 19 is disposed at the other end in the stacking direction D such that the one surface 15a faces the center of the electrode stack 11 in the stacking direction D. The positive electrode 16 provided on one surface 15 a of the positive electrode termination electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the stacking direction D via the separator 13. The other surface 15b of the electrode plate 15 of the positive electrode termination electrode 19 forms the other outer surface in the stacking direction of the electrode stack 11, and is electrically connected to the other conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. It is connected.

  The electrode plate 15 is made of, for example, a metal such as nickel or a nickel-plated steel plate. As an example, the electrode plate 15 is a rectangular metal foil made of nickel. The edge 15c of the electrode plate 15 has a rectangular frame shape, and is an uncoated region where the positive electrode active material and the negative electrode active material are not coated. As a positive electrode active material constituting the positive electrode 16, for example, nickel hydroxide is given. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the formation region of the negative electrode 17 on the other surface 15 b of the electrode plate 15 is slightly larger than the formation region of the positive electrode 16 on the one surface 15 a of the electrode plate 15.

  The separator 13 is formed in a sheet shape, for example. Examples of the separator 13 include a porous film made of a polyolefin-based resin such as polyethylene (PE) and polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, methylcellulose, or the like. The separator 13 may be reinforced with a vinylidene fluoride resin compound. In addition, the separator 13 is not limited to a sheet shape, and may be a bag shape.

  The sealing body 12 is formed, for example, of an insulating resin into a rectangular tube as a whole. The sealing body 12 is provided on the side surface 11 a of the electrode stack 11 so as to surround the edge 15 c of the electrode plate 15. The sealing body 12 holds the edge 15c on the side surface 11a. The sealing body 12 surrounds the plurality of first sealing portions 21 coupled to the edge portion 15c of the electrode plate 15 and the first sealing portion 21 from the outside along the side surface 11a. And a second sealing portion 22 coupled to each of them. The first sealing portion 21 and the second sealing portion 22 are, for example, an insulating resin having alkali resistance. The constituent material of the first sealing portion 21 and the second sealing portion 22 includes, for example, polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

  The first sealing portion 21 is provided continuously over the entire circumference of the edge portion 15c on one surface 15a of the electrode plate 15, and has a rectangular ring shape when viewed from the laminating direction D. The first sealing portion 21 is welded to one surface 15a of the electrode plate 15 by, for example, ultrasonic waves or heat, and is air-tightly joined. The first sealing portion 21 is, for example, a film having a predetermined thickness in the stacking direction D. 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. The outside of the first sealing portion 21 projects beyond the edge of the electrode plate 15, and the tip portion is embedded in the second sealing portion 22. The first sealing portions 21 adjacent to each other along the stacking direction D may be separated from each other or may be in contact with each other. Further, the outer edge portions of the first sealing portion 21 may be connected to each other by, for example, hot plate welding.

  A region where the edge portion 15c and the first sealing portion 21 on the one surface 15a of the electrode plate 15 overlap is a coupling region K between the electrode plate 15 and the first sealing portion 21. In the coupling region K, the surface of the electrode plate 15 is roughened. The roughened region may be only the coupling region K, but in this embodiment, the entire one surface 15a of the electrode plate 15 is roughened. Roughening can be achieved by forming a plurality of protrusions by, for example, electrolytic plating. By forming a plurality of protrusions on one surface 15a, the resin in a molten state enters between the plurality of protrusions formed by roughening at the bonding interface with first sealing portion 21 on one surface 15a, and anchors are formed. The effect is exhibited. Thereby, the bonding strength between the electrode plate 15 and the first sealing portion 21 can be improved. The projection formed at the time of roughening has, for example, a shape that becomes tapered from the base end side to the tip end side. Thereby, the cross-sectional shape between the adjacent projections becomes an undercut shape, and the anchor effect can be enhanced.

  The second sealing portion 22 is provided outside the electrode stack 11 and the first sealing portion 21, and forms an outer wall (housing) of the power storage module 4. The second sealing portion 22 is formed, for example, by injection molding of a resin, and extends over the entire length of the electrode stack 11 along the stacking direction D. The second sealing portion 22 has a rectangular tubular shape (annular shape) extending in the stacking direction D as an axial direction. The second sealing portion 22 is welded to the outer surface of the first sealing portion 21 by, for example, heat during injection molding.

  The first sealing portion 21 and the second sealing portion 22 form an internal space V between adjacent electrodes and seal the internal space V. More specifically, the second sealing portion 22 is, together with the first sealing portion 21, between the bipolar electrodes 14 adjacent to each other along the stacking direction D, and the negative electrode termination electrodes 18 adjacent to each other along the stacking direction D. And the bipolar electrode 14 and between the positive electrode terminal electrode 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D. Thereby, air-tightly partitioned internal spaces V are formed between the adjacent bipolar electrodes 14, between the negative electrode termination electrode 18 and the bipolar electrode 14, and between the positive electrode termination electrode 19 and the bipolar electrode 14, respectively. ing. The internal space V contains an electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution. The electrolyte is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

  Next, the configuration around the negative electrode termination electrode 18 will be described in more detail. FIG. 3 is an enlarged view of a main part showing the internal configuration of power storage module 4.

  As shown in the figure, a metal plate 20 is further stacked outside the negative electrode termination electrode 18 in the stacking direction D in the electrode stack 11. The metal plate 20 is substantially the same member as the electrode plate 15, and is made of a metal such as nickel or a nickel-plated steel plate. As an example, the metal plate 20 is a rectangular metal foil made of nickel. One surface 20a and the other surface 20b of the metal plate 20 are uncoated regions where neither the positive electrode active material layer nor the negative electrode active material layer is coated. Due to the metal plate 20, the negative electrode terminal electrode 18 is arranged between the metal plate 20 and the bipolar electrode 14 along the stacking direction D.

  The other surface 20b side of the edge 20c of the metal plate 20 is provided on the edge 15c of the electrode plate 15 of the negative electrode termination electrode 18 with a first sealing portion 21 (hereinafter, referred to as a "first sealing portion 21A"). The central portion 20d of the metal plate 20 is depressed toward the negative electrode termination electrode 18 in accordance with the thickness of the first sealing portion 21A. The first sealing portion 21 (hereinafter referred to as the “first electrode portion 15”) is in contact with the one surface 20 a of the edge portion 20 c of the metal plate 20 in the same manner as the bipolar electrode 14 and the negative electrode terminal electrode 18. 1 sealing portion 21B "). The first sealing portion 21B is welded to one surface 20a of the metal plate 20 by, for example, ultrasonic waves or heat. The one surface 20a and the other surface 20b of the metal plate 20 may be roughened similarly to the one surface 15a of the electrode plate 15. The roughened region may be only the coupling region K between the metal plate 20 and the first sealing portions 21A and 21B, or may be the entire one surface 20a and the other surface 20b.

  In the electrode laminate 11, a surplus space S in which no electrolytic solution is stored is provided around the negative electrode terminal electrode 18. In the present embodiment, as shown in FIG. 3, a first surplus space S1, a second surplus space S2, and a third surplus space S3 are provided.

  The first surplus space S1 is a space surrounded by the first sealing portion 21A, the electrode plate 15 of the negative electrode terminal electrode 18, and the metal plate 20. Specifically, the first surplus space S1 is defined by the inner side surface 21Aa of the first sealing portion 21A, the one surface 15a of the electrode plate 15 of the negative terminal electrode 18, and the other surface 20b of the metal plate 20. I have.

  The second surplus space S2 is a space surrounded by the first sealing portion 21A, the first sealing portion 21B, the second sealing portion 22, and the metal plate 20. Specifically, the second surplus space S2 includes a first surface 21Ab of the first sealing portion 21A (a surface facing the stacking end side in the stacking direction D) and a second surface (the stacking direction D) of the first sealing portion 21B. Of the second sealing portion 22, and a side surface 20e of the metal plate 20.

  The third surplus space S3 includes a first sealing portion 21A, a first sealing portion 21 coupled to an edge 15c of the electrode plate 15 of the bipolar electrode 14, a second sealing portion 22, and a negative terminal electrode 18. Is a space surrounded by the electrode plate 15 of FIG. In detail, the third surplus space S3 includes the second surface (the surface facing the center side in the stacking direction D) 21Ac of the first sealing portion 21A and the first surface (the surface in the stacking direction D) of the first sealing portion 21. A surface 21a facing the lamination end), an inner surface 22a of the second sealing portion 22, and a side surface 15d of the electrode plate 15 are defined.

  In each of the first surplus space S1, the second surplus space S2, and the third surplus space S3, a moisture absorbing member 31 that absorbs moisture in the space is disposed. As the moisture absorbing member 31, for example, a sheet type silica gel, a coating-type desiccant using an alkaline earth metal oxide powder, or the like can be used. The first moisture absorbing member 31 </ b> A in the first surplus space S <b> 1 is disposed, for example, on the entire surface of the one surface 15 a of the electrode plate 15 of the negative terminal electrode 18, which defines the first surplus space S <b> 1. The second moisture absorbing member 31B in the second surplus space S2 is disposed, for example, on the entire portion of the first surface 21Ab of the first sealing portion 21A that defines the second surplus space S2. The third moisture absorbing member 31 </ b> C in the third surplus space S <b> 3 is disposed, for example, on the entire portion of the first surface 21 a of the first sealing portion 21 that defines the third surplus space S <b> 3.

  Next, the operation and effect of the power storage module 4 will be described. FIG. 4 is an enlarged cross-sectional view of a main part of a power storage module according to a comparative example. As shown in the figure, the power storage module 100 according to the comparative example is different from the embodiment in that the electrode laminate 11 does not include the metal plate 20 and the moisture absorbing member 31 is not disposed in the surplus space S. This is different from the power storage module 4.

  In the power storage module 100, the electrolyte present in the internal space V is transmitted along the surface of the electrode plate 15 of the negative electrode terminal electrode 18 due to the so-called alkali creep phenomenon, and between the electrode plate 15 and the first sealing portion 21 in the coupling region K. May ooze out to the one surface 15a side of the electrode plate 15 through the gap. In FIG. 4, the traveling path of the electrolytic solution L in the alkaline creep phenomenon is indicated by an arrow A. The alkaline creep phenomenon may occur at the time of charging and discharging of the power storage device and at the time of no load due to electrochemical factors and fluid phenomena. The alkali creep phenomenon occurs due to the existence of the paths of the negative electrode potential, moisture, and the electrolyte solution L, respectively, and progresses with the passage of time.

  The alkali creep phenomenon can also occur when one surface 15a of the electrode plate 15 in the bonding region K is roughened. Even when the bonding strength between the electrode plate 15 and the first sealing portion is enhanced by the roughening, the electrolytic solution L is provided with the plurality of protrusions formed on the one surface 15a of the electrode plate 15 and the first sealing portion. The resin may be peeled off from the electrode plate 15 when passing between the resin constituting the portion 21. When the internal pressure increases due to the hydrogen gas generated by the self-discharge reaction of the negative electrode active material (hydrogen storage alloy), and when the stress generated by the internal pressure exceeds the breaking stress of the resin, the resin breaks and the first It is also conceivable that the sealing portion 21 swells.

  On the other hand, in the power storage module 4, the metal plate 20 is disposed on the electrode plate 15 of the negative terminal electrode 18. By disposing the relatively high rigidity metal plate 20 with respect to the electrode plate 15, the expansion of the gap between the first sealing portion 21 </ b> A and the electrode plate 15 is suppressed, and the progress path of the alkali creep phenomenon is suppressed. Generation is suppressed. Further, intrusion of moisture from the outside into the internal space V between the electrodes is also suppressed. Furthermore, in the power storage module 4, the first moisture absorbing member 31A is disposed in the first surplus space S1 surrounded by the first sealing portion 21A, the electrode plate 15 of the negative terminal electrode 18, and the metal plate 20. By disposing the first moisture absorbing member 31A in the first surplus space S1, moisture, which is a requirement for the occurrence of the alkali creep phenomenon, is removed from the first surplus space S1. Thus, the traveling path of the alkaline creep phenomenon from the internal space V to the outside of the negative electrode termination electrode 18 can be blocked in the first surplus space S1. Therefore, in the power storage module 4, oozing of the electrolytic solution L due to the alkali creep phenomenon can be suppressed.

  In the power storage module 4, the second moisture absorbing member 31 </ b> B is provided in the second excess space S <b> 2 surrounded by the first sealing portion 21 </ b> A, the first sealing portion 21 </ b> B, the second sealing portion 22, and the metal plate 20. Is arranged. Thereby, the traveling path of the alkali creep phenomenon from the internal space V to the outside of the negative electrode termination electrode 18 can be blocked stepwise in the first surplus space S1 and the second surplus space S2. Therefore, oozing of the electrolyte solution L due to the alkali creep phenomenon can be suppressed more reliably.

  Further, in the power storage module 4, the third surplus space S <b> 3 surrounded by the first sealing portion 21 </ b> A, the first sealing portion 21, the second sealing portion 22, and the electrode plate 15 of the negative terminal electrode 18 is formed. The third moisture absorbing member 31C is provided. Thereby, the traveling path of the alkali creep phenomenon from the internal space V to the outside of the negative electrode termination electrode 18 can be blocked stepwise in the first surplus space S1, the second surplus space S2, and the third surplus space S3. Therefore, oozing of the electrolyte solution L due to the alkali creep phenomenon can be suppressed more reliably.

  In addition, from the viewpoint of enhancing the effect of suppressing the seepage of the electrolytic solution L due to the alkali creep phenomenon of the third moisture absorbing member 31C in the third excess space S3, both surfaces of the edge 15c of the electrode plate 15 of the negative electrode terminal electrode 18 are the first. Preferably, it is connected to the sealing portion 21. That is, a coupling region is formed between the edge 15c of the electrode plate 15 of the negative electrode termination electrode 18 and the first sealing portion 21 provided on the edge 15c of the electrode plate 15 of the bipolar electrode 14 adjacent to the negative electrode termination electrode 18. Preferably, K is further formed.

  In the power storage module 4, the metal plate 20 is formed of the same member as the electrode plate 15 of the negative terminal electrode 18. For this reason, cost reduction of the power storage module 4 can be realized by using common components.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the metal plate 20 is formed of the same member as the electrode plate 15 of the negative terminal electrode 18, but the metal plate 20 is formed using a metal different from the metal forming the electrode plate 15. It may be. Further, in the above-described embodiment, the moisture absorbing member 31 is disposed in each of the first surplus space S1, the second surplus space S2, and the third surplus space S3, but the second surplus space S2 and the third surplus space S3 The arrangement of the moisture absorbing member 31 may be omitted. There is no particular limitation on the arrangement of the moisture absorbing member 31 in the surplus space S. The moisture absorbing member 31 may be arranged on any surface defining the surplus space S. Further, the moisture absorbing members need not necessarily be arranged continuously along the surplus space S, but may be arranged discretely.

  Further, the metal plate 20 does not necessarily have to be provided. In this case, for example, as shown in FIG. 5, a surplus space S can be formed by a space surrounded by the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18. In the example of FIG. 5, like the third surplus space S3 (see FIG. 3), the surplus space S includes a second surface (a surface facing the center side in the stacking direction D) 21Ac of the first sealing portion 21A, and a second surplus space S3. The first sealing portion 21 is defined by a first surface (a surface facing the stacking end side in the stacking direction D) 21 a, an inner side surface 22 a of the second sealing portion 22, and a side surface 15 d of the electrode plate 15. The moisture absorbing member 31 in the surplus space S is disposed, for example, on the entire surface of the first surface 21 a of the first sealing portion 21 that defines the surplus space S. Also in such a configuration, the traveling path of the alkali creep phenomenon from the internal space V to the outside of the negative electrode termination electrode 18 can be blocked in the surplus space S. Therefore, seepage of the electrolytic solution L due to the alkali creep phenomenon can be suppressed.

  Further, the first sealing portion 21 having a rectangular frame shape may be coupled to the other surface 15b of the edge portion 15c of the electrode plate 15 of the positive electrode terminal electrode 19. In this case, the first sealing portion 21 is also connected to another first sealing portion 21 by the second sealing portion 22. Further, the outer edge portion of the first sealing portion 21 may be connected to the outer edge portion of another first sealing portion 21 by hot plate welding or the like.

  DESCRIPTION OF SYMBOLS 4 ... Electric storage module, 11 ... Electrode laminated body, 11a ... Side surface, 12 ... Sealing body, 14 ... Bipolar electrode, 15 ... Electrode plate, 15c ... Edge part, 18 ... Negative terminal electrode, 20 ... Metal plate, 20c ... Edge , 21, 21A, 21B: first sealing portion, 22: second sealing portion, 31 (31A to 31C): moisture absorbing member (first moisture absorbing member to third moisture absorbing member), K: coupling region, L: electrolytic solution, S (S1 to S3): surplus space, V: internal space.

Claims (6)

A stacked body of a plurality of bipolar electrodes, and an electrode stacked body including a negative electrode termination electrode disposed at one end in the stacking direction of the stacked body,
A sealing body provided so as to surround the side surface of the electrode laminate, forming an internal space between adjacent electrodes and sealing the internal space,
And an electrolytic solution containing an alkaline solution contained in the internal space,
The electrode laminate has a surplus space on a path of the alkali creep phenomenon of the alkali solution from the internal space to the outside of the negative electrode termination electrode,
A power storage module in which a moisture absorbing member is disposed in the surplus space. The electrode laminate has a metal plate disposed outside the electrode plate of the negative terminal electrode in the laminating direction, and is surrounded by the sealing body, the electrode plate of the negative terminal electrode, and the metal plate. Having a first surplus space,
The power storage module according to claim 1, wherein a first moisture absorbing member is disposed in the first excess space. A first sealing portion coupled to an edge of the electrode plate of the bipolar electrode, an edge of the electrode plate of the negative terminal electrode, and an edge of the metal plate; A second sealing portion provided to surround the stop portion from the outside,
The electrode laminate includes the first sealing portion coupled to an edge of the electrode plate of the negative electrode, the first sealing portion coupled to an edge of the metal plate, and the second sealing portion. A stop portion and a second surplus space surrounded by the metal plate,
The power storage module according to claim 2, wherein a second moisture absorbing member is disposed in the second excess space. The electrode laminate, the first sealing portion coupled to an edge of the electrode plate of the negative electrode termination electrode, the first sealing portion coupled to the edge of the electrode plate of the bipolar electrode, A second sealing portion, and a third surplus space surrounded by the electrode plate of the negative terminal electrode;
The power storage module according to claim 3, wherein a third moisture absorbing member is disposed in the third excess space.   The power storage module according to claim 1, wherein the surplus space is a space surrounded by the sealing body and an electrode plate of the negative terminal electrode.   The power storage module according to any one of claims 1 to 4, wherein the metal plate is formed of the same member as the electrode plate of the negative terminal electrode.

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