JP2020030950A - Power storage module - Google Patents

Abstract

To provide a manufacturing method for a power storage module capable of inhibiting an electrolyte from leaking out of the power storage module, and the power storage module.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 side 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 containing an alkaline solution housed in the internal space V, and both surfaces of the electrode plate 15 of the negative electrode termination electrode 18 are connected to the sealing body 12, and the sealing body 12 and the electrode plate 15 of the negative electrode termination electrode 18 form a surplus space VB.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

  By the way, in the above-described power storage module, a negative electrode termination electrode having a negative electrode formed inside the electrode laminate is disposed at one end of the electrode laminate in the stacking direction. The electrode plate of the negative terminal electrode is also sealed by the sealing body. However, when the electrolytic solution contains an alkaline solution, the electrolytic solution is transmitted along the surface of the negative electrode terminal electrode by a so-called alkali creep phenomenon. In addition, the liquid may leak out of the power storage module through the space between the sealing body and the electrode plate. If the electrolyte leaks out of the power storage module and diffuses, for example, corrosion of a conductive plate disposed in contact with the power storage module or a short circuit between the power storage module and the restraint member may occur, which may cause a reduction in reliability. Can be

  SUMMARY An advantage of some aspects of the invention is to provide a power storage module that can suppress an electrolyte from leaking out of a power storage module due to an alkali 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 on one end side in the stacking direction of the stacked body; A sealing body that is provided to surround the side surface of the body, forms an internal space between adjacent electrodes and seals the internal space, and an electrolytic solution containing an alkaline solution housed in the internal space, Each of both surfaces of the electrode plate of the negative terminal electrode is connected to the sealing body, and an extra space is formed by the sealing body and the electrode plate of the negative terminal electrode.

  In this power storage module, both surfaces of the electrode plate of the negative terminal electrode are connected to the sealing body, and a surplus space is formed by the sealing body and the electrode plate of the negative terminal electrode. Since this surplus space is formed by the sealing body and the electrode plate of the negative terminal electrode, it is located on the movement path of the electrolytic solution due to the alkaline creep phenomenon. Thereby, it is possible to suppress the water contained in the external air from entering the gap between the first sealing portion and the electrode plate of the negative terminal electrode, which is the starting point of the electrolyte bleeding. Therefore, the influence of external humidity, which is a condition for accelerating the alkaline creep phenomenon, is suppressed, so that it is possible to suppress the electrolyte from leaking out of the power storage module.

  The electrode laminate further includes a metal plate disposed outside in the stacking direction with respect to the electrode plate of the negative electrode termination electrode, and another surplus space is formed by the sealing body, the electrode plate of the negative electrode termination electrode, and the metal plate. It may be formed. According to this configuration, in addition to the surplus space, another surplus space is provided on the movement path of the electrolytic solution due to the alkali creep phenomenon. Therefore, it is possible to more reliably prevent the water contained in the external air from entering the gap between the negative electrode terminal electrode and the electrode plate, which is the starting point of the electrolyte bleeding.

  Another surplus space may be further formed outside the other surplus space in the stacking direction by the sealing body and the metal plate. According to this configuration, in addition to the surplus space and the other surplus spaces, another surplus space formed by the sealing body and the metal plate is further provided on the movement path of the electrolytic solution due to the alkali creep phenomenon. Therefore, it is possible to more reliably prevent the water contained in the external air from entering the gap between the negative electrode terminal electrode and the electrode plate, which is the starting point from which the electrolyte oozes out.

  The internal pressure of the surplus space may be lower than the atmospheric pressure. According to this configuration, since the air containing moisture that causes the alkali creep phenomenon to be accelerated is removed in the surplus space, the amount of moisture in the surplus space is reduced. Therefore, the electrolyte is prevented from seeping into the surplus space from between the electrode plate of the negative electrode terminal electrode and the sealing body, so that the electrolyte can be prevented from seeping out of the power storage module due to the alkaline creep phenomenon. .

  The electrode plate may be roughened in a joint region between the sealing body and the electrode plate of the negative terminal electrode. According to this configuration, the bonding strength between the sealing body and the electrode plate of the negative terminal electrode can be improved by the anchor effect.

  The sealing body may include a resin portion disposed between the adjacent electrodes, and outer edges of the adjacent resin portions in the stacking direction may be joined by hot plate welding. According to this configuration, since the outer edges of the adjacent resin portions are joined to each other, the extra space formed by the sealing body and the electrode plate of the negative terminal electrode is equal to the excess space formed by the resin portion and the electrode plate of the negative terminal electrode. It is surrounded by. Similarly, another extra space formed by the sealing body and the metal plate is in a state surrounded by the resin portion and the metal plate. When the outer edges of the resin portions are joined by hot plate welding, the dimensions of the resin portion after hot plate welding are changed by adjusting the pressing strength of the hot plate. Therefore, the size of the surplus space and another surplus space can be adjusted by connecting the outer edges of the resin portions by hot plate welding.

  Advantageous Effects of Invention According to the present invention, there is provided a power storage module capable of suppressing an electrolyte from leaking out of the power storage module due to an alkali creep phenomenon.

FIG. 1 is a schematic cross-sectional view illustrating a power storage device according to one 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 cross-sectional view illustrating a part of the power storage module of FIG. 2. FIG. 5 is a partially enlarged cross-sectional view of a power storage module according to a comparative example. FIG. 13 is a schematic cross-sectional view illustrating an internal configuration of a power storage module according to a modification. FIG. 6 is an enlarged cross-sectional view illustrating a part of the power storage module of FIG. 5. FIG. 10 is an enlarged cross-sectional view illustrating a part of a power storage module according to another modification.

  Hereinafter, various embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description will be omitted.

  Hereinafter, various embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description will be omitted.

  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 radiator plate for radiating heat generated in the power storage module 4 by circulating a coolant 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 cross-sectional view showing a part of the power storage module 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. Note that the separator 13 preferably extends in a direction intersecting with the laminating direction D as it comes into contact with a first sealing portion 21 described later. Thereby, a short circuit between the electrodes can be suppressed.

  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. One surface 15a of electrode plate 15 of negative electrode terminal electrode 18 forms one outer surface in stacking direction D of electrode stack 11, and is electrically connected to one conductive plate 5 (see FIG. 1) adjacent to power storage module 4. It is connected to the. The negative electrode 17 provided on the other surface 15 b of the electrode plate 15 of the negative electrode termination 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, for example, on a sheet. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, 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 (resin portions) 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 the sealing portions 21. 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 held by 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.

  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. Since a plurality of protrusions can be formed on the one surface 15a, the resin in a molten state enters between the plurality of protrusions formed by the roughening at the bonding interface with the first sealing portion 21 on the 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 electrode adjacent to each other along the stacking direction D. The space between the bipolar electrode 18 and the bipolar electrode 14 and the space between the positive terminal electrode 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D are sealed. 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.

  Here, the first sealing portion 21 is also coupled to the other surface 15 b of the electrode plate 15 of the negative electrode terminal electrode 18. That is, both surfaces of the electrode plate 15 of the negative electrode terminal electrode 18 are connected to the sealing body 12. The first sealing part 21 includes a first sealing part 21A and a first sealing part 21B. The first sealing portion 21A is coupled to one surface 15a of the electrode plate 15 of the negative terminal electrode 18, and the first sealing portion 21B is coupled to the other surface 15b of the electrode plate 15 of the negative terminal electrode 18. The first sealing portion 21B is also coupled to one surface 15a of the electrode plate 15 of the bipolar electrode 14 stacked adjacent to the negative electrode termination electrode 18. That is, the first sealing portion 21B is also coupled to one surface 15a of the other electrode plate 15 facing the other surface 15b of the electrode plate 15 to which the first sealing portion 21B is coupled. The other surface 15b of the electrode plate 15 of the negative electrode termination electrode is also roughened, and the region where the edge 15c and the first sealing portion 21B on the other surface 15b of the electrode plate 15 overlap with each other, It is a coupling region K with the stop 21B.

  The first sealing portion 21 </ b> B has a rectangular annular shape when viewed from the laminating direction D, and is provided continuously over the entire periphery of the edge 15 c of the electrode plate 15. The first sealing portion 21B is, for example, a film having a predetermined thickness in the stacking direction D. The thickness of the first sealing portion 21B is smaller than the thickness of the first sealing portion 21A. In the present embodiment, the thickness of the first sealing portion 21B is about half the thickness of the first sealing portion 21A. As an example, the thickness of the first sealing portion 21B can be not less than 50 μm and not more than 150 μm. Note that the thickness of the first sealing portion 21B can be appropriately set according to the distance between the adjacent electrode plates 15, 15.

  Since both the one surface 15a and the other surface 15b of the electrode plate 15 of the negative electrode termination electrode 18 are coupled to the first sealing portion 21, the power storage module 4 is configured such that the surplus space VB is formed between the sealing body 12 and the negative electrode termination. There is a surplus space VB formed by the electrode 18 and the electrode plate 15. More specifically, the surplus space VB is surrounded by the first sealing portion 21 (the first sealing portion 21A and the first sealing portion 21B), the second sealing portion 22, and the electrode plate 15 of the negative terminal electrode 18. Have been. The surplus space VB is a closed space in which no electrolytic solution is stored, and is provided on a moving path of the electrolytic solution when the alkaline creep phenomenon occurs in the power storage module 4. The surplus space VB is formed so as to surround the outside of the edge 15c of the electrode plate 15 of the negative terminal electrode 18. When viewed from a cross section along the stacking direction D, the surplus space VB has a substantially rectangular shape.

  Subsequently, the operation and effect of the power storage module 4 will be described with reference to FIG. 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 FIG. 4, in the power storage module 100 according to the comparative example, the first sealing portion 21 (sealing body 12) is coupled to only one surface 15 a of the electrode plate 15 of the negative terminal electrode 18, and the other surface 15 b Is that the first sealing portion 21 is not joined to the first sealing portion.

  In the power storage module 100, the electrolyte present in the internal space V is transmitted on 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 121A 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 movement 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.

  On the other hand, both surfaces (one surface 15a and the other surface 15b) of the electrode plate 15 of the negative electrode terminal electrode 18 of the power storage module 4 according to the present embodiment are respectively connected to the sealing body 12 (the first sealing portion 21). A surplus space VB is formed by the sealing body 12 and the electrode plate 15 of the negative terminal electrode 18. Since this surplus space VB is formed by the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18, it is located on the movement path of the electrolytic solution due to the alkali creep phenomenon. Thereby, it is possible to suppress the entry of the moisture contained in the external air into the gap between the electrode plate 15 of the negative electrode terminal electrode 18 and the first sealing portion 21, which is the starting point of the electrolyte bleeding. Therefore, the influence of external humidity, which is a condition for accelerating the alkaline creep phenomenon, is suppressed, so that it is possible to suppress the electrolyte from leaking out of the power storage module.

  The electrode plate 15 is roughened in a joint region K between the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18. Thereby, the bonding strength between the sealing body 12 and the electrode plate 15 of the negative terminal electrode 18 can be improved by the anchor effect.

  Next, a power storage module 40 according to a modified example will be described with reference to FIGS. FIG. 5 is a schematic cross-sectional view illustrating an internal configuration of a power storage module 40 according to a modification. FIG. 6 is an enlarged cross-sectional view showing a part of the power storage module 40 of FIG. Like the power storage module 4, the power storage module 40 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 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 power storage module 40 is different from the power storage module 4 in that the electrode stack 11 further includes a metal plate 20.

  The metal plate 20 is arranged outside the electrode plate 15 of the negative terminal electrode 18 in the stacking direction D. The metal plate 20 has another surface 20b facing the one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and one surface 20a opposite to the other surface 20b. The positive electrode active material and the negative electrode active material are not coated on one surface 20a and the other surface 20b of the metal plate 20, and the entire surface of the one surface 20a and the other surface 20b is an uncoated region. That is, in the present embodiment, the metal plate 20 is an uncoated electrode plate on which neither the positive electrode 16 nor the negative electrode 17 is provided. The metal plate 20 has a rectangular contact portion C that is recessed toward the negative electrode terminal electrode 18 and contacts the electrode plate 15 of the negative electrode terminal electrode 18. More specifically, at the contact portion C, the other surface 20b of the metal plate 20 contacts one surface 15a of the electrode plate 15 of the negative terminal electrode 18, and the one surface 20a of the metal plate 20 is connected to the conductive plate 5 (see FIG. 1). ). Thus, the negative electrode terminal electrode 18 is electrically connected to the conductive plate 5 via the metal plate 20. Like the electrode plate 15, the metal plate 20 is made of a metal such as nickel or a nickel-plated steel plate.

  A region where the edge portion 20c and the first sealing portion 21 on the one surface 20a and the other surface 20b of the metal plate 20 overlap is roughened similarly to the surface of the electrode plate 15. The roughened region may be only the region where the edge portion 20c and the first sealing portion 21 are combined, but in the present embodiment, the entirety of the one surface 20a and the other surface 20b of the metal plate 20 is roughened. I have. First sealing portions 21 are respectively coupled to edges 20c of the one surface 20a and the other surface 20b of the metal plate 20. Thus, the first sealing portion 21, the electrode plate 15 of the negative terminal electrode 18, and the metal plate 20 form a surplus space VA in which no electrolyte is contained. When viewed from the stacking direction D, the surplus space VA is formed so as to surround the periphery of the contact portion C. When viewed from a cross section along the stacking direction D, the surplus space VA has a substantially triangular shape whose height (dimension along the stacking direction D) decreases from the first sealing portion 21 side toward the contact portion C side. Has made. The pressure inside the surplus space VA is reduced, and the internal pressure is lower than the atmospheric pressure. Further, the internal pressure of the surplus space VA is lower than the internal pressure of the internal space V in which the electrolyte is stored. As an example, the internal pressure of the surplus space VA can be set to 0 MPa or more and 0.1 MPa or less, and the internal pressure of the internal space V can be set to 0.1 MPa or more and 1 MPa or less. In the present embodiment, when no internal gas is generated, the internal pressure of the internal space V is about atmospheric pressure.

  The power storage module 40 further has another surplus space VC in which no electrolytic solution is stored. Another surplus space VC is located outside the surplus space VA in the stacking direction D. The surplus space VC is formed by the electrode plate 15 of the negative terminal electrode 18, the first sealing portion 21 (first sealing portion 21 </ b> A), and the second sealing portion 22. The surplus space VC is formed so as to surround the outside of the edge 20 c of the metal plate 20. When viewed from a cross section along the stacking direction D, the surplus space VC has a substantially rectangular shape.

  As described above, also in the power storage module 40, the surplus space VB is formed by the sealing body 12 and the electrode plate 15 of the negative terminal electrode 18. Since the surplus space VB is located on the movement path of the electrolytic solution due to the alkali creep phenomenon, the surplus space VB is located between the electrode plate 15 of the negative electrode terminal electrode 18 and the first sealing portion 21 from which the electrolytic solution oozes. It is possible to suppress entry of moisture contained in external air into the gap. Therefore, the influence of external humidity, which is a condition for accelerating the alkaline creep phenomenon, is suppressed, so that the electrolyte solution can be prevented from seeping out of the power storage module 40.

  Further, the electrode laminate 11 further includes a metal plate 20 disposed outside the electrode plate 15 of the negative electrode termination electrode 18 in the laminating direction D, and includes the sealing body 12 and the electrode plate 15 of the negative electrode termination electrode 18. Another surplus space VA is formed by the metal plate 20. Thus, in addition to the surplus space VB, another surplus space VA is provided on the movement path of the electrolytic solution due to the alkali creep phenomenon. Therefore, it is possible to more reliably prevent the water contained in the external air from entering the gap between the negative electrode terminal electrode 18 and the electrode plate 15, which is the starting point from which the electrolyte oozes out.

  In the power storage module 40, another surplus space VC is further formed outside the other surplus space VA in the stacking direction D by the sealing body 12 and the metal plate 20. Thus, in addition to the surplus space VB and the other surplus space VA, another surplus space VC formed by the sealing body 12 and the metal plate 20 is further provided on the movement path of the electrolyte due to the alkali creep phenomenon. Therefore, it is possible to more reliably prevent the water contained in the external air from entering the gap between the negative electrode terminal electrode 18 and the electrode plate 15, which is the starting point from which the electrolyte oozes out.

  Further, the internal pressure of the surplus space VA is lower than the atmospheric pressure. Accordingly, since the air containing moisture which causes the alkali creep phenomenon to be accelerated is removed in the surplus space VA, the amount of moisture in the surplus space VA is reduced. Therefore, the electrolyte is prevented from seeping into the surplus space VA from between the electrode plate 15 of the negative electrode terminal electrode 18 and the sealing body 12, so that the electrolyte leaks out of the power storage module 40 due to the alkali creep phenomenon. Outgoing can be suppressed.

  Next, a power storage module 50 according to another modification will be described with reference to FIG. FIG. 7 is an enlarged cross-sectional view illustrating a part of a power storage module 50 according to another modification. As shown in FIG. 7, the power storage module 50 includes an electrode stack 11 and a resin sealing body 12 that seals the electrode stack 11, similarly to the power storage modules 4 and 40. The electrode stack 11 includes a plurality of electrodes stacked along the stacking direction D 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. Similarly to the power storage module 40, the power storage module 50 has three extra spaces VA, VB, and VC on the movement path of the electrolyte due to the alkali creep phenomenon. The power storage module 50 is different from the power storage module 40 in that the outer edges of the first sealing portions 21 adjacent in the stacking direction D are joined by hot plate welding. Thus, in the power storage module 50, the surplus space VB is in a state surrounded by the first sealing portion 21 and the electrode plate 15 of the negative terminal electrode 18. Similarly, the surplus space VC is in a state surrounded by the first sealing portion 21 and the metal plate 20.

  Also in the above-described power storage module 50, since the extra spaces VA, VB, and VC are provided on the movement path of the electrolytic solution due to the alkaline creep phenomenon, the electrode plate 15 of the negative electrode terminal electrode 18 serving as a starting point from which the electrolytic solution oozes out. It is possible to prevent moisture contained in the outside air from entering the gap between the first sealing portion 21 and the first sealing portion 21. Therefore, the influence of external humidity, which is a condition for accelerating the alkaline creep phenomenon, is suppressed, so that the electrolyte solution can be prevented from seeping out of the power storage module 50.

  Further, the sealing body 12 includes first sealing portions 21 arranged between adjacent electrodes, and outer edges of the first sealing portions 21 adjacent in the stacking direction D are joined by hot plate welding. I have. In this case, since the outer edges of the adjacent first sealing portions 21 are connected to each other, the surplus space VB formed by the sealing body 12 and the electrode plate 15 of the negative electrode termination electrode 18 is removed by the first sealing portion 21. 21 and the electrode plate 15 of the negative terminal electrode 18. Similarly, another surplus space VC formed by the sealing body 12 and the metal plate 20 is in a state surrounded by the first sealing portion 21 and the metal plate 20. When the outer edges of the first sealing portions 21 are joined to each other by hot plate welding, the dimensions of the first sealing portions 21 after hot plate welding (in the stacking direction D) are adjusted by adjusting the pressing strength of the hot plate. (The dimension in the direction crossing) changes. Therefore, the size of the surplus space VB and the surplus space VC can be adjusted by connecting the outer edges of the first sealing portions 21 to each other by hot plate welding.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made. For example, in the above embodiment, an example in which the internal pressure of the surplus space VA is lower than the atmospheric pressure has been described, but the internal pressure of the surplus space VA does not have to be lower than the atmospheric pressure. Further, the internal pressure of the surplus spaces VB and VC may be lower than the atmospheric pressure.

  Further, in the above embodiment, the example in which the power storage module 4 has one surplus space VB and the example in which the power storage modules 40 and 50 have three surplus spaces VA, VB, and VC have been described. 40 and 50 may have more surplus space.

  Further, the surplus spaces VA, VB, and VC only need to be arranged on the movement path of the electrolyte when the alkali creep phenomenon occurs, and the components of the power storage module that forms the respective surplus spaces VA, VB, and VC are: There is no particular limitation.

  Further, the first sealing portion 21 having a rectangular frame shape may be connected to the other surface 15b side of the electrode plate 15 of the positive electrode termination electrode 19. This first sealing portion 21 can also be connected to another first sealing portion 21 by the second sealing portion 22. Further, the edge of the first sealing portion 21 coupled to the other surface 15b side of the electrode plate 15 of the positive electrode terminal electrode 19, and the first sealing portion 21 on the one surface 15a side of the electrode plate 15 of the positive electrode terminal electrode 19 May be joined by hot plate welding or the like.

  4, 40, 50: power storage module, 11: electrode laminate, 11a: side surface, 12: sealing body, 14: bipolar electrode, 15: electrode plate, 15a: one surface, 15b: other surface, 18: negative electrode termination electrode , 20: metal plate, 21: first sealing portion (resin portion), 22: second sealing portion, D: stacking direction, K: coupling region, V: internal space, VA: surplus space (other surplus space) ), VB... Surplus space, VC... Surplus space (another surplus space).

Claims (6)

A stacked body of a plurality of bipolar electrodes, and an electrode stacked body including a negative electrode termination electrode disposed on one end side 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,
Each of both surfaces of the electrode plate of the negative terminal electrode is coupled with the sealing body,
A power storage module in which a surplus space is formed by the sealing body and the electrode plate of the negative terminal electrode. The electrode laminate further includes a metal plate disposed on the outside in the laminating direction with respect to the electrode plate of the negative electrode termination electrode,
The power storage module according to claim 1, wherein another surplus space is formed by the sealing body, the electrode plate of the negative electrode termination electrode, and the metal plate.   The power storage module according to claim 2, wherein another surplus space is further formed outside the other surplus space in the stacking direction by the sealing body and the metal plate.   The power storage module according to claim 2, wherein an internal pressure of the other surplus space is lower than an atmospheric pressure.   5. The power storage module according to claim 1, wherein a surface of the electrode plate is roughened in a bonding region between the sealing body and the electrode plate of the negative electrode terminal electrode. 6. The sealing body includes a resin portion disposed between adjacent electrodes,
The power storage module according to any one of claims 1 to 5, wherein outer edge portions of the resin portions adjacent to each other in the stacking direction are joined by hot plate welding.

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