JP2019192543A - Power storage module - Google Patents

Abstract

To provide a power storage module in which reliability is improved.SOLUTION: A power storage module 4 includes an electrode laminate 11 including multiple electrodes, a metal plate 50 and a first encapsulation part 21. The electrode includes a bipolar electrode 14 and a negative electrode termination electrode 18. The negative electrode termination electrode 18 includes an electrode plate 15, and a negative electrode 17 provided on the second face 15b, and placed between the bipolar electrode 14 and the metal plate 50. The first encapsulation part 21 includes a first resin part 21A deposited on the first face 15a of the negative electrode termination electrode 18. The metal plate 50 includes a third face 50a facing the first face 15a of the negative electrode termination electrode 18, and a fourth face 50b opposite to the third face 50a, and is deposited to the first resin part 21A on the third face 50a. A liquid-absorbing member 60 is placed in an area A6 extending inward from the peripheral part of the first face 15a, and/or an area A7 extending inward from the peripheral part of the fourth face 50b.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power storage module.

  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). The bipolar battery is provided with a laminate formed by laminating a plurality of bipolar electrodes via a separator. A sealing body that seals between bipolar electrodes adjacent to each other in the stacking direction is provided on a side surface of the stacked body, and an electrolytic solution is accommodated in an internal space formed between the bipolar electrodes.

JP 2011-204386 A

  In the power storage module as described above, a negative electrode termination electrode composed of an electrode plate having a negative electrode formed on the inner surface is disposed at one end in the stacking direction of the stacked body. The edge of the electrode plate of the negative electrode termination electrode is also sealed with a sealing body. However, when the electrolyte solution is made of an alkaline solution, the electrolyte solution covers the surface of the electrode plate of the negative electrode termination electrode due to a so-called alkali creep phenomenon. It may be transmitted to the outer surface side of the electrode plate through the sealing body and the electrode plate. If the electrolyte leaks to the outer surface side and diffuses, for example, corrosion of the 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. It is not preferable.

  Therefore, an object of the present invention is to provide a power storage module with improved reliability.

  The power storage module according to the present invention is welded to a laminated body including a plurality of electrodes laminated along a first direction, a metal plate provided at one end of the laminated body in the first direction, and a peripheral portion of the electrodes, An electrode is provided with a first sealing portion for forming an internal space between adjacent electrodes and sealing the internal space, and an electrolytic solution made of an alkaline solution accommodated in the internal space. The bipolar electrode includes an electrode plate including 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 electrode termination electrode includes an electrode plate and a negative electrode provided on the second surface, and a bipolar electrode at one end of the stack in the first direction so that the second surface is inside the stack. It is arrange | positioned between metal plates, and a metal plate is the 1st surface of a negative electrode termination electrode The first sealing portion is welded to the peripheral portion of the first surface of the negative electrode termination electrode and the peripheral portion of the third surface of the metal plate, including an opposing third surface and a fourth surface opposite to the third surface. A first resin portion, a peripheral portion of the fourth surface of the metal plate, and a second resin portion welded to the first resin portion, wherein the first surface, the third surface, and the fourth surface are peripheral portions. The liquid absorbing member is disposed in an area extending inward from the peripheral edge of the first surface of the negative electrode termination electrode and / or an area extending inward from the peripheral edge of the fourth surface. .

  In this power storage module, an internal space for accommodating the electrolytic solution is formed between the electrodes of the laminated body by the first sealing portion. Moreover, the negative electrode termination electrode is arrange | positioned so that the 2nd surface of an electrode plate may become the inner side of a laminated body among the some electrodes at the end of a laminated body. A first resin portion as a first sealing portion is welded to the first surface of the negative electrode termination electrode facing the outside of the laminate. On the other hand, a metal plate is provided at one end of the laminate. Thus, the negative electrode termination electrode is disposed between the bipolar electrode of the electrodes and the metal plate. That is, a metal plate is provided further outside the negative electrode termination electrode. The metal plate is welded to the first resin portion welded to the first surface of the negative electrode termination electrode at the periphery of the third surface facing the first surface of the negative electrode termination electrode. Furthermore, the peripheral part of the 4th surface of a metal plate is welded to the 2nd resin part as a 1st sealing part. And the liquid absorption member is arrange | positioned in the area extended inward from the peripheral part in the 1st surface and / or the area extended inward from the peripheral part in the 4th surface.

  By adopting such a configuration, the following effects can be obtained. That is, as a first effect, the first resin portion and the negative electrode termination electrode are obtained by welding a metal plate having higher rigidity than the first resin portion to the first resin portion on the first surface of the negative electrode termination electrode. The first resin portion is prevented from being deformed such that the first surface is peeled off. In addition, as a second effect, since a metal plate is further provided outside the negative terminal electrode, entry of moisture from the outside into the internal space between the electrodes is suppressed. Further, as a third effect, on the path leading from the negative electrode termination electrode to the outside, the welding location between the first surface of the negative electrode termination electrode and the first resin portion, the welding of the third surface of the metal plate and the first resin portion. The seal | sticker of at least 3 steps | paragraphs of a location and the welding location of the 4th surface and 2nd resin part of a metal plate is formed.

  Due to the first effect, it is possible to suppress a gap between the first resin portion and the first surface of the negative electrode termination electrode from being generated as a path for electrolyte leakage due to alkali creep. Moreover, the influence of the external humidity used as the acceleration condition of alkali creep is suppressed by the 2nd effect. In addition, due to the third effect, the liquid leakage rate is reduced by multi-stage sealing. Further, as a fourth effect, the liquid absorbing member is disposed in an area extending inward from the peripheral portion on the first surface of the negative electrode termination electrode and / or in an area extending inward from the peripheral portion on the fourth surface of the metal plate. Thus, even if the electrolytic solution exceeds the seal at each stage, the electrolytic solution is absorbed by the liquid absorbing member. According to this power storage module, these effects are obtained in combination, and as a result, leakage due to alkali creep is reliably suppressed and reliability is improved.

  In the power storage module according to the present invention, the third surface is spaced apart from the first surface via the first resin portion, and is located on the inner side of the annular outer area corresponding to the peripheral portion and the outer area. An inner area that is in contact with the surface, and an intermediate area that is between the outer area and the inner area and that is inclined so as to approach the first surface toward the inner area, the first resin portion, the first surface The intermediate area forms a surplus space, and the liquid absorbing member may be arranged in the surplus space. In this case, it is suppressed that electrolyte solution reaches the contact location (inner area) of a negative electrode termination electrode and a metal plate. Therefore, it is suppressed that electrolyte solution interposes on the conductive path in the said electrical storage module, and the increase in contact resistance is avoided.

  In the power storage module according to the present invention, the liquid absorbing member may be filled in an excess space. In this case, the electrolytic solution can be reliably absorbed.

  In the power storage module according to the present invention, the liquid absorbing member may be disposed in a part of the surplus space. In this case, the cost of the adsorption member can be suppressed.

  In the power storage module according to the present invention, the liquid absorbing member may be a woven fabric or a non-woven fabric. In this case, it becomes easier to handle the adsorbing member as compared with a case where, for example, a particulate material is used as the adsorbing member material.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage module by which the improvement of reliability was achieved can be provided.

It is a schematic sectional drawing which shows one Embodiment of an electrical storage apparatus. It is a schematic sectional drawing which shows the internal structure of the electrical storage module shown by FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a partial expanded sectional view of the electrical storage module which concerns on a comparative example.

  Hereinafter, an embodiment of a power storage module will be described with reference to the drawings. In the description of the drawings, the same elements or corresponding elements may be denoted by the same reference numerals, and overlapping descriptions may be omitted.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a power storage device. The power storage device 1 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. 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.

  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 from the stacking direction. The power storage module 4 is, for example, a secondary battery such as a nickel 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 illustrated.

  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 respectively disposed between the power storage modules 4 adjacent to each other in the stacking direction and the outside of the power storage module 4 positioned at the stacking end. A positive electrode terminal 6 is connected to one conductive plate 5 disposed outside the power storage module 4 located at the end of the stack. A negative electrode terminal 7 is connected to the other conductive plate 5 disposed outside the power storage module 4 located at the stacking 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 stacking direction. The power storage device 1 is charged and discharged by the positive electrode terminal 6 and the negative electrode terminal 7.

  Inside the conductive plate 5, a plurality of flow paths 5 a for circulating a refrigerant such as air are provided. The flow path 5a extends, for example, along a direction intersecting (orthogonal) with each other in the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. In addition to the function as a connection member for electrically connecting the power storage modules 4 to each other, the conductive plate 5 serves as a heat dissipation plate that dissipates heat generated in the power storage module 4 by circulating a refrigerant through these flow paths 5a. It has both functions. In the example of FIG. 1, the area of the conductive plate 5 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 the area of the power storage module 4. It may be the same as or larger than the area of the power storage module 4.

  The restraining member 3 includes a pair of end plates 8 that sandwich the module laminate 2 in the stacking direction, and fastening bolts 9 and nuts 10 that fasten the end plates 8 together. The end plate 8 is a rectangular metal plate having an area that is slightly larger than the areas of the power storage module 4 and the conductive plate 5 as viewed from the stacking direction. On the inner side surface of the end plate 8 (surface on the module laminate 2 side), a film F having electrical insulation is provided. The film F insulates the end plate 8 from the conductive plate 5.

  An insertion hole 8 a is provided at the edge of the end plate 8 at a position outside the module laminate 2. The fastening bolt 9 is passed from the insertion hole 8 a of one end plate 8 toward the insertion hole 8 a of the other end plate 8, and at the tip of the fastening bolt 9 protruding from the insertion hole 8 a of the other end plate 8. The nut 10 is screwed together. As a result, the power storage module 4 and the conductive plate 5 are sandwiched between the end plates 8 and unitized as the module stacked body 2, and a restraining load is applied to the module stacked body 2 in the stacking direction.

  Next, the configuration of the power storage module 4 will be described in detail. FIG. 2 is a schematic cross-sectional view showing an internal configuration of the power storage module shown in FIG. FIG. 3 is a partially enlarged view of FIG. As shown in FIGS. 2 and 3, 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 electrode termination electrode (electrode) 18), and a single electrode laminated along a lamination direction D (first direction) via a separator 13. One positive terminal electrode 19). Here, the stacking direction D of the electrode stack 11 coincides with the stacking direction of the module stack 2. The electrode stack 11 has a side surface 11a extending in the stacking direction D.

  The bipolar electrode 14 includes an electrode plate 15 including a first surface 15a and a second surface 15b opposite to the first surface 15a, a positive electrode 16 provided on the first surface 15a, and a negative electrode 17 provided on the second surface 15b. It is out. 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 in the stacking direction D across the separator 13. 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 in the stacking direction D across the separator 13.

  The negative electrode termination electrode 18 includes an electrode plate 15 and a negative electrode 17 provided on the second surface 15 b of the electrode plate 15. The negative electrode termination electrode 18 is disposed at one end in the stacking direction D so that the second surface 15b is inside the electrode stack 11 (center side in the stacking direction D). The negative electrode 17 of the negative electrode termination electrode 18 is opposed to 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 includes an electrode plate 15 and a positive electrode 16 provided on the first 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 so that the first surface 15 a is inside the electrode stack 11. The positive electrode 16 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 first surface 15 a of the electrode plate 15 of the negative electrode termination electrode 18 is a surface facing the outside of the electrode laminate 11. The conductive plate 5 is electrically connected to the first surface 15a of the negative electrode termination electrode 18 via a metal plate 50 described later. Further, another conductive plate 5 adjacent to the power storage module 4 is in contact with the second surface 15 b of the electrode plate 15 of the positive electrode termination 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.

  The electrode plate 15 is made of a metal such as nickel or a nickel-plated steel plate, for example. As an example, the electrode plate 15 is a rectangular metal foil made of nickel. A peripheral portion of the electrode plate 15 (peripheral portions of the bipolar electrode 14, the negative electrode termination electrode 18, and the positive electrode termination electrode 19) 15c has a rectangular frame shape and is not coated with a positive electrode active material and a negative electrode active material. It has become. An example of the positive electrode active material constituting the positive electrode 16 is nickel hydroxide. As a negative electrode active material which comprises the negative electrode 17, a hydrogen storage alloy is mentioned, for example. In the present embodiment, the formation region of the negative electrode 17 on the second surface 15 b of the electrode plate 15 is slightly larger than the formation region of the positive electrode 16 on the first 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 resin such as polyethylene (PE) and polypropylene (PP), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 is not limited to a sheet shape, and may be a bag shape.

  The sealing body 12 is formed in a rectangular cylinder as a whole, for example, with an insulating resin. The sealing body 12 is provided on the side surface 11a of the electrode laminate 11 so as to surround the peripheral edge portion 15c. The sealing body 12 holds the peripheral edge portion 15c on the side surface 11a. The sealing body 12 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 and the plurality of first sealing portions 21 welded to the peripheral edge portion 15c. And a single second sealing portion 22.

  The first sealing portion 21 has a rectangular ring shape when viewed from the stacking direction D, and is continuously provided over the entire circumference of the peripheral edge portion 15c. The first sealing portion 21 is welded to the first surface 15a of the electrode plate 15 and is airtightly joined. The first sealing portion 21 is welded by, for example, ultrasonic waves or heat. The first sealing portion 21 is a film having a predetermined thickness (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 part 21 is located between the peripheral parts 15c of the electrode plates 15 adjacent to each other in the stacking direction D, and a part of the outside protrudes outward from the electrode plate 15. Yes. The first sealing portion 21 is embedded in the second sealing portion 22 at a part of the outside. 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 21 </ b> A welded to the first surface 15 a of the negative electrode termination electrode 18. Here, one of the first sealing portions 21 is the first resin portion 21A.

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

  The second sealing portion 22, together with the first sealing portion 21, is between the bipolar electrodes 14 adjacent to each other along the stacking direction D, and between the negative electrode termination electrode 18 and the bipolar electrode 14 adjacent to each other along the stacking direction D. The positive electrode termination electrode 19 and the bipolar electrode 14 that are adjacent to each other along the stacking direction D are sealed. As a result, airtightly partitioned internal spaces V are formed between the 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. Yes. That is, the first sealing portion 21 and the second sealing portion 22 are for forming the internal space V between adjacent electrodes and sealing the internal space V. In the internal space V, an electrolytic solution (not shown) made of an alkaline solution such as an aqueous potassium hydroxide solution is accommodated. The electrolytic solution is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

  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 of the electrode stack 11 in the stacking direction D (the end on the negative electrode termination electrode 18 side). The metal plate 50 includes a third surface 50a facing the first surface 15a of the negative electrode termination electrode 18, and a fourth surface 50b opposite to the third surface 50a. The fourth surface 50 b of the metal plate 50 is in contact with the conductive plate 5. The metal plate 50 is laminated together with the electrodes along the lamination direction D. Thus, the negative electrode termination electrode 18 is disposed between the metal plate 50 and the bipolar electrode 14 along the stacking direction D. In other words, in the power storage module 4, the metal plate 50 is provided further outside the negative electrode termination electrode 18.

  The metal plate 50 is welded to the first resin portion 21 </ b> A and is in contact with the first surface 15 a of the negative electrode termination electrode 18. More specifically, the metal plate 50 includes a rectangular annular welded portion 52 disposed on the first resin portion 21A and the first surface 15a and welded to the first resin portion 21A, and an inner side of the welded portion 52. And a rectangular contacted portion 53 located on the first surface 15a side of the negative electrode termination electrode 18 with respect to the welded portion 52 (depressed) and in contact with the first surface 15a. The welded portion 52 and the contacted portion 53 are continuous with each other.

  Between the metal plate 50 and the negative electrode termination electrode 18 (between the third surface 50a and the first surface 15a), a surplus corresponding to the thickness (the length along the stacking direction D) of the first resin portion 21A Although the space VA can be formed, the surplus space VA is narrowly limited because the metal plate 50 is recessed toward the negative electrode termination electrode 18 in the contacted portion 53. In addition, although the metal plate 50 can be comprised with arbitrary metals, it can be made the same as the electrode plate 15 as an example. 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 (uncoated foil) on which no active material layer is formed.

  The second resin portion 51 has substantially the same shape as the first resin portion 21 </ b> A when viewed from the stacking direction D. That is, the second resin portion 51 is a film having a rectangular ring shape and a predetermined thickness. The second resin portion 51 is disposed so as to extend from the peripheral portion of the fourth surface 50b of the metal plate 50 over the first resin portion 21A. The second resin portion 51 is welded to the fourth 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 that overlaps 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.

  The first sealing part 21 (first resin part 21A), the second sealing part 22, and the second resin part 51 are, for example, insulating resins such as polypropylene (PP) and polyphenylene sulfide (PPS). Or modified polyphenylene ether (modified PPE) or the like.

  An area welded to the first resin portion 21A or the second resin portion 51 is formed on the first surface 15a, the third surface 50a, and the fourth surface 50b. Specifically, when viewed from the stacking direction D, the area A1 overlapping the first resin portion 21A on the first surface 15a and the area A2 overlapping the first resin portion 21A on the third surface 50a are the first resin. It is an area welded to the part 21A. In addition, when viewed from the stacking direction D, an area A3 overlapping the second resin portion 51 on the fourth surface 50b is an area welded to the second resin portion 51. The areas A1 to A3 are rectangular. At least these areas A1 to A3 are roughened. Here, the entire first surface 15a, third surface 50a, and fourth surface 50b are roughened.

  Furthermore, the third surface 50a includes areas A4 and A5. Area A <b> 2 is an annular outer area corresponding to the peripheral edge of the metal plate 50. The area A5 is an inner area located inside the area A2, and is in contact with the first surface 15a. The area A4 is an intermediate area between the area A2 and the area A5, and is inclined so as to approach the first surface 15a toward the area A5. The surplus space VA is formed by the first resin portion 21A, the first surface 15a, and the area A4.

  Here, the entire surfaces of the first surface 15a, the third surface 50a, and the fourth surface 50b are roughened by forming a plurality of protrusions by, for example, electrolytic plating. As a result, the first resin portion 21A or the second resin portion in the molten state at the bonding interface with the first resin portion 21A or the second resin portion 51 on the first surface 15a, the third surface 50a, and the fourth surface 50b. 51 enters the recess formed by the roughening, and the anchor effect is exhibited. Thereby, the mutual binding force can be improved. The protrusion formed at the time of roughening has, for example, a shape that tapers from the proximal end side toward the distal end side. Thereby, the cross-sectional shape between mutually adjacent protrusions becomes an undercut shape, and an anchor effect is likely to occur.

  Here, the power storage module 4 further includes a liquid absorbing member 60 for absorbing the electrolytic solution. The liquid absorbing member 60 is formed from an area (area facing the area A4) A6 extending inward from the peripheral edge 15c of the first surface 15a of the negative electrode termination electrode 18 and / or a peripheral edge of the fourth surface 50b of the metal plate 50. It is arranged in an area A7 extending inward. Here, the liquid absorbing member 60 is disposed in the surplus space VA on the area A6. The liquid absorbing member 60 may be filled in the surplus space VA, but here is disposed in a part of the surplus space VA. The liquid absorbing member 60 is formed in a sheet shape by, for example, a nonwoven fabric. Examples of the material constituting the nonwoven fabric include polyolefin. The nonwoven fabric may be subjected to plasma treatment in order to improve water absorption. The thickness (the length along the stacking direction D) of the liquid absorbing member 60 is, for example, about several hundred μm. The liquid absorbing member 60 has, for example, a rectangular ring shape when viewed from the stacking direction D, and surrounds an area where the conductive plate 5 is disposed (an area overlapping the area A5). The liquid absorbing member 60 may be a woven fabric.

  Then, an example of the manufacturing method of the electrical storage apparatus 1 is demonstrated. In this method, first, the above-described power storage module 4 is manufactured. The manufacturing method of the electrical storage module 4 includes a primary molding process, a stacking process, a secondary molding process, and an injection process. In the primary forming step, a predetermined number of bipolar electrodes 14, a negative electrode termination electrode 18, and a positive electrode termination electrode 19 are prepared, and the first sealing portion 21 is welded to the first surface 15 a of the peripheral edge portion 15 c of each electrode plate 15. Moreover, the metal plate 50 is prepared and the 2nd resin part 51 is welded to the 4th surface 50b.

  In the laminating step, the bipolar electrode 14, the negative electrode termination electrode 18, and the positive electrode termination electrode 19 are laminated via the separator 13 so that the first sealing portion 21 is disposed between the peripheral portions 15 c of the electrode plate 15. Thus, the electrode laminate 11 is formed. 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 step, the electrode laminate 11 and the metal plate 50 are arranged in an injection mold (not shown), and then the molten resin is injected into the mold, whereby the first sealing portion 21 and the first sealing portion 21 are formed. The second sealing portion 22 is formed so as to surround the two resin portions 51. Thereby, the sealing body 12 is formed on the side surface 11a of the electrode laminate 11. In the injection step, the electrolytic solution is injected into the internal space V between the bipolar electrodes 14 and 14 after the secondary forming step. Thereby, the electrical storage module 4 is obtained.

  Then, the effect | action and effect of the electrical storage module 4 are demonstrated. FIG. 4 is a partially enlarged cross-sectional view of a power storage module according to a comparative example. In the example shown in FIG. 4, the metal plate 50 is not provided. For this reason, for example, when a load is applied to the electrode plate 15 of the negative electrode termination electrode 18 as the internal pressure increases, the first resin portion 21A welded to the electrode plate 15 may be deformed. In this case, a gap is generated between the first resin portion 21 </ b> A and the electrode plate 15, and there is a possibility that the electrolyte solution L leaks through the gap.

  In the power storage module, the electrolyte solution L is transmitted on the electrode plate 15 of the negative electrode termination electrode 18 by a so-called alkali creep phenomenon, passes through the gap between the first resin portion 21A and the electrode plate 15, and the first surface of the electrode plate 15. It may ooze out to the 15a side. In FIG. 4, the movement path of the electrolyte L in the alkali creep phenomenon is indicated by an arrow A. This alkaline creep phenomenon can occur during charging, discharging, and no load of the power storage device due to electrochemical factors and fluid phenomena. The alkali creep phenomenon is caused by the presence of a negative electrode potential, moisture, and a path for the electrolyte L, respectively.

  On the other hand, in the power storage module 4, an internal space V that stores the electrolytic solution is formed between the electrodes of the electrode stack 11 by the first sealing portion 21. Moreover, the negative electrode termination electrode 18 is arrange | positioned at the end of the electrode laminated body 11 so that the 2nd surface 15b of the electrode plate 15 may become inside the electrode laminated body 11 among several electrodes. A first resin portion 21 </ b> A as the first sealing portion 21 is welded to the first surface 15 a facing the outside of the electrode stack 11 in the negative electrode termination electrode 18. On the other hand, a metal plate 50 is provided at one end of the electrode laminate 11. Thus, the negative electrode termination electrode 18 is disposed between the bipolar electrode 14 of the electrodes and the metal plate 50. That is, the metal plate 50 is provided further outside the negative electrode termination electrode 18. The metal plate 50 is welded to the first resin portion 21 </ b> A welded to the first surface 15 a of the negative electrode termination electrode 18 at the peripheral portion of the third surface 50 a facing the first surface 15 a of the negative electrode termination electrode 18. Yes. Further, the peripheral edge portion of the fourth surface 50 b of the metal plate 50 is welded to the second resin portion 51 as the first sealing portion 21. And the liquid absorption member 60 is arrange | positioned in the area A6 extended inside from the peripheral part in the 4th surface 50b and / or the area A6 extended inward from the peripheral part in the 1st surface 15a.

  By adopting such a configuration, the following effects can be obtained. That is, as a first effect, the metal plate 50 having a higher rigidity than the first resin portion 21A is welded to the first resin portion 21A on the first surface 15a of the negative electrode termination electrode 18, whereby the first resin The deformation of the first resin portion 21A is suppressed such that the portion 21A and the first surface 15a of the negative electrode termination electrode 18 are peeled off. In addition, as a second effect, the metal plate 50 is further provided outside the negative electrode termination electrode 18, thereby suppressing moisture from entering the internal space V between the electrodes. Further, as a third effect, on the path leading from the negative electrode termination electrode 18 to the outside, the welded portion between the first surface 15a of the negative electrode termination electrode 18 and the first resin portion 21A, the third surface 50a of the metal plate 50, and the second At least three stages of seals are formed: a weld location with the first resin portion 21 a and a weld location between the fourth surface 50 </ b> B of the metal plate 50 and the second resin portion 51.

  Due to the first effect, it is possible to suppress a gap between the first resin portion 21a and the first surface 15a of the negative electrode termination electrode 18 from being generated as a path for electrolyte leakage due to alkali creep. Moreover, the influence of the external humidity used as the acceleration condition of alkali creep is suppressed by the 2nd effect. In addition, due to the third effect, the liquid leakage rate is reduced by multi-stage sealing. Furthermore, as a fourth effect, in the area A6 extending inward from the peripheral edge of the first surface 15a of the negative electrode termination electrode 18 and / or in the area ZA7 extending inward from the peripheral edge of the fourth surface 50b of the metal plate 50, By disposing the liquid absorbing member 60, even if the electrolytic solution exceeds the seal at each stage, the electrolytic solution is absorbed by the liquid absorbing member 60. According to the electricity storage module 4, these effects are obtained in combination, and as a result, leakage due to alkali creep is reliably suppressed and reliability is improved.

  Moreover, in the electrical storage module 4, the 3rd surface 50a is spaced apart from the 1st surface 15a via the 1st resin part 21A, and is located inside annular area A2 corresponding to a peripheral part, and area A2. The area A5 that is in contact with the first surface 15a, and the area A4 that is between the area A2 and the area A5 and is inclined so as to approach the first surface 15a toward the area A5. The first resin portion 21A, the first surface 15a, and the area A4 form a surplus space VA, and the liquid absorbing member 60 is disposed in the surplus space VA. For this reason, it is suppressed that electrolyte solution reaches the contact location (area A5) of the negative electrode termination electrode 18 and the metal plate 50. FIG. Therefore, it is suppressed that electrolyte solution intervenes on the conductive path in the power storage module 4, and an increase in contact resistance is avoided.

  In the power storage module 4, the liquid absorbing member 60 may be filled in the surplus space VA, or may be disposed in a part of the surplus space VA. When the liquid absorbing member 60 fills the surplus space VA, the electrolyte can be reliably absorbed in the surplus space VA. Moreover, when the liquid absorption member 60 is arrange | positioned in a part of surplus space VA, cost is suppressed.

  Further, in the power storage module 4, the liquid absorbing member 60 may be a woven fabric or a non-woven fabric. In this case, as compared with the case where, for example, a particulate material is used as the material of the liquid absorbing member 60, the liquid absorbing member 60 can be easily handled.

  The power storage module 4 includes a second sealing portion 22 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. Is further provided. The second sealing portion 22 includes an overlapping portion 22A that overlaps 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. For this reason, the internal space V is reliably sealed by the second sealing portion 22. In addition, as a result of the deformation of the second resin portion 51 being suppressed by the overlapping portion 22A of the second sealing portion 22, a gap is suppressed from being generated between the second resin portion 51 and the fourth surface 50b. Thereby, the leak by alkali creep is suppressed more reliably.

  Further, in the power storage module 4, the metal plate 50 includes an annular welded portion 52 welded to the first resin portion 21 </ b> A, and a first end of the negative electrode termination electrode 18 that is inside the welded portion 52 than the welded portion 52. And a contacted portion 53 located on the surface 15a side and in contact with the first surface 15a. For this reason, the surplus space VA formed between the metal plate 50 and the negative electrode termination electrode 18 is limited. Thereby, the influence of the humidity of the surplus space VA is suppressed.

  In the power storage module 4, the metal plate 50 is the electrode plate 15. For this reason, it is not necessary to prepare the metal plate 50 separately from the electrode plate 15. Thereby, said structure is realizable at low cost.

  The above embodiment describes one embodiment of the power storage module according to the present invention. Therefore, the power storage module according to the present invention is not limited to the power storage module 4 described above, and can be arbitrarily changed.

  DESCRIPTION OF SYMBOLS 4 ... Power storage module, 11 ... Electrode laminated body (laminated body), 14 ... Bipolar electrode, 15 ... Electrode plate, 15a ... 1st surface, 15b ... 2nd surface, 17 ... Negative electrode, 18 ... Negative electrode termination electrode, 21 ... 1st 1 sealing part, 21A ... 1st resin part, 50 ... metal plate, 50a ... 3rd surface, 50b ... 4th surface, 51 ... 2nd resin part, 60 ... liquid absorption member, A1-A7 ... area.

Claims (5)

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 first sealing portion that is welded to a peripheral portion of the electrode, forms an internal space between the adjacent electrodes, and seals the internal space;
An electrolytic solution comprising an alkaline solution housed in the internal space;
With
The electrode includes a plurality of bipolar electrodes and a negative electrode termination electrode,
The bipolar electrode includes an electrode plate including 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 electrode termination electrode includes the electrode plate and a negative electrode provided on the second surface, and at the one end of the stacked body in the first direction so that the second surface is inside the stacked body. Arranged between the bipolar electrode and the metal plate;
The metal plate includes a third surface facing the first surface of the negative electrode termination electrode and a fourth surface opposite to the third surface;
The first sealing portion includes a first resin portion welded to a peripheral portion of the first surface of the negative electrode termination electrode and a peripheral portion of the third surface of the metal plate, and the fourth surface of the metal plate. And a second resin part welded to the first resin part,
The first surface, the third surface, and the fourth surface are roughened at a peripheral edge,
A liquid-absorbing member is disposed in an area extending inward from the peripheral edge portion of the first surface of the negative electrode termination electrode and / or in an area extending inwardly from the peripheral edge portion of the fourth surface.
Power storage module. The third surface is spaced apart from the first surface through the first resin portion and is located on the inner side of the outer area and in contact with the first surface, corresponding to the peripheral edge portion. An inner area, and an intermediate area inclined between the outer area and the inner area so as to approach the first surface toward the inner area,
The first resin portion, the first surface, and the intermediate area form a surplus space,
The liquid absorbing member is disposed in the surplus space,
The power storage module according to claim 1. The liquid absorbing member is filled in the surplus space,
The power storage module according to claim 2. The liquid absorbing member is disposed in a part of the surplus space,
The power storage module according to claim 2. The liquid absorbing member is a woven fabric or a non-woven fabric,
The electrical storage module as described in any one of Claims 1-3.

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