JP2020030954A - Power storage module and manufacturing method therefor - Google Patents

Abstract

To provide a power storage module with improved reliability and a manufacturing method for the power storage module.SOLUTION: A power storage module 4 includes an electrode laminate 11 including a plurality of electrodes, a metal plate 50, and a first sealing portion 21. The plurality of electrodes include a plurality of bipolar electrodes 14 and a negative electrode termination electrode 18. The electrode includes an electrode plate 15 including a first surface 15a and a second surface 15b. The negative electrode termination electrode 18 further includes a negative electrode 17 provided on the second surface 15b, and is disposed between the bipolar electrode 14 and the metal plate 50. A first resin portion 21A is welded to a peripheral portion of the first surface 15a of the negative electrode termination electrode 18. The metal plate 50 includes a third surface 50a and a fourth surface 50b, and is welded to the first resin portion 21A at the peripheral portion of the third surface 50a. A second resin portion 51 is welded to the peripheral portion of the fourth surface 50b of the metal plate 50. A water-repellent material 60 is provided on at least a part of the surface of the second resin portion 51.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage module and a method for manufacturing the 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 power storage module as described above, a negative electrode termination electrode formed of an electrode plate having a negative electrode formed on the inner surface is disposed at one end in the stacking direction of the stack. The edge of the electrode plate of the negative terminal electrode is also sealed by a sealing body. However, when the electrolytic solution is made of an alkaline solution, the electrolytic solution causes the surface of the negative electrode terminal electrode to lose its surface due to a so-called alkali creep phenomenon. In some cases, the liquid may pass through the gap between the sealing body and the electrode plate and bleed to the outer surface of 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, and from the viewpoint of reliability. Not preferred.

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

  A power storage module according to one aspect of the present invention includes a stacked body including a plurality of electrodes stacked in a first direction, a metal plate provided at one end of the stacked body in the first direction, A first sealing portion that is welded to an edge portion and forms an internal space between the adjacent electrodes and seals the internal space, and an electrolytic solution containing an alkaline solution housed in the internal space, Wherein the plurality of electrodes includes a plurality of bipolar electrodes and a negative electrode termination electrode, and the electrode includes a first surface intersecting the first direction and a second surface opposite to the first surface. A bipolar plate, wherein the bipolar electrode further includes a positive electrode provided on the first surface, and a negative electrode provided on the second surface, and the negative electrode termination electrode includes a negative electrode provided on the second surface. And the second surface is inside the laminate. The one end of the laminate in the first direction is disposed between the bipolar electrode and the metal plate, and a first resin portion is welded to a periphery of the first surface of the negative electrode termination electrode. 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, and the first resin is disposed at a peripheral portion of the third surface. A second resin portion is welded to a peripheral portion of the fourth surface of the metal plate, and a water vapor barrier layer is provided on at least a part of a surface of the second resin portion. .

In the above power storage module, since the water vapor barrier layer is provided on at least a part of the surface of the second resin portion, it is possible to prevent moisture (water vapor) from entering the second resin portion from outside the power storage module. When moisture enters the second resin portion, the moisture passes through the second resin portion, passes between the metal plate and the first resin portion, and is surrounded by the negative electrode terminal electrode, the metal plate, and the first resin portion. There is a risk of intrusion into the surplus space. In this case, a gradient of OH ^- concentration occurs between the surplus space and the internal space, and the electrolyte easily moves from the internal space toward the surplus space, so that the alkali creep phenomenon is promoted. However, in the power storage module, since the intrusion of moisture is suppressed by the water vapor barrier layer, liquid leakage due to alkali creep is reliably suppressed, and reliability is improved.

  The power storage module is joined to the first sealing portion, the first resin portion, and the second resin portion so as to surround the first sealing portion, the first resin portion, and the second resin portion from outside. A second sealing portion, wherein the second sealing portion covers a part of the surface of the second resin portion, and the water vapor barrier layer is provided on the surface of the second resin portion. Of these, a portion not covered by the second sealing portion may be covered. In this case, invasion of moisture can be suppressed in a portion of the surface of the second resin portion which is covered with the water vapor barrier layer. In addition, in the portion of the surface of the second resin portion that is covered by the second sealing portion, the invasion of moisture can be suppressed to some extent by the second sealing portion.

  The second sealing portion may include an overlapping portion overlapping the second resin portion as viewed from the first direction, and the water vapor barrier layer may be provided on a surface of the overlapping portion. In the overlapping portion of the second sealing portion, the thickness of the second sealing portion in the first direction tends to be small. If the thickness of the second sealing portion is small, the moisture easily permeates through the second sealing portion when the water enters the second sealing portion. However, when the water vapor barrier layer is provided on the surface of the overlapping portion, the penetration of moisture can be effectively suppressed.

  The water vapor barrier layer may be a water repellent material. In this case, the handleability is improved as compared with the case where the water vapor barrier layer is made of a material other than the water repellent material.

  A method for manufacturing a power storage module according to one aspect of the present invention includes a stacked body including a plurality of electrodes stacked along a first direction, a metal plate provided at one end of the stacked body in the first direction, A first sealing portion that is welded to an edge of the electrode and forms an internal space between the adjacent electrodes and seals the internal space; and an electrolysis including an alkaline solution housed in the internal space. A method for manufacturing a power storage module comprising: a liquid; and a plurality of electrodes including a plurality of bipolar electrodes and a negative electrode termination electrode, wherein the electrodes include a first surface intersecting with the first direction and the first surface. An electrode plate including a second surface opposite to the surface, wherein the bipolar electrode further includes: a positive electrode provided on the first surface; and a negative electrode provided on the second surface. Further includes a negative electrode provided on the second surface. 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, wherein the manufacturing method includes the first surface of the bipolar electrode. The first sealing portion is welded to a peripheral portion of the first electrode portion, a first resin portion is welded to a peripheral portion of the first surface of the negative electrode termination electrode, and a second resin portion is welded to a peripheral portion of the fourth surface of the metal plate. A first welding step of welding a portion, and laminating the plurality of electrodes along the first direction such that the second surface of the negative electrode terminal electrode is inside the laminate to form the laminate. A laminating step of disposing the metal plate on the negative terminal electrode at the one end of the laminate in the first direction; and a coating step of coating at least a part of the surface of the second resin portion with a water vapor barrier layer. And

  The coating step may be performed before the first welding step, may be performed between the first welding step and the laminating step, or may be performed after the laminating step.

  In the above-described method for manufacturing a power storage module, at least a portion of the surface of the second resin portion is coated with the water vapor barrier layer, so that it is possible to prevent moisture (water vapor) from entering the second resin portion from outside the power storage module. . Therefore, liquid leakage due to alkali creep is reliably suppressed, and reliability is improved.

  In the method for manufacturing a power storage module, the first sealing portion, the first resin portion, and the second resin may be configured to surround the first sealing portion, the first resin portion, and the second resin portion from outside. The method may further include a second welding step of welding a second sealing portion to the portion, and the coating step may be performed after the second welding step. In this case, the influence of the second welding step on the water vapor barrier layer (for example, heat during thermal welding) can be reduced.

  According to one embodiment of the present invention, a power storage module with improved reliability and a method for manufacturing the power storage module can be provided.

FIG. 2 is a schematic cross-sectional view illustrating one embodiment of a power storage device. FIG. 2 is a schematic sectional view illustrating an internal configuration of the power storage module illustrated in FIG. 1. 3 is a flowchart illustrating an example of a method for manufacturing the power storage module of FIG. 2. It is an outline sectional view expanding and showing a part of internal configuration of an electric storage module concerning a modification. 5 is a flowchart illustrating an example of a method for manufacturing the power storage module of FIG. 4. FIG. 5 is a partially enlarged cross-sectional view of a power storage module according to a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference symbols, without redundant description.

  FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a power storage device. The power storage device 1 illustrated 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 restraint member 3 that applies a restraining load to the module stack 2 in the stacking direction.

  The module stack 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 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 smaller than the area of the power storage module 4. And may be larger than 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. An electrically insulating film F is provided on the inner side surface of the end plate 8 (the surface 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. As illustrated in FIG. 2, the power storage module 4 includes an electrode stack (stack) 11 and a resin sealing body 12 that seals the electrode stack 11. The electrode stack 11 includes a plurality of electrodes (a plurality of bipolar electrodes 14, a single negative electrode termination electrode (electrode) 18, and a single electrode) stacked in the stacking direction D (first direction) via the 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 intersecting with the stacking direction D and a second surface 15b opposite to the first surface 15a, a positive electrode 16 provided on the first surface 15a, and a second surface 15b. The negative electrode 17 provided is included. 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 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 that is adjacent in the stacking direction D with the separator 13 interposed therebetween.

  The negative terminal electrode 18 includes the electrode plate 15 and the 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 such 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 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 includes the electrode plate 15 and the positive electrode 16 provided on the first surface 15 a of the electrode plate 15. The positive electrode terminating electrode 19 is arranged at the other end in the laminating direction D such that the first surface 15a is inside the electrode laminated body 11. The positive electrode 16 of the positive electrode terminal 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 terminal electrode 18 is a surface facing the outside of the electrode stack 11. The conductive plate 5 is electrically connected to the first surface 15a of the negative electrode terminal electrode 18 via a metal plate 50 described later. Another conductive plate 5 adjacent to the power storage module 4 is in contact with the second surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19. The restraint load from the restraint member 3 is applied to the electrode stack 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 constraint member that applies a constraint load to the electrode stack 11 along the stacking direction D.

  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 edges 15 c of the electrode plate 15 (the edges of the bipolar electrode 14, the negative electrode termination electrode 18, and the positive electrode termination electrode 19) have a rectangular frame shape, and are uncoated areas where the positive electrode active material and the negative electrode active material are not applied. It has become. 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 second surface 15b of the electrode plate 15 is slightly larger than the formation region of the positive electrode 16 on the first surface 15a 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 11a of the electrode stack 11 so as to surround the edge 15c. The sealing body 12 holds the edge 15c on the side surface 11a. The sealing body 12 is joined to the plurality of first sealing portions 21 welded to the edge 15c and to the first sealing portion 21 so as to surround the first sealing portion 21 from the outside along the side surface 11a. And a single second sealing portion 22.

  The first sealing portion 21 has a rectangular annular shape when viewed from the laminating direction D, and is provided continuously over the entire periphery of the edge portion 15c. The first sealing portion 21 is welded to the first surface 15a of the electrode plate 15 and joined in an airtight manner. 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 (the length in the stacking direction D). The end face of the electrode plate 15 is exposed from the first sealing portion 21. Part of the inside of the first sealing portion 21 is located between the edges 15c of the electrode plates 15 adjacent to each other in the stacking direction D, and part of the outside protrudes outward from the electrode plate 15. I have. The first sealing portion 21 is buried 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. A first resin portion 21A is welded to a peripheral portion of the first surface 15a of the negative electrode terminal electrode 18. In the present embodiment, the first resin portion 21A has the same configuration as one first sealing portion 21.

  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 tubular (annular) shape extending in the stacking direction D as an axial direction. The second sealing portion 22 is welded (joined) to the outer surface of the first sealing portion 21 by, for example, heat during injection molding.

  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 between the negative electrode termination electrode 18 and the bipolar electrode 14 adjacent to each other along the stacking direction D. The space between the electrodes and the space between the positive electrode terminal electrode 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D are sealed. Thereby, 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. I have. That is, the first sealing portion 21 and the second sealing portion 22 are for forming the internal space V between the adjacent electrodes and for sealing the internal space V. 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 power storage module 4 includes a metal plate 50 and a second resin portion 51. The metal plate 50 is provided at one end (the end on the negative electrode termination electrode 18 side) of the electrode stack 11 in the stacking direction D. The metal plate 50 includes a third surface 50a facing the first surface 15a of the negative electrode terminal electrode 18, and a fourth surface 50b opposite to the third surface 50a. The fourth surface 50b of the metal plate 50 is in contact with the conductive plate 5. The metal plate 50 is stacked with the electrodes along the stacking direction D. Thereby, the negative electrode termination electrode 18 is arranged 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 terminal electrode 18.

  The metal plate 50 is welded to the first resin portion 21A and is in contact with the first surface 15a of the negative electrode terminal 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 contact portion 53 that is located (recessed) on the first surface 15a side of the negative electrode terminal electrode 18 with respect to the welded portion 52 and is in contact with the first surface 15a. The welded part 52 and the contacted part 53 are continuous with each other. Between the metal plate 50 and the negative electrode terminating electrode 18 (between the third surface 50a and the first surface 15a), an excess corresponding to the thickness of the first resin portion 21A (the length along the lamination direction D). Although a space VA can be formed, the surplus space VA is narrowly limited because the metal plate 50 is recessed at the contacted portion 53 toward the negative electrode termination electrode 18. The metal plate 50 can be made of any metal, but can be 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 on which no active material layer is formed (uncoated foil).

  The second resin portion 51 has substantially the same shape as the first resin portion 21A when viewed from the laminating 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 extends from the peripheral portion of the fourth surface 50b of the metal plate 50 to the first resin portion 21A. The second resin portion 51 is welded to the peripheral portion of 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 outside. The second sealing portion 22 includes an overlapping portion 22A overlapping the metal plate 50 and the second resin portion 51 when viewed from the laminating direction D, and is welded to the second resin portion 51 at the overlapping portion 22A.

  The first sealing portion 21, the first resin portion 21A, the second sealing portion 22, and the second resin portion 51 are, for example, insulating resins, such as polypropylene (PP), polyphenylene sulfide (PPS), Alternatively, it may be composed of modified polyphenylene ether (modified PPE) or the like.

  The first surface 15a, the third surface 50a, and the fourth surface 50b are roughened, for example, by forming a plurality of protrusions by electrolytic plating. Thereby, at the joining interface between 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, the first resin portion 21A or the second resin portion in a molten state. 51 enters the recess formed by the roughening, and the anchor effect is exhibited. Thereby, the mutual coupling force 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. As a result, the cross-sectional shape between the adjacent protrusions becomes an undercut shape, and the anchor effect is easily generated.

  Here, the power storage module 4 further includes a water repellent material 60 as an example of a water vapor barrier layer. The water-repellent material 60 is located on the outermost side of the power storage module 4 and faces the outside of the power storage module 4. The water-repellent material 60 is provided on at least a part of the surface of the second resin portion 51. In the present embodiment, the second sealing portion 22 covers a part of the surface of the second resin portion 51. The water-repellent material 60 covers a portion of the surface of the second resin portion 51 that is not covered by the second sealing portion 22. For example, the water-repellent material 60 covers a part of the upper surface 51 s intersecting in the laminating direction D on the surface of the second resin portion 51 and the inner surface 51 e along the laminating direction D. The upper surface 51s is a surface opposite to the surface of the second resin portion 51 welded to the fourth surface 50b of the metal plate 50. The inner surface 51e connects the edge of the upper surface 51s and the fourth surface 50b of the metal plate 50. Therefore, the water-repellent material 60 is formed from the upper surface 51s to the inner surface 51e of the second resin portion 51. The height from the fourth surface 50b of the metal plate 50 to the upper surface 51s of the second resin portion 51 may be, for example, 200 μm or less, or 100 μm or less. The second sealing portion 22 covers the remaining portion of the upper surface 51s of the surface of the second resin portion 51 and the outer surface 51f along the stacking direction D.

  In the present embodiment, the water repellent material 60 is provided on the surface of the overlapping portion 22A of the second sealing portion 22. For example, the water repellent material 60 covers the entire upper surface 22s of the second sealing portion 22 and the inner surface 22e of the second sealing portion 22 along the stacking direction D. The upper surface 22s is a surface opposite to the surface of the second sealing portion 22 that is welded to the upper surface 51s of the second resin portion 51. The inner surface 22e connects the edge of the upper surface 22s and the upper surface 51s of the second resin portion 51. Therefore, the water-repellent material 60 is formed from the upper surface 22s to the inner surface 22e of the second sealing portion 22. The water-repellent material 60 does not cover the outer surface 22f of the second sealing portion 22 along the stacking direction D, but may cover at least a part of the outer surface 22f.

  The water repellent material 60 is formed in a film shape as an example. The water-repellent material 60 can be formed by applying a fluorine-based resin material (for example, “OS-90HF” manufactured by Harves Co., Ltd.), a fluorine rubber, a polymer having a fluorine-based / methyl-based functional group, or the like. The thickness of the water repellent material 60 may be, for example, 5 μm or less, or 1 μm or less.

  Further, the power storage module 4 further includes a liquid absorbing member 31. The liquid absorbing member 31 is provided on the fourth surface 50b of the metal plate 50. The liquid absorbing member 31 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 a plasma treatment in order to improve water absorption. The thickness (length along the stacking direction D) of the liquid absorbing member 31 is, for example, about several hundred μm. The liquid absorbing member 31 has, for example, a rectangular annular shape when viewed from the laminating direction D, and surrounds the conductive plate 5.

  Next, the operation and effect of the power storage module 4 will be described. FIG. 6 is a partially enlarged cross-sectional view of a power storage module according to a comparative example. In the example shown in FIG. 6, the metal plate 50 is not provided. Therefore, for example, if a load is applied to the electrode plate 15 of the negative electrode terminal electrode 18 with an increase in the internal pressure, the first resin portion 21A welded to the electrode plate 15 may be deformed. In this case, a gap is formed between the first resin portion 21A and the electrode plate 15, and there is a possibility that the electrolyte solution L may leak through the gap.

  In the power storage module, the electrolytic solution L propagates on the electrode plate 15 of the negative electrode terminal electrode 18 due to a so-called alkali creep phenomenon, and passes through the gap between the first resin portion 21A and the electrode plate 15 so that the first surface of the electrode plate 15 It may seep to the 15a side. In FIG. 6, the movement path of the electrolytic solution L in the alkaline creep phenomenon is indicated by an arrow A. The alkaline creep phenomenon can occur during charging and discharging of the power storage device and during no load due to electrochemical factors and fluid phenomena. The alkali creep phenomenon is caused by the existence of the passages of the negative electrode potential, moisture, and the electrolytic solution L, respectively.

  On the other hand, in the power storage module 4, an internal space V that accommodates the electrolytic solution is formed by the first sealing portion 21 between the electrodes of the electrode stack 11. In addition, at one end of the electrode stack 11, a negative electrode termination electrode 18 is arranged such that the second surface 15 b of the electrode plate 15 among the plurality of electrodes is inside the electrode stack 11. A first resin portion 21A is welded to a first surface 15a of the negative electrode terminal electrode 18 facing the outside of the electrode stack 11. On the other hand, a metal plate 50 is provided at one end of the electrode stack 11. As a result, the negative terminal electrode 18 is arranged 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. Then, the metal plate 50 is welded to the first resin portion 21A welded to the first surface 15a of the negative electrode termination electrode 18 at the peripheral portion of the third surface 50a facing the first surface 15a of the negative electrode termination electrode 18. I have. The second resin portion 51 is welded to the fourth surface 50 b of the metal plate 50, and a water-repellent material 60 is provided on at least a part of the surface of the second resin portion 51.

  With such a configuration, the following effects can be obtained. That is, as a first effect, the first resin portion 21A on the first surface 15a of the negative electrode termination electrode 18 is welded to the first resin portion 21A on the first surface 15a of the negative electrode terminal electrode 18 as a first resin portion. The deformation of the first resin portion 21A such that the portion 21A and the first surface 15a of the negative electrode terminal electrode 18 are separated is suppressed. As a second effect, since the metal plate 50 is further provided outside the negative electrode termination electrode 18, the intrusion of moisture from the outside into the internal space V is suppressed. Further, as a third effect, on the path leading from the negative electrode terminal electrode 18 to the outside, the welding portion between the first surface 15a of the negative electrode terminal electrode 18 and the first resin portion 21A, the third surface 50a of the metal plate 50 and the third At least three stages of seals are formed at the welding portion of the one resin portion 21A and at the welding portion of the fourth surface 50b of the metal plate 50 and the second resin portion 51.

The first effect suppresses the occurrence of a gap between the first resin portion 21A and the first surface 15a of the negative electrode terminating electrode 18 that can serve as a path for electrolyte leakage due to alkali creep. Further, the second effect suppresses the influence of external humidity, which is the condition for accelerating alkali creep. In addition, the liquid leakage speed is reduced by the multi-stage sealing by the third effect. Furthermore, as a fourth effect, since the water repellent material 60 is provided on at least a part of the surface of the second resin portion 51, moisture (water vapor) enters the second resin portion 51 from outside the power storage module 4. Can be suppressed. When moisture enters the second resin portion 51, the moisture passes through the second resin portion 51 and passes between the metal plate 50 and the first resin portion 21 </ b> A, and the negative terminal electrode 18, the metal plate 50, There is a possibility of invading the surplus space VA surrounded by the one resin portion 21A. In this case, an OH ⁻ concentration gradient is generated between the surplus space VA and the inner space V, and the electrolyte easily moves from the inner space V toward the surplus space VA, so that the alkali creep phenomenon is promoted. . However, in the power storage module 4, intrusion of moisture is suppressed by the water repellent material 60. The effect increases as the area of the portion of the surface of the second resin portion 51 and the second sealing portion 22 covered with the water repellent material 60 increases. As described above, in the power storage module 4, liquid leakage due to alkali creep is reliably suppressed, and reliability is improved.

  When the water repellent material 60 is used as the water vapor barrier layer, the handleability is improved and the cost is reduced as compared with the case where the water vapor barrier layer is made of a material other than the water repellent material 60. Further, since the thickness of the water repellent material 60 is small, it is possible to suppress an increase in the size of the power storage module 4.

  Further, in the present embodiment, the second sealing portion 22 covers a part of the surface of the second resin portion 51, and the water-repellent material 60 is formed of the second sealing portion of the surface of the second resin portion 51. The portion not covered by 22 is covered. In this case, invasion of moisture can be suppressed in a portion of the surface of the second resin portion 51 which is covered with the water repellent material 60. In addition, in the portion of the surface of the second resin portion 51 that is covered by the second sealing portion 22, the penetration of moisture can be suppressed to some extent by the second sealing portion 22.

  Further, in the present embodiment, the second sealing portion 22 includes the overlapping portion 22A, and the water repellent material 60 is provided on the surface of the overlapping portion 22A of the second sealing portion 22 (the upper surface 22s of the second sealing portion 22). Is provided. In the overlapping portion 22A of the second sealing portion 22, the thickness of the second sealing portion 22 in the stacking direction D tends to be small. When the thickness of the second sealing portion 22 is small, the moisture easily permeates through the second sealing portion 22 when the moisture enters the second sealing portion 22. However, if the water-repellent material 60 is provided on the surface of the overlapping portion 22A, the penetration of moisture can be effectively suppressed.

  Subsequently, an example of a method for manufacturing the power storage module 4 will be described.

  FIG. 3 is a flowchart illustrating an example of a method for manufacturing the power storage module 4. This manufacturing method includes a first welding step S1, a laminating step S2, a second welding step S3, a coating step S4, and an injection step S5. By performing the steps S1 to S5 in this order, the power storage module 4 can be manufactured. Hereinafter, steps S1 to S5 will be described with reference to FIG.

  In the first welding step S1, a predetermined number of bipolar electrodes 14 and positive terminal electrodes 19 are prepared, and the first sealing portion 21 is welded to the peripheral edge of the first surface 15a of the edge 15c of each electrode plate 15. Also, a negative electrode terminal electrode 18 is prepared, and the first resin portion 21A is welded to the peripheral portion of the first surface 15a. Further, a metal plate 50 is prepared, and the second resin portion 51 is welded to a peripheral portion of the fourth surface 50b.

  In the laminating step S2, the electrode laminate 11 is formed by laminating the bipolar electrode 14, the negative terminal electrode 18 and the positive terminal electrode 19 along the laminating direction D. The lamination is performed such that the second surface 15b of the negative electrode termination electrode 18 and the first surface 15a of the positive electrode termination electrode 19 are inside the electrode laminate 11. The first sealing portion 21 is disposed between the edges 15c of the electrode plate 15. The separator 13 is arranged between the electrode plates 15. In addition, a metal plate 50 is disposed on the negative electrode termination electrode 18 at one end of the electrode stack 11 in the stacking direction D. The first resin portion 21 </ b> A is disposed between the peripheral portion of the first surface 15 a of the negative electrode terminal electrode 18 and the peripheral portion of the third surface 50 a of the metal plate 50. The second resin part 51 is disposed on the first resin part 21A.

  In the second welding step S3, after disposing the electrode laminate 11 and the metal plate 50 in an injection-molding mold (not shown), a molten resin is injected into the mold to form the first sealing portion 21, The second sealing portion 22 is formed so as to surround the first resin portion 21A and the second resin portion 51. Thereby, the sealing body 12 is formed on the side surface 11a of the electrode laminate 11.

  In the coating step S4, the water repellent material 60 is coated on at least a part of the surface of the second resin portion 51. For example, a part of the upper surface 51s and the inner surface 51e of the second resin portion 51 and the entire upper surface 22s and the inner surface 22e of the second sealing portion 22 are coated with the water repellent material 60. The water-repellent material 60 can be formed by applying a liquid material of the water-repellent material 60 to the surfaces of the second resin portion 51 and the second sealing portion 22 and drying the liquid material. Examples of the application method include immersion (dip), application using an applicator such as a brush, and spraying.

  In the injection step S5, an electrolyte is injected into the internal space V between the bipolar electrodes 14,. The electrolyte is also injected into the internal space V between the negative terminal electrode 18 and the bipolar electrode 14 and the internal space V between the positive terminal electrode 19 and the bipolar electrode 14. The electrolyte can be injected from an injection port provided in the sealing body 12. The injection port is sealed after the injection step S5. Thereby, the power storage module 4 is obtained.

  In the above manufacturing method, since the surfaces of the second resin portion 51 and the second sealing portion 22 are coated with the water repellent material 60, moisture (water vapor) enters the second resin portion 51 from outside the power storage module 4. Can be suppressed. Therefore, according to the above manufacturing method, liquid leakage due to alkali creep is reliably suppressed, and reliability is improved.

  In the present embodiment, since the coating step S4 is performed after the second welding step S3, the influence of the second welding step S3 on the water-repellent material 60 can be reduced. In the second welding step S3, thermal welding is performed at, for example, 250 ° C. Therefore, if the coating step S4 is performed after the second welding step S3, the heating of the water-repellent material 60 in the second welding step S3 can be prevented.

  FIG. 4 is a schematic cross-sectional view showing an enlarged part of the internal configuration of a power storage module according to a modification. The power storage module 4a shown in FIG. 4 has the same configuration as the power storage module 4 except that a water repellent material 160 is provided instead of the water repellent material 60. The water-repellent material 160 covers the upper surface 51s, the inner surface 51e, and the outer surface 51f of the second resin portion 51. The water-repellent material 160 also covers a portion of the surface of the second resin portion 51 which is covered by the second sealing portion 22 (a part of the upper surface 51s and the outer surface 51f). On the other hand, the water-repellent material 160 does not cover the surface (the upper surface 22s, the inner surface 22e, and the outer surface 22f) of the second sealing portion 22. The water-repellent material 160 may be provided on the outer surface of the first resin portion 21A connected to the outer surface 51f of the second resin portion 51. The example of the material of the water repellent material 160 is the same as the example of the water repellent material 60.

  FIG. 5 is a flowchart illustrating an example of a method for manufacturing the power storage module of FIG. 5 includes a first welding step S1, a coating step S4, a lamination step S2, a second welding step S3, and an injection step S5. By performing each step in the order of step S1, step S4, step S2, step S3, and step S5, the power storage module 4a can be manufactured. This manufacturing method is the same as the method shown in FIG. 3 except that the coating step S4 is performed not between the second welding step S3 and the injection step S5 but between the first welding step S1 and the laminating step S2. It is.

  In the coating step S4, as shown in FIG. 4, the upper surface 51s, the inner surface 51e, and the outer surface 51f of the second resin portion 51 are coated with the water repellent material 160. In the second welding step S3, the second sealing portion 22 is formed so as to surround a part of the water repellent material 160.

  The same effect as that of the power storage module 4 can be obtained in the power storage module 4a.

  As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments.

  For example, a sealing material may be provided on at least a part of the surface of the second resin portion 51 instead of the water repellent material 60 as a water vapor barrier layer. The sealing material is, for example, a cured product of a liquid sealing agent. In this case, formation of the sealing material is easy. The liquid sealant is, for example, a polyolefin resin material such as polypropylene (PP), an adhesive mainly containing blown asphalt (asphalt pitch), or the like. Asphalt pitch is obtained, for example, by dissolving blown asphalt and polybutene in toluene. Specifically, the sealing material can be formed by applying a liquid sealing agent to at least a part of the surface of the second resin portion 51 and curing the liquid sealing material. Even when a sealing material is provided instead of the water-repellent material 60, the same effect as the above-described effect of the water-repellent material 60 can be obtained.

  In the power storage module 4, the water repellent material 60 may not be provided on the upper surface 22 s and the inner surface 22 e of the second sealing unit 22.

  Further, in the method for manufacturing the electricity storage module 4 shown in FIG. 3, the coating step S4 may be performed after the injection step S5. Further, in the method for manufacturing power storage module 4a shown in FIG. 5, coating step S4 may be performed between laminating step S2 and second welding step S3, or may be performed before first welding step S1. You may.

  4, 4a: electricity storage module, 11: electrode laminate (laminate), 14: bipolar electrode, 15: electrode plate, 15a: first surface, 15b: second surface, 15c: edge, 16: positive electrode, 17 ... Negative electrode, 18 Negative electrode termination electrode, 21 First sealing portion, 21A First resin portion, 22 Second sealing portion, 22A Overlapping portion, 50 Metal plate, 50a Third surface, 50b Second Four surfaces, 51: second resin part, 60: water repellent material (water vapor barrier layer), V: internal space.

Claims (6)

A laminate including a plurality of electrodes laminated along the first direction;
A metal plate provided at one end of the laminate in the first direction;
A first sealing portion that is welded to an edge of the electrode and forms an internal space between the adjacent electrodes and seals the internal space;
An electrolytic solution containing an alkaline solution contained in the internal space,
With
The plurality of electrodes include a plurality of bipolar electrodes and a negative terminal electrode,
The electrode includes an electrode plate including a first surface crossing the first direction and a second surface opposite to the first surface,
The bipolar electrode further includes a positive electrode provided on the first surface, and a negative electrode provided on the second surface.
The negative electrode termination electrode further includes a negative electrode provided on the second surface, and the bipolar electrode and the bipolar electrode at one end of the laminate in the first direction such that the second surface is inside the laminate. Disposed between the metal plate,
A first resin portion is welded to a peripheral portion of the first surface of the negative electrode termination electrode,
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, and a peripheral portion of the third surface is provided on the first resin portion. Welded,
A second resin portion is welded to a peripheral portion of the fourth surface of the metal plate,
A power storage module, wherein a water vapor barrier layer is provided on at least a part of a surface of the second resin portion. A second seal bonded to the first seal, the first resin, and the second resin so as to surround the first seal, the first resin, and the second resin from outside. Further equipped with a stop,
The second sealing portion covers a part of the surface of the second resin portion,
The power storage module according to claim 1, wherein the water vapor barrier layer covers a portion of the surface of the second resin portion that is not covered by the second sealing portion. The second sealing portion includes an overlapping portion overlapping the second resin portion when viewed from the first direction,
The power storage module according to claim 2, wherein the water vapor barrier layer is provided on a surface of the overlapping portion.   The power storage module according to any one of claims 1 to 3, wherein the water vapor barrier layer is a water repellent material. A stacked body including a plurality of electrodes stacked in a first direction, a metal plate provided at one end of the stacked body in the first direction, and a metal plate that is welded to an edge of the electrode and is adjacent to the electrode. A method for manufacturing a power storage module, comprising: a first sealing portion for forming an internal space therebetween and sealing the internal space; and an electrolytic solution containing an alkaline solution accommodated in the internal space,
The plurality of electrodes include a plurality of bipolar electrodes and a negative terminal electrode,
The electrode includes an electrode plate including a first surface crossing the first direction and a second surface opposite to the first surface,
The bipolar electrode further includes a positive electrode provided on the first surface, and a negative electrode provided on the second surface.
The negative electrode termination electrode further includes a negative electrode provided on the second surface,
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 manufacturing method comprises:
The first sealing portion is welded to a peripheral portion of the first surface of the bipolar electrode, and a first resin portion is welded to a peripheral portion of the first surface of the negative electrode termination electrode. A first welding step of welding a second resin portion to a peripheral portion of the surface;
Stacking the plurality of electrodes along the first direction to form the stack so that the second surface of the negative electrode termination electrode is inside the stack, and forming the stack in the first direction; A laminating step of arranging the metal plate on the negative terminal electrode at the one end,
A coating step of coating at least a part of the surface of the second resin portion with a water vapor barrier layer;
A method for manufacturing a power storage module, comprising: A second sealing portion is provided on the first sealing portion, the first resin portion, and the second resin portion so as to surround the first sealing portion, the first resin portion, and the second resin portion from outside. Further comprising a second welding step of welding;
The method for manufacturing a power storage module according to claim 5, wherein the coating step is performed after the second welding step.

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