JP6858165B2 - Power storage module and manufacturing method of power storage module - Google Patents

Description

The present invention relates to a power storage module and a method for manufacturing the power storage module.

As a conventional power storage module, a bipolar battery including a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface is known (see Patent Document 1). The bipolar battery includes a laminate formed by laminating a plurality of bipolar electrodes via a separator. On the side surface of the laminated body, a sealing body for sealing between the bipolar electrodes adjacent to each other in the stacking direction is provided, and the electrolytic solution is housed in the internal space formed between the bipolar electrodes.

Japanese Unexamined Patent Publication No. 2011-204386

By the way, in the power storage module as described above, a negative electrode terminal electrode having a negative electrode formed inside the electrode laminated body is arranged at one end in the stacking direction of the electrode laminated body. The electrode plate of the negative electrode terminal electrode is also sealed by the sealant. However, when the electrolytic solution contains an alkaline solution, the electrolytic solution propagates on the surface of the electrode plate of the negative electrode terminal electrode due to the so-called alkaline creep phenomenon, passes between the sealant and the electrode plate, and is outside the power storage module. There is a risk of seeping out. If the electrolytic solution leaks to the outside of the power storage module and diffuses, for example, the conductive plate arranged in contact with the power storage module may be corroded, or the power storage module and the restraint member may be short-circuited.

The present invention has been made to solve the above problems, and provides a power storage module and a method for manufacturing a power storage module capable of suppressing the electrolytic solution from seeping out of the power storage module due to an alkaline creep phenomenon. The purpose.

The power storage module according to one aspect of the present invention includes an electrode laminate including a laminate of a plurality of bipolar electrodes and a negative electrode terminal electrode arranged on one end side in the stacking direction of the laminate, and an electrode laminate. A sealant which is provided so as to surround the side surface of the body and forms an internal space between adjacent electrodes and seals the internal space, and an electrolytic solution containing an alkaline solution contained in the internal space are provided. The negative electrode terminal electrode includes an electrode plate including one surface and the other surface on the opposite side of the one surface, and an excess space is formed by the encapsulant and the electrode plate of the negative electrode terminal electrode. It includes a first sealing portion bonded to one surface of the electrode plate of the terminal electrode, and a second sealing portion bonded to the other surface of the electrode plate of the negative electrode terminal electrode and the electrode plate of the bipolar electrode.

In this power storage module, the sealing body includes a first sealing portion bonded to one surface of the electrode plate of the negative electrode terminal electrode and a second sealing portion bonded to the other surface of the electrode plate of the negative electrode terminal electrode. Have. Therefore, a surplus space is formed by the sealing body and the electrode plate of the negative electrode terminal electrode on the moving path of the electrolytic solution due to the alkaline creep phenomenon, and the surplus space is the first sealing portion and the second sealing portion. Will be sealed in two stages. By forming such a surplus space, it is possible to prevent moisture in the outside air from entering between the second sealing portion, which is the starting point for the electrolytic solution to exude, and the electrode plate of the negative electrode terminal electrode. Further, the rigidity of the second sealing portion is increased by joining the second sealing portion to both the electrode plate of the negative electrode terminal electrode and the electrode plate of the bipolar electrode. As a result, it is possible to prevent the second sealing portion from peeling off from the electrode plate of the negative electrode terminal electrode due to the alkaline creep phenomenon, and it is possible to suppress the progress of the alkaline creep phenomenon. Therefore, in this power storage module, it is possible to prevent the electrolytic solution from seeping out of the power storage module due to the alkaline creep phenomenon.

The first sealing portion and the second sealing portion form an integral coupling by heat welding, and the surplus space may be formed by the coupling and the electrode plate of the negative electrode terminal electrode. By doing so, the configuration around the negative electrode terminal electrode can be unitized, so that the manufacturing process of the power storage module can be facilitated.

The electrode plate may be roughened in the joint region between at least one of the first sealing portion and the second sealing portion and the electrode plate of the negative electrode terminal electrode. According to this configuration, it is possible to improve the bonding strength between at least one of the first sealing portion and the second sealing portion and the electrode plate of the negative electrode terminal electrode by the anchor effect. Therefore, the peeling of the first sealing portion and the second sealing portion can be further suppressed, and the progress of the alkaline creep phenomenon can be further suppressed.

The method for manufacturing a power storage module according to another aspect of the present invention includes a first step of forming a bipolar electrode unit including a plurality of bipolar electrodes and a second step of forming a negative electrode terminal unit including a bipolar electrode and a negative electrode terminal electrode. The process, the third step of joining the negative electrode terminal electrode unit to one end of the bipolar electrode unit to form the electrode laminate, and the third step of forming the electrode laminate so as to surround the side surface of the electrode laminate to seal the electrode laminate. The fourth step is provided. In the second step, the first resin body is bonded to one surface of the electrode plate of the negative electrode terminal electrode, and the second resin body is bonded to the other surface of the electrode plate of the negative electrode terminal electrode and the electrode plate of the bipolar electrode. In the fourth step, an excess space is formed by the sealing body and the electrode plate of the negative electrode terminal electrode.

In this method of manufacturing a power storage module, the first resin body is bonded to one surface of the electrode plate of the negative electrode terminal electrode, and the second resin body is bonded to the other surface of the electrode plate of the negative electrode terminal electrode. Therefore, a surplus space is formed by the sealing body and the electrode plate of the negative electrode terminal electrode on the moving path of the electrolytic solution due to the alkaline creep phenomenon, and the surplus space is the first sealing portion and the second sealing portion. Will be sealed in two stages. By forming such a surplus space, it is possible to prevent moisture in the outside air from entering between the second resin body, which is the starting point for the electrolytic solution to exude, and the electrode plate of the negative electrode terminal electrode. Further, by joining the second resin body to both the electrode plate of the negative electrode terminal electrode and the electrode plate of the bipolar electrode, the synthesis of the second resin body is enhanced. As a result, it is possible to prevent the second sealing portion from peeling off from the electrode plate of the negative electrode terminal electrode due to the alkaline creep phenomenon, and it is possible to suppress the progress of the alkaline creep phenomenon. Therefore, in this power storage module, it is possible to prevent the electrolytic solution from seeping out of the power storage module due to the alkaline creep phenomenon.

In the second step, the outer edge of the first resin body and the outer edge of the second resin body may be heat-welded. In this case, since the configuration around the negative electrode terminal electrode can be unitized, the manufacturing process of the power storage module can be facilitated.

The outer edge of the first resin body and the outer edge of the second resin body may be heat-welded between the third step and the fourth step. In this case, since the configuration around the negative electrode terminal electrode can be unitized, the manufacturing process of the power storage module can be facilitated.

According to the present invention, there is provided a power storage module capable of suppressing the electrolytic solution from seeping out of the power storage module due to the alkaline creep phenomenon.

It is a schematic sectional drawing which shows the power storage device which concerns on one Embodiment. It is the schematic sectional drawing which shows the internal structure of the power storage module shown in FIG. It is an enlarged sectional view which shows a part of the power storage module of FIG. It is a flowchart which shows one Embodiment of the manufacturing method of the power storage module. It is a partially enlarged sectional view of the power storage module which concerns on a comparative example. It is an enlarged sectional view which shows a part of the power storage module in the power storage device which concerns on the modification of this embodiment.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate description will 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 restraint member 3 that applies a restraining load to the module stack 2 in the stacking direction of the module stack 2.

The module laminate 2 includes a plurality of (three in this case) power storage modules 4 and a plurality of (four in this case) conductive plates 5. The power storage module 4 is a bipolar battery and has a substantially rectangular shape when viewed from the stacking direction. The power storage module 4 is, for example, a nickel hydrogen secondary battery, a secondary battery such as a lithium ion secondary battery, an electric double layer capacitor, or the like. In the following description, a nickel-metal hydride secondary battery will be illustrated.

The power storage modules 4 adjacent to each other in the stacking direction are electrically connected to each other 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 modules 4 located at the stacking ends. A positive electrode terminal 6 is connected to one of the conductive plates 5 arranged outside the power storage module 4 located at the laminated end. The negative electrode terminal 7 is connected to the other conductive plate 5 arranged outside the power storage module 4 located at the laminated end. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out from the edge of the conductive plate 5, for example, in a direction intersecting with each other in the stacking direction. The positive electrode terminal 6 and the negative electrode terminal 7 charge and discharge the power storage device 1.

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

The restraint member 3 is composed of 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 to each other. The end plate 8 is a substantially rectangular metal plate having an area one size larger than the area of the power storage module 4 and the conductive plate 5 when viewed from the stacking direction. A film F having electrical insulation is provided on the surface of the end plate 8 on the module laminate 2 side. The film F insulates between the end plate 8 and the conductive plate 5.

An insertion hole 8a 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 8a of one end plate 8 toward the insertion hole 8a of the other end plate 8, and is attached to the tip portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. , The nut 10 is screwed. As a result, the power storage module 4 and the conductive plate 5 are sandwiched by the end plates 8 to be unitized as the module laminate 2, and a restraining load is applied to the module laminate 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 the internal configuration of the power storage module shown in FIG. FIG. 3 is an enlarged cross-sectional view showing a part of the power storage module of FIG. As shown in FIGS. 2 and 3, the power storage module 4 includes an electrode laminate 11 and a resin sealant 12 that seals the electrode laminate 11. The electrode laminate 11 is composed of a plurality of electrodes laminated along the stacking direction D of the power storage module 4 via the separator 13. These electrodes are arranged on a laminated body of a plurality of bipolar electrodes 14, a negative electrode terminal electrode 18 arranged on one end side of the laminated body in the stacking direction D, and on the other end side of the laminated body in the stacking direction D. Includes a positive electrode termination electrode 19.

The electrode laminate 11 includes a negative electrode terminal unit 31 including one bipolar electrode 14 and a negative electrode terminal electrode 18, and a bipolar electrode unit 32 including a plurality of bipolar electrodes 14. The negative electrode terminal electrode unit 31 is joined to one end of the bipolar electrode unit 32. Along the stacking direction D, the bipolar electrode 14 of the negative electrode terminal electrode unit 31 is laminated on the bipolar electrode 14 on one end side of the bipolar electrode unit 32 with the separator 13 interposed therebetween. In the negative electrode terminal unit 31, the negative electrode terminal 18 is laminated on the bipolar electrode 14 with the separator 13 interposed therebetween along the stacking direction D.

The bipolar electrode 14 has an electrode plate 15 including one surface 15a and the other surface 15b on the opposite side of the one surface 15a, a positive electrode 16 provided on the one surface 15a, and a negative electrode 17 provided on the other surface 15b. ing. The positive electrode 16 is a positive electrode active material layer formed by coating the electrode plate 15 with the positive electrode active material. The negative electrode 17 is a negative electrode active material layer formed by applying the negative electrode active material to the electrode plate 15. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to one of the stacking directions D with the separator 13 interposed therebetween. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent to the other in the stacking direction D with the separator 13 interposed therebetween.

The negative electrode terminal electrode 18 has an electrode plate 15 and a negative electrode 17 provided on the other surface 15b of the electrode plate 15. The negative electrode terminal electrode 18 is arranged at one end of the stacking direction D so that the other surface 15b faces the center side of the stacking direction D in the electrode laminated body 11. One surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 constitutes one outer surface of the electrode laminate 11 in the stacking direction D, and is electrically connected to the one conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. It is connected to the. The negative electrode 17 provided on the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D via the separator 13.

The positive electrode terminal electrode 19 has an electrode plate 15 and a positive electrode 16 provided on one surface 15a of the electrode plate 15. The positive electrode terminal electrode 19 is arranged at the other end of the stacking direction D so that one surface 15a faces the center side of the stacking direction D in the electrode laminated body 11. The positive electrode 16 provided on one surface 15a 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 other surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19 constitutes the other outer surface in the stacking direction of the electrode laminate 11, and is electrically connected to the other conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. It is connected.

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

The separator 13 is formed on a sheet, 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 made of polypropylene, polypropylene, methyl cellulose and the like, or a non-woven fabric. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 is not limited to a sheet shape, and a bag shape may be used.

The sealing body 12 is formed in a substantially rectangular tubular shape as a whole by, for example, an insulating resin. The sealing body 12 is provided on the side surface 11a of the electrode laminated body 11 so as to surround the edge portion 15c of the electrode plate 15. That is, the sealing body 12 is provided so as to surround the side surface 11a of the electrode laminated body 11. The sealing body 12 holds the edge portion 15c on the side surface 11a. The sealing body 12 surrounds the plurality of electrode support portions 21 joined to the edge portion 15c of the electrode plate 15 and the plurality of electrode support portions 21 along the side surface 11a from the outside, and each of the plurality of electrode support portions 21. Includes a housing portion 22 joined to. The electrode support portion 21 and the housing portion 22 are, for example, an insulating resin having alkali resistance. Examples of the constituent materials of the electrode support portion 21 and the housing portion 22 include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

Each electrode support portion 21 is continuously provided on one surface 15a of the electrode plate 15 over the entire circumference of the edge portion 15c, and has a substantially rectangular frame shape when viewed from the stacking direction D. The cross section of each electrode support portion 21 is substantially rectangular. The electrode support portion 21 is welded to the electrode plate 15 by, for example, ultrasonic waves or heat, and is airtightly bonded. The electrode support portion 21 is, for example, a film having a predetermined thickness in the stacking direction D. The inside of each electrode support portion 21 overlaps with the edge portion 15c of the electrode plate 15 when viewed from the stacking direction D. The outside of each electrode support portion 21 projects outward from the edge of the electrode plate 15, and the tip portion thereof is supported by the housing portion 22.

The plurality of electrode support portions 21 include a first sealing portion 41 (first resin body), a second sealing portion 42 (second resin body), a plurality of third sealing portions 43 (third resin body), and a first. It includes a 4 sealing portion 44 (fourth resin body) and a fifth sealing portion 45 (fifth resin body). The first sealing portion 41 and the second sealing portion 42 are included in the negative electrode terminal electrode unit 31 described above. The plurality of third sealing portions 43, the fourth sealing portion 44, and the fifth sealing portion 45 are included in the bipolar electrode unit 32 described above.

The first sealing portion 41 is joined to the edge portion 15c of the one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18. The first sealing portion 41 is airtightly joined on one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 over the entire circumference of the edge portion 15c. In the present embodiment, the first sealing portion 41 is in contact with only the housing portion 22 without being bonded to the electrode plate 15 on the surface opposite to the surface bonded to one surface 15a of the negative electrode terminal electrode 18. ..

The second sealing portion 42 is joined to the edge portion 15c of the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18 and the edge portion 15c of the electrode plate 15 of the bipolar electrode 14 facing the negative electrode terminal electrode 18. ing. That is, the second sealing portion 42 is sandwiched between the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18 and the edge portion 15c of the electrode plate 15 of the bipolar electrode 14. The second sealing portion 42 is airtightly joined over the entire circumference of the edge portion 15c of the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18. The second sealing portion 42 is airtightly joined over the entire circumference of the edge portion 15c of the one side surface 15a of the electrode plate 15 of the bipolar electrode 14.

The plurality of third sealing portions 43 are each of the other surface 15b of the electrode plate 15 of the bipolar electrode 14 and the one surface 15a of the electrode plate 15 of another bipolar electrode 14 adjacent to the bipolar electrode 14 with the separator 13 interposed therebetween. Is joined with. That is, each third sealing portion 43 is sandwiched between the edge portions 15c of the electrode plates 15 of the two bipolar electrodes 14 adjacent to each other. Each third sealing portion 43 is airtightly joined over the entire circumference of the edge portion 15c of one surface 15a of the electrode plate 15 of the bipolar electrodes 14 adjacent to each other and the entire circumference of the edge portion 15c of the other surface 15b. There is.

The fourth sealing portion 44 is joined to the edge portion 15c of one surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19 and the edge portion 15c of the electrode plate 15 of the bipolar electrode 14 facing the positive electrode terminal electrode 19. ing. That is, the fourth sealing portion 44 is sandwiched between the edge portion 15c of the electrode plate 15 of the positive electrode terminal electrode 19 and the edge portion 15c of the electrode plate 15 of the bipolar electrode 14. The fourth sealing portion 44 is airtightly joined over the entire circumference of the edge portion 15c of the one side surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19. The fourth sealing portion 44 is airtightly joined over the entire circumference of the edge portion 15c of the other surface 15b of the electrode plate 15 of the bipolar electrode 14.

The fifth sealing portion 45 is joined to the edge portion 15c of the other surface 15b (outer surface side) of the electrode plate 15 of the positive electrode terminal electrode 19. The fifth sealing portion 45 is airtightly joined over the entire circumference of the edge portion 15c of the electrode plate 15 of the positive electrode terminal electrode 19. In the present embodiment, the fifth sealing portion 45 is joined to the housing portion 22 on the surface opposite to the surface of the positive electrode terminal electrode 19 which is joined to the electrode plate 15.

The surface of the electrode plate 15 is roughened in the joint region K where the edge portion 15c of the electrode plate 15 and the electrode support portion 21 are joined. It is sufficient that the electrode plate 15 is roughened in the joint region K between at least one of the first sealing portion 41 and the second sealing portion 42 and the electrode plate 15 of the negative electrode terminal electrode 18. In the present embodiment, the joint region between the electrode plate 15 and all of the first sealing portion 41, the second sealing portion 42, the third sealing portion 43, the fourth sealing portion 44, and the fifth sealing portion 45. At K, the electrode plate 15 is roughened. In the present embodiment, the entire one surface 15a and the other surface 15b of the electrode plate 15 are roughened. Only the joint region K may be roughened.

Roughening can be achieved, for example, by forming a plurality of protrusions by electroplating. By forming a plurality of protrusions on one surface 15a and the other surface 15b, a plurality of molten resins are formed by roughening at the bonding interface with the electrode support portion 21 on the one surface 15a and the other surface 15b. Get in between the protrusions. As a result, the anchor effect is exhibited. As a result, the joint strength between the electrode plate 15 and the electrode support portion 21 can be improved. The protrusions formed at the time of roughening have a shape in which the protrusions formed on the surface become thicker from the base end to the tip end side, for example, with the convex portion formed on the surface as the base end. As a result, the cross-sectional shape between the adjacent protrusions becomes an undercut shape, and the anchor effect can be enhanced.

The housing portion 22 is provided outside the electrode laminate 11 and the electrode support portion 21, and constitutes the outer wall of the power storage module 4. The housing portion 22 is formed by, for example, injection molding of a resin, and extends along the stacking direction D over the entire length of the electrode laminate 11. The housing portion 22 has a substantially rectangular tubular shape (frame shape) extending with the stacking direction D as the axial direction. The housing portion 22 is welded to the outer surface of the electrode support portion 21 by heat during injection molding, for example.

The electrode support portion 21 and the housing portion 22 (sealing body 12) form an internal space V between adjacent electrodes and seal the internal space V. In the present embodiment, the housing portion 22 together with the electrode support portion 21 is between the bipolar electrodes 14 adjacent to each other along the stacking direction D, and the negative electrode termination electrodes 18 and the bipolar electrodes 14 adjacent to each other along the stacking direction D. And between the positive electrode termination electrode 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D, respectively. As a result, an airtightly partitioned internal space V is formed between the adjacent bipolar electrodes 14, between the negative electrode terminal 18 and the bipolar electrode 14, and between the positive electrode 19 and the bipolar electrode 14. ing. An electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution is housed in the internal space V. The electrolytic solution is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

In the negative electrode terminal electrode unit 31, a surplus space VA is formed by the first sealing portion 41, the second sealing portion 42, the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18, and the housing portion 22. ing. That is, the surplus space VA is formed by the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18. The excess space VA does not contain the electrolytic solution. The surplus space VA is provided on the movement path of the electrolytic solution when the alkaline creep phenomenon occurs in the power storage module 4. The surplus space VA is formed so as to surround the periphery of the electrode plate 15 of the negative electrode terminal electrode 18 when viewed from the stacking direction D. Further, the surplus space VA is substantially rectangular when viewed from the cross section along the stacking direction D.

Next, an example of a method for manufacturing the power storage module 4 will be described with reference to FIG. FIG. 4 is a flowchart showing an embodiment of the above-described storage module manufacturing method.

First, the negative electrode terminal electrode unit 31 and the bipolar electrode unit 32 are formed, respectively (step S1). In forming the negative electrode terminal unit 31, one bipolar electrode 14 and a negative electrode terminal 18 are prepared. Subsequently, the negative electrode terminal electrode 18 and the bipolar electrode 14 are laminated via the separator 13. Subsequently, the first resin body (first sealing portion 41) is joined to the edge portion 15c of the one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18. A second resin body (second sealing portion 42) is bonded to the edge portion 15c of the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18 and the edge portion 15c of the one surface 15a of the electrode plate 15 of the bipolar electrode 14. From this, the negative electrode terminal electrode unit 31 is formed.

In forming the bipolar electrode unit 32, a predetermined number of bipolar electrodes 14 and positive electrode termination electrodes 19 are prepared. Subsequently, the plurality of bipolar electrodes 14 and the positive electrode termination electrodes 19 are laminated via the separator 13. Subsequently, a third resin body (third sealing portion 43) is bonded to the edge portion 15c of the one surface 15a of the electrode plate 15 of each bipolar electrode 14 and the edge portion 15c of the other surface 15b. A fourth resin body (fourth sealing portion) is formed on an edge portion 15c of one surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19 and an edge portion 15c of the electrode plate 15 of the bipolar electrode 14 facing the positive electrode terminal electrode 19. 44) are joined. A fifth resin body (fifth sealing portion 45) is joined to the edge portion 15c of the other surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19. As a result, the bipolar electrode unit 32 is formed.

Next, the negative electrode terminal electrode unit 31 is joined to one end of the bipolar electrode unit 32 to form the electrode laminate 11 (step S2). At this time, the bipolar electrode 14 of the negative electrode terminal electrode unit 31 is laminated on the bipolar electrode 14 on one end side of the bipolar electrode unit 32 via the separator 13.

Next, after arranging the electrode laminate 11 in the injection molding mold (not shown), the molten resin is injected into the mold to surround the electrode support portion 21 so as to surround the housing portion 22 (sealing). The stopper 12) is molded (step S3). That is, the sealing body 12 is formed so as to surround the side surface 11a of the electrode laminated body 11, and the electrode laminated body 11 is sealed. As a result, the excess space VA is formed by the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18. Next, the electrolytic solution is injected into the internal space V between the bipolar electrodes 14 and 14 (step S4). By the above steps, the power storage module 4 is obtained.

Next, the operation and effect of the power storage module 4 will be described with reference to FIG. FIG. 5 is an enlarged cross-sectional view of a main part of the power storage module according to the comparative example. As shown in FIG. 5, in the power storage module 100 according to the comparative example, the electrode support portion 21 (sealing body 12) is bonded only to one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and the electrode is attached to the other surface 15b. The support portion 21 is not joined.

In the power storage module 100, the electrolytic solution existing in the internal space V propagates on the surface of the electrode plate 15 of the negative electrode terminal electrode 18 due to the so-called alkaline creep phenomenon, and the gap between the electrode plate 15 and the electrode support portion 21 in the bonding region K. It may seep out to the one side 15a side of the electrode plate 15 through the electrode plate 15. In FIG. 5, the movement path of the electrolytic solution L in the alkaline creep phenomenon is indicated by an arrow A. This alkaline creep phenomenon can occur during charging and discharging of the power storage device and when there is no load due to an electrochemical factor and a fluid phenomenon. The alkaline creep phenomenon occurs due to the existence of the negative electrode potential, the water content, and the passage of the electrolytic solution L, and progresses with the passage of time.

On the other hand, in the power storage module 4 according to the present embodiment, the first sealing portion 41 (first resin body) is bonded to one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and the second sealing portion 42 (1st resin body) The second resin body) is joined to the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18. Therefore, a surplus space VA is formed by the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18 on the moving path of the electrolytic solution due to the alkaline creep phenomenon, and the surplus space VA is the first sealing portion 41. And it is sealed in two stages by the second sealing portion 42. By forming such a surplus space VA, it is possible to prevent moisture in the outside air from entering between the second sealing portion 42, which is the starting point for the electrolytic solution to exude, and the electrode plate 15 of the negative electrode terminal electrode 18. ..

Further, the rigidity of the second sealing portion 42 is increased by joining the second sealing portion 42 to both the electrode plate 15 of the negative electrode terminal electrode 18 and the electrode plate 15 of the bipolar electrode 14. As a result, it is possible to prevent the second sealing portion 42 from peeling off from the electrode plate 15 of the negative electrode terminal electrode 18 due to the alkaline creep phenomenon, and it is possible to suppress the progress of the alkaline creep phenomenon. Therefore, in the power storage module 4, it is possible to prevent the electrolytic solution from seeping out of the power storage module 4 due to the alkaline creep phenomenon.

The electrode plate 15 is roughened in the joint region K between the first sealing portion 41 and the second sealing portion 42 and the electrode plate 15 of the negative electrode terminal electrode 18. According to this configuration, the bonding strength between the first sealing portion 41 and the second sealing portion 42 and the electrode plate 15 of the negative electrode terminal electrode 18 can be improved by the anchor effect. Therefore, the peeling of the first sealing portion 41 and the second sealing portion 42 can be further suppressed, and the progress of the alkaline creep phenomenon can be further suppressed.

Next, the power storage module 50 according to the modified example will be described with reference to FIG. FIG. 6 is an enlarged cross-sectional view showing a part of the power storage module 50. FIG. 6 shows a part corresponding to a part of the power storage module 4 shown in FIG.

Like the power storage module 4, the power storage module 50 includes an electrode laminate 11 and a resin sealant 12 that seals the electrode stack 11. The sealing body 12 surrounds the plurality of electrode support portions 21 joined to the edge portion 15c of the electrode plate 15 and the plurality of electrode support portions 21 along the side surface 11a from the outside, and each of the plurality of electrode support portions 21. Includes a housing portion 22 joined to. The plurality of electrode support portions 21 include a first sealing portion 41 (first resin body), a second sealing portion 42 (second resin body), and a plurality of third sealing portions 43 (third resin body). The fourth sealing portion 44 (fourth resin body) and the fifth sealing portion 45 (fifth resin body) are included. The power storage module 50 is different from the power storage module 4 in that the first sealing portion 41 and the second sealing portion 42 are joined by heat welding.

In the power storage module 50, the first sealing portion 41 and the second sealing portion 42 are integrally formed by the heat welding portion 47. In the present embodiment, the heat welding portion 47 is formed by hot plate welding. The heat-welded portion 47 surrounds the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18. The heat-welded portion 47 has a substantially rectangular frame shape when viewed from the stacking direction D, and is continuously provided over the entire circumference. Therefore, in the negative electrode terminal unit 31 of the power storage module 50, the first sealing portion 41, the second sealing portion 42, the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18, and the heat welding portion 47 are used. A surplus space VB is formed instead of the surplus space VA. That is, the surplus space VB is formed by the coupling 55 and the electrode plate 15 of the negative electrode terminal electrode 18.

The excess space VB does not contain the electrolytic solution. The surplus space VB is provided on the movement path of the electrolytic solution when the alkaline creep phenomenon occurs in the power storage module 4. When viewed from the stacking direction D, the surplus space VB is formed so as to surround the periphery of the electrode plate 15 of the negative electrode terminal electrode 18. Further, the surplus space VB is substantially rectangular when viewed from the cross section along the stacking direction D.

Next, an example of a method for manufacturing the power storage module 50 will be described. The method for manufacturing the power storage module 50 is a method for manufacturing the power storage module 4 in that it includes a step of heat welding the first resin body (first sealing portion 41) and the second resin body (second sealing portion 42). Is different from.

In the method of manufacturing the power storage module 50, first, the negative electrode terminal electrode unit 31 and the bipolar electrode unit 32 are formed, respectively, as in the method of manufacturing the power storage module 4 (step S1). At this time, in forming the negative electrode terminal unit 31, the first resin body is bonded to the edge portion 15c of the one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and the second resin body is bonded to the electrode plate 15 of the negative electrode terminal electrode 18. The edge portion 15c of the other surface 15b of the above and the edge portion 15c of the one surface 15a of the electrode plate 15 of the bipolar electrode 14 are joined. After that, the outer edge of the first resin body and the outer edge of the second resin body are hot-plate welded to each other.

By the hot plate welding described above, the heat welding portion 47 is formed between the first resin body and the second resin body. As a result, an integral composite body 55 including the first resin body and the second resin body is formed. A surplus space VB is formed between the coupling body 55 which becomes the sealing body 12 and the electrode plate 15 of the negative electrode terminal electrode 18 by the step described later. In the negative electrode terminal electrode unit 31, the first resin body and the second resin body function as the first sealing portion 41 and the second sealing portion 42, respectively.

Next, the negative electrode terminal electrode unit 31 is joined to one end of the bipolar electrode unit 32 to form the electrode laminate 11 (step S2). At this time, the bipolar electrode 14 of the negative electrode terminal electrode unit 31 is laminated on the bipolar electrode 14 on one end side of the bipolar electrode unit 32 via the separator 13. Next, after arranging the electrode laminate 11 in the injection molding mold (not shown), the molten resin is injected into the mold to surround the electrode support portion 21 so as to surround the housing portion 22 (sealing). The stopper 12) is molded (step S3). That is, the sealing body 12 is formed so as to surround the side surface 11a of the electrode laminated body 11, and the electrode laminated body 11 is sealed. Next, the electrolytic solution is injected into the internal space V between the bipolar electrodes 14 and 14 (step S4). By the above steps, the power storage module 50 is obtained.

The thermal welding of the outer edge of the first resin body and the outer edge of the second resin body is not limited to the order of the steps described above. For example, after the outer edge of the first resin body and the outer edge of the second resin body are hot-plate welded, the first resin body is bonded to one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18, and the second resin body is the negative electrode. The other surface 15b of the electrode plate 15 of the terminal electrode 18 and the one surface 15a of the electrode plate 15 of the bipolar electrode 14 may be joined. After joining the bipolar electrode unit 32 and the negative electrode terminal electrode unit 31 to form the electrode laminate 11, the outer edge of the first resin body and the outer edge of the second resin body are heated before molding the housing portion 22. Plate welding may be performed.

Next, the operation and effect of the power storage module 50 will be described. In the power storage module 50, the first sealing portion 41 (first resin body) and the second sealing portion 42 (second resin body) form an integral combined body 55 by heat welding. The surplus space VB is formed by the coupling 55 and the electrode plate 15 of the negative electrode terminal electrode 18. In this case, since the configuration around the negative electrode terminal electrode 18 can be unitized, the manufacturing process of the power storage module 50 can be facilitated.

4,50 ... power storage module, 11 ... electrode laminate, 11a ... side surface, 12 ... sealant, 14 ... bipolar electrode, 15 ... electrode plate, 15a ... one side, 15b ... other side, 18 ... negative electrode terminal electrode, 31 ... Negative electrode termination electrode unit, 32 ... Bipolar electrode unit, 41 ... First sealing portion (first resin body), 42 ... Second sealing portion (second resin body), 55 ... Combined body, D ... Lamination direction, K ... junction region, V ... internal space, VA, VB ... A surplus space.

Claims (6)

An electrode laminate composed of a laminate of a plurality of bipolar electrodes and a negative electrode terminal electrode arranged on one end side in the lamination direction of the laminate.
A sealing body provided so as to surround the side surface of the electrode laminate, forming an internal space between adjacent electrodes and sealing the internal space.
An electrolytic solution containing an alkaline solution housed in the internal space is provided.
The negative electrode terminal electrode includes an electrode plate including one surface and the other surface on the opposite side of the one surface.
An excess space is formed by the sealing body and the electrode plate of the negative electrode terminal electrode.
The sealing body includes a first sealing portion bonded to the one surface of the electrode plate of the negative electrode terminal electrode, the other surface of the electrode plate of the negative electrode terminal electrode, and an electrode plate of the bipolar electrode. A power storage module including a second sealing portion joined to. The first sealing portion and the second sealing portion are integrally formed by a heat welding portion.
The power storage module according to claim 1, wherein the surplus space is formed by the coupling and the electrode plate of the negative electrode terminal electrode. The power storage according to claim 1 or 2, wherein the electrode plate is roughened in a joint region between at least one of the first sealing portion and the second sealing portion and the electrode plate of the negative electrode terminal electrode. module. The first step of forming a bipolar electrode unit including a plurality of bipolar electrodes,
The second step of forming the negative electrode terminal electrode unit including the bipolar electrode and the negative electrode terminal electrode, and
The third step of joining the negative electrode terminal electrode unit to one end of the bipolar electrode unit to form an electrode laminate, and
A fourth step of forming a sealing body so as to surround the side surface of the electrode laminated body and sealing the electrode laminated body is provided.
In the second step, the first resin body is bonded to one surface of the electrode plate of the negative electrode terminal electrode, and the second resin body is bonded to the other surface of the electrode plate of the negative electrode terminal electrode and the electrode plate of the bipolar electrode. Join and
A method for manufacturing a power storage module, wherein in the fourth step, an excess space is formed by the sealing body and the electrode plate of the negative electrode terminal electrode. The method for manufacturing a power storage module according to claim 4, wherein in the second step, the outer edge of the first resin body and the outer edge of the second resin body are heat-welded. The method for manufacturing a power storage module according to claim 4, wherein the outer edge of the first resin body and the outer edge of the second resin body are heat-welded between the third step and the fourth step.

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