JP7079694B2 - Power storage module - Google Patents

Description

The present invention relates to a 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 laminate is arranged at one end of the electrode laminate in the stacking direction. The electrode plate of this negative electrode terminal electrode is also sealed by the encapsulant. 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 into. If the electrolytic solution leaks to the outside of the power storage module and diffuses, for example, corrosion of the conductive plate arranged in contact with the power storage module, short circuit between the power storage module and the restraint member, and the like may occur.

The present invention has been made to solve the above problems, and to provide 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 in which a plurality of bipolar electrodes are laminated and a negative electrode terminal electrode arranged at one end of the laminate in the stacking direction. A metal plate laminated on the outside of the negative electrode termination electrode, a sealant provided so as to surround the side surface of the electrode laminate, forming an internal space between adjacent electrodes, and sealing the internal space, and the inside. An electrolytic solution containing an alkaline solution housed in a space is provided, and the encapsulating body includes a first encapsulating portion bonded to a peripheral portion of a metal plate and an electrode plate of a negative electrode terminal electrode, and an electrode of a bipolar electrode. It has a second sealing portion bonded to the peripheral edge of the plate, and the electrode plate of the negative electrode terminal electrode, the metal plate, and the first sealing portion form an extra space in which the electrolytic solution is not accommodated. The thickness of the 1-sealed portion is smaller than the thickness of the 2nd sealed portion.

In this power storage module, the first sealing portion is bonded to both the electrode plate and the metal plate of the negative electrode terminal electrode, so that the sealing structure of the surplus space on the movement path of the electrolytic solution due to the alkaline creep phenomenon is in two stages. Is formed in. Further, by joining the metal plate to the first sealing portion, the rigidity of the first sealing portion is increased. As a result, the first sealing portion is suppressed from peeling from the electrode plate of the negative electrode termination electrode due to the alkaline creep phenomenon, and the progress of the alkaline creep phenomenon can be suppressed. Further, in this power storage module, the thickness of the first sealing portion is smaller than the thickness of the second sealing portion. As a result, the volume of the surplus space can be sufficiently suppressed, and the water content existing in the space can be suppressed. By suppressing the amount of water existing in the surplus space, the progress of the alkaline creep phenomenon can be suppressed more reliably. As described above, 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.

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

The thickness of the first sealing portion may be larger than the maximum value of the heights of the plurality of protrusions formed by roughening on at least one of the electrode plate and the metal plate of the negative electrode terminal electrode. According to this configuration, it is possible to prevent the rough surface from penetrating the first sealing portion.

A third sealing portion may be joined to the peripheral edge portion on the outer surface side of the metal plate. According to this configuration, a three-stage sealing structure is formed on the moving path of the electrolytic solution due to the alkaline creep phenomenon.

In the joint region between the metal plate and the third sealing portion, the metal plate may be roughened. According to this configuration, the bonding strength between the third sealing portion and the metal plate can be improved by the anchor effect. Therefore, the peeling of the third sealing portion can be further suppressed, and the progress of the alkaline creep phenomenon can be further suppressed.

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. FIG. 3 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. 1. It is an enlarged sectional view which shows a part of the power storage module of FIG. It is a partially enlarged sectional view of the power storage module which concerns on a comparative example. It is a partially enlarged sectional view of the power storage module which concerns on a comparative example.

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 stack 2 includes a plurality of (here, three) power storage modules 4 and a plurality of (here, four) conductive plates 5. The power storage module 4 is a bipolar battery and has a substantially rectangular shape when viewed from the stacking direction. The power storage module 4 is, for example, a nickel-metal hydride 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 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 through which a refrigerant such as air flows 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 dissipation 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 plate 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 is laminated on the electrode laminate 11, the resin sealant 12 that seals the electrode laminate 11, and one end of the electrode laminate 11. It is provided with a metal plate 50. 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 metal plate 50 is laminated on the outside of the negative electrode termination electrode 18 of the electrode laminate 11. In other words, the negative electrode termination electrode 18 is arranged between the bipolar electrode 14 and the metal plate 50. A part of the metal plate 50 is in contact with the negative electrode termination electrode 18.

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 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 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 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 of the electrode laminate 11 in the stacking direction, 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 leaf made of nickel. The peripheral 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 of, for example, an insulating resin into a substantially rectangular cylinder as a whole. The sealing body 12 is provided on the side surface 11a of the electrode laminated body 11 so as to surround the peripheral 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 peripheral edge portion 15c on the side surface 11a. The sealing body 12 surrounds the plurality of electrode support portions 21 joined to the peripheral 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), modified polyphenylene ether (modified PPE), and the like.

Each electrode support portion 21 is continuously provided on one surface 15a of the electrode plate 15 over the entire circumference of the peripheral edge portion 15c, and has a substantially rectangular frame shape when viewed from the stacking direction D. 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 peripheral 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 housing portion 22 is provided on the outside of 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, for example, by 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 has a negative electrode terminal electrode 18 and a bipolar electrode 14 adjacent to each other along the stacking direction D between 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 termination electrode 18 and the bipolar electrode 14, and between the positive electrode termination electrode 19 and the bipolar electrode 14. ing. The internal space V contains an electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution. The electrolytic solution is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

The metal plate 50 includes a one-sided surface 50a facing the negative electrode termination electrode 18 and the other side surface 50b on the opposite side of the one-sided surface 50a. The metal plate 50 has a peripheral edge portion 50c and a central portion 50d surrounded by the peripheral edge portion 50c. The metal plate 50 has a substantially rectangular shape when viewed from the stacking direction D. The peripheral edge portion 50c has a substantially rectangular frame shape. The peripheral portion 50c and the central portion 50d are continuous with each other. One surface 50a of the metal plate 50 is in contact with one surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 at the central portion 50d. The metal plate 50 can be made of any metal, but can be the same as the electrode plate 15 as an example. For example, the metal plate 50 is a metal foil (uncoated foil) on which an active substance layer is not formed.

The plurality of electrode support portions 21 include a first resin portion 41 (third sealing portion), a second resin portion 42 (first sealing portion), a third resin portion 43, and a plurality of fourth resin portions 44 (second sealing portion). A sealing portion), a fifth resin portion 45, and a sixth resin portion 46 are included. The first resin portion 41 (third sealing portion) is joined to the peripheral edge portion 50c of the other surface 50b (outer surface side) of the metal plate 50. The first resin portion 41 is airtightly joined over the entire circumference of the peripheral edge portion 50c of the other surface 50b of the metal plate 50. In the present embodiment, the first resin portion 41 is in contact with the housing portion 22 on the surface opposite to the peripheral surface 50c of the other surface 50b of the metal plate 50.

The second resin portion 42 is located between the peripheral edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18 and the peripheral edge portion 50c of the metal plate 50. The second resin portion 42 is joined to the peripheral edge portion 15c of the one side surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 and the peripheral edge portion 50c of the one side surface 50a of the metal plate 50. The second resin portion 42 is airtightly bonded over the entire circumference of the peripheral edge portion 15c of the one side surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18. The second resin portion 42 is airtightly joined over the entire circumference of the peripheral edge portion 50c of the one side surface 50a of the metal plate 50. The second resin portion 42 and the first resin portion 41 are welded to each other at the outer edge.

The third resin portion 43 is located between the peripheral edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18 and the peripheral edge portion 15c of the electrode plate 15 of the bipolar electrode 14 facing the negative electrode terminal electrode 18. The third resin portion 43 is joined to the peripheral edge portion 15c of the one surface 15a of the electrode plate 15 of the bipolar electrode 14 facing the negative electrode terminal electrode 18. The third resin portion 43 is airtightly bonded over the entire circumference of the peripheral edge portion 15c of one surface 15a of the electrode plate 15 of the bipolar electrode 14 facing the negative electrode terminal electrode 18.

The plurality of fourth resin portions 44 each have a peripheral edge portion 15c of the electrode plate 15 of the bipolar electrode 14 and a peripheral edge portion 15c of the electrode plate 15 of another bipolar electrode 14 adjacent to the bipolar electrode 14 with the separator 13 interposed therebetween. It is located between. Each fourth resin portion 44 is bonded to at least one of bipolar electrodes adjacent to each other. In the present embodiment, each of the fourth resin portions 44 is joined to the peripheral edge portion 15c of the one side surface 15a of the electrode plate 15 of the bipolar electrode 14. Each of the fourth resin portions 44 is airtightly bonded over the entire circumference of the peripheral edge portion 15c of one surface 15a of the electrode plate 15 of the bipolar electrode 14.

The fifth resin portion 45 is located between the peripheral edge portion 15c of the electrode plate 15 of the positive electrode termination electrode 19 and the peripheral edge portion 15c of the electrode plate 15 of the bipolar electrode 14 facing the positive electrode termination electrode 19. The fifth resin portion 45 is joined to the peripheral edge portion 15c of the one side surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19. The fifth resin portion 45 is airtightly bonded over the entire circumference of the peripheral edge portion 15c of one surface 15a of the electrode plate 15 of the positive electrode terminal electrode 19.
The sixth resin portion 46 is joined to the peripheral edge portion 15c of the other surface 15b (outer surface side) of the electrode plate 15 of the positive electrode terminal electrode 19. The sixth resin portion 46 is airtightly bonded over the entire circumference of the peripheral edge portion 15c of the electrode plate 15 of the positive electrode terminal electrode 19. In the present embodiment, the sixth resin portion 46 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 K1 where the peripheral edge portion 15c of the electrode plate 15 and the electrode support portion 21 are joined. In the present embodiment, all of the second resin portion 42 (first sealing portion), the third resin portion 43, the fourth resin portion 44, the fifth resin portion 45, and the sixth resin portion 46 are provided with the electrode plate 15. In the joint region K1, the electrode plate 15 is roughened. In the present embodiment, the entire one surface 15a of the electrode plate 15 is roughened. Only the joint region K1 may be roughened.

In the joint region K2 where the peripheral edge portion 50c of the metal plate 50 and the electrode support portion 21 are joined, one surface 50a and the other surface 50b of the metal plate 50 are roughened. In the present embodiment, the metal plate 50 is rough in the joint region K2 between the first resin portion 41 (third sealing portion) and the second resin portion 42 (first sealing portion) and the peripheral portion 50c of the metal plate 50. It has been surfaced. In the present embodiment, the entire one surface 50a and the other surface 50b of the metal plate 50 are roughened. Only the joint region K2 may be roughened. The electrode plate 15 may be roughened only in the joint region K1 between the second resin portion 42 and the electrode plate 15 of the negative electrode end electrode 18, or may be formed with at least one of the first resin portion 41 and the second resin portion 42. The metal plate 50 may be roughened only in the joint region K2 with the metal plate 50.

Roughening can be achieved, for example, by forming a plurality of protrusions by electrolytic plating. By forming a plurality of protrusions on the surface of the electrode plate 15 or the metal plate 50, a molten resin is formed by roughening at the joint interface between the electrode plate 15 or the metal plate 50 and the electrode support portion 21. It gets in between multiple protrusions. As a result, the anchor effect is exhibited. As a result, the bonding strength between the electrode plate 15 or the metal plate 50 and the electrode support portion 21 can be improved. The protrusions formed during roughening have, for example, a shape in which the protrusions formed on the surface become thicker from the base end toward the tip end side 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.

In the power storage module 4, a surplus space VA is formed by the electrode plate 15 of the negative electrode terminal electrode 18, the metal plate 50, and the second resin portion 42. The excess space VA does not contain the electrolytic solution. The volume of the surplus space VA depends on the thickness T1 (length along the stacking direction D) of the second resin portion 42. In the present embodiment, the second resin portion 42, the third resin portion 43, the plurality of fourth resin portions 44, the fifth resin portion 45, and the sixth resin portion 46 all have a substantially rectangular cross section. The thickness T1 of the second resin portion 42 (first sealing portion) is smaller than the thickness T2 of the fourth resin portion 44 (second sealing portion). In the present embodiment, the third resin portion 43, the plurality of fourth resin portions 44, the fifth resin portion 45, and the sixth resin portion 46 all have the same thickness. In the present embodiment, the thickness T2 of the fourth resin portion 44 is the minimum value among the thicknesses of the plurality of fourth resin portions 44. That is, the thickness T1 of the second resin portion 42 (first sealing portion) is smaller than the minimum value among the thicknesses of the plurality of fourth resin portions 44.

When the thickness values of the second resin portion 42 and the fourth resin portion 44 vary in the width direction, the heights of the inner edges of the second resin portion 42 and the fourth resin portion 44 are compared. That is, the height of the inner edge of the second resin portion 42 is smaller than the height of the inner edge of the fourth resin portion 44. The second resin portion 42 and the fourth resin portion 44 have a frame shape. Therefore, if there is a variation in the circumferential direction of the second resin portion 42 and the fourth resin portion 44, the comparison is made by averaging the entire circumference.

The thickness T1 of the second resin portion 42 (first sealing portion) is a plurality of protrusions (for example, electric field plating) formed by roughening on at least one of the electrode plate 15 and the metal plate 50 of the negative electrode terminal electrode 18. It is larger than the maximum value of the height of the protrusion). In the present embodiment, the thickness T1 of the second resin portion 42 is the maximum value of the heights of the plurality of protrusions formed by roughening the electrode plate 15 of the negative electrode terminal electrode 18 and the roughening of the metal plate 50. It is larger than the sum of the maximum heights of the plurality of protrusions formed by.

When the thickness of the second resin portion 42 varies, the average of the thicknesses of the second resin portion 42 over the entire circumference is compared with the height of the protrusion described above. That is, the average of the thickness of the second resin portion 42 over the entire circumference is the maximum value of the heights of the plurality of protrusions formed by roughening on at least one of the electrode plate 15 and the metal plate 50 of the negative electrode terminal electrode 18. Is also getting bigger. The height of the protrusion may be measured by contacting the surface with a probe or the like, or may be measured by non-contact with a laser beam or the like.

Next, an example of the manufacturing method of the power storage device 1 will be described. In this method, first, the above-mentioned power storage module 4 is manufactured. The method for manufacturing the power storage module 4 includes a primary molding step, a laminating step, a secondary molding step, and an injection step. In the primary molding step, a predetermined number of bipolar electrodes 14, negative electrode termination electrodes 18 and positive electrode termination electrodes 19 are prepared, and the electrode support portion 21 is welded to one surface 15a of the peripheral edge portion 15c of each electrode plate 15. Further, a metal plate 50 is prepared, and the first resin portion 41 and the second resin portion 42 are welded to the metal plate 50.

In the laminating step, the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal 19 are laminated via the separator 13 so that the electrode support portion 21 is arranged between the peripheral edges 15c of the electrode plate 15. The electrode laminate 11 is formed. Further, the metal plate 50 is arranged at one end of the electrode laminate 11 so that the first resin portion 41 is arranged on the second resin portion 42. In the secondary molding step, after the electrode laminate 11 and the metal plate 50 are placed in the injection molding die (not shown), the molten resin is injected into the die to surround the electrode support portion 21. The housing portion 22 is formed on the surface. As a result, the sealing body 12 is formed on the side surface 11a of the electrode laminated body 11. In the injection step, after the secondary molding step, the electrolytic solution is injected into the internal space V between the bipolar electrodes 14 and 14. As a result, the power storage module 4 is obtained.

Next, the operation and effect of the power storage module 4 will be described with reference to FIGS. 4 and 5. 4 and 5 are enlarged cross-sectional views of a main part of the power storage module according to the comparative example. As shown in FIG. 4, 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 K1. It may seep out to the one side 15a side of the electrode plate 15 through the electrode plate 15. In FIG. 4, the movement path of the electrolytic solution L in the alkaline creep phenomenon is shown by an arrow A. This alkaline creep phenomenon can occur during charging, discharging, and no load of the power storage device due to electrochemical factors, fluid phenomena, and the like. The alkaline creep phenomenon occurs due to the presence of each 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 second resin portion 42 (first sealing portion) is bonded to both the electrode plate 15 and the metal plate 50 of the negative electrode terminal electrode 18 to be alkaline. A sealing structure for excess space is formed in two stages on the moving path of the electrolytic solution due to the creep phenomenon. Further, by joining the metal plate to the second resin portion 42 (first sealing portion), the rigidity of the second resin portion 42 is increased. As a result, the second resin portion 42 is suppressed from peeling from the electrode plate 15 of the negative electrode terminal electrode 18 due to the alkaline creep phenomenon, and the progress of the alkaline creep phenomenon can be suppressed.

In the power storage module 101 according to the comparative example shown in FIG. 5, the thickness T1 of the second resin portion 42 (first sealing portion) is higher than the thickness T2 of the fourth resin portion (second sealing portion). Is also getting bigger. On the other hand, in the power storage module 4, the thickness T1 of the second resin portion 42 (first sealing portion) is smaller than the thickness T2 of the fourth resin portion (second sealing portion). As a result, the volume of the surplus space VA can be sufficiently suppressed, and the amount of water existing in the space can be suppressed. By suppressing the amount of water existing in the surplus space VA, the progress of the alkaline creep phenomenon can be suppressed more reliably. As described above, in this 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 thickness T1 of the second resin portion 42 (first sealing portion) is the maximum value of the heights of a plurality of protrusions formed by roughening on at least one of the electrode plate 15 and the metal plate 50 of the negative electrode terminal electrode 18. Is bigger than. According to this configuration, it is possible to prevent the rough surface from penetrating the second resin portion 42.

The sealing body 12 has a first resin portion 41 (third sealing portion) bonded to the other surface 50b of the peripheral edge portion 50c of the metal plate 50. According to this configuration, a three-stage sealing structure is formed on the moving path of the electrolytic solution due to the alkaline creep phenomenon.

Negative electrode termination electrodes in the joint regions K1 and K2 of the electrode plate 15 and metal plate 50 of the negative electrode termination electrode 18 and the first resin portion 41 (third sealing portion) and the second resin portion 42 (first sealing portion). The electrode plate 15 and the metal plate 50 of 18 are roughened. According to this configuration, it is possible to improve the bonding strength between the first resin portion 41 and the second resin portion 42 and the electrode plate 15 and the metal plate 50 of the negative electrode terminal electrode 18 by the anchor effect. Therefore, the peeling of the first resin portion 41 and the second resin portion 42 can be further suppressed, and the progress of the alkaline creep phenomenon can be further suppressed.

4 ... Energy storage module, 11 ... Electrode laminate, 11a ... Side surface, 12 ... Sealed body, 14 ... Bipolar electrode, 15 ... Electrode plate, 15a, 50a ... One side, 15b, 50b ... The other side, 18 ... Negative electrode termination electrode , 41 ... 1st resin part (3rd sealing part), 42 ... 2nd resin part (1st sealing part), 44 ... 4th resin part (2nd sealing part), 50 ... Metal plate, 50c ... Peripheral portion, 50d ... central portion, D ... stacking direction, K1, K2 ... junction region, T1, T2 ... thickness, V ... internal space.

Claims (5)

An electrode laminate composed of a laminate in which a plurality of bipolar electrodes are laminated and a negative electrode terminal electrode arranged at one end of the laminate in the stacking direction.
A metal plate laminated on the outside of the negative electrode terminal electrode and
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 contained in the internal space is provided.
The encapsulating body has a first encapsulating portion bonded to the peripheral edge portion of the metal plate and the electrode plate of the negative electrode terminal electrode, and a second encapsulating body bonded to the peripheral edge portion of the electrode plate of the bipolar electrode. Has a sealing part and
An extra space in which the electrolytic solution is not accommodated is formed by the electrode plate of the negative electrode terminal electrode, the metal plate, and the first sealing portion.
A power storage module in which the thickness of the first sealing portion is smaller than the thickness of the second sealing portion. The claim that at least one of the electrode plate and the metal plate of the negative electrode terminal electrode is roughened in the joint region between the electrode plate and the metal plate of the negative electrode terminal electrode and the first sealing portion. The power storage module according to 1. The thickness of the first sealing portion is larger than the maximum value of the heights of the plurality of protrusions formed by roughening on at least one of the electrode plate and the metal plate of the negative electrode terminal electrode. The power storage module according to claim 2. The power storage module according to any one of claims 1 to 3, wherein a third sealing portion is bonded to the peripheral edge portion on the outer surface side of the metal plate. The power storage module according to claim 4, wherein the metal plate is roughened in a joint region between the metal plate and the third sealing portion.

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