JP6942080B2 - 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

In the power storage module as described above, a negative electrode terminal electrode made of an electrode plate having a negative electrode formed on the inner surface is arranged at one end of the laminated body in the stacking direction. The edge of the electrode plate of the negative electrode terminal electrode is also sealed by a sealant, but when the electrolytic solution is composed of an alkaline solution, the electrolytic solution causes the electrolytic solution to cover the surface of the electrode plate of the negative electrode terminal electrode due to the so-called alkaline creep phenomenon. It may be transmitted, pass between the sealing body and the electrode plate, and exude to the outer surface side of the electrode plate. If the electrolytic solution leaks to the outer surface side and diffuses, for example, corrosion of the conductive plate arranged adjacent to the negative electrode terminal electrode or short circuit between the negative electrode terminal electrode and the restraint 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.

The power storage module according to the present invention is welded to 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, and an edge of the electrodes. A first sealing portion for forming an internal space between adjacent electrodes and sealing the internal space, and an electrolytic solution containing an alkaline solution contained in the internal space are provided, and the electrodes are a plurality of bipolar electrodes. The bipolar electrode includes an electrode and a negative electrode terminal electrode, and the bipolar electrode is provided on an electrode plate including a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a second surface. The negative electrode terminal electrode includes the negative electrode, and the negative electrode terminal electrode includes the electrode plate and the negative electrode provided on the second surface, and the bipolar electrode is provided at one end of the laminated body in the first direction so that the second surface is inside the laminated body. The first sealing portion is arranged between the metal plate and the metal plate, and the first sealing portion includes a first resin portion welded to the first surface of the negative electrode terminal electrode, and the metal plate faces the first surface of the negative electrode terminal electrode. The third surface and the fourth surface opposite to the third surface are included, and are welded to the first resin portion at the peripheral edge portion of the third surface, and are welded to the first resin portion of the first surface and the third surface. The region is roughened, and is inside the third surface from the region facing the first sealing portion on the second surface of the negative electrode terminal electrode and the region welded to the first resin portion on the third surface. A water repellent material is provided on at least one of the regions extending to.

In this power storage module, an internal space for accommodating the electrolytic solution is formed between the electrodes of the laminated body by the first sealing portion. Further, at one end of the laminated body, a negative electrode terminal electrode is arranged so that the second surface of the electrode plate is inside the laminated body among the plurality of electrodes. A first resin portion as a first sealing portion is welded to the first surface of the negative electrode terminal electrode facing the outside of the laminate. On the other hand, a metal plate is provided at one end of the laminated body. As a result, the negative electrode termination electrode is arranged between the bipolar electrode of the electrodes and the metal plate. That is, a metal plate is provided on the outer side of the negative electrode terminal electrode. The metal plate is welded to the first resin portion welded to the first surface of the negative electrode terminal electrode at the peripheral edge portion of the third surface facing the first surface of the negative electrode terminal electrode. Further, at least one of the region of the negative electrode terminal electrode facing the first sealing portion on the second surface and the region extending inward of the third surface from the region welded to the first resin portion of the third surface A water repellent material is provided.

With such a configuration, the following effects can be obtained. That is, as the first effect, the metal plate having higher rigidity than the first resin portion is welded to the first resin portion on the first surface of the negative electrode terminal electrode, whereby the first resin portion and the negative electrode terminal electrode are welded. It is suppressed that the first resin portion is deformed so as to be peeled off from the first surface of the above. Further, as a second effect, by further providing a metal plate on the outside of the negative electrode termination electrode, the invasion of moisture from the outside into the internal space between the electrodes is suppressed. Further, as a third effect, on the path leading from the negative electrode terminal electrode to the outside, the welded portion between the first surface and the first resin portion of the negative electrode terminal electrode, and the third surface and the first resin portion of the metal plate. A at least two-step seal of the weld is formed.

The first effect suppresses the formation of a gap between the first resin portion and the first surface of the negative electrode terminal electrode, which can serve as a path for leakage of the electrolytic solution due to alkaline creep. In addition, the second effect suppresses the influence of external humidity, which is an acceleration condition for alkaline creep. Also, due to the third effect, the liquid leakage rate is reduced by the multi-step sealing. Further, as a fourth effect, when a water-repellent material is provided in the region of the second surface of the negative electrode terminal electrode facing the first sealing portion, leakage of the electrolytic solution from the internal space can be suppressed, and the metal can be suppressed. When the water repellent material is provided in the region extending inward of the third surface from the region welded to the first resin portion of the third surface of the plate, the surplus space formed between the metal plate and the negative electrode terminal electrode. Leakage from the outside to the outside and invasion of water from the outside into the excess space are suppressed. According to this power storage module, as a result of obtaining these effects in combination, leakage due to alkaline creep is surely suppressed, and reliability is improved.

In the power storage module according to the present invention, a second resin portion extending from the peripheral edge portion of the fourth surface to the first resin portion and welded to the fourth surface and the first resin portion is further provided, and the fourth The region where the second resin portion of the surface is welded may be roughened. In this case, a seal is further formed as a welding point between the fourth surface and the second resin portion of the metal plate on the path leading from the negative electrode terminal electrode to the outside. As a result, the liquid leakage rate is surely reduced by the multi-step (three-step) sealing, and the liquid leakage due to alkaline creep is more surely suppressed.

In the power storage module according to the present invention, a water repellent material may be provided in a region extending inward of the fourth surface from the region where the second resin portion of the fourth surface is welded. In this case, the intrusion of water from the outside into the surplus space is surely suppressed.

The power storage module according to the present invention further includes a second sealing portion joined to the first sealing portion and the second resin portion so as to surround the plurality of first sealing portions and the second resin portion from the outside. The second sealing portion may include an overlapping portion that overlaps the metal plate and the second resin portion when viewed from the first direction, and may be welded to the second resin portion at the overlapping portion. In this case, the internal space is surely sealed by the second sealing portion. Further, as a result of suppressing the deformation of the second resin portion by the overlapping portion of the second sealing portion, it is possible to suppress the formation of a gap between the second resin portion and the fourth surface. As a result, leakage due to alkaline creep is more reliably suppressed.

In the power storage module according to the present invention, the metal plate is located on the first surface side of the negative electrode terminal electrode with respect to the annular welded portion welded to the first resin portion and the welded portion inside the welded portion. It may include a contacted portion that is in contact with the first surface. In this case, the excess space formed between the metal plate and the negative electrode terminal electrode is limited. As a result, the influence of humidity in the excess space is suppressed.

In the power storage module according to the present invention, the metal plate may be an electrode plate. In this case, it is not necessary to prepare a metal plate separately from the electrode plate. As a result, the above configuration can be realized at low cost.

According to the present invention, it is possible to provide a power storage module with improved reliability.

It is a schematic cross-sectional view which shows one Embodiment of a power storage device. It is a schematic cross-sectional view which shows the internal structure of the power storage module shown in FIG. It is a partially enlarged view of FIG. It is a partially enlarged sectional view of the power storage module which concerns on a comparative example.

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

FIG. 1 is a schematic cross-sectional view showing an embodiment of a power storage device. The power storage device 1 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a module stack 2 including a plurality of stacked power storage modules 4, and a restraint member 3 that applies a restraint load to the module stack 2 in the stacking direction.

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 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 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 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 not only functions as a connecting member that electrically connects the power storage modules 4 to each other, but 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 area of the power storage module 4. It may be the same as, 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 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 inner 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.

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 a partially enlarged view of FIG. As shown in FIGS. 2 and 3, the power storage module 4 includes an electrode laminate (laminate) 11 and a resin sealant 12 that seals the electrode laminate 11. The electrode laminate 11 includes a plurality of electrodes (a plurality of bipolar electrodes 14, a single negative electrode terminal electrode (electrode) 18, and a single electrode) laminated along the stacking direction D (first direction) via a separator 13. One positive electrode termination electrode 19) is included. Here, the stacking direction D of the electrode laminated body 11 coincides with the stacking direction of the module laminated body 2. The electrode laminate 11 has a side surface 11a extending in the stacking direction D.

The bipolar electrode 14 includes an electrode plate 15 including a first surface 15a and a second surface 15b opposite to the first surface 15a, a positive electrode 16 provided on the first surface 15a, and a negative electrode 17 provided on the second surface 15b. Includes. The positive electrode 16 is a positive electrode active material layer formed by applying the positive electrode active material to the electrode plate 15. 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 each other in the stacking direction 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 yet another bipolar electrode 14 adjacent to the stacking direction D with the separator 13 interposed therebetween.

The negative electrode terminal electrode 18 includes an electrode plate 15 and a negative electrode 17 provided on the second 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 its second surface 15b is inside the electrode laminated body 11 (center side with respect to 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 terminal electrode 19 includes an electrode plate 15 and a positive electrode 16 provided on the first 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 the first surface 15a thereof 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 15a of the electrode plate 15 of the negative electrode terminal electrode 18 is a surface facing the outside of the electrode laminate 11. A 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. Further, 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 laminate 11 from the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19 via the conductive plate 5. That is, the conductive plate 5 is also a restraining member that applies a restraining load to the electrode laminated body 11 along the stacking direction D.

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 rectangular metal leaf made of nickel. The edge portion of the electrode plate 15 (the edge portion of the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19) 15c has a rectangular frame shape, and the positive electrode active material and the negative electrode active material are not coated in the uncoated region. It has become. 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 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 resin such as polyethylene (PE) and polypropylene (PP), a woven fabric made of polypropylene, polyethylene terephthalate (PET), methyl cellulose and the like, and 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 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. The sealing body 12 holds the edge portion 15c on the side surface 11a. The sealing body 12 is joined to a plurality of first sealing portions 21 welded to the edge portion 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. It has a single second sealing portion 22 and the like.

The first sealing portion 21 has a rectangular annular shape when viewed from the stacking direction D, and is continuously provided over the entire circumference of the edge portion 15c. The first sealing portion 21 is welded to the first surface 15a of the electrode plate 15 and airtightly joined. The first sealing portion 21 is welded by, for example, ultrasonic waves or heat. The first sealing portion 21 is a film having a predetermined thickness (length in the stacking direction D). The end face of the electrode plate 15 is exposed from the first sealing portion 21. A part of the inside of the first sealing portion 21 is located between the edge portions 15c of the electrode plates 15 adjacent to each other in the stacking direction D, and a part of the outside projects outward from the electrode plate 15. There is. The first sealing portion 21 is embedded in the second sealing portion 22 in a part of the outer side. The first sealing portions 21 adjacent to each other along the stacking direction D are separated from each other. The first sealing portion 21 includes a first resin portion 21A welded to the first surface 15a of the negative electrode terminal electrode 18. Here, one of the first sealing portions 21 is the first resin portion 21A.

The second sealing portion 22 is provided outside the electrode laminate 11 and the first sealing portion 21, and constitutes 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 along the stacking direction D over the entire length of the electrode laminate 11. The second sealing portion 22 has a cylindrical shape (annular shape) extending with the stacking direction D as the axial direction. The second sealing portion 22 is welded (bonded) to the outer surface of the first sealing portion 21 by, for example, heat during injection molding.

The second sealing portion 22, together with the first sealing portion 21, has a bipolar electrode 14 adjacent to each other along the stacking direction D, and a negative electrode terminal 18 and a bipolar electrode 14 adjacent to each other along the stacking direction D. The space and the space between the positive electrode terminal 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D are sealed. As a result, an airtightly partitioned internal space V is formed between the bipolar electrodes 14, between the negative electrode terminating electrodes 18 and the bipolar electrodes 14, and between the positive electrode terminating electrodes 19 and the bipolar electrodes 14. There is. That is, the first sealing portion 21 and the second sealing portion 22 are for forming an internal space V between adjacent electrodes and 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 electrolytic solution is impregnated in the separator 13, the positive electrode 16 and the negative electrode 17.

Here, the power storage module 4 includes a metal plate 50 and a second resin portion 51. The metal plate 50 is provided at one end (the end on the negative electrode end electrode 18 side) of the electrode laminate 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 on the opposite side of 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 laminated together with the electrodes along the stacking direction D. As a result, the negative electrode terminal 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 on the outer side of the negative electrode 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 has a rectangular annular welded portion 52 arranged on the first resin portion 21A and the first surface 15a and welded to the first resin portion 21A, and the inside of the welded portion 52. Includes a rectangular contacted portion 53 located on the first surface 15a side of the negative electrode terminal electrode 18 with respect to the welded portion 52 and in contact with the first surface 15a (recessed). The welded portion 52 and the contacted portion 53 are continuous with each other. Between the metal plate 50 and the negative electrode terminal electrode 18 (between the third surface 50a and the first surface 15a), there is a surplus corresponding to the thickness of the first resin portion 21A (the length along the stacking direction D). Although the space VA can be formed, the excess space VA is narrowly limited because the metal plate 50 is recessed on the negative electrode terminal electrode 18 side in the contacted portion 53. 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 an electrode plate 15. In this case, the metal plate 50 is a metal foil (uncoated foil) on which the active material layer is not formed.

The second resin portion 51 has substantially the same shape as the first resin portion 21A when viewed from the stacking direction D. That is, the second resin portion 51 is a film having a rectangular annular shape and a predetermined thickness. The second resin portion 51 extends from the peripheral edge 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 fourth surface 50b and the first resin portion 21A. The second sealing portion 22 is joined to the first sealing portion 21 and the second resin portion 51 so as to surround the plurality of first sealing portions 21 and the second resin portion 51 from the outside. The second sealing portion 22 includes an overlapping portion 22A that overlaps the metal plate 50 and the second resin portion 51 when viewed from the stacking direction D, and is welded to the second resin portion 51 at the overlapping portion 22A.

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

A region to be welded to the first resin portion 21A or the second resin portion 51 is formed on the first surface 15a, the third surface 50a, and the fourth surface 50b. Specifically, when viewed from the stacking direction D, the region A1 overlapping the first resin portion 21A on the first surface 15a and the region A2 overlapping the first resin portion 21A on the third surface 50a are the first resins. This is a region to be welded to the portion 21A. Further, when viewed from the stacking direction D, the region A3 overlapping the second resin portion 51 on the fourth surface 50b is a region welded to the second resin portion 51. Regions A1 to A3 are rectangular and annular. At least these regions A1 to A3 are roughened. Here, the entire first surface 15a, the third surface 50a, and the fourth surface 50b are roughened.

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

Here, the power storage module 4 further has a water repellent material 60. The water repellent material 60 can be provided in the regions of the first surface 15a, the second surface 15b, the third surface 50a, and the fourth surface 50b that are not subjected to welding. Here, the water-repellent material 60 is formed in a region A4 facing the first sealing portion 21 of the second surface 15b of the negative electrode terminal electrode 18, and a region A2 to a third welded to the first resin portion 21A of the third surface 50a. It is provided in a region A5 extending inward of the surface 50a and a region A6 extending inward of the fourth surface 50b from the region A3 where the second resin portion 51 of the fourth surface 50b is welded. However, the water repellent material 60 may be provided in at least one of these regions A4 to A6. The region A4 faces the first sealing portion 21 welded to the bipolar electrode 14 adjacent to the negative electrode terminal electrode 18. Region A5 is a region facing the surplus space VA. The area A6 is an area facing the outside of the power storage module 4.

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 fluororesin material (for example, "OS-90HF" manufactured by Harves Co., Ltd.), a fluororubber, a polymer having a fluorine-based / methyl-based functional group, or the like.

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 non-woven fabric. Examples of the material constituting this non-woven fabric include polyolefins. The non-woven fabric may be subjected to plasma treatment in order to improve water absorption. The thickness of the liquid absorbing member 31 (the length along the stacking direction D) is, for example, about several hundred μm. The liquid absorbing member 31 has, for example, a rectangular annular shape when viewed from the stacking direction D, and surrounds the conductive plate 5.

Subsequently, 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 first sealing portion 21 is welded to the first surface 15a of the edge portion 15c of each electrode plate 15. Further, a metal plate 50 is prepared, and the second resin portion 51 is welded to the fourth surface 50b thereof.

In the laminating step, the bipolar electrode 14, the negative electrode terminating electrode 18, and the positive electrode terminating electrode 19 are laminated via the separator 13 so that the first sealing portion 21 is arranged between the edge portions 15c of the electrode plate 15. Therefore, the electrode laminate 11 is formed. Further, the metal plate 50 is arranged at one end of the electrode laminate 11 so that the second resin portion 51 is arranged on the first resin portion 21A. In the secondary molding step, after arranging the electrode laminate 11 and the metal plate 50 in the injection molding mold (not shown), the molten resin is injected into the mold to form the first sealing portion 21 and the first sealing portion 21. 2 The second sealing portion 22 is formed so as to surround the resin portion 51. 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.

Subsequently, the operation / effect of the power storage module 4 will be described. FIG. 4 is a partially enlarged cross-sectional view of the power storage module according to the comparative example. In the example shown in FIG. 4, the metal plate 50 is not provided. Therefore, for example, when a load is applied to the electrode plate 15 of the negative electrode terminal electrode 18 as the internal pressure rises, 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 electrolytic solution L may leak through the gap.

In the power storage module, the electrolytic solution L is transmitted on the electrode plate 15 of the negative electrode terminal electrode 18 due to the so-called alkaline creep phenomenon, passes through the gap between the first resin portion 21A and the electrode plate 15, and is the first surface of the electrode plate 15. It may seep to the 15a side. In FIG. 4, 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, discharging, and no load of the power storage device due to electrochemical factors, fluid phenomena, and the like. The alkaline creep phenomenon is caused by the presence of each of the negative electrode potential, the water content, and the path of the electrolytic solution L.

On the other hand, in the power storage module 4, an internal space V for accommodating the electrolytic solution is formed between the electrodes of the electrode laminate 11 by the first sealing portion 21. Further, at one end of the electrode laminate 11, the negative electrode terminal electrode 18 is arranged so that the second surface 15b of the electrode plate 15 is inside the electrode laminate 11 among the plurality of electrodes. The first resin portion 21A as the first sealing portion 21 is welded to the first surface 15a of the negative electrode terminal electrode 18 facing the outside of the electrode laminate 11. On the other hand, a metal plate 50 is provided at one end of the electrode laminate 11. As a result, the negative electrode 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 on the outer side of the negative electrode terminal 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 terminal electrode 18 at the peripheral edge of the third surface 50a facing the first surface 15a of the negative electrode terminal electrode 18. There is.

With such a configuration, the following effects can be obtained. That is, as the first effect, the metal plate 50 having higher rigidity than the first resin portion 21A is welded to the first resin portion 21A on the first surface 15a of the negative electrode terminal electrode 18, thereby causing the first resin. Deformation of the first resin portion 21A is suppressed so that the portion 21a and the first surface 15a of the negative electrode terminal electrode 18 are peeled off. Further, as a second effect, by further providing the metal plate 50 on the outside of the negative electrode terminal electrode 18, the invasion of moisture from the outside into the internal space V is suppressed. Further, as a third effect, a welded portion between the first surface 15a of the negative electrode terminal electrode 18 and the first resin portion 21A and the third surface 50a of the metal plate 50 on the path leading from the negative electrode terminal electrode 18 to the outside. And at least two stages of sealing of the welded portion of the first resin portion 21A are formed.

The first effect suppresses the formation of a gap between the first resin portion 21A and the first surface 15a of the negative electrode terminal electrode 18, which can serve as a path for leakage of the electrolytic solution due to alkaline creep. In addition, the second effect suppresses the influence of external humidity, which is an acceleration condition for alkaline creep. In addition, due to the third effect, the leakage rate is reduced by the multi-step sealing. According to the power storage module 4, as a result of obtaining these effects in combination, leakage due to alkaline creep is surely suppressed, and reliability is improved.

Further, the power storage module 4 is arranged so as to extend from the peripheral edge of the fourth surface 50b of the metal plate 50 to the first resin portion 21A, and is welded to the fourth surface 50b and the first resin portion 21A. It also has 51. The region A3 to which the second resin portion 51 of the fourth surface 50b is welded is roughened. Therefore, a seal is further formed as a welded portion (region A3) between the fourth surface 50b of the metal plate 50 and the second resin portion 51 on the path leading from the negative electrode terminal electrode 18 to the outside. As a result, the liquid leakage rate is surely reduced by the multi-step (three-step) sealing, and the liquid leakage due to alkaline creep is more surely suppressed.

Further, the power storage module 4 has a second sealing portion 22 joined to the first sealing portion 21 and the second resin portion 51 so as to surround the plurality of first sealing portions 21 and the second resin portion 51 from the outside. Further prepare. The second sealing portion 22 includes an overlapping portion 22A that overlaps the metal plate 50 and the second resin portion 51 when viewed from the stacking direction D, and is welded to the second resin portion 51 at the overlapping portion 22A. Therefore, the internal space V is surely sealed by the second sealing portion 22. Further, as a result of suppressing the deformation of the second resin portion 51 by the overlapping portion 22A of the second sealing portion 22, it is possible to suppress the formation of a gap between the second resin portion 51 and the fourth surface 50b. As a result, leakage due to alkaline creep is more reliably suppressed.

Further, in the power storage module 4, the metal plate 50 has an annular welded portion 52 welded to the first resin portion 21A and a first negative electrode terminal 18 of the negative electrode terminal electrode 18 inside the welded portion 52 rather than the welded portion 52. Includes a contacted portion 53 located on the surface 15a side and in contact with the first surface 15a. Therefore, the excess space VA formed between the metal plate 50 and the negative electrode terminal electrode 18 is limited. As a result, the influence of the humidity of the surplus space VA is suppressed.

Further, in the power storage module 4, the metal plate 50 is an electrode plate 15. Therefore, it is not necessary to prepare the metal plate 50 separately from the electrode plate 15. As a result, the above configuration can be realized at low cost.

Further, in the power storage module 4, the region A4 facing the first sealing portion 21 of the second surface 15b of the negative electrode terminal electrode 18 and the region A2 to the first resin portion 21A of the third surface 50a are welded to the first to second. A water repellent material 60 is provided in the region A5 extending inward of the three surfaces 50a. By providing the water repellent material 60 in the region A4, leakage of the electrolytic solution from the internal space V can be suppressed. Further, by providing the water repellent material 60 in the region A5, leakage of liquid from the surplus space VA to the outside and invasion of water from the outside into the surplus space VA are suppressed.

Further, in the power storage module 4, a water repellent material 60 is provided in a region A6 extending inward from the region A3 where the second resin portion 51 of the fourth surface 50b is welded to the inside of the fourth surface 50b. As a result, the intrusion of water from the outside into the excess space VA is surely suppressed.

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

For example, in the power storage module 4, a sealing material can be provided instead of the water repellent material 60. That is, a sealing material can be provided in at least one of the regions A4, A5, and A6. The sealing material is, for example, a cured product of a liquid sealing agent. In this case, the sealing material can be easily formed. The liquid sealant is, for example, a polyolefin resin material such as polypropylene (PP), an adhesive containing blown asphalt as a main component (asphalt pitch), or the like. The asphalt pitch is, for example, blown asphalt and polybutene dissolved in toluene. Specifically, the sealing material can be formed by applying a liquid sealing agent to at least one of the regions A4, A5, and A6 and curing the liquid sealing material. Even when a sealing material is provided instead of the water-repellent material 60, the same effect as that of the water-repellent material 60 can be obtained.

Further, in the power storage module 4, both the water repellent material 60 and the sealing material can be provided. That is, the water repellent material 60 may be provided in a part of the areas A4, A5, and A6, and the sealing material may be provided in the remaining part. As described above, in the power storage module 4, the water repellent material 60 and the sealing material can be used properly according to the characteristics required for each region and the state of each region.

4 ... Energy storage module, 11 ... Electrode laminate (laminate), 14 ... Bipolar electrode, 15 ... Electrode plate, 15a ... First surface, 15b ... Second surface, 17 ... Negative electrode, 18 ... Negative electrode terminal electrode, 21 ... 1 Sealing part, 21A ... 1st resin part, 22 ... 2nd sealing part, 22A ... Overlapping part, 50 ... Metal plate, 50a ... 3rd surface, 50b ... 4th surface, 51 ... 2nd resin part, 52 ... Welded portion, 53 ... Contacted portion, 60 ... Water repellent material, A1 to A6 ... Region.

Claims (6)

A laminate containing a plurality of electrodes laminated along the first direction, and
A metal plate provided at one end of the laminated body in the first direction and
A first sealing portion that is welded to the edge of the electrode to form an internal space between the adjacent electrodes and seal the internal space.
An electrolytic solution containing an alkaline solution contained in the internal space and
With
The electrode includes a plurality of bipolar electrodes and a negative electrode terminal electrode.
The bipolar electrode includes an electrode plate including a first surface and a second surface opposite to the first surface, a positive electrode provided on the first surface, and a negative electrode provided on the second surface. ,
The negative electrode terminal electrode includes the electrode plate and the negative electrode provided on the second surface, and at one end of the laminate in the first direction so that the second surface is inside the laminate. It is arranged between the bipolar electrode and the metal plate, and is arranged between the bipolar electrode and the metal plate.
The first sealing portion includes a first resin portion welded to the first surface of the negative electrode terminal electrode.
The metal plate includes a third surface of the negative electrode terminal electrode facing the first surface and a fourth surface opposite to the third surface, and is welded to the first resin portion at a peripheral edge of the third surface. Has been
The regions welded to the first resin portion of the first surface and the third surface are roughened.
At least a region of the negative electrode terminal electrode facing the first sealing portion on the second surface and a region extending inward of the third surface from a region welded to the first resin portion on the third surface. A water repellent material is provided on one side,
Power storage module. A second resin portion extending from the peripheral edge portion of the fourth surface to the first resin portion and welded to the fourth surface and the first resin portion is further provided.
The region where the second resin portion of the fourth surface is welded is roughened.
The power storage module according to claim 1. A water-repellent material is provided in a region extending inward of the fourth surface from a region where the second resin portion of the fourth surface is welded.
The power storage module according to claim 2. A second sealing portion joined to the first sealing portion and the second resin portion so as to surround the plurality of the first sealing portion and the second resin portion from the outside is further provided.
The second sealing portion includes an overlapping portion that overlaps the metal plate and the second resin portion when viewed from the first direction, and is welded to the second resin portion at the overlapping portion.
The power storage module according to claim 2 or 3. The metal plate is located on the first surface side of the negative electrode terminal electrode with respect to the welded portion and the annular welded portion welded to the first resin portion and the welded portion inside the welded portion. Including the contacted portion in contact with one surface,
The power storage module according to any one of claims 1 to 4. The metal plate is the electrode plate.
The power storage module according to any one of claims 1 to 5.

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