JP6939258B2 - Power storage module - Google Patents

Description

The present invention relates to a power storage module.

Patent Document 1 describes a bipolar battery assembly in which bipolar battery plates are stacked while being held in a plastic casing frame. In this bipolar battery assembly, the casing frame and the bipolar battery plate are bonded together by ultrasonic welding.

Special Table 2017-508241

In the above-mentioned bipolar battery assembly, the coupling force between the casing frame and the bipolar battery plate is insufficient, and the electrolytic solution may leak.

The present invention has been made to solve the above problems, and provides a power storage module capable of improving sealing performance.

The power storage module according to the present invention includes an electrode laminate in which a plurality of electrodes are laminated, and a resin portion provided for each of the plurality of electrodes, and each of the plurality of electrodes is a metal electrode plate and an electrode. It has an active material layer provided on at least one surface of the plate and an intermediate layer covering the edge portion of the electrode plate, and the resin portion is provided on the edge portion via the intermediate layer.

In this power storage module, the edge portion of the electrode plate of the electrode is covered with an intermediate layer, and the resin portion is provided on the edge portion via the intermediate layer. Therefore, even if the metal electrode plate and the resin portion are difficult to bond with each other, if a material that is easily bonded to the electrode plate and the resin portion is selected as the intermediate layer, the electrode plate and the resin portion are intermediate. It can be easily bonded via a layer. Thereby, the sealing property of the power storage module can be improved.

In the power storage module according to the present invention, the intermediate layer may contain at least one element selected from the group consisting of titanium, silicon, chromium, and tungsten. According to the intermediate layer containing these elements, the resin portion and the electrode plate can be easily bonded to each other via the intermediate layer.

In the power storage module according to the present invention, the edge portion may be roughened and may have a plurality of protrusions. In this case, the bonding force between the electrode plate and the resin portion via the intermediate layer is improved by the anchor effect.

In the power storage module according to the present invention, the thickness of the intermediate layer may be thinner than the protrusion height of each of the plurality of protrusions. In this case, it is possible to prevent the protrusions from being buried in the intermediate layer and the anchor effect from being lost.

In the power storage module according to the present invention, the thickness of the intermediate layer may be thicker on the proximal end side of the plurality of protrusions than on the distal end side. Since it is more difficult to bond the base end side to the resin portion than the tip end side of the protrusion, by arranging the intermediate layer thickly on the base end side, the resin portion and the electrode plate can be easily bonded to the resin portion also on the base end side. Can be made to.

According to the present invention, it is possible to provide a power storage module capable of improving the sealing property.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a power storage device. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module of FIG. FIG. 3 is a partially enlarged view of the power storage module of FIG. FIG. 4 is a schematic cross-sectional view showing the internal configuration of the power storage module according to the modified example. FIG. 5 is a partially enlarged view of the power storage module of FIG. 6 (a) and 6 (b) are schematic views for explaining the effect of the intermediate layer when the electrode plate is roughened.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, 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 the same 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a power storage module stack 2 obtained by stacking a plurality of power storage modules 4, and a restraint member 3 that applies a restraint load to the power storage module stack 2 in the stacking direction.

The power storage module stack 2 is composed of a plurality of (three in this embodiment) power storage modules 4 and a plurality of (four in this embodiment) conductive plates 5. The power storage module 4 is, for example, a bipolar battery provided with a bipolar electrode 14 described later, 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 and 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 and 4 adjacent to each other in the stacking direction and outside the power storage modules 4 located at the stacking ends, respectively. 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 each conductive plate 5, a plurality of flow paths 5a through which a refrigerant such as air flows are provided. Each flow path 5a extends parallel to each other, for example, in a direction orthogonal to the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. By circulating the refrigerant through these flow paths 5a, the conductive plate 5 not only functions as a connecting member for electrically connecting the storage modules 4 and 4 to each other, but also a heat radiating plate that dissipates heat generated by the power storage module 4. It also has the function of. 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 and 8 that sandwich the power storage module laminate 2 in the stacking direction, and a fastening bolt 9 and a nut 10 that fasten the end plates 8 and 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 side of the storage module laminate 2). 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 power storage 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 and 8 to be unitized as the power storage module stack 2, and a restraining load is applied to the power storage module stack 2 in the stacking direction.

Next, the configuration of the power storage module 4 will be described in more detail. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module 4. FIG. 3 is a partially enlarged view 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 sealant 12 that seals the electrode laminate 11.

The electrode laminate 11 is formed by laminating a plurality of bipolar electrodes (electrodes) 14 via a separator 13. In this example, the stacking direction D of the electrode laminated body 11 coincides with the stacking direction of the power storage module laminated body 2. The bipolar electrode 14 has an electrode plate 15, a positive electrode 16 provided on one surface 15a of the electrode plate 15, a negative electrode 17 provided on the other surface 15b of the electrode plate 15, and an intermediate layer 25. .. Note that the intermediate layer 25 is not shown in FIG. The positive electrode 16 is a positive electrode active material layer coated with a positive electrode active material. The negative electrode 17 is a negative electrode active material layer coated with a negative electrode active material. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of one of the bipolar electrodes 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 the other 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 terminal electrode 18 is arranged at one end in the stacking direction D, and the positive electrode terminal 19 is arranged at the other end in the stacking direction D. The negative electrode terminal electrode 18 includes an electrode plate 15 and a negative electrode 17 provided on the other surface 15b of the electrode plate 15. The positive electrode terminal electrode 19 includes an electrode plate 15 and a positive electrode 16 provided on one surface 15a of the electrode plate 15. 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 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 electrode plate 15 is made of metal, and is made of, for example, nickel or a nickel-plated steel plate. At least the surface layer portion of the electrode plate 15 contains nickel as a main component. The "main component" means that the weight ratio of the component to the total weight is 50% or more. The electrode plate 15 is a rectangular metal leaf made of, for example, nickel. The edge portion 15c of the electrode plate 15 has a 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 intermediate layer 25 covers the edge portion 15c of the electrode plate 15. The intermediate layer 25 covers the surface of the edge portion 15c where the first resin portion 21 described later is provided. That is, the intermediate layer 25 is provided on the edge portion 15c of the electrode plate 15 from the one side 15a side to the end face. The intermediate layer 25 is provided on the entire surface of the end surface of the electrode plate 15. Seen from the stacking direction D, the intermediate layer 25 is continuously provided, for example, over the entire circumference of the edge portion 15c. The intermediate layer 25 is formed of a material that is more easily bonded to the resin than nickel, which is the main component of the surface layer portion of the electrode plate 15. Since the electrolytic solution is an alkaline solution, a material having alkali resistance is selected as the material for the intermediate layer 25. The intermediate layer 25 contains at least one element selected from the group consisting of titanium, silicon, chromium, and tungsten. The intermediate layer 25 is formed by, for example, a plating method, a sputtering method, or a CVD method.

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 by, for example, an insulating resin. Examples of the resin material constituting the sealing body 12 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like. The sealing body 12 is configured to hold the edge portion 15c of the electrode plate 15 on the side surface 11a of the electrode laminated body 11 extending in the stacking direction D and to surround the side surface 11a.

The sealing body 12 is provided on the edge portion 15c of the electrode plate 15 of each of the plurality of bipolar electrodes 14, and has a first resin portion (resin portion) 21 for holding the edge portion 15c, and the entire first resin portion 21 is outside. It has a second resin portion 22 provided so as to surround the surface. The first resin portion 21 is provided on the edge portion 15c of the electrode plate 15 via the intermediate layer 25. The first resin portion 21 is provided so as to cover the intermediate layer 25 as a whole and not to protrude from the intermediate layer 25. That is, the first resin portion 21 is provided on the edge portion 15c of the electrode plate 15 from the one side 15a side to the end face. When viewed from the stacking direction D, the first resin portion 21 has a rectangular frame shape and is continuously provided over the entire circumference of the edge portion 15c of the electrode plate 15.

The first resin portion 21 is not in contact with the one surface 15a and the end surface of the electrode plate 15, and is separated from them. The first resin portion 21 is provided on the edge portion 15c of the electrode plate 15 by, for example, ultrasonic welding, heat welding, laser welding, or the like, or injection molding. The first resin portion 21 may protrude from the intermediate layer 25, and the first resin portion 21 may be in contact with one surface 15a of the electrode plate 15. Further, the end face of the electrode plate 15 may be exposed from the intermediate layer 25, and the first resin portion 21 may be in contact with the end face of the electrode plate 15 exposed from the intermediate layer 25.

The first resin portion 21 has an inner portion 21a arranged inside the side surface 11a and an outer portion 21b arranged so as to project outward from the side surface 11a when viewed from the stacking direction D. .. The inner portion 21a is arranged between the edge portions 15c and 15c adjacent to each other in the stacking direction D, and is sandwiched by these edge portions 15c and 15c. The length of the outer portion 21b in the stacking direction D is longer than the length of the inner portion 21a in the stacking direction D. Therefore, the first resin portion 21 has a stepped surface 21c between the inner portion 21a and the outer portion 21b. The stepped surface 21c covers an end surface of the electrode plate 15, that is, a part of the side surface 11a. The difference between the length of the stepped surface 21c in the stacking direction D, that is, the length of the outer portion 21b in the stacking direction D and the length of the inner portion 21a in the stacking direction D is the length of the electrode plate 15 in the stacking direction D (plate). Thickness) is equivalent.

Similarly, the first resin portion 21 is also provided on the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19. As a result, similarly to each bipolar electrode 14, the edge portion 15c of the electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19 is also held in a state of being buried in the first resin portion 21. The first resin portions 21 and 21 adjacent to each other in the stacking direction D are in contact with each other on a surface extending to the outside of the other surface 15b of the electrode plate 15. As a result, a plurality of internal spaces U airtightly partitioned by the electrode plates 15 and the first resin portion 21 are formed between the electrode plates 15 and 15 adjacent to each other in the stacking direction D. The internal space U contains an electrolytic solution (not shown) composed of 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 second resin portion 22 constitutes the outer wall of the sealing body 12. The second resin portion 22 is a tubular portion extending with the stacking direction D as the axial direction. The second resin portion 22 extends over the entire length of the electrode laminate 11 in the stacking direction D. The second resin portion 22 covers the outer surface of the first resin portion 21 extending in the stacking direction D. The second resin portion 22 is welded to the outer surface of the first resin portion 21 by, for example, heat during injection molding.

As described above, in the power storage module 4, the edge portion 15c of the electrode plate 15 of the bipolar electrode 14 is covered with the intermediate layer 25, and the first resin portion 21 of the sealing body 12 is interposed via the intermediate layer 25. It is provided on the edge portion 15c. Therefore, even if the metal electrode plate 15 and the first resin portion 21 are difficult to bond with each other, if a material that is easily bonded to the electrode plate 15 and the first resin portion 21 is selected as the intermediate layer 25. , The electrode plate 15 and the first resin portion 21 can be easily bonded to each other via the intermediate layer 25. Thereby, the sealing property of the power storage module 4 can be improved.

The intermediate layer 25 contains at least one element selected from the group consisting of titanium, silicon, chromium, and tungsten. These elements are compatible with both the metal electrode plate 15 and the first resin portion 21, and are easily bonded to each other. Therefore, according to the intermediate layer 25 containing these elements, the first resin portion 21 and the electrode plate 15 can be easily bonded to each other via the intermediate layer 25.

The present invention is not limited to the above-described embodiment, and various modifications are possible.

FIG. 4 is a schematic cross-sectional view showing the internal configuration of the power storage module according to the modified example. FIG. 5 is a partially enlarged view of the power storage module of FIG. As shown in FIGS. 4 and 5, the power storage module 4A according to the modified example has the power storage module 4 according to the embodiment (see FIG. 2) in terms of the shape of the first resin portion 21 and the position where the intermediate layer 25 is provided. ) Is different. In the power storage module 4A, the intermediate layer 25 covers only one surface 15a at the edge portion 15c of the electrode plate 15, and the end surface of the electrode plate 15 is exposed from the intermediate layer 25. The first resin portion 21 does not have a stepped surface 21c (see FIG. 2) and has a flat plate shape, and the length of the outer portion 21b in the stacking direction D is equivalent to the length of the inner portion 21a in the stacking direction D. As a result, the end face of the electrode plate 15 is exposed from the first resin portion 21. The length of the stacking direction D of the inner portion 21a of the first resin portion 21 in the power storage module 4A is shorter than the length of the stacking direction D of the inner portion 21a of the first resin portion 21 in the power storage module 4. Therefore, in the power storage module 4A, although the inner portion 21a is arranged between the adjacent edge portions 15c and 15c in the stacking direction D, it is separated from one edge portion 15c and is sandwiched by the edge portions 15c and 15c. It has not been. A part of the outer portion 21b of the first resin portion 21 is buried in the second resin portion 22. The first resin portions 21 and 21 adjacent to each other in the stacking direction D are separated from each other. Therefore, in the power storage module 4A, the second resin portion 22 welded to the outer surface of the first resin portion 21 seals between the adjacent bipolar electrodes 14 and 14 in the stacking direction D, and the internal space U is formed. ing.

In the power storage modules 4 and 4A, in order to improve the bonding force between the first resin portion 21 and the electrode plate 15, the surface of the edge portion 15c to which the first resin portion 21 is attached may be roughened. Specifically, for example, one surface 15a may be roughened at the edge portion 15c by electroplating. In the case of the power storage module 4, in addition to the one surface 15a, the end surface of the electrode plate 15 may be roughened. When the electrode plate 15 is roughened in this way, the first resin portion 21 enters the recess formed by the roughening, and the anchor effect is exhibited.

The effect of the intermediate layer 25 when the electrode plate 15 is roughened will be described in detail with reference to FIGS. 6 (a) and 6 (b). 6 (a) and 6 (b) are schematic views for explaining the effect of the intermediate layer. As shown in FIGS. 6A and 6B, one surface 15a of the electrode plate 15 is roughened, and the electrode plate 15 has a plurality of protrusions 15d protruding from the one surface 15a. .. The protrusion 15d has, for example, a shape that becomes thicker from the base end side toward the tip end side. 6 (a) and 6 (b) are schematic views, and the shape and density of the protrusions 15d are not particularly limited.

FIG. 6A shows the case of the power storage module according to the comparative example. The power storage module according to the comparative example is mainly different from the power storage modules 4 and 4A in that the intermediate layer 25 is not provided. The first resin portion 21 is more difficult to bond with the proximal end side than the distal end side of the protrusion 15d. Therefore, on the tip end side of the protrusion 15d, the electrode plate 15 is bonded to the first resin portion 21, but on the base end side of the protrusion 15d, the electrode plate 15 is not bonded to the first resin portion 21, and is connected to the electrode plate 15. A gap of 15 g is formed between the resin portion 21 and the first resin portion 21. Therefore, in the power storage module according to the comparative example, although the anchor effect can be obtained on the tip end side of the protrusion 15d, it is difficult to obtain the anchor effect on the base end side of the protrusion 15d. Therefore, the sealing property cannot be sufficiently improved.

FIG. 6B shows the case of the power storage modules 4 and 4A. In the power storage modules 4 and 4A, the first resin portion 21 is provided on the electrode plate 15 via the intermediate layer 25. As a result, the base end side of the protrusion 15d is also easily bonded to the first resin portion 21, so that the formation of a gap 15g on the base end side of the protrusion 15d is suppressed. Therefore, in the power storage modules 4 and 4A, by roughening the surface of the electrode plate 15, the anchor effect can be obtained not only on the distal end side but also on the proximal end side of the protrusion 15d, so that the sealing property can be sufficiently improved. Here, the thickness (average thickness) of the intermediate layer 25 is thinner than the protrusion height (average protrusion height) of the protrusion 15d. As a result, it is possible to prevent the protrusion 15d from being buried in the intermediate layer 25 and losing the anchor effect. The thickness (average thickness) of the intermediate layer 25 may be thicker on the base end side of the plurality of protrusions 15d than on the tip end side. Since it is more difficult for the base end side to bond with the first resin portion 21 than the tip end side of the protrusion 15d, by arranging the intermediate layer 25 thicker on the base end side, the first resin portion 21 and the electrode plate 15 can also be formed on the base end side. Can be easily bonded via the intermediate layer 25.

4,4A ... power storage module, 11 ... electrode laminate, 14 ... bipolar electrode, 15 ... electrode plate, 15a ... one side, 15b ... other side, 15c ... edge, 15d ... protrusion, 16 ... positive electrode, 17 ... negative electrode, 21 ... 1st resin part (resin part), 25 ... Intermediate layer.

Claims (5)

An electrode laminate in which a plurality of electrodes are laminated, and
A resin portion provided for each of the plurality of electrodes is provided.
Each of the plurality of electrodes has a metal electrode plate, an active material layer provided on at least one surface of the electrode plate, and an intermediate layer covering the edge portion of the electrode plate.
The resin portion is provided on the edge portion via the intermediate layer.
A power storage module in which the intermediate layer contains a material made of an element that is more easily bonded to the resin portion than an element that is a main component of the surface layer portion of the electrode plate. The power storage module according to claim 1, wherein the intermediate layer contains at least one element selected from the group consisting of titanium, silicon, chromium, and tungsten. The power storage module according to claim 1 or 2, wherein the edge portion is roughened and has a plurality of protrusions. The power storage module according to claim 3, wherein the thickness of the intermediate layer is thinner than the protrusion height of each of the plurality of protrusions. The power storage module according to claim 3 or 4, wherein the thickness of the intermediate layer is thicker on the proximal end side of the plurality of protrusions than on the distal end side.

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