JP7074614B2 - Power storage module - Google Patents

Description

The present invention relates to a power storage module.

As a conventional power storage module, for example, as described in Patent Document 1, a power storage module 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 of the electrode plate is known. Has been done. The power storage module includes an electrode laminate in which a plurality of bipolar electrodes are laminated via a separator, and a sealed body that seals the electrode laminate.

Japanese Unexamined Patent Publication No. 2011-204386

In the above-mentioned power storage module, a method of insulating between electrode plates adjacent to each other in the stacking direction is an issue. As a method of insulating between the electrode plates, for example, a resin frame that forms a part of a sealing body and holds the electrode plates has a two-stage structure, and the edge of the separator is placed on the lower stage of the resin frame. Conceivable. However, in this case, it is necessary to provide a portion on the resin frame on which the edge portion of the separator is placed. Further, when the resin frame is joined to the electrode plate by heat welding, the resin of the resin frame flows during heat welding, so a certain amount or more of a gap is required between the resin frame and the electrodes (positive electrode and negative electrode). Is. Therefore, the overall dimensions of the resin frame have to be increased in the direction perpendicular to the laminating direction. As a result, the physique of the power storage module increases in the direction perpendicular to the stacking direction.

An object of the present invention is to provide a power storage module capable of insulating between adjacent electrode plates in the stacking direction without increasing the physique in the direction perpendicular to the stacking direction.

One aspect of the present invention is an electrode laminate having a positive electrode formed on one surface of the electrode plate and a negative electrode formed on the other surface of the electrode plate laminated via a separator, and an electrode laminate. In a power storage module provided so as to surround the side surface of the battery and provided with a sealing body that forms an internal space between adjacent bipolar electrodes and seals the internal space, the sealing body is a plurality of holding the electrode plate. The first sealing portion and the second sealing portion arranged around the plurality of first sealing portions are provided, and the first sealing portion is joined to the edge portion of one surface of the electrode plate. It has a first resin frame and a second resin frame mounted on the first resin frame, and the second resin frame is stretched inward in a direction perpendicular to the stacking direction with respect to the first resin frame. It has a protruding portion, and the edge portion of the separator overlaps the protruding portion in the stacking direction.

In such a power storage module, on the first resin frame joined to the edge of one surface of the electrode plate, an overhanging portion is provided inward in a direction perpendicular to the stacking direction with respect to the first resin frame. A second resin frame is placed. The edge portion of the separator overlaps the overhanging portion in the stacking direction. As a result, the electrodes adjacent to each other in the stacking direction are insulated from each other. Here, when the second resin frame is not joined to the electrode plate, the resin of the second resin frame does not flow, so that the second resin frame can be brought closer to the electrodes (positive electrode and negative electrode). Therefore, it is not necessary to increase the overall size of the first sealing portion in the direction perpendicular to the stacking direction. As described above, it is possible to insulate between the electrode plates adjacent to each other in the stacking direction without increasing the physique of the power storage module in the direction perpendicular to the stacking direction.

The edge portion of the separator may overlap the overhanging portion in the stacking direction so as to face the first resin frame. In such a configuration, the edge portion of the separator can be overlapped with the overhanging portion in the stacking direction in a state of being straightly extended outward in the direction perpendicular to the stacking direction. Therefore, the separator can be easily manufactured.

The thickness of the first resin frame may be larger than the thickness of the second resin frame. In such a configuration, when the electrolytic solution in the power storage module passes between the electrode plate and the first resin frame due to the so-called alkaline creep phenomenon, the first resin frame is less likely to be peeled off from the electrode plate. The gap between the resin frame and the electrode plate is less likely to widen. Therefore, leakage of the electrolytic solution due to the alkaline creep phenomenon is less likely to occur. Further, when the electrode plate and the first resin frame are joined, burrs generated at the edge of the electrode plate due to the cutting of the electrode plate are prevented from penetrating the first resin frame.

According to the present invention, it is possible to insulate between electrode plates adjacent to each other in the stacking direction without increasing the physique of the power storage module in the direction perpendicular to the stacking direction.

It is a schematic sectional drawing which shows the electric power storage apparatus provided with the electric power storage module which concerns on one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view of the power storage module shown in FIG. FIG. 2 is an enlarged cross-sectional view of a main part of the power storage module shown in FIG. FIG. 3 is an enlarged cross-sectional view of a main part showing a comparison between the power storage module according to the comparative example and the power storage module shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a schematic cross-sectional view showing a power storage device including a power storage module according to an embodiment of the present invention. In FIG. 1, the power storage device 1 is used as a battery for a vehicle such as a forklift, a hybrid vehicle, or an electric vehicle.

The power storage device 1 includes a plurality of (three in this case) power storage modules 2. The power storage module 2 is, for example, a secondary battery such as a nickel hydrogen secondary battery or a lithium ion secondary battery, an electric double layer capacitor, or the like. Here, a nickel-metal hydride secondary battery is exemplified as the power storage module 2.

The plurality of power storage modules 2 are laminated via a metal conductive plate 3. The conductive plate 3 is also arranged outside the stacking direction of the power storage module 2 located at both ends in the stacking direction (Z-axis direction). The power storage module 2 and the conductive plate 3 have, for example, a rectangular shape (rectangular shape in a plan view) when viewed from the stacking direction. The conductive plate 3 is electrically connected to the adjacent power storage modules 2. As a result, the plurality of power storage modules 2 are connected in series in the stacking direction. The power storage module 2 will be described in detail later.

A positive electrode terminal 4 is connected to a conductive plate 3 located at one end (here, the lower end) in the stacking direction. The negative electrode terminal 5 is connected to the conductive plate 3 located at the other end (here, the upper end) in the stacking direction. The positive electrode terminal 4 and the negative electrode terminal 5 extend in a direction perpendicular to the stacking direction (X-axis direction). By providing such a positive electrode terminal 4 and a negative electrode terminal 5, it is possible to charge and discharge the power storage device 1.

The conductive plate 3 also has a function as a heat radiating plate that releases heat generated by the power storage module 2. The conductive plate 3 is provided with a plurality of flow paths 3a extending in a direction (Y-axis direction) perpendicular to the stacking direction of the power storage module 2 and the extending direction of the positive electrode terminal 4 and the negative electrode terminal 5. By passing a refrigerant such as air through these flow paths 3a, the heat from the power storage module 2 can be efficiently discharged to the outside.

Further, the power storage device 1 includes a restraint unit 6 that restrains the power storage module 2 and the conductive plate 3 in the stacking direction. The restraint unit 6 has a pair of end plates 7 that sandwich the power storage module 2 and the conductive plate 3 in the stacking direction, and a plurality of sets of bolts 8 and nuts 9 that fasten the end plates 7 to each other.

The end plate 7 is made of metal. An insulating film 10 such as a resin film is arranged between each end plate 7 and the conductive plate 3. The end plate 7 and the insulating film 10 have, for example, a rectangular shape in a plan view. With the shaft portion 8a of the bolt 8 inserted through the insertion hole 7a provided in each end plate 7, the nut 9 is screwed into the tip portion of the shaft portion 8a, whereby the power storage module 2, the conductive plate 3, and the insulating film are screwed. A restraining load in the stacking direction is applied to 10.

FIG. 2 is a schematic cross-sectional view of the power storage module 2. In FIG. 2, the power storage module 2 has a structure (plural cell structure) in which a plurality of cells (for example, 24 cells) are laminated. The power storage module 2 includes an electrode laminated body 11 and a resin-made sealing body 12 provided so as to surround the side surface of the electrode laminated body 11.

The electrode laminate 11 has a bipolar electrode group 15 in which a plurality of bipolar electrodes 13 are laminated via a separator 14, and a positive electrode terminal arranged on one end side (in this case, the lower side) of the bipolar electrode group 15 in the stacking direction. It has an electrode 16 and a negative electrode terminal electrode 17 arranged on the other end side (here, the upper side) of the bipolar electrode group 15 in the stacking direction. The bipolar electrode 13, the separator 14, the positive electrode terminating electrode 16, and the negative electrode terminating electrode 17 have, for example, a rectangular shape in a plan view.

The separator 14 is arranged between the bipolar electrodes 13 adjacent to each other in the stacking direction. The bipolar electrode 13 has an electrode plate 18, a positive electrode 19 formed on one surface 18a of the electrode plate 18, and a negative electrode 20 formed on the other surface 18b of the electrode plate 18. The positive electrode 19 of the bipolar electrode 13 faces the negative electrode 20 of one of the bipolar electrodes 13 adjacent to each other in the stacking direction with the separator 14 interposed therebetween. The negative electrode 20 of the bipolar electrode 13 faces the positive electrode 19 of the other bipolar electrode 13 adjacent to each other in the stacking direction with the separator 14 interposed therebetween.

The positive electrode terminal electrode 16 has an electrode plate 18 and a positive electrode 19 formed on one surface 18a of the electrode plate 18. The negative electrode terminal electrode 17 has an electrode plate 18 and a negative electrode 20 formed on the other surface 18b of the electrode plate 18. The positive electrode 19 of the positive electrode terminal electrode 16 faces the negative electrode 20 of the bipolar electrode 13 in the lowermost layer of the bipolar electrode group 15 with the separator 14 interposed therebetween. The negative electrode 20 of the negative electrode terminal electrode 17 faces the positive electrode 19 of the bipolar electrode 13 on the uppermost layer of the bipolar electrode group 15 with the separator 14 interposed therebetween. The electrode plates 18 of the positive electrode termination electrode 16 and the negative electrode termination electrode 17 are electrically connected to the conductive plates 3 (see FIG. 1) adjacent to each other in the stacking direction.

The electrode plate 18 is a rectangular metal foil made of, for example, nickel or nickel plating. One surface 18a and the other surface 18b of the electrode plate 18 are roughened. The positive electrode 19 is formed by applying a positive electrode active material to one surface 18a of the electrode plate 18. As the positive electrode active material, for example, nickel hydroxide coated with a cobalt (Co) oxide is used. The negative electrode 20 is formed by applying a negative electrode active material to the other surface 18b of the electrode plate 18. As the negative electrode active material, for example, a hydrogen storage alloy is used. The edge portion of the electrode plate 18 is an uncoated area where the positive electrode active material and the negative electrode active material are not coated.

The separator 14 is arranged between the positive electrode 19 and the negative electrode 20, and separates the positive electrode 19 and the negative electrode 20. The separator 14 is formed, for example, in the form of a sheet. The separator 14 is formed of a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or a non-woven fabric or woven fabric made of PE, PP, methyl cellulose or the like. Further, the separator 14 may be reinforced with a vinylidene fluoride resin compound or the like.

The sealing body 12 is formed of, for example, an insulating resin in a rectangular ring shape. The encapsulant 12 is arranged around a plurality of first encapsulation portions 21 holding the electrode plates 18 of the bipolar electrode 13, the positive electrode termination electrode 16 and the negative electrode termination electrode 17, and the plurality of first encapsulation portions 21. It also has a second sealing portion 22 joined to each first sealing portion 21. Examples of the resin material of the first sealing portion 21 and the second sealing portion 22 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like.

The first sealing portion 21 has a frame shape. The first sealing portion 21 projects outward from the peripheral edge of the electrode plate 18 in the direction perpendicular to the stacking direction (X-axis direction and Y-axis direction).

As shown in FIG. 3, the first sealing portion 21 is placed on the first resin frame 23 bonded to the edge portion of one surface 18a of the electrode plate 18 by welding and on the first resin frame 23. It has a second resin frame 24 that has been formed. The first resin frame 23 is heat-welded to, for example, one surface 18a of the electrode plate 18. The second resin frame 24 is not welded (bonded) to the other surface 18b of the first resin frame 23 and the electrode plates 18 adjacent to each other in the stacking direction. The thickness D1 (dimension in the stacking direction) of the first resin frame 23 is larger than the thickness D2 of the second resin frame 24.

The second resin frame 24 has an overhanging portion 25 that overhangs inward in a direction perpendicular to the stacking direction with respect to the first resin frame 23. The edge portion of the separator 14 overlaps with the overhanging portion 25 in the stacking direction. Specifically, the edge portion of the separator 14 overlaps the overhanging portion 25 in the stacking direction so as to face the first resin frame 23. The edge portion of the separator 14 is arranged between the one surface 18a of the electrode plate 18 and the overhanging portion 25. As a result, insulation between the electrode plates 18 adjacent to each other in the stacking direction is achieved. At this time, the edge portion of the separator 14 is in contact with the overhanging portion 25. Further, the peripheral edge of the separator 14 may be in contact with the first resin frame 23 or may not be in contact with the first resin frame 23.

The second sealing portion 22 constitutes the outer wall (housing) of the power storage module 2. The second sealing portion 22 has a square tubular shape. The second sealing portion 22 is formed, for example, by injection molding. The second sealing portion 22 is welded (bonded) to the outer surface of each first sealing portion 21 by, for example, heat during injection molding.

Overhang portions 26 are provided at both ends of the second sealing portion 22 in the stacking direction so as to project inward in the direction perpendicular to the stacking direction and sandwich the first sealing portions 21 in the stacking direction. The overhang portion 26 has a frame shape. The overhang portion 26 overlaps with the electrode plate 18. One overhang portion 26 is in contact with the other surface 18b of the electrode plate 18 of the positive electrode terminal electrode 16. The other overhang portion 26 is welded (bonded) to the second resin frame 24 of the first sealing portion 21 at the uppermost portion. The other surface 18b of the electrode plate 18 of the positive electrode terminal electrode 16 may be welded (bonded) to the first sealing portion 21.

An electrode plate is provided between the bipolar electrodes 13 adjacent to each other in the stacking direction, between the bipolar electrodes 13 adjacent to each other in the stacking direction and the positive electrode terminal electrode 16, and between the bipolar electrodes 13 and the negative electrode terminal 17 adjacent to each other in the stacking direction. An internal space V formed by 18, a positive electrode 19, a negative electrode 20, a first sealing portion 21, and a second sealing portion 22 is provided, respectively. The first sealing portion 21 and the second sealing portion 22 seal each internal space V.

An alkaline electrolytic solution (not shown) is housed in each internal space V. As the alkaline electrolytic solution, an electrolytic solution containing an alkaline solution such as an aqueous solution of potassium hydroxide is used. The electrolytic solution is impregnated inside the separator 14, the positive electrode 19, and the negative electrode 20.

FIG. 4 is an enlarged cross-sectional view of a main part showing a comparison between the power storage module according to the comparative example and the power storage module according to the present embodiment. FIG. 4A shows a power storage module according to a comparative example, and FIG. 4B shows a power storage module according to the present embodiment. In FIG. 4, the second sealing portion 22 is omitted. Further, the dimensions of each part in FIG. 4 do not match those in FIGS. 2 and 3.

In FIG. 4A, the power storage module 100 of this comparative example includes a first sealing portion 21 having a first resin frame 23 and a second resin frame 24, similarly to the above-mentioned power storage module 2. The first resin frame 23 has an overhanging portion 101 that overhangs inward in a direction perpendicular to the laminating direction with respect to the second resin frame 24. The edge portion of the separator 14 is placed on the overhanging portion 101.

Here, the region A where the electrode plate 18, the first resin frame 23, and the second resin frame 24 overlap is the electrode plate 18 when the second sealing portion 22 (see FIGS. 2 and 3) is formed by injection molding. , A region reserved for pressing the first resin frame 23 and the second resin frame 24 in the stacking direction. Further, the region B where the first resin frame 23 and the second resin frame 24 overlap on the outside in the direction perpendicular to the stacking direction with respect to the region A is a region required as a holding allowance for the mold during injection molding. Therefore, the width (dimensions in the X-axis direction and the Y-axis direction) of the first resin frame 23 and the second resin frame 24 needs to be at least the amount corresponding to the regions A and B.

Further, since the first resin frame 23 is heat-welded to the electrode plate 18, it is necessary to increase the distance C between the first resin frame 23 and the negative electrode 20. Specifically, when the first resin frame 23 is heat-welded to the electrode plate 18, the resin forming the first resin frame 23 flows inward in the direction perpendicular to the laminating direction, and the width of the overhanging portion 101 increases. It can get bigger. Therefore, the distance C between the first resin frame 23 and the negative electrode 20 is the tolerance of the first resin frame 23 itself + the position tolerance of the first resin frame 23 + the coating position tolerance of the negative electrode 20 + the first resin frame 23. Dimensions that can absorb the deformation tolerance during heat welding are required. Therefore, since the width of the first sealing portion 21 increases outward in the direction perpendicular to the stacking direction, the overall dimension of the first sealing portion 21 increases in the direction perpendicular to the stacking direction. As a result, the physique of the power storage module 100 increases in the direction perpendicular to the stacking direction.

On the other hand, in the power storage module 2 according to the present embodiment, the second resin frame 24 has an overhanging portion 25 protruding inward in a direction perpendicular to the stacking direction with respect to the first resin frame 23, and is an edge of the separator 14. The portion overlaps with the overhanging portion 25 in the stacking direction. The second resin frame 24 is not heat-welded to the other surface 18b of the electrode plate 18 adjacent to the first resin frame 23 in the stacking direction. Therefore, the width of the overhanging portion 25 does not increase due to the flow of the resin forming the second resin frame 24. That is, it is not necessary to consider the deformation tolerance of the second resin frame 24. Therefore, the distance D between the second resin frame 24 and the negative electrode 20 is sufficient to absorb the tolerance of the second resin frame 24 itself + the position tolerance of the second resin frame 24 + the coating position tolerance of the negative electrode 20. Sufficient. This makes it possible to reduce the distance D between the second resin frame 24 and the negative electrode 20. As a result, as compared with the power storage module 100, the peripheral edge of the first sealing portion 21 is located inside in the direction perpendicular to the stacking direction by the area E, and the overall dimensions of the first sealing portion 21 are in the stacking direction. It becomes smaller in the direction perpendicular to.

As described above, according to the present embodiment, on the first resin frame 23 joined to the edge of one surface 18a of the electrode plate 18, the inside in the direction perpendicular to the stacking direction with respect to the first resin frame 23. A second resin frame 24 having an overhanging portion 25 overhanging is placed. The edge portion of the separator 14 overlaps with the overhanging portion 25 in the stacking direction. As a result, the electrodes 18 adjacent to each other in the stacking direction are insulated from each other. Here, when the second resin frame 24 is not bonded to the electrode plate 18, the resin of the second resin frame 24 does not flow, so that the second resin frame 24 can be brought closer to the negative electrode 20. Therefore, it is not necessary to increase the overall dimensions of the first sealing portion 21 in the direction perpendicular to the stacking direction. As described above, it is possible to insulate between the electrode plates 18 adjacent to each other in the stacking direction without increasing the physique of the power storage module 2 in the direction perpendicular to the stacking direction.

Further, in the present embodiment, the edge portion of the separator 14 overlaps the overhanging portion 25 in the stacking direction so as to face the first resin frame 23. Therefore, the edge portion of the separator 14 can be overlapped with the overhanging portion 25 in the stacking direction in a state of being straightly extended outward in the direction perpendicular to the stacking direction. Therefore, the separator 14 can be easily manufactured.

Further, in the present embodiment, the thickness D1 of the first resin frame 23 is larger than the thickness D2 of the second resin frame 24. In such a configuration, when the electrolytic solution in the internal space V passes between the electrode plate 18 and the first resin frame 23 due to the so-called alkaline creep phenomenon, the first resin frame 23 is less likely to be peeled off from the electrode plate 18. Therefore, the gap between the first resin frame 23 and the electrode plate 18 is less likely to expand. Therefore, leakage of the electrolytic solution due to the alkaline creep phenomenon is less likely to occur. Further, when the electrode plate 18 and the first resin frame 23 are joined, burrs generated at the edge of the electrode plate 18 due to the cutting of the electrode plate 18 are prevented from penetrating the first resin frame 23.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the thickness D1 of the first resin frame 23 is larger than the thickness D2 of the second resin frame 24, but the embodiment is not particularly limited, and the thickness D1 of the first resin frame 23 is the second resin frame 24. The thickness D2 of the second resin frame 24 may be equal to the thickness D2 of the first resin frame 23, or the thickness D2 of the second resin frame 24 may be larger than the thickness D1 of the first resin frame 23. When the thickness D1 of the first resin frame 23 is equal to the thickness D2 of the second resin frame 24, for example, by folding one frame-shaped resin film inward in the direction perpendicular to the laminating direction, the first resin frame 23 and the second resin frame 24 may be formed.

Further, in the above embodiment, the second resin frame 24 is not bonded to the first resin frame 23, but the embodiment is not particularly limited, and the second resin frame 24 is previously bonded to the first resin frame 23. May be good.

Further, in the above embodiment, the edge portion of the separator 14 overlaps the overhanging portion 25 of the second resin frame 24 in the stacking direction so as to face the first resin frame 23, but the embodiment is not particularly limited. For example, the edge of the separator 14 is placed on the electrode plate 18 side so that the edge of the separator 14 overlaps the overhanging portion 25 in the stacking direction while being arranged between the second resin frame 24 and the electrode plate 18. You may fold it.

2 ... Energy storage module, 11 ... Electrode laminate, 12 ... Sealed body, 13 ... Bipolar electrode, 14 ... Separator, 18 ... Electrode plate, 18a ... One side, 18b ... The other side, 19 ... Positive electrode, 20 ... Negative electrode, 21 ... 1st sealing portion, 22 ... 2nd sealing portion, 23 ... 1st resin frame, 24 ... 2nd resin frame, 25 ... Overhanging portion.

Claims (3)

A bipolar electrode having a positive electrode formed on one surface of the electrode plate and a negative electrode formed on the other surface of the electrode plate is laminated via a separator so as to surround the side surface of the electrode laminate. In the power storage module provided in the above, the storage module is provided with a sealing body that forms an internal space between the adjacent bipolar electrodes and seals the internal space.
The encapsulant is arranged between the adjacent electrode plates, a plurality of first encapsulation portions for holding the electrode plates, and a second encapsulation portion arranged around the plurality of first encapsulation portions. And have
The first sealing portion is formed by welding the first resin frame to the edge of the one surface of the electrode plate and the first resin without being welded to the other surface of the electrode plate adjacent to the electrode plate. It has a second resin frame placed on the frame and has.
The second resin frame has an overhanging portion that projects inward in a direction perpendicular to the stacking direction with respect to the first resin frame.
The edge portion of the separator is a power storage module that overlaps the overhanging portion in the stacking direction. The power storage module according to claim 1, wherein the edge portion of the separator overlaps the overhanging portion in the stacking direction so as to face the first resin frame. The power storage module according to claim 1 or 2, wherein the thickness of the first resin frame is larger than the thickness of the second resin frame.

Images