JP2020030962A - Power storage module - Google Patents

Abstract

To provide a power storage module that can perform insulation between electrode plates adjacent in a lamination direction without increasing a physical size in a direction perpendicular to the lamination direction.SOLUTION: A power storage module 2 includes an electrode laminate 11 in which a bipolar electrode 13 having an electrode plate 18, a positive electrode 19, and a negative electrode 20 are laminated via a separator 14, and a sealing body 12 provided so as to surround a side surface of the electrode laminate 11. The sealing body 12 includes a plurality of first sealing portions 21 holding an electrode plate 18, and a second sealing portion 22 disposed around the plurality of first sealing portions 21, and each first sealing portion 21 includes a first resin frame 23 joined to the edge of one surface 18a of the electrode plate 18, and a second resin frame 24 placed on the first resin frame 23, and the second resin frame 24 includes an overhang 25 protruding inward in a direction perpendicular to the lamination direction with respect to the first resin frame 23, and the edge of a separator 14 overlaps with the overhang 25 in the lamination direction.SELECTED DRAWING: Figure 2

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 in which a positive electrode is formed on one surface of an electrode plate and a negative electrode is formed on the other surface of the electrode plate is known. Have been. The power storage module includes an electrode stack in which a plurality of bipolar electrodes are stacked via a separator, and a sealing body that seals the electrode stack.

JP 2011-204386 A

  In the above-described power storage module, a method of insulating between electrode plates adjacent in the stacking direction is an issue. As a method of performing insulation between the electrode plates, for example, a resin frame that forms a part of the 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 for mounting the edge of the separator on the resin frame. Also, when the resin frame is joined to the electrode plate by heat welding, the resin of the resin frame flows at the time of heat welding, so that a certain amount of gap is required between the resin frame and the electrodes (positive electrode and negative electrode). It is. For this reason, the overall dimensions of the resin frame must increase in the direction perpendicular to the laminating direction. As a result, the physical size of the power storage module increases in a direction perpendicular to the stacking direction.

  An object of the present invention is to provide a power storage module that can insulate between electrode plates adjacent in the stacking direction without increasing the physical size in a direction perpendicular to the stacking direction.

  One embodiment of the present invention provides an electrode stack in which 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 stacked with a separator interposed therebetween, and an electrode stack. And a sealing body that is provided so as to surround the side surface of the electrode and forms an internal space between adjacent bipolar electrodes and seals the internal space. And a second sealing portion disposed around the plurality of first sealing portions, wherein the first sealing portion is joined to an edge 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 has a tension that protrudes inward in a direction perpendicular to the laminating direction with respect to the first resin frame. It has a protrusion, and the edge of the separator overlaps the protrusion in the stacking direction.

  In such a power storage module, the first resin frame joined to the edge of one surface of the electrode plate has a projecting portion projecting inward in a direction perpendicular to the laminating direction with respect to the first resin frame. The second resin frame is placed. The edge of the separator overlaps the overhang in the stacking direction. Thereby, the electrode plates adjacent in the laminating direction are insulated. Here, when the second resin frame is not joined to the electrode plate, since the resin of the second resin frame does not flow, it is possible to bring the second resin frame closer to the electrodes (positive electrode and negative electrode). For this reason, it is not necessary to increase the overall size of the first sealing portion in the direction perpendicular to the lamination direction. As described above, insulation between the electrode plates adjacent in the stacking direction can be performed without increasing the size of the power storage module in the direction perpendicular to the stacking direction.

  The edge of the separator may overlap the overhang in the laminating direction so as to face the first resin frame. In such a configuration, the edge portion of the separator can be overlapped with the overhang in the laminating direction in a state where the edge portion extends straight outside in the direction perpendicular to the laminating 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 electrolyte in the power storage module passes between the electrode plate and the first resin frame due to a so-called alkali 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 expand. Therefore, leakage of the electrolyte due to the alkali creep phenomenon is less likely to occur. Further, at the time of joining the electrode plate and the first resin frame, it is possible to prevent burrs generated at the edge of the electrode plate by cutting the electrode plate from breaking through the first resin frame.

  ADVANTAGE OF THE INVENTION According to this invention, insulation between the electrode plates adjacent to a lamination direction can be performed, without increasing the physique of a power storage module in the direction perpendicular to the lamination direction.

1 is a schematic sectional view illustrating a power storage device including a power storage module according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the power storage module shown in FIG. FIG. 3 is an enlarged sectional view of a main part of the power storage module shown in FIG. 2. FIG. 3 is an enlarged cross-sectional view illustrating a main part of a power storage module according to a comparative example and the power storage module illustrated in FIG. 2 in comparison.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements have the same reference characters allotted, and overlapping description will be omitted.

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

  The power storage device 1 includes a plurality (here, three) of 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, or an electric double layer capacitor. Here, a nickel-metal hydride secondary battery is illustrated as the power storage module 2.

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

  A positive electrode terminal 4 is connected to the conductive plate 3 located at one end (here, the lower end) in the stacking direction. A 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 (X-axis direction) perpendicular to the laminating direction. By providing such a positive electrode terminal 4 and a negative electrode terminal 5, charging and discharging of the power storage device 1 can be performed.

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

  In addition, the power storage device 1 includes a restraining unit 6 that restrains the power storage module 2 and the conductive plate 3 in the stacking direction. The restraining unit 6 includes 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 formed of metal. An insulating film 10 such as a resin film is disposed 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. When the nut 9 is screwed into the tip of the shaft portion 8a with the shaft portion 8a of the bolt 8 inserted through the insertion hole 7a provided in each end plate 7, the power storage module 2, the conductive plate 3, and the insulating film 10 is subjected to a constraint load in the stacking direction.

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

  The electrode stack 11 includes a bipolar electrode group 15 in which a plurality of bipolar electrodes 13 are stacked with a separator 14 interposed therebetween, and a positive electrode terminal disposed at one end side (here, a lower side) of the bipolar electrode group 15 in the stacking direction. It has an electrode 16 and a negative electrode termination electrode 17 disposed on the other end side (here, upper side) of the bipolar electrode group 15 in the laminating direction. The bipolar electrode 13, the separator 14, the positive terminal electrode 16 and the negative terminal electrode 17 have, for example, a rectangular shape in plan view.

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

  The positive electrode termination 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 18 b of the electrode plate 18. The positive electrode 19 of the positive electrode termination electrode 16 faces the negative electrode 20 of the lowermost bipolar electrode 13 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 uppermost bipolar electrode 13 of the bipolar electrode group 15 with the separator 14 interposed therebetween. The electrode plates 18 of the positive terminal electrode 16 and the negative terminal electrode 17 are each electrically connected to the conductive plate 3 (see FIG. 1) adjacent in the laminating 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 18 b of the electrode plate 18. As the negative electrode active material, for example, a hydrogen storage alloy is used. The edge of the electrode plate 18 is an uncoated area where the positive electrode active material and the negative electrode active material are not applied.

  The separator 14 is disposed 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 in a sheet shape, for example. The separator 14 is formed of a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or a nonwoven fabric or woven fabric made of PE, PP, methylcellulose, or the like. The separator 14 may be reinforced with a vinylidene fluoride resin compound or the like.

  The sealing body 12 is formed in a rectangular ring shape from, for example, an insulating resin. The sealing body 12 is disposed around the plurality of first sealing portions 21 that respectively hold the electrode plates 18 of the bipolar electrode 13, the positive terminal electrode 16, and the negative terminal electrode 17, and the plurality of first sealing portions 21. And 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), and modified polyphenylene ether (modified PPE).

  The first sealing portion 21 has a frame shape. The first sealing portion 21 extends outside the periphery of the electrode plate 18 in a direction perpendicular to the lamination direction (X-axis direction and Y-axis direction).

  As shown in FIG. 3, the first sealing portion 21 has a first resin frame 23 joined to the edge of one surface 18 a of the electrode plate 18 by welding, and is placed on the first resin frame 23. The second resin frame 24 is provided. The first resin frame 23 is, for example, thermally welded to one surface 18 a of the electrode plate 18. The second resin frame 24 is not welded (joined) to the first resin frame 23 and the other surface 18b of the electrode plate 18 adjacent in the laminating 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 a projecting portion 25 projecting inward from the first resin frame 23 in a direction perpendicular to the laminating direction. The edge of the separator 14 overlaps the overhang 25 in the stacking direction. Specifically, the edge of the separator 14 overlaps the overhang 25 in the laminating direction so as to face the first resin frame 23. The edge of the separator 14 is disposed between the one surface 18 a of the electrode plate 18 and the overhang 25. Thereby, insulation between the electrode plates 18 adjacent in the stacking direction is achieved. At this time, the edge of the separator 14 is in contact with the overhang 25. Further, the periphery 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 forms an outer wall (housing) of the power storage module 2. The second sealing portion 22 has a rectangular cylindrical shape. The second sealing portion 22 is formed by, for example, injection molding. The second sealing portion 22 is welded (joined) to the outer surface of each first sealing portion 21 by, for example, heat at the time of injection molding.

  At both end portions of the second sealing portion 22 in the stacking direction, overhang portions 26 that protrude inward in a direction perpendicular to the stacking direction and sandwich the respective first sealing portions 21 in the stacking direction are provided. The overhang portion 26 has a frame shape. The overhang portion 26 overlaps the electrode plate 18. One overhang portion 26 is in contact with the other surface 18 b of the electrode plate 18 of the positive electrode termination electrode 16. The other overhang portion 26 is welded (joined) to the second resin frame 24 of the uppermost first sealing portion 21. In addition, the other surface 18 b of the electrode plate 18 of the positive electrode terminal electrode 16 may be welded (joined) to the first sealing portion 21.

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

  Each internal space V contains an alkaline electrolyte (not shown). As the alkaline electrolyte, for example, an electrolyte containing an alkaline solution such as an aqueous solution of potassium hydroxide is used. The electrolyte is impregnated inside the separator 14, the positive electrode 19 and the negative electrode 20.

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

  4A, the power storage module 100 of the present comparative example includes a first sealing portion 21 having a first resin frame 23 and a second resin frame 24, similarly to the power storage module 2 described above. The first resin frame 23 has a projecting portion 101 projecting inward in a direction perpendicular to the laminating direction with respect to the second resin frame 24. The edge of the separator 14 is placed on the overhang 101.

  Here, the region A where the electrode plate 18, the first resin frame 23, and the second resin frame 24 overlap is formed when the second sealing portion 22 (see FIGS. 2 and 3) is formed by injection molding. This is an area secured for pressing the first resin frame 23 and the second resin frame 24 in the laminating direction. A region B where the first resin frame 23 and the second resin frame 24 overlap with each other outside the region A in a direction perpendicular to the laminating direction is a region required as a pressing allowance of a mold during injection molding. Therefore, the widths (dimensions in the X-axis direction and the Y-axis direction) of the first resin frame 23 and the second resin frame 24 need to be at least equivalent to the regions A and B.

  Further, since the first resin frame 23 is thermally 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 thermally welded to the electrode plate 18, the resin forming the first resin frame 23 flows inward in a direction perpendicular to the lamination direction, and the width of the overhang portion 101 is reduced. May be larger. For this reason, as the interval C between the first resin frame 23 and the negative electrode 20, 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 tolerance of the first resin frame 23 It is necessary to have a dimension capable of absorbing the tolerance due to deformation during heat welding. Therefore, since the width of the first sealing portion 21 increases outward in the direction perpendicular to the stacking direction, the overall size 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 a 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 the protruding portion 25 that protrudes inward in the direction perpendicular to the lamination direction with respect to the first resin frame 23, and the edge of the separator 14. The portion overlaps the overhang portion 25 in the stacking direction. The second resin frame 24 is not thermally welded to the first resin frame 23 and the other surface 18b of the electrode plate 18 adjacent in the laminating direction. Therefore, the width of the overhang portion 25 does not increase due to the flow of the resin forming the second resin frame 24. That is, there is no need to consider the tolerance of the deformation of the second resin frame 24. Therefore, the distance D between the second resin frame 24 and the negative electrode 20 is only required to be large enough 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. Is enough. Thereby, the distance D between the second resin frame 24 and the negative electrode 20 can be reduced. As a result, as compared with the power storage module 100, the peripheral edge of the first sealing portion 21 is located on the inner side in the direction perpendicular to the stacking direction by the region E, and the overall size of the first sealing portion 21 is reduced in the stacking direction. Smaller in the direction perpendicular to.

  As described above, according to the present embodiment, the first resin frame 23 joined to the edge of the one surface 18a of the electrode plate 18 has the inner side in the direction perpendicular to the laminating direction with respect to the first resin frame 23. A second resin frame 24 having an overhanging portion 25 is mounted. The edge of the separator 14 overlaps the overhang 25 in the stacking direction. As a result, the electrode plates 18 adjacent in the stacking direction are insulated. Here, when the second resin frame 24 is not joined 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 size of the first sealing portion 21 in the direction perpendicular to the lamination direction. As described above, the insulation between the electrode plates 18 adjacent in the stacking direction can be performed without increasing the size of the power storage module 2 in the direction perpendicular to the stacking direction.

  In the present embodiment, the edge of the separator 14 overlaps the overhang 25 in the stacking direction so as to face the first resin frame 23. For this reason, it is possible to overlap the overhanging portion 25 in the laminating direction with the edge portion of the separator 14 extending straight outside the direction perpendicular to the laminating direction. Therefore, the separator 14 can be easily manufactured.

  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. With such a configuration, when the electrolyte in the internal space V passes between the electrode plate 18 and the first resin frame 23 due to a so-called alkali creep phenomenon, the first resin frame 23 is less likely to be peeled off from the electrode plate 18. Therefore, it is difficult for the gap between the first resin frame 23 and the electrode plate 18 to expand. Therefore, leakage of the electrolyte due to the alkali creep phenomenon is less likely to occur. Further, at the time of joining the electrode plate 18 and the first resin frame 23, it is prevented that burrs generated at the edge of the electrode plate 18 by cutting the electrode plate 18 break through the first resin frame 23.

  Note that 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 present invention is not particularly limited to this, and the thickness D1 of the first resin frame 23 is May be equal to the thickness D2, 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, a single frame-shaped resin film is folded inward in a direction perpendicular to the laminating direction, thereby forming 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 joined to the first resin frame 23, but the present invention is not particularly limited to this, and the second resin frame 24 is joined to the first resin frame 23 in advance. Is also good.

  Further, in the above embodiment, the edge of the separator 14 overlaps the overhang 25 of the second resin frame 24 in the laminating direction so as to face the first resin frame 23, but is not particularly limited to that form. For example, the edge of the separator 14 is placed on the side of the electrode plate 18 such that the edge of the separator 14 overlaps with the overhang 25 in the stacking direction in a state where the edge of the separator 14 is disposed between the second resin frame 24 and the electrode plate 18. It may be bent.

  2 ... power storage module, 11 ... electrode laminate, 12 ... sealed body, 13 ... bipolar electrode, 14 ... separator, 18 ... electrode plate, 18a ... one surface, 18b ... other surface, 19 ... positive electrode, 20 ... negative electrode, 21 .. A first sealing portion, 22 a second sealing portion, 23 a first resin frame, 24 a second resin frame, 25 a projecting portion.

Claims (3)

An electrode laminate formed by laminating 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 via a separator, and surrounding a side surface of the electrode laminate. And a sealing body that forms an internal space between the adjacent bipolar electrodes and seals the internal space.
The sealing body has a plurality of first sealing portions that hold the electrode plate, and a second sealing portion that is arranged around the plurality of first sealing portions.
The first sealing portion includes a first resin frame joined to an edge of the one surface of the electrode plate, and a second resin frame placed on the first resin frame,
The second resin frame has a projecting portion projecting inward in a direction perpendicular to the laminating direction with respect to the first resin frame,
The power storage module, wherein an edge of the separator overlaps the overhang portion in the stacking direction.   The power storage module according to claim 1, wherein an edge of the separator overlaps the overhang in the laminating direction so as to face the first resin frame.   The power storage module according to claim 1, wherein a thickness of the first resin frame is larger than a thickness of the second resin frame.

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