JP2023144383A - Power storage device - Google Patents

Abstract

To suppress the occurrence of a short circuit when electrolyte leaks from a cell of a power storage device.SOLUTION: In a power storage device 1, a second electrode portion 13 of a second cell 10B includes a protruding portion 131 and an extending portion 132. The protruding portion 131 is a portion that protrudes from an exterior body 11. The extending portion 132 extends downward from the tip of the protruding portion 131. The second cell 10B further includes a resin film 14. The resin film 14 covers the entire upper surface of the protruding portion 131. A first electrode portion 12 of a third cell 10C is joined to the extending portion 132 of the first electrode portion 12 of the second cell 10B.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a power storage device.

Japanese Unexamined Patent Publication No. 2013-229266 (Patent Document 1) discloses a battery module as a power storage device. The battery module includes a plurality of flat batteries stacked on top of each other. The battery is a rectangular laminate type battery in which one or more rectangular positive electrodes, negative electrodes, and separators are laminated, and the battery is covered with a laminate film. Electrode tabs each made of a thin metal plate are led out in the form of a band from the center of both ends, which are the short sides. One of the pair of electrode tabs is a positive electrode, and the other is a negative electrode. The plurality of batteries are stacked in alternate directions so that the electrode tabs on the positive electrode side and the electrode tabs on the negative electrode side alternate. By connecting adjacent positive electrode tabs and negative electrode tabs to each other, the plurality of batteries are connected in series as a whole. The battery is, for example, a lithium ion secondary battery.

JP2013-229266A

In the power storage device described in Patent Document 1, the electrolyte may leak from the inside of the exterior to the outside. The leaked electrolyte flows downward along the side surfaces of the exteriors of the plurality of cells stacked on top of each other. Therefore, electrodes that are arranged in the vertical direction but are not directly connected to each other and have different potentials may be electrically connected via the electrolyte. This may cause a short circuit in the power storage device.

The present disclosure has been made in view of the above object, and provides a power storage device that can suppress the occurrence of a short circuit when an electrolyte leaks from a cell of the power storage device.

A power storage device according to one aspect of the present disclosure includes a plurality of cells stacked in the vertical direction. Each of the plurality of cells includes an exterior body, a first electrode part, and a second electrode part. The exterior body has an electrolytic solution inside. The first electrode portion protrudes from the exterior body in a direction intersecting the vertical direction. The second electrode portion protrudes from the exterior body in a direction intersecting the vertical direction. The plurality of cells include a first cell, a second cell, and a third cell. The second cell is stacked above the first cell so as to be adjacent to the first cell. The third cell is stacked above the second cell so as to be adjacent to the second cell. The second electrode part of the first cell is connected to the first electrode part of the second cell. The second electrode section of the second cell is connected to the first electrode section of the third cell. The second electrode portion of the second cell has a protrusion and an extension. The protrusion is a portion that protrudes from the exterior body. The extending portion extends downward from the tip of the protruding portion. The second cell further includes a resin film. The resin film covers the entire upper surface of the protrusion. The first electrode part of the third cell is joined to the extension part of the first electrode part of the second cell.

According to the above configuration, for example, when the electrolytic solution leaks from the third cell, the electrolytic solution travels along the outer surface of the outer casing of the third cell and reaches the outer surface of the outer casing of the second cell. The electrolytic solution travels along the outer surface of the exterior body of the second cell and reaches the upper surface of the resin film on the second electrode portion of the second cell. The electrolytic solution further travels along the upper surface of the resin film, and then reaches the tip of the protrusion of the second electrode part. The electrolytic solution that has reached the tip of the protrusion flows downward along the extension and the first electrode portion of the third cell joined to the extension. The electrolyte that has reached the tip of the extension and the tip of the first electrode portion of the third cell drips further downward toward the first cell. As a result, the flow path of the leaked electrolyte is cut off, so that the second electrode part of the second cell, the first electrode part of the third cell, and the first electrode part of the first cell are connected to each other through the electrolyte. electrical connection is suppressed. Therefore, occurrence of short circuit in the power storage device can be suppressed.

According to the present disclosure, it is possible to suppress the occurrence of a short circuit when electrolyte leaks from a cell of a power storage device.

FIG. 1 is a schematic cross-sectional view showing a power storage device according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view showing an example of a state in which electrolyte leaks in a power storage device according to an embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view showing an example of a state in which an electrolytic solution leaks in a power storage device according to a comparative example.

Hereinafter, a power storage device according to an embodiment of the present disclosure will be described. In the following description of the embodiments, the same or corresponding parts in the figures are denoted by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a schematic cross-sectional view showing a power storage device according to an embodiment of the present disclosure. Power storage device 1 according to an embodiment of the present disclosure is mounted, for example, on an electric vehicle such as an electric vehicle. As shown in FIG. 1, a power storage device 1 according to an embodiment of the present disclosure includes a plurality of cells 10 stacked in the vertical direction and a case 20.

Examples of the cell 10 include a lithium ion battery. Each of the plurality of cells 10 is a so-called laminate type cell. Each of the plurality of cells 10 includes an exterior body 11, a first electrode section 12, and a second electrode section 13.

The exterior body 11 is formed of, for example, a pair of aluminum laminate films arranged in the vertical direction. The exterior body 11 has an electrolytic solution (not shown) therein. Furthermore, the exterior body 11 further includes a plurality of separators, a plurality of current collector plates (none of which are shown), etc. therein. At least a portion of the upper surface of the exterior body 11 slopes downward toward the side ends.

The first electrode portion 12 protrudes from the exterior body 11 in a direction intersecting the vertical direction. A portion of the first electrode section 12 is housed inside the exterior body 11. The first electrode portion 12 is connected to a current collector plate at a portion housed inside the exterior body 11 . In this embodiment, the first electrode section 12 is the positive electrode in the cell 10. The first electrode portion 12 is made of aluminum or an alloy containing aluminum as a main component.

The second electrode portion 13 protrudes from the exterior body 11 in a direction intersecting the vertical direction. A portion of the second electrode section 13 is housed inside the exterior body 11. The second electrode portion 13 is connected to the current collector plate at a portion housed inside the exterior body 11 . In this embodiment, the second electrode section 13 is the negative electrode in the cell 10. The second electrode portion 13 is made of copper or an alloy containing copper as a main component.

Note that the first electrode section 12 may be the negative electrode in the cell 10, and the second electrode section 13 may be the positive electrode in the cell 10.

The plurality of cells 10 include a first cell 10A, a second cell 10B, and a third cell 10C.

The second cell 10B is stacked above the first cell 10A so as to be adjacent to the first cell 10A. In this embodiment, the second cell 10B is adjacent to the first cell 10A. That is, the exterior body 11 of the second cell 10B is in contact with the exterior body 11 of the first cell 10A. The second cell 10B may be stacked on the first cell 10A via another member such as an expansion absorbing material.

The third cell 10C is stacked above the second cell 10B so as to be adjacent to the second cell 10B. In this embodiment, the third cell 10C is adjacent to the second cell 10B. That is, the exterior body 11 of the third cell 10C is in contact with the exterior body 11 of the second cell 10B. The third cell 10C may be stacked on the second cell 10B via another member such as an expansion absorbing material.

In addition to the first cell 10A, the second cell 10B, and the third cell 10C, the plurality of cells 10 may further include one or more other cells 10. Other cells may be further stacked below the first cell 10A. Other cells may be stacked above the third cell 10C.

The first electrode section 12 of the first cell 10A may be drawn out of the case 20. The first electrode portion 12 of the first cell 10A may be connected to one external terminal (not shown) of the power storage device 1. When another cell is stacked below the first cell 10A, the first electrode section 12 of the first cell 10A is connected to the second electrode section of the cell stacked below the first cell 10A. You can.

The second electrode section 13 of the first cell 10A is connected to the first electrode section 12 of the second cell 10B. The second electrode section 13 of the second cell 10B is located above the first electrode section 12 of the first cell 10A. The second electrode section 13 of the second cell 10B is connected to the first electrode section 12 of the third cell 10C.

The second electrode part 13 of the third cell 10C may be drawn out of the case 20. The second electrode portion 13 of the third cell 10C may be connected to another external terminal (not shown) of the power storage device 1. When another cell 10 is stacked above the third cell 10C, the second electrode section 13 of the third cell 10C is the same as the first electrode section of the cell 10 stacked above the third cell 10C. May be connected.

Next, the first electrode section 12 of the third cell 10C will be explained. The first electrode portion 12 of the third cell 10C has a first protrusion 121 and a first extension 122. The first protruding portion 121 is a portion of the first electrode portion 12 that protrudes from the exterior body 11 . The first protrusion 121 protrudes in a direction perpendicular to the up-down direction. The first extending portion 122 extends downward from the tip of the first protruding portion 121 in the protruding direction. Specifically, the first extending portion 122 extends in the vertical direction.

Next, the second electrode section 13 of the second cell 10B will be explained. The second electrode section 13 of the second cell 10B has a second protrusion 131 and a second extension 132. The second protruding portion 131 is a portion of the second electrode portion 13 that protrudes from the exterior body 11 . The second protrusion 131 protrudes in a direction perpendicular to the up-down direction. The second extending portion 132 extends downward from the tip of the second protruding portion 131 in the protruding direction. Specifically, the second extending portion 132 extends in the vertical direction.

The first electrode portion 12 of the third cell 10C is joined to the second extension portion 132 of the second electrode portion 13 of the second cell 10B. More specifically, the first extension part 122 of the first electrode part 12 of the third cell 10C is joined to the second extension part 132 of the second electrode part 13 of the second cell 10B. There is. The second extending portion 132 is joined to the second extending portion 132 on the side opposite to the exterior body 11 when viewed from the second extending portion 132 . These are joined together, for example by welding.

Note that the first electrode section 12 of each of the first cell 10A and the second cell 10B may have the same configuration as the first electrode section 12 of the third cell 10C. The second electrode section 13 of each of the first cell 10A and the third cell 10C may have the same configuration as the second electrode section 13 of the second cell 10B.

The second cell 10B further includes a first resin film 14. The first resin film 14 covers the entire upper surface of the second protrusion 131 . A portion of the first resin film 14 may be housed inside the exterior body 11. The first resin film 14 is in contact with the first electrode section 12 of the third cell 10C. The first resin film 14 is in contact with the first extending portion 122 of the first electrode portion 12 of the third cell 10C. The first resin film 14 is welded to the exterior body 11 and the second electrode section 13 of the second cell 10B.

The second cell 10B further includes a second resin film 15. The second resin film 15 covers the entire lower surface of the second protrusion 131 . A portion of the second resin film 15 may be housed inside the exterior body 11. The second resin film 15 is in contact with the second extending portion 132 of the second electrode portion 13 in the second cell 10B. The second resin film 15 is welded to the exterior body 11 and the second electrode section 13 of the second cell 10B.

The second cell 10B may further include two resin films arranged with respect to the first electrode part 12, similarly to the first resin film 14 and the second resin film 15 with respect to the second electrode part 13. Furthermore, the first cell 10A and the third cell 10C may further include a plurality of resin films, similar to the four resin films included in the second cell 10B.

It is preferable that the first resin film 14, the second resin film 15, and the other resin films all have electrolyte resistance. The first resin film 14, the second resin film 15, and other resin films contain, for example, polypropylene (PP), polyamide (PA), or polytetrafluoroethylene (PTFE) as a main component. Consists of a synthetic resin composition.

Case 20 accommodates a plurality of cells 10. Case 20 is made of metal such as aluminum. Between the case 20 and the plurality of cells 10, an expansion absorbing material having insulation properties may be arranged, or a filler material having insulation properties may be arranged.

Next, in the power storage device 1 according to an embodiment of the present disclosure, a path through which the electrolytic solution flows when the electrolytic solution leaks from the exterior body 11 of the third cell 10C will be described. FIG. 2 is a schematic cross-sectional view illustrating an example of a state in which electrolyte leaks in a power storage device according to an embodiment of the present disclosure. In FIG. 2, the route through which the leaked electrolyte flows is shown by a broken line arrow.

As shown in FIG. 2, in the power storage device according to an embodiment of the present disclosure, for example, when the exterior body 11 of the third cell 10C is damaged at a position P and the electrolyte leaks from the position P of the third cell 10C. Then, the leaked electrolyte travels along the outer surface of the outer case 11 of the third cell 10C and reaches the outer surface of the outer case 11 of the second cell 10B. The electrolytic solution travels along the outer surface of the exterior body 11 of the second cell 10B and reaches the upper surface of the first resin film 14 on the second electrode section 13 of the second cell 10B. The electrolytic solution further travels along the upper surface of the first resin film 14 and then reaches the tip of the second protrusion 131 of the second electrode section 13 . The electrolytic solution that has reached the tip of the second protruding portion 131 flows downward along the second extending portion 132 and the first electrode portion 12 of the third cell 10C joined to the second extending portion 132. The electrolytic solution that has reached the second extension portion 132 and the tip of the first electrode portion 12 of the third cell 10C drips further downward toward the first cell 10A. As a result, the flow path of the leaked electrolyte is cut off, so that the second electrode section 13 of the second cell 10B, the first electrode section 12 of the third cell 10C, and the first electrode section 12 of the first cell 10A are connected to each other. However, electrical connection via the electrolyte is suppressed. Therefore, occurrence of short circuit in power storage device 1 can be suppressed.

Here, a power storage device according to a comparative example will be described. FIG. 3 is a schematic cross-sectional view showing an example of a state in which electrolyte leaks in a power storage device according to a comparative example. In FIG. 3 as well, the route through which the leaked electrolyte flows is shown by a broken line arrow. As shown in FIG. 3, the power storage device 9 according to the comparative example differs from the power storage device 1 according to the embodiment of the present disclosure in the configurations of the first electrode part, the second electrode part, and each resin film.

In the power storage device 9 according to the comparative example, the first resin film 94 covers only a part of the upper surface of the protruding part 931 of the second electrode part 93. A portion of the protrusion 931 on the side opposite to the exterior body 11 when viewed from the protrusion 931 is exposed to the outside. Therefore, the electrolytic solution leaking from the position P of the third cell 10C flows downward from the side surface of the first resin film 94 while coming into contact with the protrusion 931. Furthermore, in the comparative example, the extending portion 932 of the second electrode portion 93 faces upward. Therefore, the leaked electrolyte is transmitted to the first electrode portion 92 of the first cell 10A through the outer surface of the exterior body 11 of the second cell 10B, the exterior body 11 of the first cell 10A, and the like. As a result, the second electrode part 93 of the second cell 10B and the first electrode part 92 of the first cell 10A, which have different potentials in the power storage device 9, are connected by the leaked electrolyte. In this way, a short circuit occurs in power storage device 1.

On the other hand, as shown in FIGS. 1 and 2, in the power storage device 1 according to an embodiment of the present disclosure, the second electrode part 13 of the second cell 10B has a (second) protrusion 131 and a (second) ) has an extending portion 132. The protruding portion 131 is a portion that protrudes from the exterior body 11. The extending portion 132 extends downward from the tip of the protruding portion 131 . The second cell 10B further includes a (first) resin film 14. The resin film 14 covers the entire upper surface of the protrusion 131 . The first electrode portion 12 of the third cell 10C is joined to the extension portion 132 of the first electrode portion 12 of the second cell 10B. Thereby, even when the electrolytic solution leaks from the cells 10 of the power storage device 1, the flow path of the electrolytic solution led out as described above is cut off, so that the occurrence of a short circuit in the power storage device 1 can be suppressed.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Reference Signs List 1, 9 power storage device, 10 cell, 10A first cell, 10B second cell, 10C third cell, 11 exterior body, 12, 92 first electrode part, 121 first protrusion, 122 first extension part, 13 , 93 second electrode section, 131,931 (second) protruding section, 132,932 (second) extending section, 14,94 (first) resin film, 15 second resin film, 20 case.

Claims (1)

A power storage device including a plurality of cells stacked in the vertical direction,
Each of the plurality of cells is
an exterior body having an electrolyte therein;
a first electrode portion protruding from the exterior body in a direction intersecting the up-down direction;
a second electrode portion protruding from the exterior body in a direction intersecting the up-down direction;
The plurality of cells are
The first cell,
a second cell stacked above the first cell so as to be adjacent to the first cell;
a third cell stacked above the second cell so as to be adjacent to the second cell,
The second electrode part of the first cell is connected to the first electrode part of the second cell,
The second electrode part of the second cell is connected to the first electrode part of the third cell,
The second electrode part of the second cell has a protrusion that is a part that protrudes from the exterior body, and an extension that extends downward from the tip of the protrusion,
The second cell further includes a resin film covering the entire upper surface of the protrusion,
In the power storage device, the first electrode part of the third cell is joined to the extension part of the first electrode part of the second cell.

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