Battery and buffer sheet

Abstract

Disclosed is a battery which includes: a plurality of cells; a plurality of buffer sheets 100 which are each disposed between adjacent cells; and a coolant passage for flowing a coolant so that the coolant passes through a region where the buffer sheet 100 is disposed between adjacent cells. This battery is characterized in that the buffer sheets 100 each include: a flat plate part 110; a plurality of projection parts 120 that protrude to both surface sides of the flat plate part 110; and a plurality of through holes 130 that are provided so as to penetrate both surfaces of the flat plate part 110.

Description

Batteries and cushioning sheets

[0001] The present invention relates to a battery and a buffer sheet.

[0002] Batteries such as lithium-ion batteries and all-solid-state batteries are typically constructed as cell stacks, stacking multiple cells to achieve the required battery capacity and voltage. These batteries can expand and contract during charging and discharging, leading to a deterioration in quality. For example, lithium-ion batteries face the challenge of developing needle-shaped lithium metal crystals (dendrites) during repeated charging and discharging. If these crystals continue to grow, they can cause short circuits between the positive and negative electrodes. Furthermore, in all-solid-state batteries, variations in surface pressure due to expansion and contraction are known to lead to performance variations and affect battery life. Therefore, measures have been taken to suppress cell expansion by applying appropriate pressure to the cells, or to mechanically suppress the growth of such crystals in lithium-ion batteries. For example, a technique has been developed in which a buffer sheet is placed between adjacent cells.

[0003] Furthermore, as batteries such as those described above continue to grow in size and power output, it has become increasingly necessary to suppress overheating due to increased heat generation in order to prevent cell degradation. Therefore, research is being conducted into technologies that allow a refrigerant to flow between adjacent cells. However, if a typical buffer sheet is used and the refrigerant is flowed through the area where the buffer sheet is located, it is believed that a stable cooling effect cannot be obtained. This point will be explained with reference to Figures 5 and 6.

[0004] Fig. 5 is a plan view of a buffer sheet according to the prior art. Fig. 6 is a schematic cross-sectional view of a buffer sheet according to the prior art. Fig. 6(a) is a cross-sectional view taken along line B-B in Fig. 5, and Fig. 6(b) is an enlarged view of the area surrounded by Y in Fig. 6(a) when a refrigerant is flowed through an area where a buffer sheet according to the prior art is provided.

[0005] A buffer sheet 500 according to the prior art includes a flat plate portion 510 and a plurality of protruding portions 520 protruding from both sides of the flat plate portion 510. When this buffer sheet 500 is placed between adjacent cells and a refrigerant is passed between the cells, the refrigerant flows through spaces formed in areas where the protruding portions 520 are not provided. However, depending on the usage environment, the flat plate portion 510 may bend. This results in a difference in the area of ​​the flow paths formed on one side of the flat plate portion 510 and the other side, resulting in differences in cooling performance on both sides. In particular, when multiple cells are stacked vertically, the deflection of the flat plate portion 510 becomes significant.

[0006] 6(b) shows the state of the buffer sheet 500 when multiple cells are stacked vertically and a refrigerant flows between the cells. In this figure, the positions of the cell surfaces are indicated by dotted lines 11. As shown in this figure, as the flat plate portion 510 bends downward, the flow path area of ​​the flow path R1 formed on the upper surface of the flat plate portion 510 increases, while the flow path area of ​​the flow path R2 formed on the lower surface decreases. This results in differences in cooling performance on both sides of the flat plate portion 510.

[0007] International Publication No. 2020 / 004039 International Publication No. 2020 / 166357 International Publication No. 2022 / 004076

[0008] The present invention provides a battery and a buffer sheet that can suppress cell deterioration.

[0009] The present invention employs the following means to solve the above problems.

[0010] That is, the battery of the present invention comprises a plurality of cells, a plurality of buffer sheets respectively arranged between adjacent cells, and a refrigerant passage for allowing the refrigerant to flow through the area between the adjacent cells where the buffer sheets are arranged, wherein the buffer sheet comprises a flat plate portion, a plurality of protrusions protruding from both sides of the flat plate portion, and a plurality of through holes provided so as to penetrate both sides of the flat plate portion.

[0011] Furthermore, the buffer sheet of the present invention is a buffer sheet that is disposed between adjacent cells in a battery configured to allow a refrigerant to flow between the adjacent cells, and is characterized by comprising a flat plate portion, a plurality of protruding portions that protrude from both sides of the flat plate portion, and a plurality of through holes that are provided so as to penetrate both sides of the flat plate portion.

[0012] According to the present invention, since the buffer sheet is provided with a plurality of through holes, the refrigerant can move between the flow path formed on one side of the flat plate portion and the flow path formed on the other side of the flat plate portion. In addition, the provision of the plurality of through holes can reduce the amount of deflection of the flat plate portion.

[0013] The plurality of protrusions may be aligned in a direction in which the refrigerant flows and may be arranged in a plurality of rows.

[0014] This makes it difficult for the protruding portion to obstruct the flow of the refrigerant.

[0015] The through holes may be arranged in a plurality of rows so as to extend in the direction in which the refrigerant flows.

[0016] This makes it possible to more reliably suppress the amount of deflection of the flat plate portion, thereby suppressing the difference in flow path area on both sides of the flat plate portion caused by the deflection of the flat plate portion.

[0017] The above configurations may be combined as much as possible.

[0018] As described above, according to the present invention, cell deterioration can be suppressed.

[0019] Fig. 1 is a schematic diagram of a battery according to this embodiment. Fig. 2 is a plan view of a buffer sheet according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view of a buffer sheet according to an embodiment of the present invention. Fig. 4 is a diagram showing various examples of shapes of protrusions. Fig. 5 is a plan view of a buffer sheet according to the prior art. Fig. 6 is a schematic cross-sectional view of a buffer sheet according to the prior art.

[0020] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0021] (Example) A battery and a buffer sheet according to an example of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a schematic diagram of the battery according to this example, showing a portion of the battery. Figure 2 is a plan view of a buffer sheet according to this example. Figure 3 is a schematic cross-sectional view of a buffer sheet according to this example. Note that Figure 3(a) is a cross-sectional view taken along line AA in Figure 2, and Figure 3(b) is an enlarged view of the area surrounded by X in Figure 3(a) when a refrigerant is flowing through the area where the buffer sheet according to this example is provided.

[0022] <Battery> Referring to FIG. 1 , a battery 1 according to an embodiment of the present invention will be described. The battery 1 is composed of a cell stack in which multiple cells (single cells) 10 are stacked. Specific examples of the battery 1 according to this embodiment include secondary batteries such as lithium-ion batteries and all-solid-state batteries. The cell stack in such batteries is generally compressed by a pair of clamping plates or the like. This allows a predetermined compressive force to act on the cell stack. In the battery 1 according to this embodiment, a buffer sheet 100 is disposed between each adjacent cell 10. As described above, the cell stack according to this embodiment includes multiple cells 10 and multiple buffer sheets 100 disposed between the adjacent cells 10. The provision of the buffer sheets 100 allows an appropriate compressive force to be applied to each cell 10 even when the cells 10 expand and contract due to charging and discharging. This suppresses deterioration of the battery 1 and extends its lifespan. The buffer sheet 100 is an elastic body formed of an elastomer material such as rubber.

[0023] The battery 1 according to this embodiment is provided with refrigerant passages for allowing the refrigerant to flow through the regions between adjacent cells 10 where the buffer sheets 100 are arranged. These refrigerant passages are provided on both sides of the cell stack in the width direction. For convenience, in FIG. 1 , the refrigerant passage on the left side is referred to as the first passage 21, and the refrigerant passage on the right side is referred to as the second passage 22. In FIG. 1 , the cross sections of the walls forming the first passage 21 and the second passage 22 are indicated by bold lines.

[0024] In this embodiment, the multiple cells 10 are stacked vertically. The refrigerant flows vertically from bottom to top in the first passages 21. The refrigerant flowing through the first passages 21 flows upward, and a portion of the refrigerant passes between adjacent cells 10 and flows into the second passages 22. The refrigerant flowing into the second passages 22 flows vertically from bottom to top in the second passages 22.

[0025] As the refrigerant, a cooling liquid such as cooling oil can be suitably used. The drive source (e.g., a pump) for flowing the refrigerant, the valves for flowing the refrigerant in the desired direction, and the sealing structure and sealing device for preventing refrigerant leakage can be appropriately configured by using known techniques, and therefore a description thereof will be omitted. The key point is that the refrigerant should be configured to flow in the region where the buffer sheet 100 is arranged between adjacent cells 10.

[0026] Buffer Sheet The buffer sheet 100 according to this embodiment will be described with particular reference to Figures 2 and 3. The buffer sheet 100 according to this embodiment is used in a state where it is incorporated into the battery 1 so that the refrigerant flows in the vertical direction (from top to bottom or from bottom to top) in Figure 2. This buffer sheet 100 includes a flat plate portion 110, a plurality of protruding portions 120 protruding from both sides of the flat plate portion 110, and a plurality of through holes 130 provided so as to penetrate both sides of the flat plate portion 110.

[0027] As shown in the figure, the multiple protrusions 120 are lined up in multiple rows along the direction of refrigerant flow. In the example shown, the protrusions 120 are lined up in groups of four along the direction of refrigerant flow, and are arranged in 11 rows. Furthermore, the through holes 130 are arranged in multiple rows so as to extend along the direction of refrigerant flow. In the example shown, the through holes 130 are arranged in 10 rows.

[0028] <Advantages of the battery and buffer sheet according to this embodiment> According to this embodiment, the buffer sheet 100 is provided with a plurality of through holes 130, which allows the refrigerant to move between the flow path formed on one side of the flat plate portion 110 and the flow path formed on the other side of the flat plate portion 110. Furthermore, the provision of the plurality of through holes 130 can reduce the amount of deflection of the flat plate portion 110.

[0029] In this embodiment, the protrusions 120 are arranged in a row along the direction in which the refrigerant flows, making it difficult for the protrusions 120 to obstruct the flow of the refrigerant.

[0030] Furthermore, the through-holes 130 are arranged in multiple rows so as to extend in the direction of refrigerant flow. This makes it possible to suppress the difference in flow path area on both sides of the flat plate portion 110 caused by bending of the flat plate portion 110. This point will be explained in particular with reference to FIG. 3(b). This figure shows the state of the buffer sheet 100 when multiple cells 10 are stacked vertically and refrigerant flows between the cells 10. In this figure, the positions of the cell surfaces are indicated by dotted lines 11.

[0031] In this embodiment, by arranging the protruding portions 120 and the through holes 130 as described above, the flat plate portion 110 is composed of an outer frame portion along the four sides and a portion that connects the protruding portions 120 along the direction of refrigerant flow, as shown in Figure 2. Therefore, because the through holes 130 create space on both sides of the portion of the flat plate portion 110 that connects the protruding portions 120, even if that portion flexes, the amount of flexure is small (see Figure 3(b)). As a result, the difference in flow path area on both sides of the flat plate portion 110 can be reduced.

[0032] As described above, the difference in flow path area between both sides of the flat plate portion 110 can be reduced, and combined with the through-holes 130 allowing the refrigerant to freely move between both sides of the flat plate portion 110, the occurrence of temperature differences in the refrigerant flowing on both sides of the flat plate portion 110 can be reduced. This allows the cooling performance to be equalized on both sides of the flat plate portion 110, resulting in a stable cooling effect. Therefore, the buffer sheet 100 applies an appropriate pressing force to the cells 10, and combined with the stable cooling effect, deterioration of the cells 10 can be effectively suppressed.

[0033] (Others) In the above embodiment, the protrusion 120 is cylindrical, but the shape of the protrusion in the present invention is not particularly limited. An example of the shape of the protrusion will be described with reference to FIG. 4 . Note that FIG. 4 shows a plan view of a portion near the protrusion. For example, as shown in FIG. 4( a), a triangular prism-shaped protrusion 120a can be used. Note that the triangles may all face the same direction, as shown on the left side of the figure, or may be arranged in different directions, as shown on the right side. Furthermore, as shown in FIG. 4( b), a protrusion 120b having an oval planar shape can be used. Furthermore, as shown in FIG. 4( c), a square prism-shaped protrusion 120c can be used. In this manner, various shapes of the protrusion can be used.

[0034] 1: Battery 10: Cell 21: First passage 22: Second passage 100: Buffer sheet 110: Flat plate portion 120, 120a, 120b, 120c: Protrusion 130: Through hole

Claims

1. A battery comprising: a plurality of cells; a plurality of buffer sheets each arranged between adjacent cells; and a refrigerant passage for allowing a refrigerant to flow through the area between adjacent cells where the buffer sheets are arranged, wherein the buffer sheet comprises a flat plate portion, a plurality of protrusions protruding from both sides of the flat plate portion, and a plurality of through holes provided so as to penetrate both sides of the flat plate portion.

2. The battery according to claim 1, wherein the plurality of protrusions are aligned in a plurality of rows in the direction in which the refrigerant flows.

3. The battery according to claim 1 or 2, characterized in that the through holes extend in the direction in which the refrigerant flows and are arranged in a plurality of rows.

4. A buffer sheet disposed between adjacent cells in a battery configured to allow a refrigerant to flow between the cells, the buffer sheet comprising: a flat plate portion; a plurality of protruding portions protruding from both sides of the flat plate portion; and a plurality of through holes provided so as to penetrate both sides of the flat plate portion.

5. The buffer sheet according to claim 4, wherein the plurality of protrusions are aligned in a plurality of rows along the direction in which the refrigerant flows.

6. The buffer sheet according to claim 4 or 5, characterized in that the through holes extend in the direction in which the refrigerant flows and are arranged in a plurality of rows.

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