Battery cell seat and battery pack

Abstract

The utility model provides a base for a battery unit and a battery pack. The base for a battery cell suppresses heat from a battery cell in which thermal runaway has occurred from being transferred through a cooling plate. Also provided is a highly safe battery pack in which heat from a battery cell in which thermal runaway has occurred is prevented from being transferred via a cooling plate. A base (3) for a battery cell is interposed between a cooling plate (1) and the battery cell (20), and the base for the battery cell is a long sheet-shaped base along the edge of the lower part of the battery cell, or a sheet-shaped base supporting the edge of the battery cell at an interval. The base for a battery cell is a product formed from one of thermally expandable graphite, vermiculite, thermally expandable microcapsules, and a thermally decomposable chemical foaming agent. Furthermore, in the battery pack (100), the plurality of battery cells (20) are placed on the battery cell base (3), and the battery cells (20) are connected in series or in parallel with each other.

Description

Technical Field

[0001] The utility model relates to a battery cell base which is interposed between a cooling plate and a battery cell in a battery pack and on which the battery cell is placed, and the battery pack. Background Art

[0002] In recent years, from the perspective of environmental protection, electric vehicles and hybrid vehicles driven by electric motors have been developed. These electric vehicles and hybrid vehicles are equipped with a battery pack composed of a plurality of battery cells connected in series or in parallel as a power source for the driving electric motor.

[0003] Battery cells mainly use lithium-ion secondary batteries that can achieve high capacity and high output compared to lead-acid batteries, nickel-metal hydride batteries, etc. In addition, in the case of thermal runaway (i.e., battery abnormality) where a battery cell rapidly heats up and continues to heat up due to internal short circuit, overcharging, etc. of the battery, the high heat and flame from the battery cell that has thermal runaway may spread to other adjacent battery cells. Therefore, a heat transfer suppression sheet is placed between battery cells to prevent the transmission and spread of thermal runaway.

[0004] In addition, if Figure 4 As shown in the figure, in the battery pack 100, the battery cell 20 is also placed on the cooling plate 10 having a cooling function to cool the battery cell 20. In addition, the reference numeral 50 shown in the figure is a heat transfer suppression sheet. As the cooling plate 10, for example, in Patent Document 1, a circulation path is provided inside a metal plate such as aluminum or aluminum alloy having excellent thermal conductivity, so that a coolant flows in the circulation path. In addition, a gap filler 30 having heat dissipation is sandwiched between the cooling plate 10 and the battery cell 20.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2020 / 013120 Utility Model Content

[0008] Technical problems to be solved by the utility model

[0009] However, the cooling plate 10 is, for example, a metal plate, and thus has high thermal conductivity. Figure 4 As shown in FIG. 1 , it is assumed that the battery cell that has thermal runaway is represented by reference numeral 20A, and the high heat from the battery cell 20A is as follows: Figure 4 As shown by the arrows in , heat is easily transferred to the adjacent battery cells 20 via the cooling plate 10 .

[0010] The present invention is made in view of the above problems, and its purpose is to suppress the high heat from the battery cell that has thermal runaway from being transferred through the cooling plate. In addition, the present invention aims to provide a battery pack with high safety that suppresses the high heat from the battery cell that has thermal runaway from being transferred through the cooling plate.

[0011] Means for solving technical problems

[0012] The above-mentioned object of the present invention is achieved by the following structure [1] of the battery cell base.

[0013] [1] A battery cell base, characterized in that, in a battery pack, the battery cell base is interposed between a cooling plate and a battery cell and mounts the battery cell, and the battery cell base is a long sheet-shaped base along the edge of the lower portion of the battery cell, or a sheet-shaped base that supports the edge of the battery cell at intervals,

[0014] The battery cell base is a product formed of one of thermally expandable graphite, vermiculite, thermally expandable microcapsules and thermally decomposable chemical foaming agents.

[0015] In addition, the above-mentioned object of the present invention is achieved by the following [2] structure of the battery pack.

[0016] [2] A battery pack, characterized in that a battery cell base of [1] is sandwiched between a plurality of battery cells and a cooling plate, and the battery cells are placed on the battery cell base, and the battery cells are connected in series or in parallel with each other.

[0017] Preferred embodiments of the battery pack of the present invention relate to the following [3] to [7].

[0018] [3] In the battery pack of [2], it is characterized in that a gap filler having the same thickness as the battery cell base is filled between the battery cell bases, and the battery cell is placed on a surface formed by the battery cell bases and the gap filler.

[0019] [4] In the battery pack of [2], it is characterized in that for each of the battery cells, two elongated battery cell bases are arranged in parallel along a pair of opposing edges of the lower portion of the battery cell.

[0020] [5] In the battery pack of [2], it is characterized in that for each of the battery cells, a plurality of the battery cell bases are arranged at intervals along a pair of opposing edges of the lower portion of the battery cell.

[0021] [6]. In the battery pack of [2], it is characterized in that the battery cell is supported by a base at a corner of the battery cell.

[0022] [7]. In the battery pack of [2], it is characterized in that a heat transfer suppression sheet is sandwiched between the plurality of battery cells.

[0023] Utility Model Effect

[0024] The battery cell base of the utility model absorbs the high heat from the battery cell that has thermal runaway and expands, lifting the battery cell that has thermal runaway and forming an air layer between the cooling plate. The air layer has excellent heat insulation, so when the battery is abnormal, heat transfer to the battery cell adjacent to the battery cell that has thermal runaway is prevented.

[0025] Therefore, the battery pack including the battery cell mount of the present invention can suppress the transmission of high heat and flame from a battery cell that has thermal runaway to adjacent battery cells when a battery abnormality occurs, and has excellent safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a cross-sectional view schematically showing the periphery of a battery cell in a battery pack according to an embodiment of the present invention.

[0027] Figure 2A and Figure 2B 1 is a diagram showing an example of the arrangement of a battery cell base according to the present invention. Figure 2A This shows a case where a long strip of battery cell base is arranged in parallel. Figure 2B This shows a case where a plurality of short battery cell bases are arranged.

[0028] Figure 3 This is a schematic diagram for explaining the function of the battery cell base.

[0029] Figure 4 is in accordance with Figure 1 A schematic diagram showing a conventional battery pack.

[0030] Description of symbols

[0031] 3. 3A: Base for battery unit;

[0032] 7: Air layer;

[0033] 10: Cooling plate;

[0034] 15: Bus bar;

[0035] 16: bending part;

[0036] 20, 20A: battery unit;

[0037] 30: gap filler;

[0038] 50: heat transfer suppression sheet;

[0039] 100: Battery pack. DETAILED DESCRIPTION

[0040] Hereinafter, a battery cell base and a battery pack according to an embodiment of the present invention will be described in detail. In addition, the present invention is not limited to the embodiment described below, and can be implemented with arbitrary changes within the scope not departing from the gist of the present invention.

[0041] [Battery unit base]

[0042] Figure 1 1 is a cross-sectional view schematically showing the periphery of a battery cell of a battery pack 100 of the present invention. As shown in the figure, a battery cell base 3 of the present invention is interposed between a cooling plate 10 and a battery cell 20 .

[0043] In this embodiment, there is no particular limitation on the type of cooling plate 10 as long as it has a cooling function. For example, as in the battery pack described in Patent Document 1, a circulation path is provided inside a metal plate such as aluminum or aluminum alloy, and a coolant is circulated in the circulation path. In addition, as the type of cooling plate 10, in addition to the above-mentioned metal plate, a gel sheet with high thermal conductivity can also be used.

[0044] The battery cell base 3 is made of a thermal expansion material. As described later, the battery cell base 3 does not expand during normal charge and discharge of the battery cell 20 (i.e., during normal use of the battery), but expands when thermal runaway occurs in the battery cell 20 (i.e., when the battery is abnormal). Therefore, the thermal expansion start temperature of the thermal expansion material is preferably above 150°C, more preferably above 200°C, further preferably above 250°C, and further preferably above 300°C. In addition, since the battery cell 20 is placed on the battery cell base 3, the thermal expansion material needs to have a compression strength that can withstand the weight of the battery cell 20. From the perspective of having such a thermal expansion start temperature and compression strength and being easy to handle, the thermal expansion material is preferably at least one of thermal expansion graphite, vermiculite, thermal expansion microcapsules, and thermal decomposition type chemical foaming agents.

[0045] Thermally expandable microcapsules are obtained by enclosing liquid low-boiling hydrocarbons in a resin shell. When heated, the resin shell softens, and the liquid hydrocarbons therein change into gas. Under its pressure, the capsule itself expands. In addition, it can also be obtained from the market, and commercial products such as "クレハマイクロスフェアー" of クレハ Co., Ltd. and "マツモトマイクロスフェアーF、FNシリーズ" (registered trademark) of Matsumoto Oil Pharmaceutical Co., Ltd. can be used. It should be noted that they are packed into a bag to form a base of a specified shape, which is set at a specified position at the bottom of the battery cell 20.

[0046] As thermal decomposition type chemical foaming agents, azodicarbonamide (ADCA), N,N'-dinitrosopentamethylenetetramine (DPT), 4,4'-oxybisbenzenesulfonylhydrazide (OBSH) and the like can be cited. In addition, they can also be obtained from the market, and commercial products such as "Uniform AZ" of Otsuka Chemical Co., Ltd. can be used. It should be noted that they are also packed into bags to form a pedestal of a prescribed shape, which is set at a prescribed position below the battery cell 20.

[0047] In particular, heat-expandable graphite expands to about 10 times its volume when it reaches 180°C or above, has a high expansion rate, and does not require a bagging process like heat-expandable microcapsules and pyrolytic chemical foaming agents, and has high handleability, so it is more preferred. However, since heat-expandable graphite has relatively poor insulation properties, it is preferably covered with an organic sheet (shrink film, etc.).

[0048] Preferably, the battery cell base 3 supports the corners of the battery cell 20. Figure 3 As shown, the battery cell 20 that has thermal runaway is indicated by reference numeral 20A, and the battery cell base 3 absorbs the high heat from the battery cell 20A and expands, thereby raising the battery cell 20A. At this time, if the battery cell base 3 supports the corner of the battery cell 20A, the battery cell 20A can be raised efficiently and reliably.

[0049] Therefore, if Figure 2A As shown, it is preferred that two long battery cell bases 3 having a length substantially equal to the lateral width W of the battery cell 20 are arranged in parallel at a distance substantially equal to the thickness D of the battery cell 20. Alternatively, as Figure 2B As shown, a plurality of shorter battery cells may also be dispersed along the lateral width W of the battery cell 20 at intervals using the base 3 .

[0050] That is, in Figure 2A In the case of the battery cell base 3, the battery cell base 3 is a long sheet-shaped base along the lower edge of the battery cell 20. Figure 2B In the case of , the battery cell base 3 is a sheet-like base that supports the lower edge of the battery cell 20 at a distance.

[0051] The battery cell base 3 is bonded to the cooling plate 10 by, for example, a double-sided adhesive tape.

[0052] In addition, by interposing the battery cell base 3 between the cooling plate 10 and the battery cell 20, a gap corresponding to the thickness of the battery cell base 3 is formed between the cooling plate 10 and the battery cell 20 in the battery pack 100. Therefore, a gap filler 30 having the same thickness as the battery cell base 3 is filled between the battery cell base 3 and the battery cell 20, and the battery cell 20 is placed on the surface formed by the battery cell base 3 and the gap filler 30. The gap filler 30 has heat dissipation properties, and by interposing the gap filler 30, the heat from the battery cell 20 can be efficiently dissipated during normal charge and discharge of the battery cell 20 (that is, during normal use of the battery).

[0053] Furthermore, as long as the effect produced by interposing the gap filler 30 can be achieved, the thickness of the interposed gap filler 30 may be substantially the same as the thickness of the battery cell base 3 and may not be completely the same.

[0054] The gap filler 30 may be a gap filler in the form of grease, which is applied between the battery cell bases 3 and then cured.

[0055] By providing such a battery cell base 3, Figure 3 As shown in the figure, when thermal runaway occurs in the battery cell 20A (when the battery is abnormal), the battery cell base 3A on which the battery cell 20A is mounted absorbs the high heat from the battery cell 20A and expands. As shown in the figure, a gap filler 30 is arranged between the battery cell bases 3 and 3A, and a heat transfer suppression sheet 50 is arranged between the battery cells 20 (20A), so the battery cell base 3A expands in its thickness direction (upward in the figure). Then, as the battery cell base 3A expands, the battery cell 20A is lifted.

[0056] When the battery cell 20A is lifted, an air layer 7 is formed between the battery cell 20A and the gap filler 30. The air layer 7 has high heat insulation properties, and thus can suppress the propagation of high heat from the battery cell 20A.

[0057] However, as a material for expanding the battery cell base 3 when the battery is abnormal, at least one of the above-mentioned heat-expandable microcapsules and thermal decomposition type chemical foaming agents can be used, as long as it does not hinder the following effect of the present embodiment, that is, when the battery is abnormal, the battery cell 20A is lifted due to the expansion of the battery cell base 3, and a highly insulating air layer 7 is formed between the battery cell 20A and the gap filler 30, thereby suppressing the spread of high heat from the battery cell 20A (that is, suppressing the chain reaction of thermal runaway). For example, at least one of the above-mentioned heat-expandable microcapsules and thermal decomposition type chemical foaming agents can also be mixed into the gap filler 30.

[0058] However, in this case, if the expansion coefficient of the battery cell base 3 is equal to the expansion coefficient of the gap filler 30 , the above-mentioned air layer 7 with high heat insulation may not be formed, so the expansion coefficient of the gap filler 30 needs to be lower than the expansion coefficient of the battery cell base 3 .

[0059] As described above, in the battery pack 100 , by using the thermally expandable battery cell base 3 , it is possible to prevent the propagation of thermal runaway caused by the battery cell 20A that has undergone thermal runaway.

[0060] [Battery Pack]

[0061] like Figure 1 As shown, in the battery pack 100 of the present invention, a plurality of battery cells 20 are placed on a battery cell base 3 on the surface of a cooling plate 10, or on a surface formed by the battery cell base 3 and a gap filler 30. In addition, a heat transfer suppression sheet 50 is sandwiched between the battery cells 20 and housed in a battery case (not shown).

[0062] In addition, the heat transfer suppressing sheet 50 is not limited, and a heat transfer suppressing sheet used in the past can be used.

[0063] Then, if Figure 3 As shown, the battery cell base 3A lifts the battery cell 20A in thermal runaway to form an air layer 7. This prevents the spread of thermal runaway caused by the battery cell 20A in thermal runaway, so the battery pack 100 of the present invention has high safety.

[0064] In addition, the battery cells 20 (20A) are connected in series or in parallel with each other through the bus bar, but the battery cell 20A that has thermal runaway is lifted by the battery cell base 3A, so that a height difference corresponding to the amount of lifting occurs between the electrode 25 and the electrode 25A. Therefore, the bus bar 15 preferably has a bent portion 16 that deforms like a leaf spring so as to absorb the displacement of the electrode 25 (25A) in the height direction.

[0065] Above, various embodiments are described with reference to the accompanying drawings, but the present invention is certainly not limited to such examples. It is clear to those skilled in the art that various variations or modifications can be thought of within the scope described in the application documents, and it should be understood that they will naturally fall within the technical scope of the present invention. In addition, within the scope of not departing from the gist of the utility model, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined.

[0066] In addition, this application is an application based on the Japanese patent application (Japanese Patent Application No. 2023-090498) filed on May 31, 2023, and the contents thereof are incorporated herein by reference.

Claims

1. A battery cell base, characterized in that: In the battery pack, the battery cell base is interposed between the cooling plate and the battery cell and places the battery cell thereon. The battery cell base is a long sheet-shaped base along the edge of the lower portion of the battery cell, or a sheet-shaped base supporting the edge of the battery cell at intervals. The battery cell base is a product formed of one of thermally expandable graphite, vermiculite, thermally expandable microcapsules and thermally decomposable chemical foaming agents.

2. A battery pack, characterized in that: The battery cell base according to claim 1 is interposed between a plurality of battery cells and a cooling plate. Furthermore, the battery cells are placed on the battery cell base, and the battery cells are connected in series or in parallel.

3. The battery pack according to claim 2, characterized in that: A gap filler having the same thickness as that of the battery cell bases is filled between the battery cell bases, and the battery cell is placed on a surface formed by the battery cell bases and the gap filler.

4. The battery pack according to claim 2, characterized in that: For each of the battery cells, two elongated battery cell bases are arranged in parallel along a pair of opposing edge portions of the lower portion of the battery cell.

5. The battery pack according to claim 2, characterized in that: For each of the battery cells, a plurality of the battery cell bases are arranged at intervals along a pair of opposing edge portions of a lower portion of the battery cell.

6. The battery pack according to claim 2, characterized in that: The battery cell base supports corners of the battery cell.

7. The battery pack according to claim 2, characterized in that: A heat transfer suppressing sheet is interposed between the plurality of battery cells.

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