Battery pack

Abstract

To provide a battery pack capable of inhibiting dew condensation in a case effectively.SOLUTION: A battery pack includes: multiple battery cells arranged along a first direction; a case having an internal space which houses the multiple battery cells; and a sheet member which is provided at the case and has air permeability. The sheet member is provided at a cooling plate forming a bottom part of the case or a member integrated with the cooling plate.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present technology relates to battery packs. [Background technology]

[0002] Battery packs in which multiple battery cells are housed in a case are described in JP 2012-015121 A (Patent Document 1) and JP 2018-041614 A (Patent Document 2). For example, the battery pack described in Patent Document 2 has a side wall of the pack case provided with a breathing hole and a breathing membrane that communicate between the inside and outside of the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-015121 A [Patent Document 2] JP 2018-041614 A Summary of the Invention [Problem to be solved by the invention]

[0004] In terms of efficiency, there is still room for improvement in the dew condensation prevention mechanism of the battery pack. An object of the present technology is to provide a battery pack that can effectively suppress dew condensation inside the case. [Means for solving the problem]

[0005] The battery pack according to the present technology includes a plurality of battery cells arranged along a first direction, a case having an internal space for accommodating the plurality of battery cells, and a breathable sheet member provided in the case. The sheet member is provided on a cooling plate constituting a bottom of the case or on a member integrated with the cooling plate. Effect of the Invention

[0006] According to the present technology, a battery pack can be provided that can effectively suppress condensation inside the case by providing a breathable sheet member on a cooling plate that forms the bottom of the case or on a member integrated with the cooling plate. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing a battery cell included in the battery pack. [Diagram 2] FIG. 2 is an external view of the battery pack. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is a cross-sectional view of a cooling plate. [Figure 6] 4 is an enlarged cross-sectional view showing a gas exhaust passage provided in the cooling plate. FIG. [Figure 7] FIG. 11 is an enlarged cross-sectional view (part 1) showing a modified example of a gas discharge passage. [Figure 8] FIG. 2 is an enlarged cross-sectional view (part 2) showing a modified example of the gas discharge passage. [Figure 9] FIG. 11 is an enlarged cross-sectional view (part 3) showing a modified example of the gas discharge passage. [Figure 10] FIG. 11 is an enlarged cross-sectional view (part 4) showing a modified example of the gas discharge passage. [Figure 11] FIG. 5 is an enlarged cross-sectional view (part 5) showing a modified example of the gas discharge passage. [Figure 12] 4 is a cross-sectional perspective view showing the structure of a joint between a case and a cooling plate. FIG. [Figure 13] FIG. 13 is a view of the cooling plate shown in FIG. 12 as viewed from the back surface side. [Figure 14] FIG. 1 is a top view (part 1) showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 15] FIG. 2 is a top view (part 2) showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 16]FIG. 11 is a top view (part 3) showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 17] FIG. 11 is a fourth top view showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 18] FIG. 5 is a top view (part 5) showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 19] FIG. 6 is a top view (part 6) showing an example of a cooling plate in which a cooling medium passage and a gas discharge passage are formed. [Figure 20] FIG. 11 is a cross-sectional view of a modified example of the battery pack. [Figure 21] 21 is a cross-sectional view showing a structure near an end of the battery pack shown in FIG. 20. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated in some cases.

[0009] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0010] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0011] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0012] In this specification, the term "battery" is not limited to a lithium ion battery, but may include other batteries such as nickel-metal hydride batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode. In addition, the term "electrode plate" may collectively refer to a positive electrode plate and a negative electrode plate.

[0013] Fig. 1 is a diagram showing a battery cell 100 included in a battery pack according to the present embodiment. As shown in Fig. 1, the battery cell 100 is formed in a generally rectangular parallelepiped shape with a flat surface. In the battery pack, the battery cells 100 are stacked in the Y-axis direction (first direction).

[0014] The electrode terminals 110 include a positive terminal 111 and a negative terminal 112. The positive terminal 111 and the negative terminal 112 are aligned in the X-axis direction (second direction). The electrode terminals 110 are provided on the upper surface of a rectangular housing 120.

[0015] The top and bottom surfaces of the housing 120, which face each other along the Z-axis direction (third direction), have a generally rectangular shape with the long side direction being the X-axis direction and the short side direction being the Y-axis direction. An electrode body and an electrolyte are contained in the housing 120. A gas exhaust valve 121 is provided on the top surface of the housing 120. When the pressure inside the housing 120 increases, the gas exhaust valve 121 opens to exhaust gas inside the housing 120.

[0016] It should be noted that the battery cell according to the present technology is not limited to the rectangular battery cell 100, and may be, for example, a cylindrical battery cell.

[0017] FIG. 2 is an external view of the battery pack 1. As shown in FIG. 2, the battery pack 1 includes a case 200. The case 200 includes a cover 210, a main body 220, and a cooling plate 230. The cover 210, the main body 220, and the cooling plate 230 constitute structural members for ensuring the strength of the case 200. The main body 220 may be a bottomed container, and the bottom and the cooling plate 230 may be integrated, or the bottom of the main body 220 may be formed by the cooling plate 230. The cooling plate 230 has an inlet portion 231A and an outlet portion 231B that communicate with a cooling medium passage 231 (see FIG. 5) formed therein.

[0018] FIG. 3 is a perspective view showing the inside of the case 200, and FIG. 4 is a top view showing the inside of the case 200. As shown in FIGS. 3 and 4, a plurality of battery cells 100 are arranged in the internal space of the case 200. The plurality of battery cells 100 are arranged along the Y-axis direction (first direction). The plurality of battery cells 100 are stored in the internal space of the case 200 while being restrained in the Y-axis direction. The plurality of battery cells 100 are electrically connected to each other by bus bars 300. It is also possible to cool the cooling plate 230 by bringing a cooling means such as a Peltier element into contact with the cooling plate 230 without providing the cooling medium passage 231 in the cooling plate 230.

[0019] FIG. 5 is a diagram showing a cross section of the cooling plate 230. As shown in FIG. 5, the cooling plate 230 (plate-shaped portion) constitutes the bottom of the case 200. Inside the cooling plate 230, a cooling medium passage 231 through which the cooling medium flows and a discharge passage 232 capable of discharging gas in the internal space of the case 200 to the outside of the case 200 are formed. The cooling plate 230 can be formed, for example, from an extruded material. The cooling medium passage 231 and the discharge passage 232 are formed within the thickness of the cooling plate 230 so as to extend in the extension direction of the plate-shaped cooling plate 230. Therefore, it is possible to form the cooling plate 230 by extrusion molding and the cooling medium passage 231 and the discharge passage 232 at the same time.

[0020] For example, when one of the battery cells 100 housed in the case 200 experiences thermal runaway, gas inside the housing 120 is discharged from the gas discharge valve 121 of the battery cell 100, and the internal pressure inside the case 200 rises. In the battery pack 1 according to this embodiment, by providing the cooling plate 230, which is a structural member of the case 200, with a discharge passage 232 as a gas discharge path, even a high-capacity battery pack 1 can discharge gas emitted during thermal runaway from the case 200 without providing a separate safety valve. Therefore, the case 200 can be provided with a gas discharge function without increasing the manufacturing cost or making the battery pack 1 larger.

[0021] Furthermore, gas ejected from the battery cells 100 when the internal pressure of the case 200 rises passes through exhaust passages 232 formed in the cooling plate 230 and is then exhausted to the outside of the case 200, facilitating cooling of the gas. Therefore, the temperature of the gas exhausted from the case 200 can be lowered.

[0022] Fig. 6 is an enlarged cross-sectional view showing the gas exhaust passage 232. The exhaust passage 232 shown in Fig. 6 is constituted by a hole formed by extrusion molding when forming the cooling plate 230. A through hole 220A is provided in the bottom of the main body 220 of the case 200. The cooling plate 230 is provided with an inlet portion 232A that communicates with the exhaust passage 232. The through hole 220A and the inlet portion 232A communicate with each other. Therefore, the exhaust passage 232 communicates with the internal space of the case 200 via the through hole 220A and the inlet portion 232A.

[0023] A breathable and waterproof sheet member 233 (breathable waterproof sheet) is provided inside the through hole 220A. The sheet member 233 is provided so as to close the inlet portion 232A of the discharge passage 232. The sheet member 233 is provided so as to face the internal space of the case 200.

[0024] The sheet member 233 can allow gas (air) to pass through while blocking water (liquid). The sheet member 233 functions as a breathing valve that reduces the pressure difference between the inside and outside of the case 200 under normal conditions. The sheet member 233 can be made of a waterproof, moisture-permeable material such as Gore-Tex (registered trademark).

[0025] When the internal pressure of the case 200 rises, the sheet member 233 breaks or peels off, and gas and other ejected matter ejected from the battery cells 100 are discharged to the outside of the case 200. By providing the sheet member 233 at the inlet portion 232A of the exhaust passage 232, it is possible to suppress the intrusion of moisture and dust into the internal space of the case 200 under normal conditions (waterproofing and dustproofing) without impeding the discharge of gas from the internal space of the case 200 via the exhaust passage 232. In addition, since the gas exhaust passage 232 when the internal pressure rises can be used as a breathing passage under normal conditions, it is possible to reduce the size of the battery pack 1 and reduce manufacturing costs (reducing the number of parts).

[0026] When the cooling plate 230 is cooled, condensation is likely to occur in the exhaust passages 232 formed in the cooling plate 230. This causes moisture (water vapor) around the sheet member 233 to condense, which prevents water vapor from entering the internal space of the case 200, and effectively prevents condensation from occurring in the internal space of the case 200.

[0027] By providing the sheet member 233 at a position facing the internal space of the case 200, it is possible to prevent the sheet member 233 from being damaged due to the external environment (for example, water pressure during a high-pressure car wash). However, the installation position of the sheet member 233 is not limited to a position facing the internal space of the case 200, and the sheet member 233 may be provided so as to face the outside of the case 200.

[0028] As a result of the above, in battery pack 1 according to the present embodiment, the occurrence of condensation inside case 200 is suppressed.

[0029] 7 to 11 are diagrams showing modified examples of the gas discharge passage. As shown in FIG. 7, the discharge passage 232 may be formed of a groove portion opening toward the upper surface of the cooling plate 230. Also, as shown in FIG. 8 and FIG. 9, a sheet member 233 may be provided between the bottom of the main body 220 of the case 200 and the cooling plate 230. Furthermore, as shown in FIG. 10 and FIG. 11, an outlet portion 232B of the discharge passage 232 may be formed so as to open to the back side of the cooling plate 230 (the side opposite to the main body 220 of the case 200), and the sheet member 233 may be provided on the outside of the outlet portion 232B (on the back surface of the cooling plate 230).

[0030] FIG. 12 is a cross-sectional perspective view showing the structure of the joint between main body 220 of case 200 and cooling plate 230, and FIG. 13 is a view of cooling plate 230 shown in FIG. 12 as seen from the back side.

[0031] 12 and 13, exhaust passages 232 are formed on both sides in the X-axis direction of a cooling medium passage 231 extending in the Y-axis direction. A through hole 220A formed in the bottom of a main body 220 of the case 200 communicates with an inlet portion 232A of the exhaust passage 232 formed in the cooling plate 230, thereby communicating the internal space of the case 200 with the exhaust passage 232. An outlet portion 232B of the exhaust passage 232 is formed at a position away from the inlet portion 232A in the Y-axis direction. The outlet portion 232B is provided so as to open to the rear surface side of the cooling plate 230.

[0032] 14 to 19 are top views showing examples of cooling plate 230. As shown in Fig. 14 to 19, cooling plate 230 has a generally rectangular shape with long sides extending in the Y-axis direction and short sides extending in the X-axis direction. Cooling medium passage 231 through which the cooling medium flows and exhaust passage 232 through which gas is exhausted extend along the Y-axis direction.

[0033] 14, outlets 232B of the exhaust passage 232 are formed at both ends of the cooling plate 230 in the Y-axis direction. By providing a plurality of outlets 232B, the outlet area of ​​the exhaust passage 232 can be increased. The flow path cross-sectional area of ​​the exhaust passage 232 shown in FIG. 14 is, for example, 200 mm2 More than 1500mm 2 Approximately 400mm or less (preferably 400mm 2 More than 1000mm 2 The flow rate of gas flowing through exhaust passage 232 when the internal pressure of case 200 is increasing is, for example, a maximum of 200 liters / second or more (continuing for about several seconds). When the internal pressure of case 200 is increasing, gas is discharged from exhaust passage 232 for, for example, a period ranging from a dozen seconds to about 30 seconds. However, the flow path cross-sectional area of ​​exhaust passage 232 and the flow rate of gas are not limited to the above ranges.

[0034] 14, one exhaust passage 232 is provided in the cooling plate 230, but the form of the exhaust passage 232 is not limited to this. A plurality of exhaust passages 232 that are not connected to each other may be provided in the cooling plate 230, and each exhaust passage 232 may be provided with an inlet portion 232A and an outlet portion 232B. This can further increase the gas flow rate.

[0035] 15 to 19, a trap portion 232C is formed in communication with the discharge passage 232. The tip of the trap portion 232C is closed. The trap portion 232C is formed within the thickness of the cooling plate 230 so as to extend in the extension direction of the cooling plate 230 (the XY plane direction).

[0036] As shown in Fig. 15, the outlet portion 232B of the discharge passage 232 may be formed at both ends of the cooling plate 230 in the X-axis direction. As shown in Fig. 16, the outlet portion 232B of the discharge passage 232 may be formed on the back surface of the cooling plate 230. As shown in Fig. 17, a part of the discharge passage 232 and the trap portion 232C may extend in parallel. As shown in Fig. 18, the outlet portion 232B may be formed at only one location. As shown in Fig. 19, a part of the discharge passage 232 may extend in the X-axis direction and reach the opposite side in the X-axis direction across the cooling medium passage 231.

[0037] As shown in the examples of Figures 15 to 19, by providing a bent portion in the exhaust passage 232 or by providing a trap portion 232C with a blocked tip, it is possible to prevent ejections and sparks other than gas generated from a battery cell 100 experiencing thermal runaway from being discharged from the outlet portion 232B.

[0038] According to the battery pack 1 of this embodiment, by providing the gas exhaust passage 232 within the thickness of the cooling plate 230, it is possible to provide the structural members of the case 200 with the function of a gas exhaust path when the internal pressure increases. This makes it possible to provide the battery pack 1 with the function of exhausting gas when the internal pressure increases without increasing the manufacturing cost or making the battery pack 1 larger.

[0039] Moreover, the outlet portion 232B of the exhaust passage 232 is also formed inside the cooling plate 230, and a portion protruding to the outside of the case 200 can be omitted.

[0040] The member that forms the exhaust passage 232 is not necessarily limited to the cooling plate 230 , and the exhaust passage 232 may be formed in the side surface of the case 200 .

[0041] Fig. 20 is a cross-sectional view of a modified example of the battery pack 1. In this modified example, as shown in Fig. 20, the battery pack 1 is formed by stacking two battery packs 1A and 1B.

[0042] Fig. 21 is a cross-sectional view showing the structure near an end of a battery pack 1A. As shown in Fig. 21, an end plate 400 is provided at the end of a stack of battery cells 100. Separators 500 are provided between the multiple battery cells 100.

[0043] In this modification, main body 220 of case 200 is integrated with cooling plate 230. Main body 220 is provided with a normal breathing passage (not shown) and sheet member 233. Note that the normal breathing passage and gas exhaust passage 232 when the internal pressure rises do not necessarily have to be used together.

[0044] The main body 220 may be made of the same material as the cooling plate 230, or may be made of separate materials that are integrated together by welding, etc. In any case, a material that can be evaluated as being thermally integrated with the cooling plate 230 should be interpreted as a material that is integrated with the cooling plate 230.

[0045] A hole 220B is formed in the main body 220. Gas that has passed through the sheet member 233 can be introduced into the hole 220B. Furthermore, it is also possible to communicate a passage formed in the cooling plate 230 with the hole 220B, and freely adjust the position or direction of the outlet of the passage.

[0046] In the modified example shown in Figures 20 and 21, as in the case where sheet member 233 is provided on cooling plate 230, the intrusion of water vapor into the internal space of case 200 is suppressed, and the occurrence of condensation in the internal space of case 200 is effectively suppressed.

[0047] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0048] 1, 1A, 1B battery pack, 100 battery cell, 110 electrode terminal, 111 positive electrode terminal, 112 negative electrode terminal, 120 housing, 121 gas exhaust valve, 200 case, 210 cover, 220 main body, 220A through hole, 220B hole portion, 230 cooling plate, 231 cooling medium passage, 231A inlet portion, 231B outlet portion, 232 exhaust passage, 232A inlet portion, 232B outlet portion, 232C trap portion, 233 sheet member, 300 bus bar, 400 end plate, 500 separator.

Claims

1. A plurality of battery cells arranged along a first direction; a case having an internal space for housing the plurality of battery cells; A breathable sheet member is provided in the case, the sheet member is provided on a cooling plate constituting a bottom of the case or on a member integrated with the cooling plate, and faces the cooling plate; a discharge passage capable of discharging gas from the internal space is formed in the cooling plate, and the sheet member is provided on the discharge passage so as to close the discharge passage.

2. The battery pack according to claim 1 , wherein the member integrated with the cooling plate constitutes a side surface or a bottom surface of the case.

3. The battery pack according to claim 1 , wherein the sheet member is disposed so as to face the internal space.

4. A plurality of battery cells arranged along a first direction; a case having an internal space for housing the plurality of battery cells; a sheet member provided in the case and having air permeability; the sheet member is provided on a cooling plate constituting a bottom of the case or on a member integrated with the cooling plate, an exhaust passage capable of exhausting gas from the internal space is formed within a thickness of the cooling plate so as to extend in an extension direction of the cooling plate; The sheet member is provided on the discharge passage so as to close the discharge passage.

5. the cooling plate includes an extrusion material formed by extrusion molding, The battery pack according to claim 4 , wherein the exhaust passage includes a groove or a hole formed by the extrusion molding.

6. The cooling plate has a substantially rectangular shape including long sides and short sides, The battery pack according to claim 4 or 5, wherein the discharge passage includes a portion extending in a direction along the long side.

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