Battery pack

Abstract

To provide a battery pack having a simple configuration and capable of discharging an ejected material to the outside.SOLUTION: A battery pack 100 includes a battery module 10 in which a plurality of battery cells 11 are stacked, the battery module 10 includes a battery cell 11 having a safety valve that opens when the internal pressure rises, a case 20 that houses the battery module 10, an exhaust path 23 provided along a first direction at a position opposite the safety valve of the case 20 in the second direction, and a sealing member 42 provided between the case 20 and the battery module 10 and arranged around the exhaust path 23 to partition the exhaust path 23.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a battery pack.

Background Art

[0002] Patent Document 1 discloses a battery pack having a plurality of stacked battery cells and an exhaust duct through which gas discharged from the battery cells flows. Each battery cell has an exhaust valve. The internal space of the exhaust duct forms a smoke exhaust path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the ejecta discharged from the exhaust valve flows through the exhaust duct. Therefore, when the exhaust duct is small, if a large amount of ejecta is discharged, there is a risk that the exhaust path will be blocked. Furthermore, since it is necessary to provide the exhaust duct on the resin frame, the number of parts increases.

[0005] The present disclosure provides a battery pack that can discharge ejecta to the outside with a simple configuration.

Means for Solving the Problems

[0006] A battery pack according to an aspect of the present disclosure includes a battery cell having a safety valve that opens when the internal pressure rises, a battery module in which a plurality of the battery cells are stacked in a first direction, a case that houses the battery module, an exhaust path provided in the case along the first direction and facing the safety valve in a second direction, and a seal member provided between the case and the battery module and disposed around the exhaust path so as to partition the exhaust path.

Advantages of the Invention

[0007] According to the present disclosure, a battery pack with a simple configuration that can discharge the ejecta to the outside can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0009] Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are appropriately simplified.

[0010] First, with reference to FIG. 1, the battery pack 100 will be described. FIG. 1 is a top view schematically showing the configuration of the battery pack 100. For clarity of explanation, in the figure, the description will be made using the xyz three-dimensional orthogonal coordinate system. Usually, the positive direction of the +z axis is vertically upward, and the xy plane is the horizontal plane. The y direction is the stacking direction of the battery cells. That is, in the battery module, a plurality of battery cells are stacked in the y direction. Also, the vertical direction and the like are relative directions, and they change appropriately according to the orientation of the battery pack 100.

[0011] The battery pack 100 includes a case 20 and a battery module 10. In a view in the xy plane, the case 20 is a substantially rectangular housing that houses the battery module 10. As will be described later, since the case 20 is separated into two upper and lower cases, the upper case is omitted in FIG. 1. In FIG. 1, four battery modules 10 are housed in the case 20. The four battery modules 10 are of substantially the same size and are arranged side by side in the y direction. In the case 20, the space for housing the battery module 10 is defined as a housing space 20a.

[0012] The battery module 10 has a plurality of battery cells 11. The battery cells 11 are secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. The battery cells 11 are prismatic batteries having a substantially rectangular shape in the xz plane. An electrode body is housed inside the cell case of the battery cell 11. The electrode body is formed, for example, by laminating a positive electrode and a negative electrode with a separator interposed therebetween and further winding them in a cylindrical shape. The electrode body is not limited to a wound type and may be a stacked type. The electrode body is immersed in an electrolytic solution. Also, terminals (not shown) of the positive electrode and the negative electrode are taken out from the upper surface or the side surface of the battery cell 11. In the battery module 10, the terminals of the plurality of battery cells 11 are connected by a bus bar (not shown).

[0013] As described above, in each battery module 10, a plurality of battery cells 11 are stacked in the y direction. Each battery cell 11 has a safety valve 12. The safety valve 12 opens when the internal pressure of the battery cell 11 rises. That is, when gas, smoke, etc. (hereinafter collectively referred to as ejecta) are generated from the battery cell 11, the pressure in the internal space of the battery cell 11 rises. When the pressure in the internal space rises, the safety valve 12 opens, and the ejecta in the internal space are discharged to the outside of the battery cell 11. Thereby, the safety can be enhanced.

[0014] Each of the battery cells 11 has a safety valve 12. The safety valve 12 is formed on the upper surface of the battery cell 11. In one battery module 10, a plurality of safety valves 12 are arranged in a row. Specifically, in each battery module 10, a plurality of safety valves 12 are arranged in a row along the y direction. Here, since four battery modules 10 are provided, the safety valves 12 are arranged in four rows. In each battery module 10, the safety valve 12 is arranged at the central portion of the battery module 10 in the x direction.

[0015] The safety valve 12 is connected to an exhaust path 23 provided in the case 20. That is, an exhaust path 23 is provided at a location of the case 20 facing the safety valve 12. The exhaust path 23 includes a first path 23a provided along the y direction and a second path 23b provided along the x direction. The intersection of the first path 23a and the second path 23b is defined as an intersection portion 23c.

[0016] The first path 23a is a portion arranged directly above the row of the safety valves 12. Here, since four battery modules 10 are provided, the first path 23a is provided in four rows. Each first path 23a is arranged at the central portion of the battery module 10 in the x direction. The second path 23b is a portion connecting the plurality of first paths 23a to the exhaust valve 50. The second path 23b is formed to cross the plurality of first paths 23a along the x direction. The second path 23b is arranged at the central portion of the first path 23a in the y direction.

[0017] The ejecta discharged from the safety valve 12 reaches the exhaust valve 50 through the first path 23a and the second path 23b. Therefore, the exhaust valve 50 can discharge the ejecta to the outside of the case. Thereby, an increase in the pressure inside the case 20 can be suppressed. The exhaust valve 50 functions as a smoke exhaust valve that exhausts the smoke generated from the battery cell 11. The exhaust valve 50 may be a safety valve that opens when the internal pressure of the case 20 rises. Also, instead of the exhaust valve 50, an exhaust port may be provided.

[0018] A buffer material 45 is disposed between two adjacent battery modules 10. That is, the battery modules 10 face each other via the buffer material 45. The buffer material 45 is a plate-shaped member and is formed of an elastic resin or the like. Thereby, the impact received by the battery module 10 can be mitigated.

[0019] Next, with reference to FIGS. 2 and 3, the exhaust path 23 and the surrounding configuration will be described. FIG. 2 is a cross-sectional view taken along the cutting line II-II of FIG. 1 and shows the configuration in the xz plane. FIG. 3 is a cross-sectional view taken along the cutting line III-III of FIG. 1 and shows the configuration in the yz plane.

[0020] The case 20 includes a first case 21 and a second case 22. The first case 21 is an upper case (UPR case) disposed above the battery cell 11. The second case 22 is a lower case (LWR case) disposed below the battery cell 11. The second case 22 has a box shape with an open upper side. The first case 21 has a box shape with an open lower side. The first case 21 serves as a lid covering the upper side of the second case 22.

[0021] The first case 21 and the second case 22 are formed of, for example, a metal material. For example, the first case 21 and the second case 22 are formed by pressing a metal plate or the like. With the battery module 10 disposed inside the second case 22, the first case 21 is placed over it from above, so that the battery module 10 is accommodated in the case 20. Further, after the battery module 10 is accommodated in the case 20, the first case 21 and the second case 22 may be fixed by welding or the like.

[0022] The first case 21 has a convex portion 25 protruding upward. The convex portion 25 is disposed directly above the safety valve 12 and partitions the exhaust path 23. The space below the convex portion 25 becomes the exhaust path 23. In a view from the xy plane, the convex portion 25 is disposed at a position facing the safety valve 12. The convex portion 25 protrudes in a direction away from the battery cell 11. For example, the convex portion 25 can be formed on the first case 21 by pressing a metal plate.

[0023] More specifically, the convex portion 25 includes a facing portion 25a and an inclined portion 25b. The facing portion 25a is a plane parallel to the xy plane. The inclined portion 25b is a plane inclined from the xy plane. Also, in the first case 21, a portion outside the convex portion 25 is defined as a holding portion 26. The holding portion 26 is a plane parallel to the xy plane and serves as a plane for holding the battery module 10.

[0024] In the first path 23a, the facing portion 25a is located at a position facing the row of the safety valves 12. The inclined portion 25b is a plane connecting the facing portion 25a and the holding portion 26. Thus, the inclined portions 25b are formed on both sides of the facing portion 25a. The inclined portion 25b is a tapered plane extending in the +z direction from the holding portion 26 toward the facing portion 25a. Thus, the facing portion 25a is located on the +z side of the holding portion 26.

[0025] By providing the convex portion 25, the exhaust path 23 can be widened. Thereby, even when a large amount of ejecta 60 is discharged, it is possible to prevent the exhaust path 23 from being blocked. For this reason, the ejecta 60 can be efficiently discharged to the outside, and the safety can be improved. The convex portion 25 can be formed by processing a metal plate. For this reason, the convex portion 25 functions as a rib for improving the rigidity of the first case 21. Thus, it becomes possible to use a thin metal plate for weight reduction. Furthermore, the exhaust path 23 can be secured without increasing the number of separate parts. An increase in the number of components can be suppressed. Thereby, since the exhaust path 23 can be formed with a simple configuration, the component cost can be reduced.

[0026] Between the first case 21 and the battery cell 11, a seal member 42 and a mica member 41 are arranged. The seal member 42 is arranged between the mica member 41 and the first case 21. The seal member 42 is, for example, an elastic member. Also, the seal member 42 may be an adhesive. For example, the seal member 42 may be a double-sided tape having elasticity in the thickness direction. The mica member 41 is formed of a mica material with excellent insulation and heat resistance. That is, the mica member 41 is an insulating material with excellent heat resistance.

[0027] The seal member 42 is in contact with the first case 21. Also, the seal member 42 is arranged so as to be in contact with the mica member 41. Therefore, the seal member 42 can partition the exhaust path 23 formed by the convex portion 25. The seal member 42 is arranged around the exhaust path 23 so as to partition the exhaust path 23. That is, the exhaust path 23 is partitioned from the accommodation space 20a.

[0028] Specifically, the seal member 42 is arranged outside the convex portion 25 and surrounds the exhaust path 23. As shown in FIG. 2, in the x direction, it is arranged on both sides of the convex portion 25 that becomes the first path 23a. Similarly, as shown in FIG. 3, in the y direction, it is arranged on both sides of the convex portion 25 that becomes the second path 23b. The seal member 42 is in contact with the holding portion 26. The seal member 42 seals the gap between the mica member 41 and the holding portion 26. Thereby, since the exhaust path 23 can be partitioned from the accommodation space 20a, it is possible to prevent the ejecta from the safety valve 12 from entering the accommodation space 20a in the case 20. Therefore, the ejecta can be efficiently discharged from the exhaust valve 50.

[0029] Also, by providing the convex portion 25, the distance between the opposing portion 25a and the battery module 10 can be increased. That is, since the distance from the safety valve 12 to the opposing portion 25a can be increased, damage to the first case 21 due to the ejecta 60 can be suppressed.

[0030] As shown in Fig. 2, in a top view of the xz plane, the mica member 41 has an L shape so as to cover the upper surface and the side surface of the battery cell 11. That is, the mica member 41 is bent so as to extend from the upper surface to the side surface of the battery cell 11. The mica member 41 is disposed outside the location where the first path 23a is formed. The seal member 42 is in contact with the mica member 41. Further, as shown in Fig. 3, the mica member 41 is disposed directly below the second path 23b. The mica member 41 is in contact with the buffer member 45.

[0031] Further, the buffer member 45 includes a protruding portion 45a that protrudes toward the first case 21 side. As shown in Fig. 3, the buffer member 45 has two protruding portions 45a. The two protruding portions 45a are spaced apart in the y direction. And the second path 23b is disposed between the two protruding portions 45a.

[0032] The protruding portion 45a is provided so as to contact the holding portion 26. Even when a load is applied to the first case 21 from above, deformation of the first case 21 can be suppressed, and thus it is possible to prevent the exhaust path 23 from being blocked.

[0033] Also, the first paths 23a for the plurality of battery modules 10 communicate with the exhaust valve 50 through the second path 23b. Therefore, the opening of the exhaust valve can be controlled by the pressure in the exhaust path 23. That is, when the pressure in the exhaust path 23 rises, the ejecta 60 can be discharged to the outside of the case 20. More preferably, the ejecta 60 can be exhausted.

[0034] Modification The configuration of the battery pack 100 according to the modification will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view showing the first path 23a and its surrounding configuration in the battery pack 100. In Fig. 4, the battery pack 100 further includes a heat insulating member 46. The heat insulating member 46 is provided at a location facing the exhaust path 23 of the first case 21. Specifically, the heat insulating member 46 is a heat insulating sheet attached to the facing portion 25a. Therefore, the ejecta ejected from the safety valve 12 hits the heat insulating member 46.

[0035] For example, the fume gas from the battery cell 11 may become high-temperature gas at 600°C to 1000°C. Even when such high-temperature gas is generated, the temperature rise of the first case 21 can be suppressed. Therefore, by the heat conduction of the first case 21, it is possible to prevent the temperature of the battery cells 11 other than the opened battery cell 11 from rising.

[0036] Structural Example 1 A structural example 1 of the seal member 42 will be described with reference to FIG. 5. FIG. 5 is an xz cross-sectional view showing the configuration of the structural example 1. In the structural example 1, the seal member 42 is adhered to the first case 21. Further, the mica member 41 is attached to the battery cell 11. That is, before the battery module 10 is housed, the seal member 42 and the first case 21 are integrated. Then, the mica member 41 is attached and the first case 21 integrated with the seal member 42 is covered from above the battery cell 11.

[0037] Since the mica member 41 is attached to the battery cell 11, the high-voltage terminal of the battery cell 11 can be protected in advance. Therefore, the safety during the assembly work can be improved. Also, the risk of attachment of conductive foreign matter to the terminal portion can be suppressed. An elastic member can be used for the seal member 42. For this reason, the seal member 42 can be used as a cushioning material against impacts from above the battery pack 100.

[0038] Structural Example 2 A structural example 2 of the seal member 42 will be described with reference to FIG. 6. FIG. 6 is an xz cross-sectional view showing the configuration of the structural example 2. In FIG. 5, the first case 21, the seal member 42, and the mica member 41 are integrated. For example, the seal member 42 is a double-sided tape. Therefore, before the battery module 10 is housed, the seal member 42 can integrate the first case 21 and the mica member 41.

[0039] In Structural Example 2, the operation of fixing the mica member 41 to the battery cell 11 can be omitted. Furthermore, when disassembling the battery pack 100, the operation of removing the mica member 41 from the battery cell 11 can be reduced. As a result, the number of components and the number of processes can be decreased, thus improving productivity. Additionally, the rigidity of the first case 21 can be improved by the mica member 41. Also, since the positional variation between the mica member 41 and the first case 21 does not need to be considered, seal leakage due to misalignment can be suppressed.

[0040] A check valve may be provided in the exhaust path 23. By providing the check valve, backflow of the ejecta from the safety valve can be prevented. For example, a check valve may be provided at the intersection of the first path 23a and the second path 23b. It is possible to prevent the intrusion of the ejecta into the first path 23a corresponding to the battery module 10 in which the safety valve is not opened.

[0041] Furthermore, a rectifying fin may be provided in the exhaust path 23. The rectifying fin is installed so that the ejecta flows toward the exhaust valve 50. For example, a rectifying fin may be provided at the intersection of the first path 23a and the second path 23b. The rectifying fin preferably extends in the -x direction and is inclined toward the center side of the battery module 10 in the y direction. Thereby, the ejecta can be efficiently guided to the exhaust valve 50.

[0042] Note that the present disclosure is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist.

Description of Reference Numerals

[0043] 100 Battery pack 10 Battery module 11 Battery cell 12 Safety valve 20 Case 21 First case 22 Second case 23 Exhaust path 23a First path 23b Second path 25 Convex part 25a Opposing part 25b Inclined part 26 Holding part 41 Mica member 42 Seal member 45 Buffer material 45a Protruding part 46 Heat insulating member 50 Exhaust valve

Claims

1. A battery pack comprising a battery module having a safety valve that opens when the internal pressure rises, the plurality of battery cells being stacked in a first direction, a case that houses the battery module, an exhaust path provided along the first direction in the case and disposed at a position facing the safety valve in a second direction, and a seal member provided between the case and the battery module and disposed around the exhaust path so as to partition the exhaust path.

2. The battery pack according to claim 1, further comprising a heat insulating member provided at a location on the case facing the exhaust path.

3. The case includes a convex portion that protrudes in a direction away from the battery module, The battery pack according to claim 1 or 2, wherein the seal member is provided outside the convex portion so that the convex portion forms an exhaust path.

4. The case further includes an exhaust valve connected to the exhaust path, a plurality of the battery modules are arranged side by side in a third direction, The exhaust path includes a plurality of first paths provided along the first direction, one of the first paths being arranged to face the safety valve of the battery cells included in one of the battery modules, and a second path provided along the third direction and connecting the plurality of first paths to the exhaust valve. The battery pack according to claim 1 or 2.

5. A plurality of the battery modules are provided, a buffer member is provided between adjacent battery modules, The battery pack according to claim 4, wherein the buffer member includes a protruding portion that protrudes toward the case side so as to contact the case outside the second path.

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