Battery pack

Abstract

The present application discloses a battery pack, comprises a case, the case being provided with an accommodating cavity having one open side; a cover, the cover covering the open side of the case to seal the accommodating cavity; a battery cell group, the battery cell group being arranged in the accommodating cavity, and electrodes of the battery cell group facing the cover; and a busbar, the busbar being arranged between the battery cell group and the cover, a pressure relief space is reserved between the busbar and the cover, wherein insulating cooling oil is injected into the accommodating cavity, and the electrodes of the battery cell group and the busbar are immersed in the insulating cooling oil.

Description

A battery pack

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 29, 2024, with application number 202420646977X. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a battery pack. Background Art

[0003] With the rapid advancement of new energy vehicle technology and the continued expansion of the market, the range and charge rate of pure electric vehicles have become core metrics of increasing concern to users. To meet market demand, the energy density requirements for power batteries are constantly increasing, with high-nickel cathodes and silicon-carbon anodes gradually becoming the mainstream technology. However, as the energy content of battery cells increases, their heat generation during operation also increases dramatically. This is particularly true under high-rate charging conditions, where cell heating becomes particularly prominent, making temperature control extremely difficult. Technical issues

[0004] The cylindrical battery pack cooling solutions in related technologies, such as indirect liquid cooling technologies such as liquid cooling plates, can alleviate the heat problem during low-rate charging to a certain extent, but their cooling efficiency is obviously insufficient in high-rate charging scenarios. When thermal runaway occurs in the battery cell, the battery cell explosion-proof valve will spray flames, which may easily melt the bus and rush out of the battery pack, posing a safety risk to the passengers. Technical Solutions

[0005] The present application provides a battery pack, comprising: a shell, the shell having a accommodating cavity with one side open; a cover, the cover being arranged on the open side of the shell to close the accommodating cavity; a battery cell group, the battery cell group being arranged in the accommodating cavity, with the electrodes of the battery cell group facing the cover; a bus bar, the bus bar being arranged between the battery cell group and the cover, with a pressure relief space reserved between the bus bar and the cover; wherein insulating cooling oil is injected into the accommodating cavity, and the electrodes of the battery cell group and the bus bar are immersed in the insulating cooling oil. Beneficial effects

[0006] By injecting insulating cooling oil into the accommodating cavity and utilizing the convection heat transfer principle of the liquid, efficient cooling of the battery cell group can be achieved; when the battery cell thermal runaway occurs, the flame ejected from the explosion-proof valve can be directly extinguished by the insulating cooling oil in the pressure relief space. At the same time, the pressure relief space can provide sufficient space for the busbar. When the battery pack is mechanically impacted, the busbar is not prone to electrical short circuit problems. Finally, due to the presence of insulating cooling oil, the busbar will not melt due to thermal runaway of the battery, which greatly improves the safety performance of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1 is a schematic diagram of the three-dimensional structure of an embodiment of the present application;

[0008] FIG2 is a schematic diagram of an explosion structure of an embodiment of the present application;

[0009] FIG3 is a schematic diagram of the cross-sectional structure of an embodiment of the present application;

[0010] FIG4 is a schematic diagram of the assembly structure of a battery cell group and a busbar according to an embodiment of the present application;

[0011] FIG5 is a schematic diagram of the structure of the connecting busbar according to an embodiment of the present application;

[0012] FIG6 is a schematic diagram of the battery cell structure of an embodiment of the present application.

[0013] Among them, the meanings of the accompanying figures are as follows: 1. Shell; 11. Accommodating chamber; 12. Cold oil inlet; 13. Cold oil outlet; 2. Cover; 3. Battery cell group; 31. Battery cell; 32. Battery cell positive electrode; 33. Battery cell negative electrode; 331. Negative electrode connection area; 34. Battery cell explosion-proof valve; 4. Bus; 41. Positive busbar; 42. Negative busbar; 43. Connecting busbar; 431. Positive electrode connection part; 432. Negative electrode connection part; 433. Step part; 5. Fixed layer; 51. Battery cell slot; 6. Pressure relief space. Modes for Carrying Out the Invention

[0014] 1 to 6, a battery pack is disclosed, comprising a housing 1, a cover 2, a cell group 3, and a bus 4. In this embodiment 1, the housing 1 is a rectangular housing 1 having a receiving cavity 11 with one side open, and the cover 2 is provided on the open side of the housing 1 to close the receiving cavity 11; the cell group 3 comprises a plurality of columns of cells 31, and each column of cells 31 is staggered to maximize space, and the cell group 3 is placed in the receiving cavity 11. It should be noted that, as shown in FIG3, the bus 4 and the cover are connected. A pressure relief space 6 is reserved between the battery pack and the housing 1. To address the high heat generation and temperature control issues of the battery cell 31, the battery pack injects insulating cooling oil into the housing 11, utilizing the convection heat transfer principle of the liquid to achieve efficient cooling of the battery cell group 3. Secondly, to address the issue of safe fixation of the battery cell group 3, the battery pack provides a fixing layer 5 between at least one side of the battery cell group 3 and the housing 1, thereby enhancing the stability of the battery cell group 3 within the housing 11. Finally, due to the presence of the insulating cooling oil, the bus bar 4 will not melt due to thermal runaway of the battery, greatly improving the safety performance of the battery pack. When the battery cell 31 thermally runs away, the flame ejected from the explosion-proof valve can be directly extinguished by the insulating cooling oil in the pressure relief space 6. At the same time, the pressure relief space 6 provides sufficient space for the bus bar 4. When the battery pack is mechanically impacted, the bus bar 4 is less likely to suffer from electrical short circuit problems.

[0015] In some embodiments, a fixing layer 5 is provided between at least one side of the cell group 3 and the housing 1. In some embodiments, the fixing layer 5 is a potting compound to secure the cell group 3 within the accommodating cavity 11. Optimally, the potting compound is injected in an amount sufficient to secure at least one-third of the cell 31 within the fixing layer 5. Thus, the fixing layer 5 forms a plurality of cell slots 51 corresponding to each cell 31 within the cell group 3. The cell slots 51 are consistent in number, size, and shape with the cells 31 within the cell group 3. This potting compound significantly enhances the overall structural stability of the battery pack and reduces potential displacement or damage to the cells 31 under vibration or impact. The busbar 4 must avoid contact with the electrodes of the cell group 3 by avoiding the fixing layer 5.

[0016] It should be noted that in some embodiments, the fixing layer 5 includes but is not limited to a bottom plate with holes, foam glue, or a bracket, etc., which can fix the battery cell group 3, and this embodiment is not specifically limited. Similarly, the shape of the housing 1 can also adopt other structures, and the types of battery cells 31 include but are not limited to square or cylindrical.

[0017] During assembly, as shown in Figure 2, set the opening direction of the shell 1 to the top, and then evenly place the battery cells 31 at the bottom of the accommodating cavity 11 in the shell 1, and then start pouring glue into the accommodating cavity 11. The glue pouring height can make the battery cells 31 stable and fixed, and it is not easy to shake. Then, assemble the bus 4 on the top surface of the battery cell group 3 to gather the positive and negative electrodes of several battery cells 31 to form a total positive and negative electrode. Finally, cover the top of the accommodating cavity 11 with the cover 2, and pour the circulating heat exchange insulating cooling oil into the closed accommodating cavity 11, and the electrodes of the battery cell group 3 and the bus 4 need to be immersed in the insulating cooling oil.

[0018] When in use, the battery pack is inverted in the car so that the battery pack cover 2, the positive electrode 32 of the battery cell 31 and the bus 4 are all located at the bottom. This design can maximize the safety of the passengers and make the battery pack with the cover 2 facing down more user-friendly to the users above the battery pack. The principle is as follows: when the battery cell 31 in the battery pack generates heat during operation, it is cooled by heat exchange with the insulating cooling oil. When a mechanical impact occurs and an electrical short circuit occurs, the high-temperature and high-pressure gas and flames are extinguished by the insulating cooling oil when they are ejected from the explosion-proof valve. Even if the impact force is too strong, the impact force will be ejected from the direction of the inverted battery pack cover 2, that is, the impact force is directed towards the bottom of the car and will not affect the passengers.

[0019] Of course, this battery pack can also be used for power supply in other fields. Therefore, when the battery pack will not be used for a long time, the insulating cooling oil does not need to be set to circulate. It can only have a cooling effect when in use and cool down naturally when not in use.

[0020] In this embodiment 1, referring to Figures 1-3, in order to facilitate the injection and discharge of the insulating cooling oil in the accommodating cavity 11 of the housing 1 and improve the efficiency of insulating cooling oil replacement, a cold oil inlet 12 and a cold oil outlet 13 are respectively provided on both sides of the housing 1. The cold oil inlet 12 and the cold oil outlet 13 are connected to the accommodating cavity 11 and are used to inject insulating cooling oil into the accommodating cavity 11 or discharge insulating cooling oil from the accommodating cavity 11. In some embodiments, the cold oil inlet 12 and the cold oil outlet 13 are provided on the housing 1 near the cover 2. Since the battery pack is used in an inverted position, being close to the cover 2 is more conducive to drainage. The cold oil inlet 12 and the cold oil outlet 13 can achieve the effects of heating and liquid cooling of the insulating cooling oil by cooperating with the oil pump, radiator, and heater on the vehicle end. It should be noted that in some embodiments, the cold oil inlet 12 and the cold oil outlet 13 can be provided on the cover 2 so as not to affect the inversion of the battery pack.

[0021] In more detail, referring to FIG6 , the cover plate on the side of the battery cell 31 of the battery cell group 3 facing the cover body 2 is provided with a battery cell positive electrode 32, a battery cell negative electrode 33 and a battery cell explosion-proof valve 34, wherein the battery cell positive electrode 32 and the battery cell negative electrode 33 adopt a high nickel positive electrode and a silicon carbon negative electrode, and the battery cell positive electrode 32, the battery cell negative electrode 33 and the battery cell explosion-proof valve 34 are adjacently arranged and / or spaced apart. In this embodiment 1, there are two battery cell explosion-proof valves 34, the battery cell negative electrode 33 includes two negative electrode connection areas 331, and the battery cell positive electrode 32 is arranged on the side of the battery cell 31 facing the cover body 2. In the center of one side of the body 2, the two negative electrode connection areas 331 and the two battery cell explosion-proof valves 34 are staggered along the circumference of the battery cell positive electrode 32, and there is a height difference between the battery cell negative electrode 33 and the battery cell positive electrode 32, so that the battery cell positive electrode 32 protrudes from the battery cell negative electrode 33. Therefore, the battery cell negative electrode 33 and the battery cell positive electrode 32 can be arranged adjacent to each other, and the battery cell explosion-proof valve 34 is arranged at intervals from the battery cell positive electrode 32. The battery cell explosion-proof valve 34 faces the pressure relief space 6, and the battery cell explosion-proof valve 34 is fan-shaped, and the edges are rounded.

[0022] 4-6 , the busbar 4 includes: a positive busbar 41, a negative busbar 42 and a connecting busbar 43. The positive busbar 41 is connected to the positive electrodes 32 of a row of several battery cells 31 at one end of the battery cell group 3; the negative busbar 42 is connected to the negative electrodes 33 of a row of several battery cells 31 at the other end of the battery cell group 3; a plurality of connecting busbars 43 are provided, which are used to connect the positive electrodes 32 of several rows of battery cells 31 from one end to the other end of the battery cell group 3 with the negative electrodes of adjacent battery cells 31. In this first embodiment, to accommodate the explosion-proof valve structure, in some embodiments, the connecting busbar 43 includes a positive electrode connecting portion 431 for connecting to the positive electrode 32 of the battery cell and a negative electrode connecting portion 432 for connecting to the negative electrode 33 of the battery cell. A step 433 is provided between the positive electrode connecting portion 431 and the negative electrode connecting portion 432. The step 433 is provided at the edge of the negative electrode connecting region 331 to prevent the positive electrode connecting portion 431 from contacting the negative electrode 33 of an adjacent battery cell 31 when connecting to the positive electrode 32 of the adjacent battery cell 31, thereby causing a short circuit. The step height difference of the step 433 is equal to the height difference between the positive electrode 32 and the negative electrode 33 of the battery cell. The area of ​​the positive electrode connecting portion 431 is no larger than the area of ​​the positive electrode 32 of the battery cell, and the area of ​​the negative electrode connecting portion 432 is no larger than the area of ​​the negative electrode connecting region 331 of the negative electrode 33 of the battery cell, thereby achieving an electrode aggregation effect for the battery cell group 3.

[0023] In some embodiments, the number of the battery cell explosion-proof valves 34 can be set to one, or more than two, as long as the normal pressure relief of the battery cell 31 is met. The number of the negative electrode connection areas 331 can also be set to only one, or more than two. The structure of the busbar 4 can also be adaptively adjusted according to the position change, structural change and quantity change of the negative electrode connection area 331 to meet the assembly effect. This embodiment does not make specific limitations.

[0024] In summary, the battery pack provided by this application has the following technical effects:

[0025] 1. By providing a fixing layer 5 between at least one side of the cell group 3 and the housing 1, the stability of the cell group 3 within the accommodating cavity 11 is enhanced. The fixing layer 5 corresponds to the cell slots 51 provided in the cell group 3, ensuring that each cell 31 is precisely placed in its corresponding position, thereby preventing the cell 31 from shifting or misaligning during assembly or use.

[0026] 2. The presence of insulating cooling oil not only improves heat dissipation but also prevents the risk of busbar 4 fusing due to battery thermal runaway, significantly enhancing the safety of the battery pack. Furthermore, the presence of cell explosion-proof valve 34 and the design of pressure relief space 6 effectively divert and reduce internal pressure in the event of thermal runaway in cell 31, enhancing the safety of cell 31.

Claims

1. A battery pack comprising: A housing (1), wherein the housing (1) has a receiving cavity (11) with one side open; a cover body (2), the cover body (2) being arranged on the open side of the shell (1) to close the accommodating cavity (11); A battery cell group (3), the battery cell group (3) being arranged in the accommodating cavity (11), with electrodes of the battery cell group (3) facing the cover; A busbar (4), the busbar (4) being arranged between the battery cell group (3) and the cover body (2), and a pressure relief space (6) being reserved between the busbar (4) and the cover body (2); Insulating cooling oil is injected into the accommodating cavity (11), and the electrodes of the battery cell group (3) and the busbar (4) are immersed in the insulating cooling oil.

2. A battery pack according to claim 1, wherein: A fixing layer (5) is provided between at least one side of the battery cell group (3) and the housing (1) to fix the battery cell group (3) in the accommodating cavity (11); the busbar (4) avoids the fixing layer (5) and is connected to the electrodes of the battery cell group (3).

3. A battery pack according to claim 2, wherein: The battery cell group (3) comprises a plurality of battery cells (31); a cover plate on the side of the battery cells (31) facing the cover body (2) is provided with a battery cell positive electrode (32), a battery cell negative electrode (33) and a battery cell explosion-proof valve (34); a height difference exists between the battery cell negative electrode (33) and the battery cell positive electrode (32); and the battery cell explosion-proof valve (34) faces the pressure relief space (6).

4. A battery pack according to claim 3, wherein: At least two battery cell explosion-proof valves (34) are provided, the battery cell negative electrode (33) includes at least two negative electrode connection areas (331), and the battery cell explosion-proof valves (34) and the negative electrode connection areas (331) are staggeredly distributed along the circumference of the battery cell positive electrode (32).

5. The battery pack according to claim 1, wherein: The busbar (4) comprises: A positive busbar (41), the positive busbar (41) being connected to the positive electrodes (32) of the plurality of battery cells (31) at one end of the battery cell group (3); A negative busbar (42), the negative busbar (42) being connected to the negative electrodes (33) of the plurality of cells (31) at the other end of the cell group (3); A connecting busbar (43) is provided in plurality and is used to connect the positive electrodes (32) of a plurality of battery cells (31) from one end to the other end of the battery cell group (3) with the negative electrodes (33) of the battery cells.

6. A battery pack according to claim 5, wherein: The connecting busbar (43) comprises a positive electrode connecting portion (431) for connecting to the positive electrode (32) of the battery cell and a negative electrode connecting portion (432) for connecting to the negative electrode (33) of the battery cell, wherein a stepped portion (433) is provided between the positive electrode connecting portion (431) and the negative electrode connecting portion (432).

7. A battery pack according to claim 6, wherein: The step height difference of the step portion (433) is equal to the height difference between the battery cell positive electrode (32) and the battery cell negative electrode (33).

8. A battery pack according to claim 6, wherein: The area of ​​the positive electrode connection portion (431) is not larger than the area of ​​the battery cell positive electrode (32), and the area of ​​the negative electrode connection portion (432) is not larger than the area of ​​the negative electrode connection region (331) of the battery cell negative electrode (33).

9. A battery pack according to any one of claims 1 to 8, wherein: The fixed layer (5) is provided with a plurality of battery cell slots (51) corresponding to the battery cell group (3); the battery cell slots (51) are consistent with the number, size and shape of the battery cells (31) in the battery cell group (3).

10. A battery pack according to any one of claims 1 to 8, wherein: The shell (1) is provided with a cold oil inlet (12) and a cold oil outlet (13), and the cold oil inlet (12) and the cold oil outlet (13) are in communication with the accommodating cavity (11) and are used for injecting insulating cooling oil into the accommodating cavity (11) or discharging insulating cooling oil from the accommodating cavity (11).

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