Battery pack

Abstract

To provide a battery pack that reduces heat generation issues during high-rate charging.SOLUTION: A battery pack includes a housing 1 having a storage chamber 11 open on one side, a lid 2 that covers the open side of the housing and seals the storage chamber 11, a cell group 3 that is provided in the storage chamber with its electrodes facing the lid, a fixing layer 5 that improves the stability of the cell group within the storage chamber, and a bus bar 4 that is provided between the cell group and the lid and leaves a pressure relief space between it and the lid. Insulating and cooling oil is poured into the storage chamber, and the electrodes of the cell group and bus bar are immersed in the insulating and cooling oil.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application bearing application number 202420646977X, filed with the China Patent Office on March 29, 2024, the entire contents of which are incorporated herein by reference. This application relates to the technical field of batteries, and more particularly to battery packs. [Background technology]

[0002] With the rapid advancement of new energy vehicle technology and the continuous expansion of the market, the driving range and charging rate of pure electric vehicles have become core indicators of increasing interest to users. To meet market demand, the energy density requirements of power batteries continue to increase, and high-nickel cathodes and silicon-carbon anodes are gradually becoming the mainstream technology route. However, as the cell energy increases, the heat generated during operation also increases dramatically. Especially under high-rate charging conditions, the problem of cell heat generation becomes more pronounced, making temperature control extremely difficult. Summary of the Invention [Problem to be solved by the invention]

[0003] In related technology, cooling means for cylindrical battery packs, such as indirect liquid cooling technology using a liquid cooling plate, can reduce the heat generation problem to some extent when charging at low rates, but when charging at high rates, the cooling efficiency is clearly insufficient, and if thermal runaway occurs in a cell, flames will be emitted from the cell's explosion-proof valve, and the bus bar will likely melt and be ejected from the battery pack, threatening the safety of the occupants. [Means for solving the problem]

[0004] The technical solutions are as follows: This application is A battery pack, a housing having a chamber open on one side; a lid provided on an open side of the housing to seal the storage chamber; a group of cells provided in the storage chamber, the electrodes of which face the lid; a bus bar provided between the cell group and the lid, with a pressure relief space remaining between the bus bar and the lid; The battery pack has insulating and cooling oil poured into the housing chamber, and the electrodes of the cell group and the bus bars are immersed in the insulating and cooling oil. [Effects of the Invention]

[0005] The beneficial effects are as follows: Insulating and cooling oil is injected into the chamber, and the cells are efficiently cooled using the principle of liquid convection heat transfer. If thermal runaway occurs in a cell, flames emanating from the explosion-proof valve are directly extinguished by the insulating and cooling oil in the pressure relief space. The pressure relief space also provides ample space for the busbars, making it less likely for electrical short circuits to occur in the busbars when the battery pack is subjected to mechanical shock. Furthermore, the presence of insulating and cooling oil prevents the busbars from melting due to thermal runaway, significantly improving the safety of the battery pack. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective schematic diagram of a structure according to an embodiment of the present invention. [Figure 2] FIG. 1 is an exploded schematic diagram of a structure of an embodiment of the present application. [Figure 3] 1 is a cross-sectional schematic diagram of a structure according to an embodiment of the present invention; [Figure 4] FIG. 2 is a schematic diagram of an assembled structure of a cell group and bus bars according to an embodiment of the present invention. [Figure 5] FIG. 2 is a structural schematic diagram of a connection current collector sheet according to an embodiment of the present invention. [Figure 6] FIG. 1 is a structural schematic diagram of a cell according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] Example 1 of the present application discloses a battery pack as shown in FIGS. 1 to 6 . The battery pack includes a housing 1, a lid 2, a cell group 3, and a bus bar 4. In Example 1, the housing 1 is a rectangular housing having a storage chamber 11 open on one side, and the lid 2 is attached to the open side of the housing 1 to seal the storage chamber 11. The cell group 3 includes multiple rows of cells 31, and the cells 31 in each row are arranged in a staggered pattern to maximize space. The cell group 3 is disposed within the storage chamber 11. Note that, as shown in FIG. 3 , a pressure relief space 6 remains between the bus bar 4 and the lid 2. This causes a large amount of heat generation from the cells 31, making it difficult to control the temperature. To address this issue, the battery pack injects insulating cooling oil into the storage chamber 11 and utilizes the principle of liquid convection heat transfer to efficiently cool the cell group 3. To securely fasten the cell group 3, this battery pack includes a fastening layer 5 between at least one side of the cell group 3 and the housing 1, enhancing the stability of the cell group 3 within the accommodating chamber 11. Finally, the presence of insulating and cooling oil prevents the busbars 4 from melting due to thermal runaway of the battery, thereby significantly improving the safety of the battery pack. If thermal runaway occurs in a cell 31, flames emanating from the explosion-proof valve are directly extinguished by the insulating and cooling oil in the pressure relief space 6. Furthermore, the pressure relief space 6 provides ample space for the busbars 4, making it less likely for electrical short circuits to occur in the busbars 4 when the battery pack is subjected to mechanical shock.

[0008] 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 adhesive that fixes the cell group 3 within the accommodating chamber 11. Most preferably, the amount of potting adhesive injected allows the fixing layer 5 to fix at least one-third of the cells 31. Therefore, the fixing layer 5 has several cell grooves 51 formed in it corresponding to each cell 31 in the cell group 3, and the cell grooves 51 and the cells 31 in the cell group 3 all match in number, size, and shape. The adhesive injection means improves the stability of the overall battery pack structure and reduces displacement and damage of the cells 31 due to vibration or impact. The busbars 4 must be connected to the electrodes of the cell group 3, avoiding the fixing layer 5.

[0009] In some embodiments, the fixing layer 5 may include, but is not limited to, a perforated bottom guard, foam rubber, or a bracket, as long as it can fix the cell group 3. Similarly, the housing 1 may have a structure with other shapes, and the cells 31 may be rectangular or cylindrical.

[0010] To assemble the battery, as shown in Figure 2, place the open end of the housing 1 facing up and evenly distribute the cells 31 across the bottom of the storage chamber 11 within the housing 1. Next, pour adhesive into the storage chamber 11. The adhesive should be poured to a height that stably secures the cells 31 together and prevents them from shaking. Next, attach the bus bar 4 to the top of the cell group 3, and gather the positive and negative electrodes of some of the cells 31 together to form a positive-negative electrode assembly. Finally, cover the top of the storage chamber 11 with the lid 2, and inject insulating and cooling oil into the sealed storage chamber 11 to circulate heat. The electrodes of the cell group 3 and the bus bar 4 must be immersed in the insulating and cooling oil.

[0011] When in use, the battery pack is placed upside down in a vehicle, with the battery pack lid 2, the cell positive electrodes 32 of the cells 31, and the bus bars 4 all facing downward. This configuration maximizes the safety of passengers, and a battery pack with the lid 2 facing downward is advantageous for users who are positioned above the battery pack. The principle is as follows: When the cells 31 in the battery pack operate and generate heat, the temperature is reduced through heat exchange with the insulating cooling oil. If a mechanical shock causes an electrical short circuit, high-temperature, high-pressure gas and flames are ejected from the explosion-proof valve, which cools them and extinguishes them with the insulating cooling oil. Even if the impact is strong, the force is ejected from the lid 2 of the inverted battery pack, i.e., the force is directed downward toward the vehicle, preventing any impact on passengers.

[0012] Of course, this battery pack can also be used to supply power in other fields. Therefore, if the battery pack is not used for a long period of time, the insulating cooling oil may not be circulated, and the battery pack may cool naturally when not in use, as long as it has a temperature-reducing effect when in use.

[0013] In the first embodiment, as shown in FIGS. 1 to 3 , a cold oil supply port 12 and a cold oil discharge port 13 are provided on each side of the housing 1 to facilitate the injection and discharge of insulating cooling oil into and from the storage chamber 11 of the housing 1 and to increase the efficiency of the exchange of the insulating cooling oil. The cold oil supply port 12 and the cold oil discharge port 13 are connected to the storage chamber 11 and are used to inject insulating cooling oil into the storage chamber 11 or to discharge insulating cooling oil from the storage chamber 11. In some embodiments, the cold oil supply port 12 and the cold oil discharge port 13 are provided near the lid 2 of the housing 1. Because the battery pack is used upside down, being close to the lid 2 is advantageous for drainage. The cold oil supply port 12 and the cold oil discharge port 13 can be combined with an oil pump, radiator, or heater of the vehicle body to achieve heating and liquid cooling effects for the insulating cooling oil. In some embodiments, the cold oil supply port 12 and the cold oil discharge port 13 may be provided on the lid 2, but they should not interfere with turning the battery pack upside down.

[0014] More specifically, as shown in FIG. 6, in cell 31 of the cell group 3, a cell positive electrode 32, a cell negative electrode 33, and a cell explosion-proof valve 34 are provided on the cover plate facing the lid body 2, and of these, a high-nickel positive electrode and a silicon carbon negative electrode are used for the cell positive electrode 32 and the cell negative electrode 33, and the cell positive electrode 32, the cell negative electrode 33, and the cell explosion-proof valve 34 are provided adjacent to each other and / or spaced apart. In this Example 1, two cell explosion-proof valves 34 are provided, the cell negative electrode 33 includes two negative electrode connection regions 331, the cell positive electrode 32 is provided in the center of the side of the cell 31 facing the lid 2, the two negative electrode connection regions 331 and the two cell explosion-proof valves 34 are distributed in a staggered pattern around the cell positive electrode 32, there is a height difference between the cell negative electrode 33 and the cell positive electrode 32, and the cell positive electrode 32 protrudes from the cell negative electrode 33. Therefore, the cell negative electrode 33 and the cell positive electrode 32 are provided adjacent to each other, the cell explosion-proof valves 34 and the cell positive electrode 32 are provided at an interval, the cell explosion-proof valves 34 face the pressure relief space 6, and the cell explosion-proof valves 34 are fan-shaped with rounded edges.

[0015] 4 to 6, the bus bar 4 includes a positive electrode current collector sheet 41, a negative electrode current collector sheet 42, and a connecting current collector sheet 43, and the positive electrode current collector sheet 41 is connected to the cell positive electrodes 32 of a number of cells 31 in one row at one end of the cell group 3, and the negative electrode current collector sheet 42 is connected to the cell negative electrodes 33 of a number of cells 31 in one row at the other end of the cell group 3. A plurality of the connecting current collector sheets 43 are provided, and connect the cell positive electrodes 32 of the cells 31 in several rows from one end to the other end of the cell group 3 to the negative electrodes of the adjacent cells 31. In this Example 1, in order to match the explosion-proof valve structure, in some embodiments, the connection current collecting sheet 43 includes a positive electrode connection portion 431 for connection to the cell positive electrode 32 and a negative electrode connection portion 432 for connection to the cell negative electrode 33, and a step portion 433 is provided between the positive electrode connection portion 431 and the negative electrode connection portion 432. The step portion 433 is provided on the edge of the negative electrode connection region 331, thereby preventing the positive electrode connection portion 431 from contacting the cell negative electrode 33 of the adjacent cell 31 and causing a short circuit when connecting to the cell positive electrode 32 of the adjacent cell 31. The step height difference of the step portion 433 is equal to the height difference between the cell positive electrode 32 and the cell negative electrode 33. The area of ​​the positive electrode connection portion 431 is equal to or smaller than the area of ​​the cell positive electrode 32, and the area of ​​the negative electrode connection portion 432 is equal to or smaller than the area of ​​the negative electrode connection region 331 of the cell negative electrode 33, thereby achieving the effect of gathering the electrodes of the cell group 3.

[0016] In some embodiments, one or more cell explosion-proof valves 34 may be provided, as long as they can normally release the pressure in the cells 31. One or more negative electrode connection regions 331 may be provided, and the structure of the busbar 4 may be adjusted according to changes in the position, structure, and number of the negative electrode connection regions 331 to achieve an assembly effect, but this embodiment is not particularly limited thereto.

[0017] As described above, the battery pack according to the present invention has the following technical effects. 1. The provision of the fixing layer 5 between at least one side of the cell group 3 and the housing 1 improves the stability of the cell group 3 within the storage chamber 11. The fixing layer 5 has cell grooves 51 provided corresponding to the cell group 3, which allow all of the cells 31 to be accurately positioned in their corresponding positions, preventing displacement or misalignment of the cells 31 during assembly or use. 2. The presence of insulating cooling oil enhances heat dissipation and reduces the risk of the busbars 4 melting due to thermal runaway of the battery, significantly improving the safety of the battery pack. Furthermore, the arrangement of the cell explosion-proof valves 34 and the configuration of the pressure relief spaces 6 effectively disperse and reduce the internal pressure in the event of thermal runaway in the cells 31, improving the safety of the cells 31. [Explanation of symbols]

[0018] 1. Housing 11 Containment Room 12 Cold oil supply port 13 Cold oil outlet 2 Lid 3 Cell Group 31 cells 32 Cell positive electrode 33 Cell negative electrode 331 negative electrode connection area 34 Cell explosion-proof valve 4 Busbars 41 Positive electrode current collecting sheet 42 Negative electrode current collecting sheet 43 Connection collector sheet 431 Positive electrode connection 432 Negative electrode connection part 433 Step 5 Fixed layer 51 Cell groove 6 Pressure Relief Space

Claims

1. A battery pack, a housing (1) having a storage chamber (11) open on one side; a cover (2) that covers the open side of the housing (1) and seals the storage chamber (11); a cell group (3) provided in the storage chamber (11), with its electrodes facing the lid; a bus bar (4) provided between the cell group (3) and the cover (2), with a pressure relief space (6) remaining between the bus bar (4) and the cover (2); Insulating and cooling oil is poured into the accommodation chamber (11), and the electrodes of the cell group (3) and the bus bars (4) are immersed in the insulating and cooling oil, The battery pack includes a battery pack in which the cell group (3) includes a plurality of cells (31), and a cover plate of each of the plurality of cells (31) on a side facing the lid (2) is provided with a cell positive electrode (32), a cell negative electrode (33), and at least two cell explosion-proof valves (34), the cell negative electrode (33) includes at least two cell negative electrode connection regions (331), there is a height difference between the cell positive electrode (32) and each of the at least two cell negative electrode connection regions (331), the at least two cell explosion-proof valves (34) face the pressure relief space (6), and the at least two cell negative electrode connection regions (331) and the at least two cell explosion-proof valves (34) are distributed in a staggered pattern in the circumferential direction of the cell positive electrode (32).

2. 2. The battery pack according to claim 1, wherein a fixing layer (5) is provided between at least one side of the cell group (3) and the housing (1), thereby fixing the cell group (3) within the accommodating chamber (11), and the bus bar (4) is connected to the electrodes of the cell group (3) while avoiding the fixing layer (5).

3. The bus bar (4) is a positive electrode current collector sheet (41) connected to the cell positive electrodes (32) of the plurality of cells (31) at one end of the cell group (3); a negative electrode current collector sheet (42) connected to the cell negative electrodes (33) of the plurality of cells (31) at the other end of the cell group (3); a plurality of connection current collecting sheets (43) for connecting the cell positive electrodes (32) of the plurality of cells (31) from one end to the other end of the cell group (3) to the cell negative electrodes (33).

4. 4. The battery pack according to claim 3, wherein the connection current collecting sheet (43) includes a positive electrode connection portion (431) for connection to the cell positive electrode (32) and a negative electrode connection portion (432) for connection to the cell negative electrode (33), and a step portion (433) is provided between the positive electrode connection portion (431) and the negative electrode connection portion (432).

5. The battery pack according to claim 4, wherein a height difference of the step portion (433) is equal to a height difference between the cell positive electrode (32) and the cell negative electrode (33).

6. 5. The battery pack according to claim 4, wherein the area of ​​the positive electrode connection portion (431) is equal to or smaller than the area of ​​the cell positive electrode (32), and the area of ​​the negative electrode connection portion (432) is equal to or smaller than the area of ​​the cell negative electrode connection region (331) of the cell negative electrode (33).

7. 3. The battery pack according to claim 2, wherein the fixing layer (5) has a plurality of cell grooves (51) corresponding to the cell group (3), and the cell grooves (51) and the plurality of cells (31) in the cell group (3) all match in number, size, and shape.

8. The battery pack according to any one of claims 1 to 7, wherein the housing (1) is provided with a cold oil supply port (12) and a cold oil discharge port (13), the cold oil supply port (12) and the cold oil discharge port (13) are connected to the storage chamber (11) and are used to inject insulating cooling oil into the storage chamber (11) or to discharge insulating cooling oil from within the storage chamber (11).

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