Immersed battery cooling structure and battery pack

Abstract

The utility model relates to the technical field of electrochemical energy storage, and discloses an immersed battery cooling structure which comprises a supporting piece used for supporting a plurality of battery modules and used for circulation of immersion liquid, the supporting piece is provided with a liquid inlet hole and a first liquid return hole which are located outside a frame body, and a second liquid return hole and a plurality of liquid outlet holes which are distributed at intervals which are located in the frame body, immersion liquid flows into the battery pack through the liquid inlet in the supporting piece and the plurality of liquid outlets to immerse the battery cell, the immersion liquid dissipates heat of the battery cell and then flows out of the battery pack through the second liquid return hole and the first liquid return hole in the supporting piece, and the liquid inlet in the supporting piece, the liquid outlets, the second liquid return hole and the first liquid return hole form a circulation path of the immersion liquid for dissipating heat of the battery cell. And the plurality of liquid outlet holes are positioned between two adjacent battery modules. According to the utility model, the battery pack manufacturing cost can be saved, the temperature difference among a plurality of battery cells in the battery pack is reduced, and the service life of the battery pack is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrochemical energy storage technical field, concretely relates to a kind of immersed battery cooling structure and battery pack. BACKGROUND

[0002] In the use process, multiple battery cells in the battery pack will generate a large amount of heat, in order to dissipate heat for the battery cell, the battery cell is currently immersed in the immersion liquid located in the battery pack, but the immersion liquid needs to flow to the inside of the battery pack through the flow channel structure specially arranged between one adjacent battery module, the flow channel structure occupies the internal space of the battery pack, making the overall width of the battery pack wider, increasing the manufacturing cost of the battery pack, and the flow channel structure is usually arranged on the center line of the width direction of the battery pack. The immersion liquid flows from the center line of the width direction of the battery pack to the side of the length direction of the battery pack to dissipate heat for the battery cell, and the battery cell located in the middle of the battery pack is always first contacted with the immersion liquid, so that the temperature difference between the battery cell located in the middle of the battery pack and the battery cell close to the side of the battery pack is large, which easily accelerates the aging of the battery cell, thereby easily shortening the service life of the battery pack. SUMMARY

[0003] In order to overcome the deficiencies of the prior art, one of the purposes of the utility model is to provide an immersed battery cooling structure which can save the manufacturing cost of the battery pack, reduce the temperature difference between the multiple battery cells in the battery pack, and improve the service life of the battery pack.

[0004] The technical scheme adopted by the utility model is as follows: an immersed battery cooling structure, comprising a support member for supporting multiple battery modules and for the flow of immersion liquid, the support member is provided with a liquid inlet hole located outside the frame, a first liquid return hole, and a second liquid return hole and multiple spaced liquid outlet holes located inside the frame, the immersion liquid flows into the battery cell through the liquid inlet hole, multiple liquid outlet holes on the support member, and the immersion liquid flows out of the battery pack through the second liquid return hole and the first liquid return hole on the support member after dissipating heat for the battery cell, the liquid inlet hole, the liquid outlet hole, the second liquid return hole and the first liquid return hole on the support member form a path for the flow of immersion liquid for dissipating heat for the battery cell.

[0005] Explanation: the battery pack includes a box body and a box cover, the box body includes a support member and a frame, and the support member and the frame are connected.

[0006] Principle of technical scheme:

[0007] The immersion liquid flows into the battery pack through the liquid inlet hole, the plurality of liquid outlet holes on the support, and then flows out of the battery pack through the second liquid return hole and the first liquid return hole, and since the number of liquid outlet holes is greater than the number of second liquid return holes, the amount of immersion liquid flowing into the battery pack is greater than the amount of immersion liquid flowing out of the battery pack, so that the battery pack is filled with immersion liquid, and the battery cells in the battery pack are immersed in the immersion liquid, and since the plurality of liquid outlet holes are distributed at intervals, the immersion liquid simultaneously contacts each battery cell in the battery pack through the liquid outlet holes.

[0008] Compared with the prior art, the utility model has the advantages that:

[0009] 1) The liquid outlet hole and the second liquid return hole are directly arranged on the support, and the support is used for supporting a plurality of battery modules, that is, the bottom of the battery pack box, without the need for additional flow channel structure for the flow of immersion liquid into the battery pack, thereby saving the internal space of the battery pack and the manufacturing cost of the battery pack.

[0010] 2) The plurality of liquid outlet holes are distributed at intervals, and since the number of liquid outlet holes is greater than the number of second liquid return holes, the amount of immersion liquid flowing into the battery pack is greater than the amount of immersion liquid flowing out of the battery pack, so that the immersion liquid is stored in the battery pack and immerses the battery cells in the battery pack, and the immersion liquid simultaneously flows to the battery cells at different positions in the battery pack through the liquid outlet holes, thereby simultaneously cooling the battery cells in the battery pack, reducing the temperature difference between the plurality of battery cells in the battery pack, and improving the service life of the battery pack.

[0011] 3) Since the flow rate of the immersion liquid is fast in the support and slow in the battery pack, and the plurality of liquid outlet holes are arranged, compared with only one liquid outlet hole, the immersion liquid flowing out of the liquid outlet hole on the support can quickly flow to the periphery of the battery cells, and the plurality of battery cells can quickly contact the immersion liquid, thereby improving the heat dissipation efficiency; since the flow rate of the immersion liquid flowing out of the liquid outlet hole is greater than the flow rate of the immersion liquid in the battery pack, the immersion liquid flowing out of the plurality of liquid outlet holes can drive the immersion liquid in the battery pack to circulate, so that the immersion liquid in the battery pack is uniformly mixed, the temperature of the immersion liquid in the battery pack is uniform, the temperature of the plurality of battery cells is uniform, and the service life of the battery cells is improved.

[0012] 4) The immersion liquid flows through the support, and flows into the battery pack through the liquid inlet hole and the liquid outlet hole on the support, and the support supports a plurality of battery modules, that is, the immersion liquid flows in the support, and the support is equivalent to a liquid cooling plate, and performs heat dissipation on the bottom of the battery cells in the battery pack; after the immersion liquid flows into the battery pack through the liquid inlet hole and the liquid outlet hole on the support, the immersion liquid performs heat dissipation on the periphery of the battery cells, that is, the immersion liquid combines the liquid cooling and immersion heat dissipation modes, thereby improving the heat dissipation efficiency of the battery cells in the battery pack.

[0013] As a preferred embodiment of the utility model, the plurality of liquid outlet holes are located between adjacent two groups of battery modules.

[0014] Beneficial effects: Compared with being located below the battery module, the liquid outlet hole located between the two adjacent groups of battery modules can contact the battery cells in the two adjacent groups of battery modules at the same time, quickly dissipate heat for the battery cells, have wider heat dissipation area, improve heat dissipation efficiency, and also facilitate the immersion liquid to flow into the battery pack through the liquid outlet hole without being blocked, thereby improving the inflow speed; the liquid outlet hole is located between the two adjacent groups of battery modules, and the support member provides support for the multiple groups of battery modules, that is, when the immersion liquid flows in the support member, it is first located below the battery module, that is, below the battery cell, and dissipates heat for the battery cell by contacting the lower surface of the battery cell, and then dissipates heat for the battery cell by contacting the outer surface around the battery cell through the liquid outlet hole; when the immersion liquid flows in the support member, the support member is equivalent to a liquid cooling plate; when the immersion liquid flows into the battery pack through the liquid outlet hole on the support member, the immersion liquid dissipates heat for the battery cell, that is, the two heat dissipation modes of liquid cooling and immersion are combined.

[0015] As a preferred embodiment of the utility model, the support member comprises a bottom plate and a flow channel for the flow of the immersion liquid, the flow channel comprises a first main flow channel for liquid inflow, a plurality of branch flow channels parallel to each other, and a second main flow channel for liquid outflow, the branch flow channels are perpendicular to and communicate with the first main flow channel, the first main flow channel, the plurality of branch flow channels, and the second main flow channel are attached to the bottom plate, the liquid outlet holes are located at the attachment positions of the bottom plate and the first main flow channel and the attachment positions of the bottom plate and the branch flow channels, the liquid inlet hole is located at the attachment position of the first main flow channel and the bottom plate, and the second liquid return hole and the first liquid return hole are located at the attachment position of the second main flow channel and the bottom plate.

[0016] Beneficial effects: The design of the bottom plate and the flow channel ensures that stable support can be provided for the multiple groups of battery modules and the immersion liquid can pass through, and the flow channel can further enhance the support of the bottom plate for the multiple groups of battery modules; the plurality of branch flow channels are parallel to each other, and the branch flow channels are perpendicular to and communicate with the first main flow channel; the liquid outlet holes are located at the attachment positions of the bottom plate and the first main flow channel and the attachment positions of the bottom plate and the branch flow channels, that is, the liquid outlet holes are arranged in rows on the support member, thereby ensuring that the immersion liquid flows to each battery cell in the battery pack through the liquid outlet holes at the same time and dissipates heat for each battery cell.

[0017] As a preferred embodiment of the utility model, the first main flow channel and the second main flow channel are both L-shaped, the vertical part of the first main flow channel is arranged along the center line in the width direction of the bottom plate, the vertical part of the first main flow channel is attached to the vertical part of the second main flow channel, and the plurality of branch flow channels are each perpendicular to and communicate with the vertical part of the first main flow channel.

[0018] Beneficial effects: The design that the vertical part of the first main flow channel is arranged along the center line in the width direction of the bottom plate and the plurality of branch flow channels are each perpendicular to and communicate with the vertical part of the first main flow channel ensures that the immersion liquid flows to each battery cell through the vertical part of the first main flow channel and the branch flow channels, thereby ensuring that the immersion liquid can flow into the battery pack at the fastest speed and contact each battery cell.

[0019] As the preferred embodiment of the utility model, the support piece further comprises a reinforcing rib below the bottom plate, the reinforcing rib is connected with both ends of the branch channel, the first main channel horizontal straight part and the second main channel horizontal straight part respectively, the lower surfaces of the first main channel, the second main channel, the plurality of branch channels and the reinforcing rib are located on the same horizontal plane, and the channel height of the first main channel, the second main channel and the plurality of branch channels is greater than or equal to 4 mm.

[0020] Beneficial effect: the reinforcing rib cooperates with the first main channel, the second main channel and the plurality of branch channels to provide stable support for the bottom plate, the channel height is greater than or equal to 4 mm, and the rapid flow of the immersion liquid into the battery pack and the immersion of the battery cell in a short time can be ensured.

[0021] As the preferred embodiment of the utility model, the plurality of parallel branch channels are the first branch channel, the second branch channel, the third branch channel and the fourth branch channel, the distance between the first branch channel and the end of the battery module far from the second liquid return hole and the length of the entire battery module have a ratio range of 0.12-0.15, the distance between the second branch channel and the end of the battery module far from the second liquid return hole and the length of the entire battery module have a ratio range of 0.27-0.34, the distance between the third branch channel and the end of the battery module far from the second liquid return hole and the length of the entire battery module have a ratio range of 0.43-0.53, and the distance between the fourth branch channel and the end of the battery module far from the second liquid return hole and the length of the entire battery module have a ratio range of 0.73-0.9.

[0022] Beneficial effect: through the design of the position of the branch channel and the reasonable setting of the liquid outlet hole on the support piece, it is ensured that the immersion liquid can uniformly surround each battery cell and that all battery cells are in the same temperature environment.

[0023] As the preferred embodiment of the utility model, a plurality of support strips are arranged on the bottom plate in the length direction of the bottom plate, and the plurality of support strips cooperate to support the battery module.

[0024] Beneficial effect: the support strip can increase the safety distance between the battery module and the bottom plate, avoid the direct flow of the immersion liquid to the bottom of the battery cell, avoid the bottom of the battery cell always first contacting the immersion liquid flowing out of the liquid outlet hole, and reduce the temperature difference between the lower part of the battery cell and the upper part of the battery cell.

[0025] The utility model discloses a second purpose is to provide battery pack, including the immersion type battery cooling structure described above, still include frame, baffle, box cover, frame and support piece connection form battery pack box, baffle is located second liquid return hole outside, baffle is connected with support piece, frame inner wall respectively, the baffle inner surface, frame, support piece, box cover enclose and form the closed first containing chamber, the first containing chamber is used for accommodating multiple battery module, a plurality of liquid outlet hole, second liquid return hole all are located in the first containing chamber, the baffle outer surface, frame, support piece, box cover enclose and form the closed second containing chamber, the second containing chamber is used for accommodating battery pack internal component, be equipped with exhaust pipe for exhausting on the baffle, the exhaust pipe one end communicates with the first containing chamber, and the other end is located outside frame, and the exhaust pipe one end located outside frame is equipped with valve.

[0026] Beneficial effect: when the immersion liquid enters the battery pack, there is originally air in the battery pack, the exhaust pipe can exhaust the original air in the battery pack, so that the air can be prevented from extruding the battery pack box, thereby preventing the battery pack box from being deformed.

[0027] As a preferred embodiment of the utility model, a limiting portion close to the box cover is arranged at the connection between the baffle and the frame, the upper surface of the limiting portion is parallel to the upper surface of the frame, the limiting portion, the frame and the baffle enclose a third containing chamber with an open top, a flow guide pipe is arranged on the baffle, one end of the flow guide pipe communicates with the third containing chamber, and the other end of the flow guide pipe is located outside the frame, and a pipe cap is arranged at the end of the flow guide pipe located outside the frame.

[0028] Beneficial effect: the upper surface of the limiting portion is parallel to the upper surface of the frame, the limiting portion is close to the box cover, and the limiting portion, the frame and the baffle enclose a third containing chamber with an open top, so that the height of the immersion liquid can be measured, when the immersion liquid in the battery pack flows into the third containing chamber, it indicates that the immersion liquid in the battery pack has reached the limit height, and the flow rate of the immersion liquid entering the battery pack needs to be controlled.

[0029] As a preferred embodiment of the utility model, a cross beam for fixing one of the end plates of the battery module is further arranged, the cross beam is connected with the support piece and the frame respectively, the cross beam, the support piece and the frame enclose a fourth containing chamber with an open top, and the second liquid return hole is located outside the cross beam.

[0030] Beneficial effect: the second liquid return hole is located outside the cross beam, that is, outside the battery module, that is, outside the fourth containing chamber, so that a certain amount of immersion liquid can always be present in the fourth containing chamber, the immersion liquid can quickly dissipate heat for each battery cell, and the new immersion liquid can always first enter the fourth containing chamber and then flow to the second liquid return hole after contacting each battery cell, so that the immersion liquid can be fully and efficiently utilized, and the immersion liquid will not flow from the liquid outlet hole to the second liquid return hole directly. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0032] Figure 2 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0033] Figure 3 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0034] Figure 4 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0035] Figure 5 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0036] Figure 6 is a structural schematic view of the immersed battery cooling structure of the utility model;

[0037] Figure 7 is a structural schematic view of the immersed battery cooling structure of the utility model; DETAILED DESCRIPTION

[0038] The typical embodiments embodying the features and advantages of the utility model will be described in detail in the following description. It should be understood that the utility model can have various changes on different embodiments, which are all within the scope of the utility model, and the description and drawings in the embodiments are essentially used for description, not for limiting the utility model.

[0039] In the description of the present application, the directions or position relationships indicated by the terms "first", "second", "one side" and the like are based on the directions or position relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the structures referred to must have a particular direction, be constructed and operated in a particular direction, and therefore cannot be understood as a limitation on the present application.

[0040] The utility model will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] The reference signs include: liquid inlet hole 1, first liquid return hole 2, second liquid return hole 3, liquid outlet hole 4, bottom plate 5, first main flow channel 601, branch flow channel 602, first branch flow channel 6021, second branch flow channel 6022, third branch flow channel 6023, fourth branch flow channel 6024, second main flow channel 603, reinforcing rib 7, support strip 8, frame 9, partition plate 10, limiting part 11, battery module 12, cross beam 13.

[0042] As Figures 1-7As shown, the immersion battery cooling structure, such as Figure 1 As shown, it includes a support for supporting multiple battery modules 12 and a support for the flow of immersion liquid. The support includes a base plate 5, a flow channel for the flow of immersion liquid, and reinforcing ribs 7 located below the base plate 5, as shown. Figure 4 As shown, multiple support bars 8 are spaced apart on the base plate 5 and arranged along the length of the base plate 5. The multiple support bars 8 are used to support the battery module 12.

[0043] like Figure 5 As shown, in this embodiment, there are a total of eight support bars 8 and four sets of battery modules 12.

[0044] like Figure 2 , 3 As shown, the flow channel includes a first main channel 601 for liquid inlet, multiple parallel branch channels 602, and a second main channel 603 for liquid outlet. Both the first main channel 601 and the second main channel 603 are L-shaped. The vertical part of the first main channel 601 is arranged along the center line of the width direction of the bottom plate 5. The vertical part of the first main channel 601 is in contact with the vertical part of the second main channel 603. In this embodiment, there are a total of four branch channels 602, namely the first branch channel 6021, the second branch channel 6022, the third branch channel 6023, and the fourth branch channel 6024. The first branch channel 6021, the second branch channel 6022, the third branch channel 6023, and the fourth branch channel 6024 are all perpendicular to and connected to the vertical part of the first main channel 601.

[0045] like Figure 6 As shown, in this embodiment, the ratio of the distance L1 between the first branch channel 6021 and the end of the battery module 12 away from the second return hole 3 to the length L of the entire battery module 12 is in the range of 0.12~0.15; the ratio of the distance L2 between the second branch channel 6022 and the end of the battery module 12 away from the second return hole 3 to the length L of the entire battery module 12 is in the range of 0.27~0.34; the ratio of the distance L3 between the third branch channel 6023 and the end of the battery module 12 away from the second return hole 3 to the length L of the entire battery module 12 is in the range of 0.43~0.53; and the ratio of the distance L4 between the fourth branch channel 6024 and the end of the battery module 12 away from the second return hole 3 to the length L of the entire battery module 12 is in the range of 0.73~0.9.

[0046] In this embodiment, the first main channel 601, the first branch channel 6021, the second branch channel 6022, the third branch channel 6023, the fourth branch channel 6024, and the second main channel 603 are all in contact with the base plate 5.

[0047] In this embodiment, the reinforcing rib 7 is connected to both ends of the first branch channel 6021, the second branch channel 6022, the third branch channel 6023, and the fourth branch channel 6024, as well as the horizontal and vertical portions of the first main channel 601 and the second main channel 603. The first main channel 601, the second main channel 603, the first branch channel 6021, the second branch channel 6022, the third branch channel 6023, the fourth branch channel 6024, and the lower surface of the reinforcing rib 7 are all located on the same horizontal plane. Figure 7 As shown, the flow channel height H of the first main flow channel 601, the second main flow channel 603, the first branch flow channel 6021, the second branch flow channel 6022, the third branch flow channel 6023, and the fourth branch flow channel 6024 is greater than or equal to 4 mm.

[0048] The first main channel 601 has an inlet hole 1 located outside the frame 9 at the junction of its horizontal and vertical sections and the base plate 5. The first main channel 601 has multiple outlet holes 4 located inside the frame 9 at the junction of its vertical section and the base plate 5. The first branch channel 6021, the second branch channel 6022, the third branch channel 6023, and the fourth branch channel 6024 all have multiple outlet holes 4 located inside the frame 9 at the junction of their surfaces with the base plate 5. The second main channel 603 has a second return hole 3 located inside the frame 9 at the junction of its vertical section and the base plate 5. The second main channel 603 has a first return hole 2 located outside the frame 9 at the junction of its horizontal and vertical sections and the base plate 5.

[0049] like Figure 5 As shown, in this embodiment, four liquid outlet holes 4 are provided at the joint between the vertical part of the first main channel 601 and the bottom plate 5. The first branch channel 6021, the second branch channel 6022, the third branch channel 6023, and the fourth branch channel 6024 are symmetrically provided with two liquid outlet holes 4 on both sides of the vertical part of the first main channel 601. The liquid outlet holes 4 are all located between two adjacent battery modules 12.

[0050] In this embodiment, the immersion liquid flows into the battery pack through the inlet hole 1 and multiple outlet holes 4 on the support member to immerse the battery cells. After the immersion liquid dissipates heat from the battery cells, it flows out of the battery pack through the second return hole 3 and the first return hole 2. The inlet hole 1, outlet hole 4, second return hole 3, and first return hole 2 on the support member form a path for the immersion liquid to immerse the battery cells.

[0051] like Figure 1As shown, the battery pack, comprising the above-mentioned immersion battery cooling structure, further comprises a frame 9, a partition plate 10, a box cover, and a cross beam 13 for fixing one of the end plates of the battery module 12, the frame 9 and the support are connected to form a battery pack box, the partition plate 10 is located outside the second liquid return hole 3, the partition plate 10 is connected with the support and the inner wall of the frame 9 respectively, the inner surface of the partition plate 10, the frame 9, the support, and the box cover form a closed first containing cavity, the first containing cavity is used for containing a plurality of battery modules 12, a plurality of liquid outlet holes 4 and the second liquid return hole 3 are located in the first containing cavity, the outer surface of the partition plate 10, the frame 9, the support, and the box cover form a closed second containing cavity, the second containing cavity is used for containing internal components of the battery pack, the partition plate 10 is provided with an exhaust pipe for exhaust, one end of the exhaust pipe is communicated with the first containing cavity, and the other end of the exhaust pipe is located outside the frame 9, and the end of the exhaust pipe located outside the frame 9 is provided with a valve.

[0052] The inner surface (the surface of the partition plate 10 close to the battery module) of the partition plate 10 and the connecting part of the frame 9 are provided with a limiting part 11 close to the box cover, the upper surface of the limiting part 11 is parallel to the upper surface of the frame 9, and the upper surface of the limiting part 11 is located below the upper surface of the frame 9, the limiting part 11, the frame 9, and the partition plate 10 form a third containing cavity with an open top, and the partition plate 10 is provided with a flow guide pipe, one end of the flow guide pipe is communicated with the third containing cavity, and the other end of the flow guide pipe is located outside the frame 9, and the end of the flow guide pipe located outside the frame 9 is provided with a pipe cap.

[0053] In this embodiment, the limiting part 11 is a limiting plate, and the limiting plate is connected with the inner surface of the frame 9 and the partition plate 10.

[0054] The cross beam 13 is connected with the support and the frame 9, the cross beam 13, the support, and the frame 9 form a fourth containing cavity with an open top, and the second liquid return hole 3 is located outside the cross beam, and in this embodiment, the cross beam 13 is close to the partition plate 10.

[0055] In this embodiment, the internal components of the battery pack can be a battery management system, an explosion-proof pressure relief valve, a fuse, an aerosol fire extinguisher, etc.

[0056] The above-mentioned embodiments are only preferred embodiments of the utility model, and cannot be used to limit the range of protection of the utility model, and any non-substantial changes and replacements made by the person skilled in the art on the basis of the utility model all belong to the range of protection required by the utility model.

Claims

1. An immersion battery cooling structure, characterized by: The support includes a plurality of battery modules and a support for flow of the immersion liquid, the support is provided with an inlet hole outside the frame, a first return liquid hole, and a second return liquid hole and a plurality of spaced distribution outlet holes inside the frame, the immersion liquid flows into the battery pack through the inlet hole and the plurality of outlet holes on the support, and then flows out of the battery pack through the second return liquid hole and the first return liquid hole on the support, and the inlet hole, the outlet hole, the second return liquid hole and the first return liquid hole on the support form a path for the flow of the immersion liquid for heat dissipation of the battery cell.

2. The submerged battery cooling structure of claim 1, wherein: The plurality of outlet holes are located between the two adjacent groups of battery modules.

3. The submerged battery cooling structure of claim 1, wherein: The support includes a bottom plate, a flow channel for the flow of the immersion liquid, the flow channel includes a first main flow channel for liquid inlet, a plurality of parallel branch flow channels, and a second main flow channel for liquid outlet, the branch flow channels are perpendicular to and communicate with the first main flow channel, the first main flow channel, the plurality of branch flow channels and the second main flow channel are attached to the bottom plate, and the plurality of outlet holes are located at the attachment positions of the bottom plate and the first main flow channel and the attachment positions of the bottom plate and the branch flow channels, the inlet hole is located at the attachment position of the first main flow channel and the bottom plate, and the second return liquid hole and the first return liquid hole are located at the attachment position of the second main flow channel and the bottom plate.

4. The submerged battery cooling structure of claim 3, wherein: The first main flow channel and the second main flow channel are L-shaped, the vertical part of the first main flow channel is arranged along the center line of the width direction of the bottom plate, the vertical part of the first main flow channel is attached to the vertical part of the second main flow channel, and the plurality of branch flow channels are respectively perpendicular to and communicate with the vertical part of the first main flow channel.

5. The submerged battery cooling structure of claim 4, wherein: The support further includes a reinforcing rib below the bottom plate, the reinforcing rib is connected to the two ends of the branch flow channel, the horizontal part of the first main flow channel and the horizontal part of the second main flow channel, the lower surfaces of the first main flow channel, the second main flow channel, the plurality of branch flow channels and the reinforcing rib are located on the same horizontal plane, and the flow channel heights of the first main flow channel, the second main flow channel and the plurality of branch flow channels are greater than or equal to 4 mm.

6. The submerged battery cooling structure of claim 3, wherein: The plurality of parallel branch flow channels are respectively a first branch flow channel, a second branch flow channel, a third branch flow channel and a fourth branch flow channel, the distance between the first branch flow channel and the end of the battery module far from the second return liquid hole is in the range of 0.12-0.15 times the length of the entire battery module, the distance between the second branch flow channel and the end of the battery module far from the second return liquid hole is in the range of 0.27-0.34 times the length of the entire battery module, the distance between the third branch flow channel and the end of the battery module far from the second return liquid hole is in the range of 0.43-0.53 times the length of the entire battery module, and the distance between the fourth branch flow channel and the end of the battery module far from the second return liquid hole is in the range of 0.73-0.9 times the length of the entire battery module.

7. The submerged battery cooling structure of claim 3, wherein: A plurality of support strips are arranged on the bottom plate along the length direction of the bottom plate, and the plurality of support strips are matched for supporting the battery module.

8. A battery pack characterized by: The immersion battery cooling structure includes any one of the immersion battery cooling structures according to claims 1-7.

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