Battery cell heat exchange plate group, battery pack and fire control method of battery cell heat exchange plate group

Abstract

The invention discloses a battery cell heat exchange plate group, a battery pack and a fire control method.The battery cell heat exchange plate group comprises a bottom supporting plate and a heat exchange side plate, the bottom supporting plate is horizontally arranged, the heat exchange side plate is vertically arranged at the upper end of the bottom supporting plate, a flow channel is formed in the bottom supporting plate, the interior of the heat exchange side plate is hollow, and the flow channel is communicated with the flow channel. The lower end of the heat exchange side plate is communicated with the flow channel, the bottom supporting plate is provided with a first fluid connector communicated with the interior of the bottom supporting plate, the upper end of the heat exchange side plate is provided with an overflow component and a second fluid connector communicated with the interior of the heat exchange side plate, and the inner wall of the heat exchange side plate is provided with a moisture absorption layer. Therefore, when the battery cell is heated or cooled, the fluid medium is utilized to generate phase change on the heat exchange side plate to absorb heat or release heat, and the phase change process is performed at the inner upper end of the heat exchange side plate, so that reasonable temperature difference of the battery cell in the vertical direction is ensured.

Description

Technical Field

[0001] This invention belongs to the field of battery pack technology, and particularly relates to a cell heat exchange plate assembly, a battery pack and its fire control method. Background Technology

[0002] With the development of the lithium battery industry, the capacity and energy density of individual cells are increasing, and the demand for high-rate charging and discharging is also growing. This leads to a significant increase in heat generation in battery packs. Currently, battery packs on the market typically use air cooling or plate-type liquid cooling, which have relatively low heat transfer efficiency. Phase change direct cooling, on the other hand, has a much higher heat transfer efficiency than air cooling or plate-type liquid cooling. However, phase change direct cooling results in a larger temperature difference, making it difficult to guarantee temperature uniformity within the cells and significantly reducing the cycle life and safety of the battery system.

[0003] When a battery cell is charged / discharged, it generates heat, primarily at the top. Some of this heat is conducted vertically downwards through the cell itself. This creates a temperature difference between the top and bottom of the cell (the top of the cell is warmer than the bottom). A reasonable temperature difference is beneficial for the healthy operation of the cell, while an excessive temperature difference may affect the cell's cycle life and safe operation, or even lead to thermal runaway. Excessive temperature difference can occur when the bottom of the cell is too cold or the top of the cell is too hot. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a battery cell heat exchange plate assembly with a simple structure, good cooling effect on the battery cell, and relatively uniform temperature distribution throughout the battery cell.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: a battery cell heat exchange plate assembly for supporting battery cells, the battery cell heat exchange plate assembly including a bottom support plate and a heat exchange side plate, the bottom support plate being horizontally arranged and the heat exchange side plate being vertically arranged at the upper end of the bottom support plate, the bottom support plate having a flow channel inside, the heat exchange side plate being hollow inside, the lower end of the heat exchange side plate communicating with the flow channel, the bottom support plate having a first fluid interface communicating with its interior, the upper end of the heat exchange side plate having an overflow member, the upper end of the heat exchange side plate having a second fluid interface communicating with its interior, and the inner wall of the heat exchange side plate having a moisture-absorbing layer; When the cell heat exchange plate assembly cools the cell, the first fluid interface introduces a liquid fluid medium into the bottom plate. The fluid medium enters the heat exchange side plate, absorbs heat and vaporizes, and then exits through the second fluid interface. When the cell heat exchange plate assembly heats the cell, the second fluid interface introduces a gaseous fluid medium into the heat exchange side plate. The fluid medium releases heat and liquefies in the heat exchange side plate before entering the bottom support plate and finally being discharged through the first fluid interface.

[0006] The beneficial effects of the above technical solution are as follows: For the battery cell, the area where temperature accumulates is mainly located in the upper part. Therefore, when cooling the battery cell, it is preferable to dissipate heat from the upper part of the battery cell to avoid temperature accumulation there, while the heat exchange side plate is in close contact with the large surface of the battery cell. When cooling the battery cell, the lower inner end of the heat exchange side plate stores a liquid fluid medium. For the lower part of the battery cell, the heat transfer between it and the fluid medium is mainly inefficient, during which the fluid medium absorbs heat and heats up. For the upper part of the battery cell, the moisture-absorbing layer continuously and slowly draws the preheated fluid medium upward to form a liquid film, and eventually absorbs heat and vaporizes. The heat absorption during the vaporization process is large, but the amount of vaporization is positively correlated with the temperature of the upper part of the battery cell. This design helps to maintain a relatively stable temperature at the top of the battery cell, ultimately ensuring that the temperatures at both the top and bottom of the battery cell remain relatively stable and creating a reasonable temperature difference. An overflow component is installed at the top of the heat exchanger plate. This allows for pressure buildup within the heat exchanger plate assembly in the event of thermal runaway, until the overflow component is forced open, allowing gaseous and liquid fluids to overflow sequentially for rapid cooling and fire suppression of the thermally runaway battery cell. During preheating of the battery cell, the vaporized fluid moves downwards within the heat exchanger plate and eventually liquefies, resulting in a gradual temperature decrease from top to bottom within the heat exchanger plate and creating a reasonable temperature difference between the top and bottom of the battery cell.

[0007] The heat exchange side plates described in the above technical solution are multiple, and the multiple heat exchange side plates are parallel to each other and spaced apart on the bottom support plate.

[0008] The beneficial effect of the above technical solution is that more cells can be installed on the cell heat exchange plate assembly, and each cell can be attached to at least one heat exchange side plate.

[0009] In the above technical solution, both the bottom support plate and the heat exchange side plate are made of aluminum, and the bottom support plate is wrapped with an insulation layer.

[0010] The beneficial effects of the above technical solution are as follows: it makes the structure of the heat exchange side plate and the bottom support plate high and the connection between the two more convenient. At the same time, the heat exchange side plate has good thermal conductivity, and the insulation layer on the outside of the bottom support plate prevents heat conduction between the bottom part of the cell and the bottom support plate during normal operation, thereby keeping the bottom part of the cell at a reasonable temperature.

[0011] In the above technical solution, the bottom support plate is provided with multiple parallel flow channels, and the lower end of the heat exchange side plate is connected to each of the flow channels. One end of the multiple flow channels converges and is connected to the first fluid interface; or the bottom support plate is hollow to form the flow channels.

[0012] The beneficial effect of the above technical solution is that its structure is simple, so that the inside of the base plate is like a "reservoir" to store liquid fluid medium.

[0013] The moisture-absorbing layer described in the above technical solution is a wire mesh material or a honeycomb sheet integrally formed with the heat exchange side plate. The porosity and pore size of the moisture-absorbing layer gradually decrease from bottom to top in the vertical direction.

[0014] The beneficial effect of the above technical solution is that its structure is simple, which makes the capillary effect better as the moisture-absorbing layer goes higher.

[0015] In the above technical solution, the moisture-absorbing layer is vertically divided into three sections from bottom to top: a lower moisture-absorbing section, a middle moisture-absorbing section, and an upper moisture-absorbing section. The lower moisture-absorbing section has a porosity of 55-65% and a pore size of 1.3-1.7 mm; the middle moisture-absorbing section has a porosity of 35-45% and a pore size of 0.6-1 mm; and the upper moisture-absorbing section has a porosity of 15-25% and a pore size of 0.1-0.5 mm.

[0016] The beneficial effects of the above technical solution are as follows: the lower and middle moisture-absorbing sections store the fluid medium, while the upper moisture-absorbing section has a better capillary effect to continuously draw the fluid medium upward to form a liquid film on the upper end of the inner wall of the heat exchange side plate.

[0017] In the above technical solution, the lower moisture-absorbing section, the middle moisture-absorbing section, and the upper moisture-absorbing section have the same length in the vertical direction.

[0018] The beneficial effect of the above technical solution is that it keeps the liquid level in the heat exchange side plate at the middle position of the moisture absorption section.

[0019] The second objective of this invention is to provide a battery pack with a simple structure and convenient heating and cooling.

[0020] To achieve the above objectives, the technical solution of the present invention is as follows: a battery pack, comprising a battery box, multiple battery cells, a BMS system, a battery thermal management unit, and a battery cell heat exchange plate assembly as described above, wherein the battery cell heat exchange plate assembly is horizontally installed inside the battery box, and the multiple battery cells are distributed in multiple rows at intervals inside the battery box, and are all located at the upper end of the bottom support plate; A row of battery cells is sandwiched between two adjacent heat exchange side plates, or a heat exchange side plate is sandwiched between two adjacent rows of battery cells, with the large surface of the battery cells in contact with the heat exchange side plate. Each of the battery cells is equipped with a temperature sensor; The battery thermal management unit has a first interface and a second interface. The first interface is connected to the first fluid interface, and the second interface is connected to the second fluid interface. A solenoid valve is provided at the second fluid interface. The battery thermal management unit, solenoid valve, and temperature sensor are all electrically connected to the BMS system. The battery thermal management unit and the cell heat exchange plate assembly are filled with the fluid medium, which is an insulating phase change coolant.

[0021] The beneficial effects of the above technical solution are as follows: This ensures that at least one large surface of each cell can be in contact with the heat exchange side plate, allowing the battery pack to provide better phase change cooling or heating for each cell while avoiding excessive temperature differences between cells. By installing temperature sensors on the cells, the BMS system can monitor the temperature changes of each cell in real time to guide the fluid medium supply flow of the battery thermal management unit. If thermal runaway is detected in a cell, the heat exchange side plate absorbs a large amount of heat, causing a large amount of fluid medium to vaporize. At this point, the solenoid valve is reduced or closed, and pressure is applied within the cell's heat exchange plate assembly until the overflow component is pushed open. The gaseous fluid medium then fills the battery box, purging the oxygen in the battery box for flame retardancy. The liquid fluid medium then overflows into the battery box, providing more direct cooling to the thermally runaway cell (allowing the thermally runaway cell to release heat relatively gently, avoiding rapid heat diffusion throughout the battery pack).

[0022] The heat exchange side plate described in the above technical solution is equipped with a liquid level sensor, which is electrically connected to the BMS system.

[0023] The beneficial effect of the above technical solution is that the liquid level in the heat exchange side plate can be monitored, and a temperature sensor can be used to determine whether there is thermal runaway of the battery cell.

[0024] The third objective of this invention is to provide a fire control method for thermal runaway of cells in a battery pack, which can mitigate or prevent heat diffusion within the battery pack.

[0025] To achieve the above objectives, the technical solution of the present invention is as follows: a fire control method for a battery pack as described above, characterized in that, when the BMS system detects that any one of the battery cells has failed and thermally runaway, the operation is as follows: Reduce or close the flow rate of the solenoid valve to reduce pressure, and disconnect the charging / discharging circuit of the battery pack; When the overflow component is opened, a gaseous fluid medium enters the battery box beforehand and expels the oxygen in the battery box to retard the flame. Then, a liquid fluid medium overflows into the battery box to dissipate heat.

[0026] The beneficial effect of the above technical solution is that when the BMS system detects thermal runaway in a battery cell, it can quickly take measures, firstly by reducing or closing the solenoid valve, and secondly by increasing the supply of fluid medium, so that the heat exchange plate assembly of the battery cell can be quickly depressurized to push open the overflow component. Attached Figure Description

[0027] Figure 1 This is an elevation view of the cell heat exchanger assembly described in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional view of the cell heat exchange plate assembly described in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of multiple flow channels arranged inside the base plate as described in Embodiment 1 of the present invention; Figure 4 This is a cross-sectional view of the heat exchange side plate described in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the battery pack structure described in Embodiment 3 of the present invention; Figure 6 This is a cross-sectional view of the battery cell as described in Embodiment 3 of the present invention, mounted on a battery cell heat exchanger plate assembly. Figure 7 This is an assembly diagram of the battery cell, battery cell heat exchange plate assembly, and battery thermal management unit described in Embodiment 3 of the present invention; Figure 8 This is a cross-sectional view of the heat exchange side plate described in Embodiment 3 of the present invention; Figure 9 This is a top view of the battery cell described in Embodiment 3 of the present invention; Figure 10 This is a cross-sectional view of the battery cell as described in Embodiment 4 of the present invention, arranged on the battery cell heat exchange plate assembly.

[0028] In the diagram: 1. Base plate; 11. First fluid interface; 12. Flow channel; 13. Insulation layer; 14. Butt joint; 2. Heat exchange side plate; 21. Overflow component; 22. Second fluid interface; 23. Moisture-absorbing layer; 231. Lower moisture-absorbing section; 232. Middle moisture-absorbing section; 233. Upper moisture-absorbing section; 24. Liquid level sensor; 25. Solenoid valve; 10. Cell heat exchange plate assembly; 20. Battery box; 30. Cell; 301. Temperature sensor; 40. BMS system; 50. Battery thermal management unit; 501. First interface; 502. Second interface. Detailed Implementation

[0029] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] It is understood that spatial relation terms such as “below,” “under,” “below,” “below,” “above,” “above,” etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “below,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0032] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0033] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0034] Example 1 like Figures 1-3As shown, this embodiment provides a battery cell heat exchange plate assembly 10, which includes a bottom support plate 1 and a heat exchange side plate 2. The bottom support plate 1 is horizontally arranged, and the heat exchange side plate 2 is vertically arranged on the upper end of the bottom support plate 1. The bottom support plate 1 has a flow channel 12 inside, and the heat exchange side plate 2 is hollow inside. The lower end of the heat exchange side plate 2 communicates with the flow channel 12. The bottom support plate 1 has a first fluid interface 11 communicating with its interior. The upper end of the heat exchange side plate 2 has an overflow member 21, and the upper end of the heat exchange side plate 2 has a second fluid interface 22 communicating with its interior. The inner wall has a moisture-absorbing layer 23; when the cell heat exchange plate assembly 10 cools the cell, the first fluid interface 11 introduces a liquid fluid medium (cold liquid flow) into the bottom support plate 1, and the fluid medium enters the heat exchange side plate 2, absorbs heat and vaporizes, and then exits through the second fluid interface 22; when the cell heat exchange plate assembly 10 heats the cell 30, the second fluid interface 22 introduces a gaseous fluid medium (hot air flow) into the heat exchange side plate 2, and the fluid medium releases heat and liquefies in the heat exchange side plate 2, then enters the bottom support plate 1, and finally exits through the first fluid interface 11. For the battery cell 30, the temperature accumulation area is mainly located in the upper part. Therefore, when cooling the battery cell 30, it is preferable to dissipate heat from the upper part of the battery cell 30 to avoid temperature accumulation there. The heat exchange side plate 2 is in close contact with the large surface of the battery cell 30. When cooling the battery cell 30, the lower inner end of the heat exchange side plate 2 stores a liquid fluid medium. For the lower part of the battery cell 30, the heat transfer between it and the fluid medium is mainly inefficient. At this time, the fluid medium absorbs heat and rises in temperature. For the upper part of the battery cell 30, the moisture-absorbing layer 23 continuously and slowly draws the preheated fluid medium upward to form a liquid film, and eventually absorbs heat and vaporizes. The heat absorption during the vaporization process is large, but the amount of vaporization is positively correlated with the temperature of the upper part of the battery cell 30. This helps to keep the temperature of the upper part of the battery cell 30 relatively stable, and ultimately keeps the temperature of both the upper and lower parts of the battery cell 30 relatively stable, forming a reasonable temperature difference. An overflow component 21 is set at the upper end of the heat exchange side plate 2. In the event of thermal runaway of the battery cell 30, the heat exchange plate assembly 10 can be pressurized, so that the gaseous and liquid fluid media can overflow in sequence to quickly cool down and extinguish the thermal runaway battery cell 30. When the battery cell 30 is preheated, the vaporized fluid media moves from top to bottom in the heat exchange side plate 2 and eventually liquefies into a liquid state in the heat exchange side plate 2, so that the temperature in the heat exchange side plate 2 decreases from top to bottom, forming a reasonable temperature difference between the upper and lower parts of the battery cell 30.

[0035] In this embodiment, the moisture-absorbing layer 23 can be a layer of cotton cloth attached to the inner wall of the heat exchange side plate 2.

[0036] like Figures 1-3As shown, in this embodiment, there are multiple heat exchange side plates 2, which are parallel to each other and spaced apart on the base plate 1. This allows more battery cells 30 to be installed on the battery cell heat exchange plate assembly 10, and each battery cell 30 can be attached to at least one heat exchange side plate 2.

[0037] like Figure 2 As shown, in this embodiment, both the base plate 1 and the heat exchange side plate 2 are made of aluminum, and the base plate 1 is wrapped with an insulation layer 13. This results in high structural strength between the heat exchange side plate 2 and the base plate 1, and makes the connection between the two more convenient. At the same time, the heat exchange side plate 2 has good thermal conductivity, while the insulation layer 13 on the outside of the base plate 1 prevents heat conduction between the lower part of the battery cell 30 and the base plate 1 during normal operation, thereby keeping the lower part of the battery cell 30 at a reasonable temperature.

[0038] like Figure 2 and Figure 3 As shown, in this embodiment, the heat exchange side plate 2 and the bottom support plate 1 can be welded onto the bottom support plate 1. The lower end of the heat exchange side plate 2 is open, while the upper end of the bottom support plate 1 has a butt joint 14 communicating with its interior. When the heat exchange side plate 2 is installed on the bottom support plate 1, the lower end of the heat exchange side plate 2 is aligned with the butt joint 14 and sealed.

[0039] like Figure 3 As shown, in this embodiment, the base plate 1 is provided with multiple parallel flow channels 12, and the lower end of the heat exchange side plate 2 is connected to each of the flow channels 12. One end of the multiple flow channels 12 converges and connects to the first fluid interface 11; or the base plate 1 is hollow to form the flow channels 12. Its structure is simple, so that the interior of the base plate 1 is like a "reservoir" to store the liquid fluid medium.

[0040] In this embodiment, when the battery cell 30 is a cuboid and placed vertically, the two sides corresponding to its length and height are the larger faces, and the two sides corresponding to its width and height are the smaller faces (length and width refer to the rectangle corresponding to the bottom surface of the battery cell 30). Figure 9 As shown in the diagram, the surfaces corresponding to the two solid lines are the larger surfaces, and the surfaces corresponding to the two dashed lines are the smaller surfaces.

[0041] In this embodiment, by covering the bottom support plate 1 with a heat insulation layer 13, the cooling effect of the bottom support plate 1 on the lower part of the battery cell 30 during normal operation is negligible (this avoids the lower part of the battery cell 30 becoming too cold, thereby further avoiding excessive temperature difference between the upper and lower parts of the battery cell 30). Only when the battery cell 30 experiences thermal runaway, due to the excessively high temperature of the battery cell 30, the heat penetrates the heat insulation layer 13 and can be carried away by the bottom support plate 1.

[0042] In this embodiment, when there are multiple heat exchange side plates 2, if any one of the cells 30 experiences thermal runaway, the cell heat exchange plate group 10 can be compressed. Based on the "weakest link effect", the compression can continue until any overflow component 21 is pushed open (it does not necessarily have to be the overflow component 21 closest to the thermal runaway cell 30 that is pushed open).

[0043] In this embodiment, the overflow component 21 can be an overflow valve (with a pre-set pressure to be opened). Preferably, the overflow component 21 can also form a structurally weak area on the upper end of the heat exchange side plate 2 (for example, a circular area can be selected on the heat exchange side plate 2, and the wall thickness at that point can be reduced. At the same time, an "X"-shaped or "I"-shaped recessed area can be set on the thinned area, so that the wall thickness of the recessed area is even thinner. When the internal pressure of the cell heat exchange plate assembly 10 is compressed to a certain extent, it exceeds the pressure bearing range of the thinned area and will be opened and torn).

[0044] In this embodiment, the insulation layer can be a heat-insulating coating with flame-retardant properties, such as aluminum silicate fiber coating or ceramic fiber coating.

[0045] In this embodiment, the cell heat exchange plate assembly 10 is only needed to heat the cell 30 when the temperature is low during charging / discharging (usually below 0°C). During this process, the heat released by the cell 30 is limited and thermal runaway is not likely to occur. Of course, if thermal runaway occurs at this time, the cell heat exchange plate assembly 10 needs to be switched to cooling mode immediately. The cell heat exchange plate assembly 10 provided in this embodiment can still maintain a reasonable temperature difference between the upper and lower parts of the cell 30 when heating the cell 30.

[0046] Example 2 Same as Example 1, except that, as Figure 4As shown, in this embodiment, the moisture-absorbing layer 23 is a wire mesh material or a honeycomb sheet integrally formed with the heat exchange side plate 2. The porosity and pore size of the moisture-absorbing layer 23 gradually decrease from bottom to top vertically. Its simple structure makes the capillary effect of the moisture-absorbing layer 23 better as it rises. In this embodiment, the moisture-absorbing layer 23 is vertically divided into three sections from bottom to top: a lower moisture-absorbing section 231, a middle moisture-absorbing section 232, and an upper moisture-absorbing section 233. The lower moisture-absorbing section 231 has a porosity of 55-65% (which can be any value or any range between any two values ​​from 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, or 65%, preferably 60%) and a pore size of 1.3-1.7mm (which can be any value or any range between any two values ​​from 1.3mm, 1.4mm, 1.5mm, 1.6mm, or 1.7mm, preferably 1.5mm). The middle moisture-absorbing section 232 has a porosity of 35-45% (which can be 35%, 36%, 37%, 38%, 39%, 40%, or 41%). The porosity of the moisture-absorbing upper section 233 is 15-25% (which can be any value or a range between any two values ​​of 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25%, preferably 20%), and the porosity is 0.1-0.5mm (which can be any value or a range between any two values ​​of 0.1mm, 0.2mm, 0.3mm, 0.4mm, or 0.5mm, preferably 0.3mm). This allows the lower and middle moisture-absorbing sections to store the fluid medium, while the upper moisture-absorbing section has a better capillary effect to continuously draw the fluid medium upwards to form a liquid film on the upper end of the inner wall of the heat exchange side plate 2.

[0047] In this embodiment, since the moisture-absorbing layer 23 is also equivalent to a heat dissipation fin on the inner wall of the heat exchange side plate 2, it can increase the heat conduction area between the heat exchange side plate 2 and the fluid medium. However, the porosity of the moisture-absorbing layer 23 gradually increases from bottom to top, so the heat conduction area of ​​the moisture-absorbing layer 23 also gradually increases from bottom to top. This makes the heat dissipation performance of the moisture-absorbing layer 23 itself different in the vertical direction, which is beneficial to keep the battery cell 30 in a reasonable temperature difference in the vertical direction.

[0048] In this embodiment, the lower moisture-absorbing section 231, the middle moisture-absorbing section 232, and the upper moisture-absorbing section 233 have the same vertical length. This ensures that the liquid level inside the heat exchange side plate 2 is maintained at the position of the middle moisture-absorbing section 232.

[0049] in, Figure 4 The dashed line indicates the normal height of the liquid level.

[0050] Example 3 like Figures 5-7 As shown, this embodiment provides a battery pack, including a battery box 20, multiple battery cells 30, a BMS system 40, a battery thermal management unit 50, and a battery cell heat exchange plate assembly 10 as described in Embodiment 1 or Embodiment 2. The battery cell heat exchange plate assembly 10 is horizontally installed inside the battery box 20. The multiple battery cells 30 are distributed in multiple rows at intervals inside the battery box 20, and are all located at the upper end of the bottom support plate 1. A row of battery cells 30 is sandwiched between two adjacent heat exchange side plates 2 (the same row may have multiple battery cells 30, and two adjacent battery cells 30 in the same row are bonded together by small surfaces). The large surfaces of the battery cells 30 are attached to the heat exchange side plates. 2. Adhesion; Each of the battery cells 30 is provided with a temperature sensor 301; The battery thermal management unit 50 has a first interface 501 and a second interface 502, the first interface 501 is connected to the first fluid interface 11, the second interface 502 is connected to the second fluid interface 22, and a solenoid valve 25 is provided at the second fluid interface 22; The battery thermal management unit 50, the solenoid valve 25 and the temperature sensor 301 are all electrically connected to the BMS system 40; The battery thermal management unit 50 and the battery cell heat exchange plate assembly 10 are filled with the fluid medium, which is an insulating phase change coolant. This arrangement ensures that each cell 30 has at least one large surface area that can be in contact with the heat exchange side plate 2. This allows the battery pack to effectively cool or heat each cell 30 via phase change, while preventing excessive temperature differences between cells 30. By installing temperature sensors 301 on each cell 30, the BMS system can monitor the temperature changes of each cell 30 in real time to guide the flow rate of the fluid medium supplied to the battery thermal management unit. If thermal runaway is detected in a cell 30, the heat exchange side plate 2 absorbs a large amount of heat, leading to… A large amount of fluid medium vaporizes, at which point the solenoid valve is reduced or closed, while the cell heat exchange plate assembly 10 is pressurized until the overflow component 21 is pushed open. At this time, the gaseous fluid medium fills the battery box 20 and removes the oxygen in the battery box 20 to retard the flame. Then the liquid fluid medium overflows into the battery box 20, which can more directly cool down the thermally runaway cell 30 (this allows the thermally runaway cell 30 to release heat relatively gently, avoiding rapid thermal diffusion throughout the battery pack).

[0051] Figure 5 Solid arrows indicate the direction of fluid flow when the battery cell is cooled, while dashed arrows indicate the direction of fluid flow when the battery cell is heated.

[0052] like Figure 9As shown, the temperature sensor 301 can be disposed in the middle of the upper end of the battery cell 30.

[0053] In this embodiment, the large surface of the battery cell 30 and the adjacent heat exchange side plate 2 can be bonded together with a structural adhesive that has thermal conductivity. The structural adhesive can be an epoxy resin-based thermally conductive structural adhesive or a silicone rubber-based thermally conductive structural adhesive, etc.

[0054] like Figure 8 As shown, in this embodiment, a liquid level sensor 24 is installed inside the heat exchange side plate 2, and the liquid level sensor 24 is electrically connected to the BMS system 40. This allows for monitoring of the liquid level inside the heat exchange side plate 2, and, in conjunction with the temperature sensor 301, to determine whether a battery cell 30 is experiencing thermal runaway (when the opening of all solenoid valves 25 has not changed significantly, if the temperature of a certain battery cell 30 continues to rise, and the liquid level in the heat exchange side plate 2 near it continues to drop, and both the temperature and liquid level are close to the warning state, then it can be determined that a battery cell 30 is experiencing or about to experience thermal runaway).

[0055] For each heat exchanger side plate, the liquid level inside can be dynamically adjusted by adjusting the opening of the solenoid valve to control the liquid level in the middle of the heat exchanger side plate (when the opening of the solenoid valve is increased, the internal pressure decreases and the liquid level rises; when the opening of the solenoid valve is decreased, the internal pressure rises and the liquid level falls).

[0056] In this embodiment, the fluid medium can be R123a refrigerant. The battery thermal management unit 50 described in this embodiment belongs to the prior art (it is similar to a miniature industrial heat pump). It can heat and cool the battery cell 30. When cooling the battery cell 30, it cools the fluid medium and sends it into the battery cell heat exchange plate group 10 in liquid form through the first fluid interface 11 for circulation. When heating the battery cell 30, it heats and vaporizes the fluid medium and sends it into the battery cell heat exchange plate group 10 in gaseous form through the second fluid interface 22 for circulation. Therefore, it will not be described in detail here.

[0057] For the bottom plate 1, its interior is always filled with liquid fluid medium. When heating the battery cell 30, the gaseous fluid medium is cooled and liquefied in the heat exchange side plate 2 and is still stored in the bottom plate 1. When cooling the battery cell 30, the liquid fluid medium first fills the bottom plate 1 and then overflows into the heat exchange side plate 2, ensuring that the liquid level in the heat exchange side plate 2 is in the middle position.

[0058] When there are multiple heat exchange side plates 2, the battery pack provided in this embodiment can also ensure a balanced temperature distribution of all cells 30. If the temperature of a certain cell 30 is detected to be lower than that of other cells 30, the opening of the solenoid valve 25 on the heat exchange side plate near that cell 30 can be reduced (at this time, the pressure inside the heat exchange side plate 2 increases, resulting in a decrease in the vaporization effect) to reduce the cooling effect and allow the cell 30 to gradually heat up. If the temperature of a certain cell 30 is detected to be higher than that of other cells 30, the opening of the solenoid valve 25 on the heat exchange side plate 2 near that cell 30 can be increased (at this time, the pressure inside the heat exchange side plate 2 decreases, resulting in an increase in the vaporization effect) to improve the cooling effect and allow the cell 30 to gradually cool down.

[0059] In this embodiment, the battery box 20 is a sealed space, and the BMS system 40 and the battery thermal management unit 50 can be installed outside the battery box 20.

[0060] In this embodiment, each of the two rows of cells 30 located at both ends has only one large surface that is in contact with the nearby heat exchange side plate 2.

[0061] In this embodiment, when there are multiple heat exchange side plates 2, once the BMS system 40 detects thermal runaway in any one of the cells 30, all the solenoid valves are reduced or closed to suppress the pressure inside the cell heat exchange plate group 10. Based on the "weakest link effect", the pressure is maintained until any overflow component 21 is pushed open (it does not necessarily have to be the overflow component 21 closest to the thermal runaway cell 30 that is pushed open).

[0062] Example 4 Same as Example 3, except that, as Figure 10 As shown, a heat exchange side plate 2 is sandwiched between two adjacent rows of battery cells 30 (this ensures that the two large surfaces of each battery cell 30 are respectively in contact with the two adjacent heat exchange side plates 2).

[0063] Example 5 This embodiment provides a fire control method for a battery pack as described in Embodiment 3 or Embodiment 4. When the BMS system 40 detects a fault and thermal runaway in any of the battery cells 30, the operation is as follows: the flow rate of the solenoid valve 25 is reduced or closed to build up pressure, and the charging / discharging circuit of the battery pack is disconnected; when the overflow component 21 is opened, a gaseous fluid medium is introduced into the battery box 20 beforehand to expel oxygen from the battery box 20 for flame retardancy, and then a liquid fluid medium is introduced into the battery box 20 for heat dissipation. In this way, when the BMS system 40 detects thermal runaway in a battery cell 30, measures can be taken quickly, firstly by reducing or closing the solenoid valve 25, and secondly by increasing the supply of the fluid medium, so that the cell heat exchange plate assembly 10 can be quickly built up to build up pressure and open the overflow component 21.

[0064] For the battery pack described in this embodiment, the overall fire protection strategy is as follows: Level 1 Warning: When the BMS system 40 detects an abnormally high temperature in a battery cell 30, and the rate of liquid level drop in the heat exchange side plate 2 near that battery cell 300 is mismatched with the opening of the solenoid valve 25 (i.e., the liquid level drops abnormally without significant adjustment of the solenoid valve 25), the BMS system 40 reports a warning, increases the opening of the solenoid valve 25 of the heat exchange side plate 2, and increases the operating power of the battery thermal management unit 50. The temperature of the delivered fluid medium is lower, and the flow rate is greater to accelerate the circulation speed of the fluid medium, thereby improving the cooling effect on the battery cell 30. Level 2 warning (thermal runaway begins): If the liquid level of the heat exchange side plate 2 continues to drop rapidly to the low warning value (pre-set manually), and the temperature of the cell 30 continues to rise, the BMS system 40 can determine that the cell 30 is about to thermal runaway or has already begun. At this time, all solenoid valves 25 of the battery pack can be reduced or closed to pressurize the cell heat exchange plate group 10.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cell heat exchange plate assembly for supporting a discharge cell (30), characterized in that, The cell heat exchange plate assembly (10) includes a bottom support plate (1) and a heat exchange side plate (2). The bottom support plate (1) is horizontally arranged, and the heat exchange side plate (2) is vertically arranged at the upper end of the bottom support plate (1). The bottom support plate (1) has a flow channel (12) inside. The heat exchange side plate (2) is hollow inside. The lower end of the heat exchange side plate (2) is connected to the flow channel (12). The bottom support plate (1) has a first fluid interface (11) that communicates with its interior. The upper end of the heat exchange side plate (2) has an overflow component (21). The upper end of the heat exchange side plate (2) has a second fluid interface (22) that communicates with its interior. The inner wall of the heat exchange side plate (2) has a moisture-absorbing layer (23). When the cell heat exchange plate assembly (10) cools the cell (30), the first fluid interface (11) introduces liquid fluid medium into the bottom plate (1), and the fluid medium enters the heat exchange side plate (2) to absorb heat and vaporize before being discharged through the second fluid interface (22). When the cell heat exchange plate assembly (10) heats the cell (30), the second fluid interface (22) introduces a gaseous fluid medium into the heat exchange side plate (2). The fluid medium releases heat and liquefies in the heat exchange side plate (2) and then enters the bottom support plate (1), and is finally discharged through the first fluid interface (11).

2. The cell heat exchange plate assembly according to claim 1, characterized in that, The heat exchange side plate (2) is multiple, and the multiple heat exchange side plates (2) are parallel to each other and spaced apart on the bottom support plate (1).

3. The cell heat exchange plate assembly according to claim 1 or 2, characterized in that, Both the bottom support plate (1) and the heat exchange side plate (2) are made of aluminum, and the bottom support plate (1) is wrapped with an insulation layer (13).

4. The cell heat exchange plate assembly according to claim 1 or 2, characterized in that, The bottom plate (1) is provided with multiple parallel flow channels (12), and the lower end of the heat exchange side plate (2) is connected to each of the flow channels (12). One end of the multiple flow channels (12) converges and is connected to the first fluid interface (11); or the bottom plate (1) is hollow inside to form the flow channels (12).

5. The cell heat exchange plate assembly according to claim 1 or 2, characterized in that, The moisture-absorbing layer (23) is a wire mesh material or a honeycomb sheet integrally formed with the heat exchange side plate (2). The porosity and pore size of the moisture-absorbing layer (23) gradually decrease from bottom to top in the vertical direction.

6. The cell heat exchanger plate assembly according to claim 5, characterized in that, The moisture-absorbing layer (23) is divided into three sections vertically from bottom to top: a lower moisture-absorbing section (231), a middle moisture-absorbing section (232), and an upper moisture-absorbing section (233). The lower moisture-absorbing section (231) has a porosity of 55-65% and a pore size of 1.3-1.7 mm; the middle moisture-absorbing section (232) has a porosity of 35-45% and a pore size of 0.6-1 mm; and the upper moisture-absorbing section (233) has a porosity of 15-25% and a pore size of 0.1-0.5 mm.

7. The cell heat exchanger plate assembly according to claim 6, characterized in that, The lower moisture-absorbing section (231), the middle moisture-absorbing section (232), and the upper moisture-absorbing section (233) have the same length in the vertical direction.

8. A battery pack, characterized in that, The battery includes a battery box (20), multiple battery cells (30), a BMS system (40), a battery thermal management unit (50), and a battery cell heat exchange plate assembly (10) as described in any one of claims 1-7. The battery cell heat exchange plate assembly (10) is horizontally installed inside the battery box (20), and the multiple battery cells (30) are distributed in multiple rows at intervals inside the battery box (20) and are all located at the upper end of the bottom support plate (1). A row of battery cells (30) is sandwiched between two adjacent heat exchange side plates (2) or a heat exchange side plate (2) is sandwiched between two adjacent rows of battery cells (30), and the large surface of the battery cell (30) is in contact with the heat exchange side plate (2); Each of the said cells (30) is provided with a temperature sensor (301); The battery thermal management unit (50) has a first interface (501) and a second interface (502). The first interface (501) is connected to the first fluid interface (11), and the second interface (502) is connected to the second fluid interface (22). A solenoid valve (25) is provided at the second fluid interface (22). The battery thermal management unit (50), solenoid valve (25) and temperature sensor (301) are all electrically connected to the BMS system (40); The battery thermal management unit (50) and the cell heat exchange plate group (10) are filled with the fluid medium, which is an insulating phase change coolant.

9. The battery pack according to claim 8, characterized in that, A liquid level sensor (24) is installed inside the heat exchange side plate (2), and the liquid level sensor (24) is electrically connected to the BMS system (40).

10. A fire control method for a battery pack as described in claim 8 or 9, characterized in that, When the BMS system (40) detects that any one of the cells (30) has failed and thermally run away, the following operation shall be performed: Reduce or close the flow rate of the solenoid valve (25) to pressurize the cell heat exchange plate assembly (10) and disconnect the charging / discharging circuit of the battery pack. When the cell heat exchange plate assembly (10) is compressed to the point that the overflow component (21) is pushed open, a gaseous fluid medium is first introduced into the battery box (20) to expel the oxygen in the battery box (20) for flame retardancy, and then a liquid fluid medium is introduced into the battery box (20) for heat dissipation.

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