Battery module thermal runaway protection device

Abstract

The present invention relates to a battery module thermal runaway protection device, comprising a liquid cooling plate and a plurality of heat-conducting sleeves; the heat-conducting sleeve comprises an upper tube portion and a lower tube portion, the upper tube portion of the heat-conducting sleeve is used to be sleeved on the middle and upper part of the battery, and the inner side of the upper tube portion is in contact with the surface of the battery, the size of the area surrounded by the lower tube portion is larger than the size of the area surrounded by the upper tube portion, and there is a gap between the inner side of the lower tube portion and the surface of the battery. The above-mentioned battery module thermal runaway protection device uses a heat-conducting sleeve, sleeves the upper tube portion of the heat-conducting sleeve on the battery, and connects the lower tube portion of the heat-conducting sleeve to the liquid cooling plate, so that the heat generated by the upper part of the battery can be transferred to the liquid cooling plate along with the heat-conducting sleeve, thereby enhancing the thermal conductivity from the battery to the liquid cooling plate, and can reduce the maximum temperature of the upper part of the battery, reduce the temperature difference between the upper and lower parts of the battery, improve temperature uniformity, and slow down battery performance degradation.

Description

Technical Field

[0001] The present invention relates to the field of battery safety technology, and in particular to a thermal runaway protection device for a battery module. Background Art

[0002] As the core component of new energy vehicles, the technological progress of lithium-ion power batteries plays a key role in the development of electric vehicles. Compared with other types of power batteries, lithium-ion power batteries have the advantages of high energy density, good cycle performance, low self-discharge efficiency, and small memory effect. They can meet the requirements of electric vehicles for power batteries and have been widely used in electric vehicles. However, with the increase in battery specific energy and the continuous increase in battery size design, the risk of thermal runaway of single cells also increases. When thermal runaway occurs in a single cell, heat propagation will cause the battery module and the entire battery pack system to trigger thermal runaway, thereby causing fire and explosion accidents.

[0003] Since the temperature of the power battery is higher in the middle and lower at the bottom during normal operation, on the one hand, the heat generated by the battery needs to be dissipated under normal operating conditions to ensure that the maximum temperature and temperature difference of the battery are within the allowable range. On the other hand, once a battery triggers thermal runaway, it is necessary to avoid the heat generated by the thermal runaway battery from diffusing and spreading to the surrounding batteries as much as possible, so as to avoid the surrounding batteries triggering thermal runaway and causing large-scale fires or even explosion risks.

[0004] Therefore, for the thermal safety system of power batteries, it is necessary to ensure good heat dissipation and thermal runaway insulation protection. However, most of the existing devices for suppressing the spread of heat in battery modules focus on battery heat dissipation and lack effective thermal runaway insulation protection. Summary of the invention

[0005] Based on this, it is necessary to provide a battery module thermal runaway protection device that can effectively provide thermal runaway insulation protection for the battery module in order to address the problem that the traditional device for suppressing the heat spread of the battery module lacks effective thermal runaway insulation protection.

[0006] A battery module thermal runaway protection device comprises a liquid cooling plate and a plurality of heat-conducting sleeves; the heat-conducting sleeve comprises an upper sleeve portion and a lower sleeve portion, the upper sleeve portion of the heat-conducting sleeve is used to be sleeved on the middle and upper part of a battery, and the inner side of the upper sleeve portion is attached to the surface of the battery, the size of the area surrounded by the lower sleeve portion is larger than the size of the area surrounded by the upper sleeve portion; there is a gap between the inner side of the lower sleeve portion and the battery surface;

[0007] The multiple heat-conducting sleeves are arranged at intervals, and the space between adjacent heat-conducting sleeves is filled with heat-insulating materials; the liquid cooling plate is arranged at the bottom ends of the multiple heat-conducting sleeves and is tightly connected to the heat-conducting sleeves.

[0008] Furthermore, the height of the heat-conducting sleeve is smaller than the height of the battery, and the insulation material is filled between the portions of adjacent batteries that are higher than the heat-conducting sleeve.

[0009] Furthermore, the thickness of the lower part of the tube is not less than the thickness of the upper part of the tube.

[0010] Furthermore, the two surfaces at the narrow end of the lower part of the tube can be set as an open structure.

[0011] Furthermore, the thermal insulation material is aerogel felt or aerogel powder.

[0012] Furthermore, a shockproof thermal pad is filled between the lower end of the heat-conducting sleeve and the liquid cooling plate, and the shockproof thermal pad is tightly fitted to the liquid cooling plate and the bottom of the battery respectively.

[0013] Furthermore, a liquid inlet and a liquid outlet are provided on the liquid cooling plate, and a plurality of flow channels are provided in parallel inside the liquid cooling plate, and two ends of the plurality of flow channels converge at the liquid inlet and the liquid outlet respectively.

[0014] Furthermore, the height of the upper part of the tube is not less than 10 mm, and the height of the lower part of the tube is more than 65% of the height of the battery.

[0015] Furthermore, a small hole is opened at the lower part of the heat-conducting sleeve, and aerogel powder is filled in the gap between the lower part of the sleeve and the battery.

[0016] Furthermore, a side cover plate is arranged on the outer side of the sleeve assembly composed of the plurality of heat-conducting sleeves, and a heat insulation plate is arranged between the side cover plate and the sleeve assembly.

[0017] The above-mentioned battery module thermal runaway protection device uses a thermally conductive sleeve, and the upper part of the thermally conductive sleeve is placed on the battery, and the lower part of the thermally conductive sleeve is connected to the liquid cooling plate, so that the heat generated by the upper part of the battery can be transferred to the liquid cooling plate along with the thermally conductive sleeve, thereby enhancing the thermal conductivity from the battery to the liquid cooling plate, and can reduce the maximum temperature of the upper part of the battery, reduce the temperature difference between the upper and lower parts of the battery, improve temperature uniformity, and slow down battery performance degradation. At the same time, by filling insulation materials between each group of thermally conductive sleeves, heat transfer from thermal runaway batteries to adjacent batteries can be effectively avoided, and combined with the liquid cooling plate at the bottom, the spread of heat from thermal runaway to adjacent batteries can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the disassembled structure of the thermal runaway protection device;

[0019] Figure 2 It is a schematic diagram of the cross-sectional structure of the thermal runaway protection device;

[0020] Figure 3Temperature cloud diagram of battery module with simple heat insulation and bottom liquid cooling plate configuration;

[0021] Figure 4 The temperature curve of the battery module with simple insulation and bottom liquid cooling plate configuration;

[0022] Figure 5 The temperature cloud diagram of the battery module after the thermal runaway protection device is configured;

[0023] Figure 6 A temperature curve diagram of the battery module after the thermal runaway protection device is configured;

[0024] Figure 7 A curve diagram showing the effect of different thicknesses of thermal insulation materials on the temperature of the thermal runaway protection device;

[0025] Figure 8 A curve diagram showing the effect of thermal resistance of different insulation layers on temperature of the thermal runaway protection device;

[0026] Fig. 9 The figure is a curve diagram showing the influence of different cylinder upper part heights on the temperature of the thermal runaway protection device;

[0027] Fig.10 This is a curve chart showing the effect of different lower tube heights on the temperature of the thermal runaway protection device.

[0028] In the figure: 100, thermal sleeve; 110, upper part of the tube; 120, lower part of the tube; 200, liquid cooling plate; 300, aerogel; 400, upper cover plate; 500, side cover plate; 600, side insulation plate; 700, shockproof thermal pad; 80, battery. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 and Figure 2As shown, in one embodiment, a battery module thermal runaway protection device includes a liquid cooling plate 200 and a plurality of heat-conducting sleeves 100. The heat-conducting sleeve 100 includes a tube upper portion 110 and a tube lower portion 120. The heat-conducting sleeve tube upper portion 110 is used to be sleeved on the middle and upper part of the battery 80, and the inner side of the tube upper portion is attached to the surface of the battery 80. The size of the area surrounded by the tube lower portion 120 is larger than the size of the area surrounded by the tube upper portion 110. Silicone can be filled between the inner side of the tube upper portion 110 and the surface of the battery 80 as an interface heat conduction and structural bonding material. There is a gap between the inner side of the tube lower portion and the surface of the battery 80. Multiple heat-conducting sleeves 100 are arranged at intervals, and insulation materials are filled between adjacent heat-conducting sleeves 100. The liquid cooling plate 200 is arranged at the bottom end of the multiple heat-conducting sleeves 100 and is closely connected to the heat-conducting sleeves 100.

[0031] The above-mentioned battery module thermal runaway protection device uses a heat-conducting sleeve 100, and sleeves the upper part of the heat-conducting sleeve 100 on the battery 80, and connects the lower part of the heat-conducting sleeve 100 to the liquid cooling plate 200, so that the heat generated by the upper part of the battery 80 can be transferred to the liquid cooling plate 200 along with the heat-conducting sleeve 100, thereby enhancing the thermal conductivity of the battery 80 to the liquid cooling plate 200, and can reduce the maximum temperature of the upper part of the battery 80, reduce the temperature difference between the upper and lower parts of the battery, improve temperature uniformity, and slow down the battery performance degradation. At the same time, by filling insulation materials between each group of heat-conducting sleeves 100, it is possible to effectively prevent the thermal runaway battery from transferring heat to the adjacent battery, and combined with the liquid cooling plate 200 at the bottom, it is possible to suppress the spread of heat from the thermal runaway to the adjacent battery.

[0032] Specifically, a small hole is opened in the lower part 120 of the heat-conducting sleeve 100, and the gap between the lower part 120 and the battery 80 is filled with aerogel 300 powder. The thickness of the lower part 120 is not less than the thickness of the upper part 110, so as to enhance the thermal conductivity of the heat-conducting sleeve 100. The two sides of the narrow end of the lower part 120 can be set as an open structure to reduce the weight and facilitate installation. At the same time, the open structure at this place will not have a substantial impact on the thermal conductivity of the heat-conducting sleeve 100.

[0033] In terms of material selection, the battery 80 in this embodiment is a commercial 37Ah square ternary (Li[Ni1 / 3Co1 / 3Mn1 / 3]O2) lithium-ion battery. Its structural dimensions are 146mm×91mm×26.5mm, and its operating voltage range is 2.8-4.25V. The battery module is composed of 5 square batteries, and the spacing between battery cells is 5mm. Multiple groups of batteries 80 are connected in series with their own tabs through busbars.

[0034] In this embodiment, the height of the heat-conducting sleeve 100 is smaller than the height of the battery 80 , and the space between the adjacent batteries 80 that are higher than the heat-conducting sleeve 100 is filled with heat-insulating material.

[0035] Based on the above material selection, the thickness of the heat-conducting sleeve 100 is set to 1mm, the upper height of the sleeve is 10mm, and the lower height of the sleeve is 60mm. The introduction of the heat-conducting sleeve 100 can effectively improve the heat dissipation performance of the cooling structure. It is assembled at a height of 60mm from the bottom of the battery 80 and is sleeved around each battery 80. The heat-conducting sleeve 100 can be formed by tooling stamping aluminum, and its bottom is connected to the liquid cooling plate 200 by welding.

[0036] In this embodiment, the liquid cooling plate 200 is provided with a liquid inlet and a liquid outlet, and a plurality of flow channels are provided in parallel inside the liquid cooling plate 200, and the two ends of the plurality of flow channels converge at the liquid inlet and the liquid outlet, respectively. Specifically, the liquid cooling plate 200 adopts a micro-channel structure, and a total of 49 flow channels are arranged, the height and width of the flow channels are both 2mm, the thickness of the flow channels and the surface of the liquid cooling plate 200 is 2mm, and the interval thickness between two adjacent flow channels is 1mm. The liquid cooling plate 200 can be formed by processing the flow channels and brazing with the back plate.

[0037] The internal flow channel of the above-mentioned liquid cooling plate 200 adopts a micro-channel design, which enhances the heat dissipation performance of the battery 80 at high temperatures. At low temperatures, the liquid cooling plate 200 can also heat the upper and bottom of the battery 80 at the same time. Compared with conventional simple bottom liquid cooling, it has small thermal resistance and fast heat transfer, which greatly improves the temperature control performance of the battery 80.

[0038] In this embodiment, the bottom end surface of the thermal sleeve 100 outside the battery cell is connected to the liquid cooling plate 200, and the shockproof thermal pad 700 is filled between the lower end of the thermal sleeve 100 and the liquid cooling plate 200. The shockproof thermal pad 700 is made of a silicone gasket and glass fiber composite, and the shockproof thermal pad 700 is tightly attached to the liquid cooling plate 200 and the bottom of the battery 80. At the same time, the horizontal size of the bottom shockproof thermal pad 700 is consistent with the size of the bottom liquid cooling plate 200, and the thickness is 1mm, which can enhance the entire heat transfer rate. Ensure the uniformity of the battery 80 temperature and stable operation of the battery module under normal working conditions.

[0039] The above-mentioned thermal conductive sleeve 100 can strengthen the strength of the battery 80 and reduce the expansion and deformation amplitude of the battery 80. By arranging a shock-proof thermal conductive pad 700 between the battery module and the plane of the bottom liquid cooling plate 200, the thermal conductive sleeve 100 of the battery 80 can be assisted to adjust the temperature difference of the battery 80, thereby reducing the risk of short circuit of the battery 80 due to leakage, thereby ensuring the working reliability and stability of the battery 80.

[0040] The heat-conducting sleeve 100 can be formed by stamping a plate, or by welding the upper sleeve portion 110 and the lower sleeve portion 120 .

[0041] In this embodiment, the thermal insulation material is aerogel 300 , and the aerogel 300 is aerogel felt or aerogel powder.

[0042] When the battery module is in use, once a battery cell triggers thermal runaway, the temperature will be close to the combustion high temperature ~ 900°C, and a large amount of heat will be transferred to the surroundings. Therefore, the heat dissipation structure of the heat-conducting sleeve 100 alone cannot meet the thermal safety protection requirements of the battery 80. It is necessary to take certain insulation measures between the batteries 80. Therefore, the insulating material aerogel 300 is introduced for insulation. The aerogel 300 is filled in the heat conduction path formed by each battery 80 to prevent the heat from being transferred to the adjacent battery 80 due to thermal runaway of a battery 80.

[0043] In this embodiment, the thickness of the aerogel 300 thermal insulation material is 0.5 mm, and its thermal conductivity is 0.02 W / mk, so the aerogel 300 has good thermal insulation performance and can effectively prevent heat from being transferred to the surrounding battery 80. This avoids the occurrence of heat spread to a certain extent, solves the technical problems of power battery heat dissipation and thermal runaway insulation protection, and ensures the safety of the power battery system.

[0044] In actual use, the thickness of the aerogel 300 is not less than 0.5 mm. For example, the thickness of the aerogel 300 filled between the battery cells is set to 1 mm, which has a nanoporous grid structure with a porosity of more than 90%, so it has a low thermal conductivity and is suitable for suppressing the heat spread of the battery 80.

[0045] In this embodiment, an upper cover plate 400 is arranged above the heat-conducting sleeve 100, and the overall height of the upper cover plate 400 is greater than the height of the upper cover plate 400 protruding from the battery body after the positive and negative ears of the battery 80 are connected to the bus bar. The upper cover plate 400 has a recessed portion on one side relative to the battery 80, and the space of the recessed portion is greater than the space occupied by the positive and negative ears of the battery 80 and the bus bar after the connection. A side cover plate 500 is arranged on the outside of the sleeve set composed of multiple heat-conducting sleeves 100, and a heat insulation plate 600 is arranged between the side cover plate 500 and the sleeve set. The side cover plate 500 is connected to the upper cover plate 400; specifically, the heat insulation plate 600 can be arranged between two groups of side cover plates 500 and the sleeve set along the wide end direction of the battery 80. It can prevent the spread of heat when a battery cell in the system is under thermal runaway, and further improve the safety performance of the thermal protection system. The lower ends of the multiple groups of side cover plates 500 are fixedly connected to the liquid cooling plate 200 and are located between the liquid inlet and the liquid outlet.

[0046] The wide ends in this embodiment represent the two sides with the largest areas among the four sides of the battery.

[0047] Furthermore, the thickness of the upper cover plate is 2 mm. The material of the upper cover plate 400 in this embodiment is aluminum. Aerogel insulation material is applied to the side close to the battery, which can play a basic mechanical protection role and prevent the battery 80 from catching fire and burning the upper cover plate and other components after a battery cell triggers thermal runaway. At the same time, the use of the upper cover plate 400 reduces the overall height of the battery module and reduces the additional assembly process of the parts, showing certain advantages in the existing battery module thermal protection components and ensuring the safety of the battery module.

[0048] In this embodiment, the gap between the battery cell and the lower portion 120 of the thermal sleeve 100 is 1 mm. The lower portion 120 of the thermal sleeve 100 is provided with a small hole, and an insulating material such as aerogel 300 powder is filled in the gap space through the small hole. In addition, the air layer can be simply retained for thermal insulation, wherein the aerogel 300 powder can isolate the thermal radiation effect, and the thermal insulation effect is better than that of a simple air layer.

[0049] like Figure 3 As shown, for the battery module temperature of the thermal runaway protection device, after the #1 battery cell is used as the triggering battery cell, the #1 battery cell reaches the highest temperature at 30 seconds, which is 836.5°C. Although a small amount of heat spreads to the #2 battery cell through the bus, most of the heat is transferred to the bottom cold plate through the side heat-conducting sleeve 100. It can be seen that the highest temperature is mainly concentrated at the bus and the #2 battery cell ear, but due to the configuration of the heat-conducting sleeve 100 heat-conducting structure, the temperature of battery 80 #2 is generally lower than the thermal runaway temperature, which effectively blocks the heat from spreading to the surrounding batteries 80, thereby avoiding the risk of large-scale thermal runaway and heat spread triggered by the surrounding batteries 80.

[0050] like Figure 4As shown in the figure, the highest temperature curve of battery 80 adjacent to #1 thermal runaway battery 80 in the battery module, the thermal insulation material is 0.5mm thick aerogel 300. It can be seen that after the 1# battery cell triggers thermal runaway, it reaches the highest temperature within 30s, the highest temperature is 836.5℃, and a large amount of heat is generated in the thermal runaway process of battery 80 and spreads to the surroundings. The adjacent 2# battery cell pole reaches the highest battery temperature in 90s due to the heat conduction of the bus connection, the highest temperature is 290.7℃, and the highest temperature of the #2 battery cell core is 200℃, and the thermal runaway temperature is about 255℃ (LAI Xin, et al. Investigation of thermal runaway propagation characteristics of lithium-ion battery modules under different trigger modes. International Journal of Heat and MassTransfer, 2021, 171: 121080. Chinese translation: Lai Xin et al., Study on thermal runaway propagation characteristics of lithium-ion battery modules under different starting modes, International Journal of Heat and Mass Transfer, 2021, 171: 121080. ), below the thermal runaway temperature, no thermal runaway occurs, and there is no phenomenon that the battery 80 temperature rises sharply to the peak temperature of thermal runaway, which can be considered as the minimum insulation thickness case for thermal protection design.

[0051] like Figure 5 As shown, the maximum temperature of the #2 battery 80 adjacent to the thermal runaway battery 80 under different insulation material thicknesses is analyzed with different insulation material thicknesses of the thermal protection system, and the insulation material thicknesses are 0.5mm, 1.0mm, 1.5mm, 2.0mm, and 2.5mm respectively. The results show that the minimum aerogel 300 insulation material thickness without thermal runaway is 0.5mm, and the spread and propagation of thermal runaway does not occur when the thickness is not less than 0.5mm.

[0052] like Figure 6 , Figure 7 and Figure 8 As shown in the figure, after the thermal runaway of the #1 battery cell, the maximum temperature of the adjacent #2 battery 80 changes with the thermal resistance of the insulation layer between the battery cells 80. The thermal resistance of the insulation layer is the ratio of its thickness to its thermal conductivity. The thermal resistance of the insulation layer is 0.03m2K / W, which corresponds to the thickness of the aerogel 300 of 0.5mm and the thermal conductivity of 0.016W / mK. This indicates that the adjacent battery 80 has not experienced thermal runaway. For the flexible rubber foam and glass fiber with a thermal conductivity of 0.05W / mK, the thickness must reach 1.25mm or more to prevent and control thermal runaway. For the silicone insulation layer with a thermal conductivity of 0.1W / mK, the thickness must reach 2.5mm or more to achieve the purpose of thermal runaway protection.

[0053] like Fig. 9 As shown, the different heights of the heat-conducting sleeve 100 of the thermal runaway protection device are analyzed, and the upper height of the sleeve is 5.0mm, 10.0mm, 15.0mm, 20.0mm, and 25.0mm respectively. The results show that the upper height of the heat-conducting sleeve 100 selected for processing should not be less than 10mm, which can be used to suppress the thermal runaway of the adjacent battery 80.

[0054] like Fig.10 As shown, the different heights of the heat-conducting sleeve 100 of the thermal runaway protection device are analyzed, and the lower height of the sleeve is 50mm, 55mm, 60mm, 65mm, and 70mm respectively. The results show that the lower height of the heat-conducting sleeve 100 selected for processing should not be less than 60mm. The total height of the battery cell is 92mm, the upper height of the variable-section heat-conducting sleeve 100 is 10mm, and the upper and lower parts of the sleeve overlap by 2mm. The lower height of the sleeve should be equivalent to 65% or more of the height of the battery 80 (60mm), which can be used to suppress the thermal runaway of the adjacent battery 80.

[0055] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A battery module thermal runaway protection device, It is characterized in that It comprises a liquid cooling plate and a plurality of heat-conducting sleeves; the heat-conducting sleeve comprises an upper sleeve and a lower sleeve, the upper sleeve of the heat-conducting sleeve is used to be sleeved on the upper middle part of the battery, and the inner side of the upper sleeve is in contact with the surface of the battery, the size of the area surrounded by the lower sleeve is larger than the size of the area surrounded by the upper sleeve; there is a gap between the inner side of the lower sleeve and the battery surface; The plurality of heat-conducting sleeves are arranged at intervals, and the space between adjacent heat-conducting sleeves is filled with heat-insulating materials; the liquid cooling plate is arranged at the bottom ends of the plurality of heat-conducting sleeves and is tightly connected to the heat-conducting sleeves; The height of the heat-conducting sleeve is smaller than the height of the battery, and the insulation material is filled between the parts of adjacent batteries that are higher than the heat-conducting sleeve; The thickness of the lower part of the tube is not less than the thickness of the upper part of the tube.

2. The battery module thermal runaway protection device according to claim 1, It is characterized in that The two surfaces of the lower part of the tube at the narrow end can be set as an open structure.

3. The battery module thermal runaway protection device according to claim 1, It is characterized in that The thermal insulation material is aerogel felt or aerogel powder.

4. The battery module thermal runaway protection device according to claim 1, It is characterized in that A shockproof thermal pad is filled between the lower end of the heat-conducting sleeve and the liquid cooling plate, and the shockproof thermal pad is tightly fitted to the liquid cooling plate and the bottom of the battery respectively.

5. The battery module thermal runaway protection device according to claim 1, It is characterized in that The liquid cooling plate is provided with a liquid inlet and a liquid outlet, and a plurality of flow channels are provided in parallel inside the liquid cooling plate, and two ends of the plurality of flow channels converge at the liquid inlet and the liquid outlet respectively.

6. The battery module thermal runaway protection device according to claim 1, It is characterized in that The height of the upper part of the tube is not less than 10 mm, and the height of the lower part of the tube is more than 65% of the height of the battery.

7. The battery module thermal runaway protection device according to claim 1, It is characterized in that A small hole is opened at the lower part of the heat-conducting sleeve, and a gap between the lower part of the sleeve and the battery is filled with aerogel powder.

8. The battery module thermal runaway protection device according to claim 7, It is characterized in that A side cover plate is arranged on the outer side of the sleeve assembly composed of the plurality of heat-conducting sleeves, and a heat insulation plate is arranged between the side cover plate and the sleeve assembly.

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