Battery thermal management system
By setting a variable thermal resistance layer between the liquid cooling plate and the electric heating layer, and adjusting its thermal resistance state through a control device, the mutual interference problem between the heating unit and the heat dissipation unit is solved, and efficient heating and heat dissipation of the battery thermal management system are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGZHOU HONGJU ELECTRIC TECH CO LTD
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-12
AI Technical Summary
In existing battery thermal management systems, the operation of the heating unit and the heat dissipation unit can interfere with each other, affecting heating efficiency or heat dissipation efficiency.
A variable thermal resistance layer is set between the liquid cooling plate and the electric heating layer. The thermal resistance value of the variable thermal resistance layer is adjusted by a control device, and its state is adjusted according to the temperature requirements to achieve efficient heating or heat dissipation.
It achieves efficient independent operation of heating and cooling modes, avoiding mutual interference and ensuring efficient heating or cooling effects.
Smart Images
Figure CN122025928A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery thermal management, and in particular to a battery thermal management system. Background Technology
[0002] Battery cells include lithium-ion, sodium-ion, and magnesium-ion batteries, and are classified by packaging method as cylindrical, prismatic, and blade-shaped cells. A battery cell includes a casing, electrode assembly, and electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. Connecting a certain number of battery cells together forms a battery module. A battery refers to the final state of the battery system installed in an electric vehicle, generally including one or more battery modules and a housing for securing them.
[0003] The electrochemical cycle performance and safety performance of a battery are closely related to its operating temperature. The optimal operating temperature range and permissible temperature range for a battery are generally 20~30℃. During charging and discharging, or due to external environmental influences, the battery may overheat or overcool. Overheating or overcooling directly affects the battery's performance and lifespan, thus requiring thermal management to ensure the battery operates within a suitable temperature range.
[0004] Currently, heating-cooling components are typically installed at the bottom, sidewalls, or top of the battery module. Based on the detected battery temperature, either the heating or cooling component is activated to achieve thermal management. Existing heating-cooling components often include an electric heating plate and a liquid cooling plate. The electric heating plate contacts the battery, and the liquid cooling plate contacts the electric heating plate. The electric heating plate includes an electric heating element and an insulating layer for encapsulating the heating element; the liquid cooling plate has flow channels within which coolant circulates. When the battery temperature is too low, the electric heating plate needs to be activated for heating; however, the liquid cooling plate and its internal coolant inevitably create a heat leakage path, reducing heating efficiency. When the battery temperature is too high, the liquid cooling plate needs to be activated for cooling; in this case, the electric heating plate itself becomes an additional thermal resistance, interfering with heat dissipation efficiency. Therefore, in current systems, when one of the heating and cooling components is operating, the other inevitably interferes, affecting either heating or cooling efficiency. Summary of the Invention
[0005] The main objective of this application is to propose a battery thermal management system that aims to solve the problem in the prior art where, when one of the heating unit and the heat dissipation unit is working, the other interferes with the heating unit, affecting the heating efficiency or the heat dissipation efficiency.
[0006] This application provides a battery thermal management system, comprising: Battery module; A silicone thermally conductive interface layer is applied to the upper surface of the battery module. An electric heating layer covers the upper surface of the silicone thermally conductive interface layer. The electric heating layer includes a heating element and a thermally conductive insulating encapsulation for encapsulating the heating element. A variable thermal resistance layer covers the upper surface of the electric heating layer; A liquid cooling plate, movably disposed above the variable thermal resistance layer; and, The control device includes a temperature sensor, a controller, and a drive mechanism. The temperature sensor is connected to the battery module and communicates with the controller to detect the temperature of the battery module and transmit the detected temperature to the controller. The controller compares the received temperature with a preset temperature and generates a control command. The drive mechanism is communicated with the controller and connected to the liquid cooling plate. The drive mechanism receives the control command and controls the liquid cooling plate to move towards the variable thermal resistance layer to compress the variable thermal resistance layer, or to move away from the variable thermal resistance layer, thereby adjusting the thermal resistance value of the variable thermal resistance layer.
[0007] By adopting the above technical solution, a variable thermal resistance layer is set between the liquid cooling plate and the electric heating layer. Initially, there is a gap of 1-10 mm between the liquid cooling plate and the variable thermal resistance layer. When the battery temperature is too low and heating is required, the electric heating layer is activated. The gap between the liquid cooling plate and the variable thermal resistance layer effectively prevents heat leakage from the liquid cooling plate and its internal coolant due to contact between them. Furthermore, the variable thermal resistance layer is not compressed at this time, exhibiting a high thermal resistance state, thus acting as thermal insulation and allowing the heat generated by the electric heating layer to be efficiently conducted to the battery. The packaging material of the electric heating layer is a thermally conductive insulator with excellent thermal conductivity, thereby achieving efficient heating and heat preservation.
[0008] When the battery temperature is too high and heat dissipation is required, the driving liquid cooling plate moves towards the variable thermal resistance layer and compresses the variable thermal resistance layer, making the variable thermal resistance layer exhibit a low thermal resistance state. The variable thermal resistance layer becomes a thinner interfacial thermally conductive layer, and the packaging material of the electric heating layer is a thermally conductive insulator with excellent thermal conductivity. In this way, the electric heating layer and the variable thermal resistance layer form a thermally conductive channel located between the battery and the liquid cooling plate. At this time, the electric heating layer is not working, while the coolant in the liquid cooling plate circulates. The thermally conductive channel formed by the electric heating layer and the variable thermal resistance layer can efficiently and evenly conduct the heat generated by the battery to the liquid cooling plate. The coolant circulating in the liquid cooling plate can quickly remove the absorbed heat, achieving efficient cooling.
[0009] In the technical solution of this application, by setting a variable thermal resistance layer and a thermally conductive insulating component in the electric heating layer, and in conjunction with a liquid cooling plate that can move up and down, the variable thermal resistance layer can be adjusted to be in a compressed state or kept in a free state according to the heating or heat dissipation requirements. The thermal resistance value of the variable thermal resistance layer can be flexibly adjusted to achieve efficient heat conduction or thermal insulation, so as to promote the efficient independent operation of heating and heat dissipation modes rather than mutual interference, thereby achieving efficient heating or efficient heat dissipation.
[0010] Optionally, the variable thermal resistance layer comprises the following raw materials in parts by weight: 100 parts of polyether polyol, 35-55 parts of toluene diisocyanate, 2.0-4.5 parts of water, 0.5-2.5 parts of silicone oil foam stabilizer, 0.1-0.5 parts of amine catalyst, 0.1-0.4 parts of tin catalyst, and 30-40 parts of diamond powder; wherein the average particle size of the diamond powder is 5-50 μm.
[0011] By adopting the above technical solution, the resulting variable thermal resistance layer is in a fluffy state under normal conditions, with open pores and filled with air. The diamond powder cannot form a continuous contact network, resulting in a high thermal resistance state and providing thermal insulation. When the variable thermal resistance layer is compressed, the air is expelled, allowing the diamond powder to contact and form a continuous, dense contact network, resulting in a low thermal resistance state and becoming a highly efficient heat conduction channel.
[0012] It should be noted that if too much diamond powder is used, it can easily affect the thermal insulation performance of the variable thermal resistance layer when it is in a fluffy state; if too little diamond powder is used, it can easily affect the thermal conductivity performance of the variable thermal resistance layer when it is in a compressed state. Therefore, this application controls the amount of diamond powder to 30-40 parts by weight.
[0013] Preferably, the variable thermal resistance layer comprises the following raw materials in parts by weight: 100 parts of polyether polyol, 45 parts of toluene diisocyanate, 3 parts of water, 1.5 parts of silicone oil foam stabilizer, 0.3 parts of amine catalyst, 0.2 parts of tin catalyst, and 35 parts of diamond powder; wherein the average particle size of the diamond powder is 25 μm.
[0014] Optionally, the diamond powder is silane-modified diamond powder, and the preparation method of the silane-modified diamond powder includes the following steps: (1) Mix diamond powder with nitric acid, stir at 70~90℃, cool to obtain diamond acid solution; (2) Mix the silane coupling agent with the ethanol solution and adjust the pH to 4-5 to obtain the modified solution; (3) The modified liquid obtained in step (2) is added dropwise into the diamond acid solution obtained in step (1), stirred and dispersed, stirred and reacted, cooled, filtered to remove solvent, washed and dried to obtain the silane modified diamond powder. In step (1), the weight ratio of diamond powder to nitric acid is 50:(110~160). In step (2), the weight ratio of silane coupling agent to ethanol solution is 5:(17~22), and the ethanol solution is obtained by mixing anhydrous ethanol and water.
[0015] By adopting the above technical solution and using modified diamond powder, the dispersion stability of diamond powder in the substrate can be promoted, and the thermal insulation of the prepared variable thermal resistance layer in the fluffy state and the thermal conductivity in the compressed state can be improved.
[0016] Preferably, in step (1), the weight ratio of diamond powder to nitric acid is 50:140, and the concentration of nitric acid is 60~70 wt%. In step (2), the weight ratio of silane coupling agent to ethanol solution is 5:20, and the ethanol solution is obtained by mixing anhydrous ethanol and water in a weight ratio of 18:2; the silane coupling agent is silane coupling KH-550.
[0017] Optionally, the diamond powder includes diamond powder with an average particle size of 30-50 μm and diamond powder with an average particle size of 5-10 μm, and the weight ratio of the diamond powder with an average particle size of 30-50 μm to the diamond powder with an average particle size of 5-10 μm is (35-40):(10-15).
[0018] By adopting the above technical solution, two types of diamond powder with different particle sizes are mixed in a specific ratio to form a thermally conductive filler. The diamond powder with a larger particle size forms the skeleton of the filler, while the diamond powder with a smaller particle size fills it in order to improve the thermal insulation of the variable thermal resistance layer in the fluffy state, and to form a more complex and complete thermally conductive network when compressed, thereby improving the thermal conductivity.
[0019] Preferably, the diamond powder comprises diamond powder with an average particle size of 40 μm and diamond powder with an average particle size of 8 μm, and the weight ratio of the diamond powder with an average particle size of 40 μm to the diamond powder with an average particle size of 8 μm is 38:12.
[0020] Optionally, the method for preparing the variable thermal resistance layer includes the following steps: Step 1: Mix polyether polyol, water, silicone oil-based foam stabilizer, amine catalyst, tin catalyst and diamond powder, then mechanically stir, ultrasonically disperse and vacuum degas to obtain a mixture; Step 2: Mix the mixture obtained in Step 1 with toluene diisocyanate, control the temperature at 25~40℃, and stir at a stirring rate of 1000~3000 rpm to obtain a reaction solution; Step 3: Pour the reaction solution obtained in Step 2 into a mold, allow it to foam freely to obtain a foam block, and place the foam block at room temperature to mature to obtain the variable thermal resistance layer. In step two, the toluene diisocyanate includes toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, and the weight ratio of toluene-2,4-diisocyanate to toluene-2,6-diisocyanate is (3.5~4.5):1.
[0021] By adopting the above technical solution, the resulting variable thermal resistance layer has excellent compressibility, resilience, and pores with suitable size and uniform distribution.
[0022] Preferably, the weight ratio of toluene-2,4-diisocyanate to toluene-2,6-diisocyanate is 4:1.
[0023] Optionally, the thickness of the variable thermal resistance layer is 300~800μm.
[0024] Preferably, the thickness of the variable thermal resistance layer is 500 μm.
[0025] By adopting the above technical solution and controlling the thickness of the variable thermal resistance layer, the thermal insulation in the fluffy state and the interfacial thermal conductivity in the compressed state can be better balanced.
[0026] Optionally, the thickness of the electric heating layer is 0.2~2.0 mm.
[0027] Preferably, the thickness of the electric heating layer is 0.2~0.5mm.
[0028] More preferably, the thickness of the electric heating layer is 0.25 mm.
[0029] By adopting the above technical solution and controlling the thickness of the electric heating layer, a better balance can be achieved between heat conduction during heating and heat dissipation.
[0030] Optionally, the thickness of the silicone thermally conductive interface layer is 1-2 mm. Preferably, the thickness of the silicone thermally conductive interface layer is 1.5 mm.
[0031] Optionally, the raw materials for preparing the thermally conductive and insulating encapsulation include a polyimide precursor solution and a first thermally conductive filler, and the weight ratio of the polyimide precursor solution to the first thermally conductive filler is (40~60):(40~60). The first thermally conductive filler is selected from at least one of alumina, aluminum nitride, and boron nitride. The average particle size of the first thermally conductive filler is 0.1~18μm.
[0032] By adopting the above technical solution, the resulting insulating package has both insulating and thermally conductive properties.
[0033] Preferably, the first thermally conductive filler comprises alumina with an average particle size of 0.1~1.0μm and alumina with an average particle size of 15~18μm, and the weight ratio of alumina with an average particle size of 0.1~1.0μm and alumina with an average particle size of 15~18μm is (25~30):(70~75).
[0034] More preferably, the first thermally conductive filler comprises alumina with an average particle size of 0.5 μm and alumina with an average particle size of 16 μm, and the weight ratio of alumina with an average particle size of 0.5 μm to alumina with an average particle size of 16 μm is 27:73.
[0035] Preferably, the weight ratio of the polyimide precursor solution to the first thermally conductive filler is 60:40.
[0036] Optionally, the raw materials for preparing the silicone thermally conductive interface layer include addition-type liquid silicone rubber and a second thermally conductive filler, and the weight ratio of the addition-type liquid silicone rubber to the second thermally conductive filler is (15~20):(80~85). The second thermally conductive filler is zinc oxide or aluminum oxide, and the average particle size of the second thermally conductive filler is 1~190μm.
[0037] By adopting the above technical solution, the silicone thermal interface layer is attached to the surface of the battery module, which has high thermal conductivity, electrical insulation and shock absorption functions, ensuring uniform heat transfer.
[0038] Preferably, the second thermally conductive filler comprises alumina with an average particle size of 1-2 μm, alumina with an average particle size of 20-30 μm, and alumina with an average particle size of 180-190 μm, and the weight ratio of alumina with an average particle size of 1-2 μm, alumina with an average particle size of 20-30 μm, and alumina with an average particle size of 180-190 μm is (50-56):(32-36):(8-18).
[0039] More preferably, the second thermally conductive filler comprises alumina with an average particle size of 1.5 μm, alumina with an average particle size of 25 μm, and alumina with an average particle size of 185 μm, and the weight ratio of the alumina with an average particle size of 1.5 μm, the alumina with an average particle size of 25 μm, and the alumina with an average particle size of 185 μm is 53:34:13.
[0040] Preferably, the weight ratio of the addition-cured liquid silicone rubber to the second thermally conductive filler is 18:82.
[0041] Optionally, the battery thermal management system further includes a housing and a cover plate. The battery module is disposed in the housing, and the cover plate covers the opening end of the housing. The silicone thermal interface layer, the electric heating layer, the variable thermal resistance layer, and the liquid cooling plate are all located in the housing. The drive mechanism is disposed on the cover plate, and the drive end of the drive mechanism passes through the cover plate and is connected to the liquid cooling plate.
[0042] In summary, this application includes at least the following beneficial technical effects: In this application's technical solution, a variable thermal resistance layer is provided between the liquid cooling plate and the electric heating layer. Initially, there is a gap between the liquid cooling plate and the variable thermal resistance layer. When the battery temperature is too low and heating is required, the electric heating layer is activated. The gap between the liquid cooling plate and the variable thermal resistance layer effectively prevents heat leakage from the liquid cooling plate and its internal coolant due to contact between the liquid cooling plate and the electric heating layer. Furthermore, the variable thermal resistance layer is not compressed at this time, exhibiting a high thermal resistance state, thus acting as thermal insulation. This allows the heat generated by the electric heating layer to be conducted to the battery more fully and efficiently. The packaging material of the electric heating layer is a thermally conductive insulator with excellent thermal conductivity, thereby achieving efficient heating and heat preservation.
[0043] When the battery temperature is too high and heat dissipation is required, the driving liquid cooling plate moves towards the variable thermal resistance layer and compresses the variable thermal resistance layer, making the variable thermal resistance layer exhibit a low thermal resistance state. The variable thermal resistance layer becomes a thinner interfacial thermal conductive layer, and the packaging material of the electric heating layer is a thermally conductive insulator with excellent thermal conductivity. In this way, the electric heating layer and the variable thermal resistance layer form a thermally conductive channel located between the battery and the liquid cooling plate. At this time, the electric heating layer is not working, while the coolant in the liquid cooling plate circulates. The thermally conductive channel formed by the electric heating layer and the variable thermal resistance layer can efficiently and evenly conduct the heat of the battery to the liquid cooling plate. The coolant circulating in the liquid cooling plate can quickly remove the absorbed heat, achieving efficient cooling.
[0044] In the technical solution of this application, by setting a variable thermal resistance layer and a thermally conductive insulating component in the electric heating layer, and in conjunction with a liquid cooling plate that can move up and down, the variable thermal resistance layer can be adjusted to be in a compressed state or kept in a free state according to the heating or heat dissipation requirements. The thermal resistance value of the variable thermal resistance layer can be flexibly adjusted to achieve efficient heat conduction or thermal insulation, so as to promote the efficient independent operation of heating and heat dissipation modes rather than mutual interference, thereby achieving efficient heating or efficient heat dissipation. Attached Figure Description
[0045] Figure 1 This is a schematic diagram of the battery thermal management system provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the internal flow channel structure of the liquid cooling plate provided in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the structure of the heating element etched with copper foil provided in Embodiment 1 of this application.
[0046] In the diagram, 1 is the housing; 11 is the cover plate; 2 is the battery module; 3 is the silicone thermal interface layer; 4 is the electric heating layer; 5 is the variable thermal resistance layer; 6 is the liquid cooling plate; and 7 is the drive mechanism. Detailed Implementation
[0047] The present application will be further described in detail below with reference to the embodiments.
[0048] All raw materials involved in this application are commercially available, among which, Polyether polyols: Toluene diamine polyether series polyether polyols, Jining Huakai Resin Co., Ltd., model HK-410HN; Silicone oil-based foam stabilizers: Rigid foam silicone oil CGY-1 from Yangzhou Chenhua New Materials Co., Ltd.; Toluene diisocyanate: a mixture of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, wherein the weight ratio of toluene-2,4-diisocyanate to toluene-2,6-diisocyanate is 4:1; Addition-cure liquid silicone rubber: Shenzhen Jereh New Materials Co., Ltd., model JR; Polyimide precursor solution: Zigong Zhongtiansheng New Material Technology Co., Ltd., model ZTS-PI-800 polyimide prepreg. Preparation Examples 1-3
[0049] Preparation Examples 1-3 provide a method for preparing a variable thermal resistance layer. The raw materials and their amounts for the variable thermal resistance layer are shown in Table 1 below. The specific preparation method includes the following steps: Step 1: Mix polyether polyol, deionized water, silicone oil foam stabilizer, amine catalyst, tin catalyst and diamond powder (average particle size of 25μm), stir at 500rpm for 30min, ultrasonically disperse at 300W for 45min, vacuum degas for 5min, and control the temperature at 35℃ to obtain the mixture. Step 2: Mix the mixture obtained in Step 1 with toluene diisocyanate, control the temperature at 30℃, and stir at a stirring speed of 1500 rpm for 8 seconds to obtain the reaction solution. Step 3: Pour the reaction solution obtained in Step 2 into a mold and allow it to foam freely for 3 minutes to obtain a foam block. Place the foam block at 25°C for 18 hours to obtain a variable thermal resistance layer.
[0050] The variable thermal resistance layer was found to be 1350 mm long, 960 mm wide, and 300 μm thick.
[0051] Table 1. Raw materials and dosage of variable thermal resistance layer (unit: parts by weight)
[0052] It should be noted that the amine catalyst in Table 1 is triethylenediamine; the tin catalyst is stannous octoate. Preparation Examples 4-5
[0053] Preparation Examples 4 and 5 are based on Preparation Example 2, the difference being that the thickness of the obtained variable thermal resistance layer is different, while the other steps remain the same as in Preparation Example 2. Specifically: In Preparation Example 4, the variable thermal resistance layer has a length of 1350 mm, a width of 960 mm, and a thickness of 500 μm.
[0054] In Example 5, the variable thermal resistance layer has a length of 1350 mm, a width of 960 mm, and a thickness of 700 μm. Preparation Example 6
[0055] This preparation example is based on Preparation Example 4, except that: an equal part by weight of modified diamond powder is used to replace the diamond powder, while the other steps are the same as in Preparation Example 4.
[0056] The method for preparing the modified diamond powder in this preparation example includes the following steps: (1) Provide 500 parts by weight of diamond powder (average particle size of 25 μm), and add 1400 parts by weight of 65 wt% nitric acid while stirring (200 rpm). The feeding rate of nitric acid is 50 parts by weight / min. After the feeding is completed, stir at 400 rpm for 4 h in an oil bath at 80 °C, and cool to 60 °C to obtain diamond acid solution. (2) Mix 5 parts by weight of silane-coupled KH-550, 18 parts by weight of anhydrous ethanol and 2 parts by weight of deionized water, stir at 200 rpm for 20 min at 30 °C, and adjust the pH to 4.5 with anhydrous acetic acid to obtain the modified solution. (3) The modified liquid obtained in step (2) is added dropwise into the diamond acid solution obtained in step (1), and stirred at a stirring speed of 1000 rpm for 30 min. At a temperature of 30℃ and a relative humidity of 50±5%, it is stirred at a stirring speed of 300 rpm for 3 h. After cooling to 25℃, the solvent is removed by filtration, and the solution is washed with deionized water and anhydrous ethanol. The solution is dried under vacuum at 80℃ for 10 h to obtain modified diamond powder. Preparation Example 7
[0057] This preparation example is based on preparation example 6, the difference being that in step (1), the diamond powder includes diamond powder with an average particle size of 40 μm and diamond powder with an average particle size of 8 μm, and the weight ratio of the diamond powder with an average particle size of 40 μm to the diamond powder with an average particle size of 8 μm is 38:12, and the other steps are the same as in preparation example 6. Preparation of Comparative Example 1
[0058] This comparative example is based on Preparation Example 1, except that the amount of diamond powder used is 25 parts by weight, while the other steps are the same as in Preparation Example 1. Preparation of Comparative Example 2
[0059] This comparative example is based on Preparation Example 1, except that the average particle size of the diamond powder is 1 μm, while the other steps are the same as in Preparation Example 1. Example 1
[0060] This embodiment provides a battery thermal management system, including: a housing 1, a cover plate 11, a battery module 2, a heating / cooling assembly, a liquid cooling plate 6, and a control device. The battery module is disposed inside the housing, the heating / cooling assembly is disposed on the upper surface of the battery module, the cover plate covers the opening of the housing, and the liquid cooling plate is movably disposed directly above the heating / cooling assembly. Both the heating / cooling assembly and the liquid cooling plate are located inside the housing. Figure 1 As shown. The battery module is 1350mm long and 960mm wide, and is assembled from 100 BYD Han Blade Battery cells; the internal flow channel structure of the liquid cooling plate is as follows. Figure 2 As shown, Figure 2 The dimensions are in mm. The length of the liquid cooling plate is 1350 mm and the width is 960 mm.
[0061] The heating-heat dissipation assembly includes a silicone thermal interface layer 3, an electric heating layer 4, and a variable thermal resistance layer 5 arranged sequentially along the direction away from the battery module.
[0062] The control device includes a temperature sensor, a controller, and a drive mechanism 7. The temperature sensor is connected to the middle of the battery module and communicates with the controller. The temperature sensor is used to detect the temperature of the battery module and transmit the detected temperature to the controller. The controller is used to compare the received temperature with a preset temperature and generate a control command. The drive mechanism is mounted on the cover plate. The drive mechanism communicates with the controller and is connected to the liquid cooling plate. The drive mechanism is used to receive the control command and control the liquid cooling plate to move toward the variable thermal resistance layer to compress the variable thermal resistance layer, or control the liquid cooling plate to move away from the variable thermal resistance layer, so as to adjust the thermal resistance value of the variable thermal resistance layer.
[0063] In this embodiment, the method for preparing the heating-heat dissipation component includes the following steps: S1. Provide 82 parts by weight of alumina powder and 18 parts by weight of addition-cured liquid silicone rubber, wherein the weight ratio of A and B in the addition-cured liquid silicone rubber is 1:1; mix A with alumina powder, stir at 200 rpm for 15 min, add B, stir at 300 rpm for 10 min, ultrasonically disperse at 200W for 15 min, and vacuum degas for 5 min to obtain silicone thermally conductive interface layer material; S2. The silicone thermally conductive interface layer material obtained in step S1 is coated onto the upper surface of the battery module. The discharge heating layer and the variable thermal resistance layer prepared in Preparation Example 1 are then stacked sequentially on the silicone thermally conductive interface layer material. At 75°C, a pressure of 8 psi is applied for 30 min. The pressure is then removed, and the mixture is kept at 75°C for another 4 h to obtain a heating-heat dissipation component. The silicone thermally conductive interface layer material is cured and formed into a silicone thermally conductive interface layer. The silicone thermally conductive interface layer is measured to have a length of 1350 mm, a width of 960 mm, and a thickness of 1.5 mm.
[0064] In step S1, the alumina powder includes alumina powder with an average particle size of 1.5 μm, alumina powder with an average particle size of 25 μm, and alumina powder with an average particle size of 185 μm, and the weight ratio of the alumina powder with an average particle size of 1.5 μm, the alumina powder with an average particle size of 25 μm, and the alumina powder with an average particle size of 185 μm is 53:34:13.
[0065] The method for preparing the electric heating layer in step S2 includes the following steps: A polyimide precursor solution of 60 parts by weight and alumina powder of 40 parts by weight (alumina powder with an average particle size of 0.5 μm and alumina powder with an average particle size of 16 μm mixed at a weight ratio of 27:73) were provided. The polyimide precursor solution and alumina powder were mixed and stirred at a stirring rate of 200 rpm for 15 min, ultrasonically dispersed at 200 W for 20 min, and vacuum degassed for 5 min. The mixture was poured into a mold and cured at 285℃ for 1.5 h to obtain a PI film. The PI film was found to be 1350 mm long, 960 mm wide, and 75 μm thick.
[0066] Etched copper foil for heating elements (purchased from Weihai Joer Electric, length 1350mm, width 960mm, thickness 100μm, structure as follows) Figure 3 As shown in the figure, a PI film, an etched copper foil, and another PI film are stacked sequentially from bottom to top. A pressure of 1.5 MPa is applied at 200°C, and the mixture is hot-pressed and cured for 60 minutes to obtain the electric heating layer. The lead ends on the etched copper foil are connected to an external power source via leads. Examples 2-7
[0067] Examples 2-7 are based on Example 1, the difference being that the source of the variable thermal resistance layer in step S2 is different, while the other steps remain the same as in Example 1. Specifically: In Example 2, the variable thermal resistance layer obtained in Example 2 was used.
[0068] In Example 3, the variable thermal resistance layer obtained in Example 3 was used.
[0069] In Example 4, the variable thermal resistance layer obtained in Example 4 was used.
[0070] In Example 5, the variable thermal resistance layer obtained in Example 5 was used.
[0071] In Example 6, the variable thermal resistance layer obtained in Example 6 was used.
[0072] In Example 7, the variable thermal resistance layer obtained in Preparation Example 7 was used. Comparative Examples 1-2
[0073] Comparative Examples 1 and 2 are based on Example 1, the difference being that the source of the variable thermal resistance layer in step S2 is different, while the other steps remain the same as in Example 1. Specifically: In Comparative Example 1, the variable thermal resistance layer obtained in Comparative Example 1 was used.
[0074] In Comparative Example 2, the variable thermal resistance layer obtained in Comparative Example 2 was used. Performance testing
[0075] Performance tests were conducted on the heating efficiency and heat dissipation efficiency of the battery thermal management systems obtained in Examples 1-7 and Comparative Examples 1-2. The test results are shown in Table 2 below.
[0076] Heat dissipation efficiency test method: The battery thermal management system is placed in an environment of 60℃, and the battery module is heated by an external heat source until the temperature sensor detects that the temperature of the battery module is 60℃. This temperature is the upper limit threshold preset in the controller. The controller sends a control command to the drive mechanism, which drives the liquid cooling plate to move downward and compresses the variable resistor layer with a pressure of 30psi. The coolant in the liquid cooling plate circulates at a flow rate of 1.5m / s. The input coolant is water at a temperature of 20℃. The time when the temperature sensor detects 60℃ is taken as the test time (T=0). The time T1 corresponding to the temperature sensor detecting 25℃ is recorded.
[0077] Heating efficiency test method: The battery thermal management system, after passing the heat dissipation efficiency test, is placed in an environment of -10℃, and an external cold source is used to cool the battery module until the temperature sensor detects that the battery module temperature is -10℃. This temperature is the lower limit threshold preset in the controller. The controller sends a control command to the drive mechanism, which drives the liquid cooling plate to move upward until the distance between the lower surface of the liquid cooling plate and the upper surface of the variable thermal resistance layer is 2mm. The heating element is then activated, with a power density of 1000W / m². 2 The time when the temperature sensor detects -10℃ is taken as the experimental time (T=0), and the time T2 corresponding to the temperature sensor detecting 25℃ is recorded.
[0078] Table 2 Test results of heating efficiency and heat dissipation efficiency
[0079] As can be seen from the test results in Table 2, this application, through the setting of a variable thermal resistance layer and the setting of a thermally conductive insulating component in the electric heating layer, and in conjunction with a liquid cooling plate that can be moved up and down, can adjust the variable thermal resistance layer to be in a compressed state or remain in a free state according to the heating or heat dissipation requirements, flexibly adjust the thermal resistance value of the variable thermal resistance layer, achieve efficient heat conduction or thermal insulation, promote the efficient independent operation of heating and heat dissipation modes rather than mutual interference, and thus achieve efficient heating or efficient heat dissipation.
[0080] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the principles of this application should be covered within the scope of protection of this application.
Claims
1. A battery thermal management system, characterized in that, include: Battery module; A silicone thermally conductive interface layer is applied to the upper surface of the battery module. An electric heating layer covers the upper surface of the silicone thermally conductive interface layer. The electric heating layer includes a heating element and a thermally conductive insulating encapsulation for encapsulating the heating element. A variable thermal resistance layer covers the upper surface of the electric heating layer; A liquid cooling plate is movably disposed above the variable thermal resistance layer; as well as, The control device includes a temperature sensor, a controller, and a drive mechanism. The temperature sensor is connected to the battery module and communicates with the controller to detect the temperature of the battery module and transmit the detected temperature to the controller. The controller compares the received temperature with a preset temperature and generates a control command. The drive mechanism is communicated with the controller and connected to the liquid cooling plate. The drive mechanism receives the control command and controls the liquid cooling plate to move toward the variable thermal resistance layer to compress the variable thermal resistance layer, or controls the liquid cooling plate to move away from the variable thermal resistance layer, so as to adjust the thermal resistance value of the variable thermal resistance layer.
2. The battery thermal management system according to claim 1, characterized in that, The variable thermal resistance layer comprises the following raw materials in parts by weight: 100 parts of polyether polyol, 35-55 parts of toluene diisocyanate, 2.0-4.5 parts of water, 0.5-2.5 parts of silicone oil foam stabilizer, 0.1-0.5 parts of amine catalyst, 0.1-0.4 parts of tin catalyst, and 30-40 parts of diamond powder; wherein the average particle size of the diamond powder is 5-50 μm.
3. The battery thermal management system according to claim 2, characterized in that, The diamond powder is silane-modified diamond powder, and the preparation method of the silane-modified diamond powder includes the following steps: (1) Mix diamond powder with nitric acid, stir at 70~90℃, cool to obtain diamond acid solution; (2) Mix the silane coupling agent with the ethanol solution and adjust the pH to 4-5 to obtain the modified solution; (3) The modified liquid obtained in step (2) is added dropwise into the diamond acid solution obtained in step (1), stirred and dispersed, stirred and reacted, cooled, filtered to remove solvent, washed and dried to obtain the silane modified diamond powder. In step (1), the weight ratio of diamond powder to nitric acid is 50:(110~160). In step (2), the weight ratio of silane coupling agent to ethanol solution is 5:(17~22), and the ethanol solution is obtained by mixing anhydrous ethanol and water.
4. The battery thermal management system according to claim 2, characterized in that, The diamond powder includes diamond powder with an average particle size of 30-50 μm and diamond powder with an average particle size of 5-10 μm, and the weight ratio of the diamond powder with an average particle size of 30-50 μm to the diamond powder with an average particle size of 5-10 μm is (35-40):(10-15).
5. The battery thermal management system according to claim 2, characterized in that, The method for preparing the variable thermal resistance layer includes the following steps: Step 1: Mix polyether polyol, water, silicone oil-based foam stabilizer, amine catalyst, tin catalyst and diamond powder, then mechanically stir, ultrasonically disperse and vacuum degas to obtain a mixture; Step 2: Mix the mixture obtained in Step 1 with toluene diisocyanate, control the temperature at 25~40℃, and stir at a stirring rate of 1000~3000 rpm to obtain a reaction solution; Step 3: Pour the reaction solution obtained in Step 2 into a mold, allow it to foam freely to obtain a foam block, and place the foam block at room temperature to mature to obtain the variable thermal resistance layer. In step two, the toluene diisocyanate includes toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, and the weight ratio of toluene-2,4-diisocyanate to toluene-2,6-diisocyanate is (3.5~4.5):
1.
6. The battery thermal management system according to claim 1, characterized in that, The thickness of the variable thermal resistance layer is 300~800μm.
7. The battery thermal management system according to claim 1, characterized in that, The thickness of the electric heating layer is 0.2~2.0mm.
8. The battery thermal management system according to claim 7, characterized in that, The raw materials for preparing the thermally conductive and insulating encapsulation include a polyimide precursor solution and a first thermally conductive filler, and the weight ratio of the polyimide precursor solution to the first thermally conductive filler is (40~60):(40~60). The first thermally conductive filler is selected from at least one of alumina, aluminum nitride, and boron nitride. The average particle size of the first thermally conductive filler is 0.1~18μm.
9. The battery thermal management system according to claim 1, characterized in that, The raw materials for preparing the silicone thermally conductive interface layer include addition-type liquid silicone rubber and a second thermally conductive filler, and the weight ratio of the addition-type liquid silicone rubber to the second thermally conductive filler is (15~20):(80~85). The second thermally conductive filler is zinc oxide or aluminum oxide, and the average particle size of the second thermally conductive filler is 1~190μm.
10. The battery thermal management system according to claim 1, characterized in that, The battery thermal management system further includes a housing and a cover plate. The battery module is disposed in the housing, and the cover plate covers the opening end of the housing. The silicone thermal interface layer, the electric heating layer, the variable thermal resistance layer, and the liquid cooling plate are all located in the housing. The drive mechanism is disposed on the cover plate, and the drive end of the drive mechanism passes through the cover plate and is connected to the liquid cooling plate.