Composite phase change material applied to thermal management temperature control of battery
The double-layer composite phase change material solves the problem of uneven battery temperature caused by a single phase change temperature in the existing technology, achieves effective temperature control within a wide temperature range, and improves thermal conductivity and temperature control performance.
Patent Information
- Application Number
- CN202510682327.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-09-23
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing composite phase change materials only have a single phase change temperature and cannot effectively control the temperature within a wide temperature range, resulting in uneven battery temperature. In particular, the temperature control effect is significantly reduced when the temperature exceeds a specific range.
A double-layer composite phase change material is used, with the phase change temperature of the upper paraffin layer being 37°C and the phase change temperature of the lower paraffin layer being 46°C. By mixing the upper and lower paraffin layers, expanded graphite, carbon nanotubes, and natural rubber composite materials, a composite phase change material with high thermal conductivity and a wide phase change temperature range is formed.
It significantly improves thermal conductivity, broadens the phase change temperature range, can absorb and release heat in a wider temperature range, effectively maintains battery temperature uniformity, and achieves good temperature control performance in combination with the liquid cooling system.
Smart Images
Figure CN120682768A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of battery thermal management, and in particular to a composite phase change material used for thermal management and temperature control of batteries. Background Art
[0002] Phase change material (PCM), as a potential thermal management medium, has broad application prospects in battery thermal management systems due to its advantages such as low cost, low corrosion resistance, and high phase change latent heat. During the battery temperature change process, the phase change material undergoes a solid-liquid phase change, which can absorb or release a large amount of latent heat, thereby maintaining the battery temperature stable within a certain range, making the temperature distribution of the battery pack more uniform and reducing overheating.
[0003] Existing composite phase change materials usually only have a single phase change temperature and can only play a phase change energy storage role within a specific temperature range. Taking the common paraffin-expanded graphite composite phase change material as an example, its phase change temperature is fixed. When the battery temperature exceeds the phase change temperature range of the material, the temperature control effect will be greatly reduced. Summary of the Invention
[0004] In view of the deficiencies of the prior art, the present invention provides a composite phase change material for thermal management and temperature control of batteries, which solves the problems raised in the above background technology.
[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a composite phase change material for thermal management and temperature control of a battery, the composite phase change material having a double-layer structure and comprising the following components by weight:
[0006] Upper layer structure: upper layer paraffin 60%, upper layer expanded graphite 20%, upper layer carbon nanotube 10%, upper layer natural rubber 10%;
[0007] Lower layer structure: lower layer paraffin 60%, lower layer expanded graphite 20%, lower layer carbon nanotubes 10%, lower layer natural rubber 10%;
[0008] The upper expanded graphite layer and the lower expanded graphite layer are the same expanded graphite, the upper carbon nanotube layer and the lower carbon nanotube layer are the same carbon nanotube, and the upper natural rubber layer and the lower natural rubber layer are the same natural rubber;
[0009] The upper paraffin layer adopts paraffin with a phase transition temperature of 37°C, and the lower paraffin layer adopts paraffin with a phase transition temperature of 46°C.
[0010] Furthermore, the composite phase change material used for thermal management and temperature control of batteries includes the following preparation steps:
[0011] S1. Raw material processing:
[0012] Select two paraffin waxes with a purity of not less than 98%, place them in clean and dry containers respectively, and use a grinder to crush them into particles with a particle size of 0.5-1 mm;
[0013] The expanded graphite is purified by soaking it in a 10% hydrochloric acid solution for 2-3 hours, then repeatedly rinsing it with deionized water until it becomes neutral, and finally drying it in an oven at 80-100°C for 12-16 hours;
[0014] The carbon nanotubes are surface modified by placing them in a 5% by mass nitric acid solution, ultrasonically treating them at 60-80° C. for 1-2 hours, then rinsing them with deionized water until neutral, and vacuum drying them at 60-80° C. for 8-10 hours;
[0015] Cut the natural rubber into small pieces and set aside.
[0016] Furthermore, the composite phase change material used for thermal management and temperature control of batteries further includes the following preparation steps:
[0017] S2. Preparation of upper layer materials:
[0018] The crushed upper paraffin wax particles are placed in a reactor equipped with a stirrer and a thermometer, and heated to 60-65°C to completely melt the paraffin wax. After the paraffin wax is completely melted, the surface-modified carbon nanotubes are added to the reactor, and ultrasonic vibration equipment is turned on at a power of 300-500W for 3 hours to evenly disperse the carbon nanotubes in the melted paraffin wax.
[0019] Add the purified expanded graphite and start the stirrer to allow the expanded graphite to be fully absorbed into the paraffin wax and carbon nanotube mixture system;
[0020] Finally, add the natural rubber cut into small pieces, melt the natural rubber completely and mix it evenly with other ingredients to form a uniform liquid mixture.
[0021] Furthermore, in step S2, the stirrer stirs at a speed of 200-300 r / min for 1 hour, and after adding the natural rubber, stirring needs to be continued for 2-3 hours.
[0022] Furthermore, the composite phase change material used for thermal management and temperature control of batteries further includes the following preparation steps:
[0023] S3. Preparation of lower layer materials:
[0024] According to the same steps as those for preparing the upper layer materials, the paraffin wax, carbon nanotubes, expanded graphite and natural rubber of the lower layer are sequentially added into the reactor and mixed to obtain a uniform liquid mixture of the lower layer.
[0025] Furthermore, the composite phase change material used for thermal management and temperature control of batteries further includes the following preparation steps:
[0026] S4, molding:
[0027] First, pour the upper liquid mixture into the mold, and then place the mold in a room temperature environment to cool naturally, so that the upper layer of material is initially solidified and formed;
[0028] After the upper layer material is completely solidified, the lower layer liquid mixture is slowly poured into the mold, covering the surface of the upper layer material, and then placed in a room temperature environment for natural cooling to solidify the lower layer material to form a double-layer composite phase change material.
[0029] Furthermore, in step S4, the thickness of the upper layer liquid mixture and the lower layer liquid mixture is controlled to be 3-5 mm when poured into the mold.
[0030] Furthermore, in step S4, a layer of release agent is pre-coated on the inner wall of the mold before pouring the upper liquid mixture.
[0031] Furthermore, the composite phase change material used for thermal management and temperature control of batteries further includes the following preparation steps:
[0032] S5. Post-processing:
[0033] The formed composite phase change material is taken out of the mold, surface trimmed, and excess scraps are removed. It is then placed in a vacuum drying oven to remove residual moisture and volatile substances in the material to obtain the final composite phase change material product.
[0034] Furthermore, in step S5, when the composite phase change material is placed in a vacuum drying oven, the internal temperature of the vacuum drying oven is controlled at 40-50° C., and the drying time is controlled at 2-4 hours.
[0035] The present invention provides a composite phase change material for thermal management and temperature control of batteries, which has the following beneficial effects:
[0036] 1. This composite phase-change material is used for thermal management and temperature control of batteries. When this composite phase-change material is used for thermal management and temperature control of batteries, the thermal conductivity of this composite phase-change material is significantly improved compared to pure paraffin at each temperature point through the double-layer structure with upper and lower layers of paraffin wax with different phase change temperatures. It is also greatly improved compared to commercial phase-change materials. The double-layer structure widens the phase change temperature range, can absorb and release heat in a wider temperature range, and can more effectively transfer the heat generated by the battery. Combined with the liquid cooling system, it maintains the battery at a low and uniform temperature, indicating that it has good temperature control performance in the actual application of battery thermal management. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 This is a schematic diagram of the steps for preparing a composite phase change material for thermal management and temperature control of batteries according to the present invention;
[0038] Figure 2 This is a table showing the thermal conductivity test results of a composite phase change material used for thermal management and temperature control of batteries according to the present invention;
[0039] Figure 3 This is a table showing the test results of the phase change latent heat and phase change temperature of a composite phase change material used for thermal management and temperature control of batteries according to the present invention;
[0040] Figure 4 This is a table of battery thermal management simulation test results for a composite phase change material used for thermal management and temperature control of batteries according to the present invention. DETAILED DESCRIPTION
[0041] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.
[0042] like Figures 1-4 As shown, the present invention provides a technical solution: a composite phase change material used for thermal management and temperature control of batteries. The composite phase change material consists of a double-layer structure and includes the following components by mass:
[0043] Upper layer structure: upper layer paraffin 60%, upper layer expanded graphite 20%, upper layer carbon nanotube 10%, upper layer natural rubber 10%;
[0044] Lower layer structure: lower layer paraffin 60%, lower layer expanded graphite 20%, lower layer carbon nanotubes 10%, lower layer natural rubber 10%;
[0045] The upper expanded graphite layer and the lower expanded graphite layer are the same expanded graphite, the upper carbon nanotube layer and the lower carbon nanotube layer are the same carbon nanotube, and the upper natural rubber layer and the lower natural rubber layer are the same natural rubber;
[0046] The upper paraffin layer adopts paraffin with a phase transition temperature of 37°C, and the lower paraffin layer adopts paraffin with a phase transition temperature of 46°C.
[0047] The composite phase change material used for thermal management and temperature control of batteries includes the following preparation steps:
[0048] S1. Raw material processing:
[0049] Select two paraffin waxes with a purity of not less than 98%, place them in clean and dry containers respectively, and use a grinder to crush them into particles with a particle size of 0.5-1 mm;
[0050] The expanded graphite is purified by soaking it in a 10% hydrochloric acid solution for 2-3 hours, then repeatedly rinsing it with deionized water until it becomes neutral, and finally drying it in an oven at 80-100°C for 12-16 hours;
[0051] The carbon nanotubes are surface modified by placing them in a 5% by mass nitric acid solution, ultrasonically treating them at 60-80° C. for 1-2 hours, then rinsing them with deionized water until neutral, and vacuum drying them at 60-80° C. for 8-10 hours;
[0052] Cut the natural rubber into small pieces and set aside;
[0053] S2. Preparation of upper layer materials:
[0054] The crushed upper paraffin wax particles are placed in a reactor equipped with a stirrer and a thermometer, and heated to 60-65°C to completely melt the paraffin wax. After the paraffin wax is completely melted, the surface-modified carbon nanotubes are added to the reactor, and ultrasonic vibration equipment is turned on at a power of 300-500W for 3 hours to evenly disperse the carbon nanotubes in the melted paraffin wax.
[0055] Add the purified expanded graphite, turn on the stirrer to allow the expanded graphite to be fully adsorbed in the paraffin wax and carbon nanotube mixture, and stir the stirrer at a speed of 200-300 r / min for 1 hour;
[0056] Finally, add the natural rubber cut into small pieces, melt the natural rubber completely and mix it evenly with other ingredients to form a uniform liquid mixture. Continue stirring for 2-3 hours after adding the natural rubber.
[0057] S3. Preparation of lower layer materials:
[0058] Following the same steps as for preparing the upper layer materials, the paraffin wax, carbon nanotubes, expanded graphite, and natural rubber of the lower layer are sequentially added to the reactor and mixed to obtain a uniform liquid mixture of the lower layer;
[0059] S4, molding:
[0060] Before pouring the upper liquid mixture, a layer of release agent is applied to the inner wall of the mold. The upper liquid mixture is poured into the mold, and then the mold is placed in a room temperature environment to cool naturally, so that the upper material is initially solidified and formed;
[0061] After the upper layer material is completely solidified, the lower layer liquid mixture is slowly poured into the mold, covering the surface of the upper layer material, and then placed in a room temperature environment for natural cooling to solidify the lower layer material to form a double-layer composite phase change material. The thickness of the upper and lower liquid mixtures is controlled to be 3-5mm when poured into the mold;
[0062] S5. Post-processing:
[0063] The formed composite phase change material is taken out of the mold, and the surface is trimmed to remove excess scraps. Then, the composite phase change material is placed in a vacuum drying oven to remove residual moisture and volatile substances in the material to obtain the final composite phase change material product. When the composite phase change material is placed in the vacuum drying oven, the internal temperature of the vacuum drying oven is controlled at 40-50°C, and the drying time is controlled at 2-4 hours;
[0064] Based on the above description, the components were prepared according to the above mass proportions and multiple composite phase change material samples with a size of 5 cm × 5 cm × 1 cm were prepared according to the above preparation process, ensuring that the upper layer was a paraffin layer with a phase change temperature of 37°C and the lower layer was a paraffin layer with a phase change temperature of 46°C. The proportions of the components were accurate. Pure paraffin samples of the same specifications were prepared as a control group, as well as common commercial phase change material samples for performance comparison. The common commercial phase change material samples were common commercial phase change material samples, and the phase change temperature of the comparison samples was between 20-60°C.
[0065] The test content is as follows:
[0066] Thermal conductivity test: A laser thermal conductivity meter was used to test the thermal conductivity of composite phase change material samples, pure paraffin samples, and commercial phase change material samples. Each sample was tested at three temperatures: 25°C, 35°C, and 45°C. The measurement was repeated five times at each temperature point, and the average value was taken as the thermal conductivity data at that temperature.
[0067] Test results: The thermal conductivity of pure paraffin is 0.25W / (m·K) at 25°C, 0.26W / (m·K) at 35°C, and 0.27W / (m·K) at 45°C.
[0068] The thermal conductivity of commercial phase change materials is 0.45 W / (m·K) at 25°C, 0.48 W / (m·K) at 35°C, and 0.50 W / (m·K) at 45°C;
[0069] The thermal conductivity of this composite phase change material reaches 1.1W / (m·K) at 25°C, 1.2W / (m·K) at 35°C, and 1.3W / (m·K) at 45°C. At each temperature point, the thermal conductivity of the composite phase change material is significantly improved compared to pure paraffin wax and is also significantly improved compared to commercial phase change materials.
[0070] Phase change latent heat and phase change temperature test:
[0071] The samples were analyzed using a differential scanning calorimeter (DSC). Approximately 5 mg of sample was placed in a DSC crucible and heated from 20°C to 60°C at a heating rate of 10°C / min, then cooled to 20°C at the same rate. The heat flow change during the entire process was recorded. The phase transition temperature (onset phase transition temperature, peak phase transition temperature) and phase transition latent heat of the sample were determined from the DSC curve. Each sample was tested three times and the average value was taken.
[0072] Test results: The initial phase transition temperature of pure paraffin is 35°C, the peak phase transition temperature is 37°C, and the phase transition latent heat is 200 J / g; during the cooling process, the initial crystallization temperature is 33°C, the peak crystallization temperature is 31°C, and the phase transition latent heat is 195 J / g;
[0073] The commercial phase change material has an initial phase change temperature of 36°C, a peak phase change temperature of 38°C, and a phase change latent heat of 180 J / g; when cooled, the initial crystallization temperature is 34°C, the peak crystallization temperature is 32°C, and the phase change latent heat is 175 J / g.
[0074] The upper layer of the composite phase change material has an initial phase change temperature of 36°C, a peak phase change temperature of 37.5°C, and a phase change latent heat of 160 J / g; the lower layer has an initial phase change temperature of 45°C, a peak phase change temperature of 46.5°C, and a phase change latent heat of 150 J / g. The double-layer structure of the composite phase change material broadens the phase change temperature range and can absorb and release heat in a wider temperature range.
[0075] Battery thermal management simulation test:
[0076] A battery thermal management simulation device was constructed, using an 18650 lithium-ion battery. A composite phase-change material sample was tightly attached to the battery surface. A liquid cooling system pipe was set in contact with the battery module. The battery was subjected to constant-current charge (1C rate) and discharge (2C rate) cycle tests. The temperature changes at different locations on the battery surface were measured using thermocouples, and the battery temperature data was recorded throughout the entire charge and discharge process. At the same time, the liquid cooling system was turned on, with a coolant flow rate of 0.5 L / min and a temperature of 25°C. Under the same conditions, the same charge and discharge tests were performed on battery modules using pure paraffin and commercial phase-change materials, and the temperature data were compared.
[0077] Test results: In a 1C charge and 2C discharge cycle, when no phase change material is used and only liquid cooling is used, the battery's maximum temperature reaches 42°C, and the battery surface temperature difference is 5°C;
[0078] Using pure paraffin as phase change material, the maximum temperature of the battery is 38°C and the temperature difference on the battery surface is 4°C;
[0079] Under commercial phase change materials, the maximum battery temperature is 35°C, and the battery surface temperature difference is 3°C;
[0080] When using this composite phase-change material, the maximum battery temperature is 32°C, and the temperature difference on the battery surface is only 2°C. During the entire charge and discharge process, this composite phase-change material can more effectively transfer the heat generated by the battery. Combined with the liquid cooling system, it maintains a low and uniform battery temperature, demonstrating its excellent temperature control performance in practical battery thermal management applications.
[0081] Judging from the above test results, this composite phase change material performs well in improving thermal conductivity, broadening the phase change temperature range, and achieving actual temperature control effects in battery thermal management;
[0082] Based on the above description, when this composite phase change material is used in batteries for thermal management and temperature control, the thermal conductivity of this composite phase change material is significantly improved compared to pure paraffin at each temperature point through the double-layer structure with paraffin wax of different phase change temperatures in the upper and lower layers. It is also greatly improved compared to commercial phase change materials. The double-layer structure broadens the phase change temperature range, can absorb and release heat in a wider temperature range, and can more effectively transfer the heat generated by the battery. Combined with the liquid cooling system, it maintains the battery at a low and uniform temperature, indicating that it has good temperature control performance in the actual application of battery thermal management.
[0083] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.
Claims
1. A composite phase change material for thermal management and temperature control of batteries, characterized by: The composite phase change material is composed of a double-layer structure, which includes the following components by mass: Upper layer structure: upper layer paraffin 60%, upper layer expanded graphite 20%, upper layer carbon nanotube 10%, upper layer natural rubber 10%; Lower layer structure: lower layer paraffin 60%, lower layer expanded graphite 20%, lower layer carbon nanotubes 10%, lower layer natural rubber 10%; The upper expanded graphite layer and the lower expanded graphite layer are the same expanded graphite, the upper carbon nanotube layer and the lower carbon nanotube layer are the same carbon nanotube, and the upper natural rubber layer and the lower natural rubber layer are the same natural rubber; The upper paraffin layer adopts paraffin with a phase transition temperature of 37°C, and the lower paraffin layer adopts paraffin with a phase transition temperature of 46°C.
2. The composite phase change material for thermal management and temperature control of a battery according to claim 1, characterized in that: The composite phase change material used for thermal management and temperature control of batteries includes the following preparation steps: S1. Raw material processing: Select two paraffin waxes with a purity of not less than 98%, place them in clean and dry containers respectively, and use a grinder to crush them into particles with a particle size of 0.5-1 mm; The expanded graphite is purified by soaking it in a 10% hydrochloric acid solution for 2-3 hours, then repeatedly rinsing it with deionized water until it becomes neutral, and finally drying it in an oven at 80-100°C for 12-16 hours; The carbon nanotubes are surface modified by placing them in a 5% by mass nitric acid solution, ultrasonically treating them at 60-80° C. for 1-2 hours, then rinsing them with deionized water until neutral, and vacuum drying them at 60-80° C. for 8-10 hours; Cut the natural rubber into small pieces and set aside.
3. The composite phase change material for thermal management and temperature control of a battery according to claim 2, characterized in that: The composite phase change material used for thermal management and temperature control of batteries further comprises the following preparation steps: S2. Preparation of upper layer materials: The crushed upper paraffin wax particles are placed in a reactor equipped with a stirrer and a thermometer, and heated to 60-65°C to completely melt the paraffin wax. After the paraffin wax is completely melted, the surface-modified carbon nanotubes are added to the reactor, and ultrasonic vibration equipment is turned on at a power of 300-500W for 3 hours to evenly disperse the carbon nanotubes in the melted paraffin wax. Add the purified expanded graphite and start the stirrer to allow the expanded graphite to be fully absorbed into the paraffin wax and carbon nanotube mixture system; Finally, add the natural rubber cut into small pieces, melt the natural rubber completely and mix it evenly with other ingredients to form a uniform liquid mixture.
4. The composite phase change material for thermal management and temperature control of a battery according to claim 3, characterized in that: In step S2, the stirrer stirs at a speed of 200-300 r / min for 1 hour, and continues stirring for 2-3 hours after adding the natural rubber.
5. The composite phase change material for thermal management and temperature control of a battery according to claim 3, characterized in that: The composite phase change material used for thermal management and temperature control of batteries further comprises the following preparation steps: S3. Preparation of lower layer materials: According to the same steps as those for preparing the upper layer materials, the paraffin wax, carbon nanotubes, expanded graphite and natural rubber of the lower layer are sequentially added into the reactor and mixed to obtain a uniform liquid mixture of the lower layer.
6. The composite phase change material for thermal management and temperature control of a battery according to claim 5, characterized in that: The composite phase change material used for thermal management and temperature control of batteries further comprises the following preparation steps: S4, molding: First, pour the upper liquid mixture into the mold, and then place the mold in a room temperature environment to cool naturally, so that the upper layer of material is initially solidified and formed; After the upper layer material is completely solidified, the lower layer liquid mixture is slowly poured into the mold, covering the surface of the upper layer material, and then placed in a room temperature environment for natural cooling to solidify the lower layer material to form a double-layer composite phase change material.
7. The composite phase change material for thermal management and temperature control of a battery according to claim 6, characterized in that: In step S4, the thickness of the upper layer liquid mixture and the lower layer liquid mixture is controlled to be 3-5 mm when poured into the mold.
8. The composite phase change material for thermal management and temperature control of a battery according to claim 6, characterized in that: In step S4, a layer of release agent is pre-coated on the inner wall of the mold before pouring the upper liquid mixture.
9. The composite phase change material for thermal management and temperature control of a battery according to claim 6, characterized in that: The composite phase change material used for thermal management and temperature control of batteries further comprises the following preparation steps: S5. Post-processing: The formed composite phase change material is taken out of the mold, surface trimmed, and excess scraps are removed. It is then placed in a vacuum drying oven to remove residual moisture and volatile substances in the material to obtain the final composite phase change material product.
10. The composite phase change material for thermal management and temperature control of a battery according to claim 9, characterized in that: In step S5, when the composite phase change material is placed in a vacuum drying oven, the internal temperature of the vacuum drying oven is controlled at 40-50° C., and the drying time is controlled at 2-4 hours.