Carbon foam / paraffin composite phase change material for thermal management of lithium ion battery as well as preparation method and application of carbon foam / paraffin composite phase change material
By preparing carbon foam/paraffin composite phase change material, the problems of low thermal conductivity and easy leakage of pure paraffin have been solved, realizing a low-cost, high thermal conductivity lithium-ion battery thermal management material suitable for cylindrical lithium-ion batteries, meeting the lightweight requirements of electric vehicles.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-03
AI Technical Summary
Among existing lithium-ion battery thermal management technologies, pure paraffin has low thermal conductivity, is prone to leakage, and is expensive; metal-based composite materials have high density and are easily corroded; and traditional carbon-based composite materials are expensive and not suitable for thermal management of cylindrical lithium-ion batteries.
Carbon foam was prepared using low-cost melamine foam as a template. It was then combined with paraffin wax through a step-heating carbonization process under nitrogen protection and a vacuum impregnation process to form a carbon foam/paraffin wax composite phase change material. The porous structure of the carbon foam was used to fix the paraffin wax and improve its thermal conductivity.
A low-cost, high-thermal-conductivity, low-density, and leak-resistant carbon foam/paraffin composite phase change material has been developed, which is suitable for thermal management of cylindrical lithium-ion batteries, significantly reducing weight and cost, improving thermal stability, and is suitable for industrial production.
Smart Images
Figure CN121780136A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy materials and battery thermal management technology, specifically to a carbon foam / paraffin composite phase change material for lithium-ion battery thermal management, its preparation method, and its application. Background Technology
[0002] Lithium-ion batteries, with their core advantages such as high energy density, long cycle life, and environmental friendliness, have become the mainstream energy storage device in electric vehicles (EVs), energy storage power stations, and other fields. However, the performance, lifespan, and safety reliability of lithium-ion batteries are extremely sensitive to operating temperature. For every 1°C increase in battery temperature, its lifespan will be shortened by approximately 2 months; moreover, the battery operating temperature must be strictly controlled below 60°C. If the temperature exceeds this limit, thermal runaway can easily occur inside the battery, leading to electrolyte decomposition, damage to the positive and negative electrode materials, and in extreme cases, even serious safety accidents such as fire and explosion. Therefore, an efficient battery thermal management system is the key to ensuring the stable operation of lithium-ion batteries.
[0003] Existing battery thermal management technologies are mainly divided into two categories: active cooling and passive cooling. Active cooling technologies use air or liquid as heat transfer media and rely on external equipment such as fans and water pumps. This not only consumes additional energy but also suffers from drawbacks such as complex system structure, high maintenance costs, and large space occupation, making it difficult to meet the development requirements of lightweight and low-energy consumption in electric vehicles. Passive cooling technologies do not require external energy input. Among them, passive cooling schemes based on phase change materials (PCMs) can absorb and store a large amount of heat at a constant temperature during the phase change process by utilizing the high latent heat of phase change, which can effectively suppress the sudden rise in battery temperature and has become a research hotspot in recent years.
[0004] Among various phase change materials, industrial-grade paraffin (PA) is widely regarded as an ideal passive cooling phase change material due to its advantages such as low cost, high latent heat of phase change (pure paraffin's latent heat of melting can reach 240-250 J / g), excellent chemical stability, and non-corrosiveness. However, pure paraffin has three major technical defects that severely restrict its practical application in battery thermal management. First, its thermal conductivity is extremely low (only 0.18 W / (m・K)), resulting in low heat transfer efficiency during the phase change process and an inability to quickly respond to sudden heat release demands from the battery. Second, it is prone to changing from a solid to a liquid state and leakage during the phase change process, which not only causes material loss but may also lead to safety hazards such as battery short circuits. Third, its thermal expansion coefficient is large, and the volume change after the phase change is significant, which can easily lead to cracking and failure of the battery heat dissipation module structure.
[0005] To address the aforementioned shortcomings of pure paraffin, existing technologies primarily employ the addition of highly thermally conductive fillers to prepare composite phase change materials. The main technical approaches and their limitations are as follows: (1) Metal-based filler composite path: Copper foam, nickel foam, aluminum foam, aluminum wire mesh, etc. are used as thermally conductive reinforcing fillers and are composited with paraffin wax through impregnation, sintering and other processes. Although this approach can improve thermal conductivity to a certain extent, the high density of metal materials (such as copper density of about 8960 kg / m³ and aluminum density of about 2700 kg / m³) leads to a significant increase in the overall weight of the composite phase change material and heat dissipation module, which violates the lightweight design concept of electric vehicles; moreover, metal materials are easily corroded by electrolyte and environmental humidity, and long-term use can easily lead to damage to the filler structure, resulting in a decrease in thermal conductivity; in addition, the high cost of raw materials such as metal foam makes the cost of the composite phase change material support frame generally high, which is not conducive to large-scale mass production applications.
[0006] (2) Traditional carbon-based filler composite path: Expanded graphite, graphene, carbon nanotubes and other thermally conductive fillers have the advantages of low density and corrosion resistance, but expanded graphite has a high cost and is prone to particle agglomeration, resulting in discontinuous thermal conductive network; the preparation process of graphene and carbon nanotubes is complicated and requires multiple processes such as chemical exfoliation and purification, resulting in high production costs and making it difficult to achieve large-scale industrial application; at the same time, existing research on carbon-based composite phase change materials focuses on optimizing thermal conductivity, without designing a dedicated thermal management module for the shape and structure of cylindrical lithium-ion batteries, and without systematically solving the problem of synergistic optimization of material cost, phase change leakage and structural stability.
[0007] (3) Preliminary exploration of carbon foam-based composites: In recent years, some studies have attempted to use carbon foam as a supporting framework to composite with paraffin. Although carbon foam has advantages such as porous structure, low density and corrosion resistance, there are two major shortcomings in the existing technology: First, the carbon foam preparation process has not been optimized and the influence of carbonization temperature on pore structure and thermal conductivity has not been clarified, resulting in poor performance stability of composite phase change materials; Second, the foam carbon / paraffin composite phase change materials have not been specifically applied to the thermal management scenario of cylindrical lithium-ion batteries, and a standardized thermal management module design scheme matching the shape of cylindrical batteries has not been formed, making it difficult to directly implement and apply.
[0008] Therefore, developing a low-cost, low-density, high-thermal-conductivity, low-leakage composite phase change material suitable for thermal management of cylindrical lithium-ion batteries has become a pressing technical problem for the industry. Summary of the Invention
[0009] To overcome the shortcomings of existing pure paraffin phase change materials, such as low thermal conductivity, easy deformation and leakage, and high cost, high density, and unsuitability for thermal management of cylindrical lithium-ion batteries, this invention provides a carbon foam / paraffin composite phase change material for thermal management of cylindrical lithium-ion batteries, its preparation method, and its application.
[0010] A carbon foam / paraffin composite phase change material for thermal management of lithium-ion batteries is disclosed. The carbon foam is prepared by step-heating carbonization under nitrogen protection using low-cost commercial melamine foam as a template. The capillary action and physical adsorption of the carbon foam are used to fix the paraffin, solving the problem of paraffin leakage. At the same time, the high thermal conductivity network of the carbon foam significantly improves the thermal conductivity of the composite material. In addition, the carbon foam is corrosion resistant and has low density, which reduces the weight and cost of the thermal management system.
[0011] Preferably, industrial-grade commercial paraffin is selected, whose phase change temperature matches the optimal operating temperature range of lithium-ion batteries, and has high latent heat and low cost, ensuring the heat storage performance of the composite material.
[0012] A method for preparing a carbon foam / paraffin composite phase change material includes the following steps: Step S1: Cut the melamine foam into suitable sizes, place it in the ceramic boat of the tube furnace, purge the air with nitrogen, start the tube furnace and carbonize it according to the step heating program. After the temperature reaches the target temperature, hold it at that temperature for 1 hour. After carbonization is completed, let it cool naturally to room temperature to obtain carbon foam. Step S2: The carbon foam is washed with deionized water and anhydrous ethanol alternately 3 to 5 times to remove surface impurities, and then placed in a constant temperature drying oven to dry for 6 hours to obtain purified carbon foam. Step S3: Place commercial paraffin wax in a constant temperature oven and heat it to melt it to obtain liquid paraffin wax; Step S4: Immerse the purified carbon foam obtained in step S2 into the liquid paraffin obtained in step S3, and place them together in a vacuum drying oven for vacuum impregnation until no bubbles are generated, ensuring that the carbon foam pores are completely filled with paraffin. Step S5: Finally, remove the impregnated sample, wipe off the excess paraffin on the surface with filter paper, and allow it to cool naturally to room temperature to obtain the carbon foam / paraffin composite phase change material.
[0013] Preferably, in step S3, the temperature of the paraffin placed in the constant temperature drying oven is at least 50°C higher than the phase transition temperature of the paraffin.
[0014] Preferably, in step S4, the purified carbon foam is immersed in liquid paraffin and placed in a vacuum drying oven for vacuuming.
[0015] Preferably, in step S5, the sample surface is wiped with filter paper until no paraffin residue remains on the filter paper surface.
[0016] Preferably, the application of the carbon foam / paraffin composite phase change material in the thermal management of lithium-ion batteries is characterized in that the composite phase change material is processed into a through-hole heat dissipation module with the shape of a lithium-ion battery, wherein the through-hole size of the heat dissipation module is approximately proportional to the size of the lithium-ion battery. This ensures that the cylindrical lithium-ion battery can be tightly embedded in the through-hole, forming a battery heat dissipation module.
[0017] The composite phase change material, its preparation method, and its application of the present invention have the following beneficial effects: Carbon foam prepared using low-cost melamine foam as a template and then combined with paraffin wax results in a low-cost carbon foam / paraffin composite phase change material. Furthermore, the density of this foamed carbon / paraffin composite phase change material is low, significantly lower than that of metal foams such as copper and aluminum foams, thus significantly reducing the weight of the battery heat dissipation module; its thermal conductivity is also significantly improved compared to pure paraffin wax.
[0018] This invention has good thermal stability, meeting the operating temperature requirements of lithium-ion batteries; the porous structure of carbon foam fixes paraffin through capillary action, with no leakage or cracking during the phase change process, and the morphological change rate of its battery heat dissipation module does not exceed 5% after repeated use.
[0019] When applied to lithium-ion batteries, it can effectively control the battery surface temperature at a safe operating temperature for a longer period of time; moreover, its preparation process does not require complex equipment, the carbonization and vacuum impregnation processes are easy to scale up, and the raw materials are readily available, making it suitable for industrial promotion. Attached Figure Description
[0020] Figure 1 This is a flowchart of the preparation method of the foamed carbon / paraffin composite phase change material; Figure 2 This diagram illustrates the application of carbon foam / paraffin composite phase change materials in the thermal management of lithium-ion batteries. Detailed Implementation
[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0022] like Figure 1 As shown, a method for preparing a carbon foam / paraffin composite phase change material includes the following steps: Step S1: Cut the melamine foam into suitable sizes, place it in the ceramic boat of the tube furnace, purge the air with nitrogen, start the tube furnace and carbonize it according to the step heating program. After the temperature reaches the target temperature, hold it at that temperature for 1 hour. After carbonization is completed, let it cool naturally to room temperature to obtain carbon foam. Step S2: The carbon foam is washed with deionized water and anhydrous ethanol alternately 3 to 5 times to remove surface impurities, and then placed in a constant temperature drying oven to dry for 6 hours to obtain purified carbon foam. Step S3: Place commercial paraffin wax in a constant temperature oven and heat it to melt it to obtain liquid paraffin wax; Step S4: Immerse the purified carbon foam obtained in step S2 into the liquid paraffin obtained in step S3, and place them together in a vacuum drying oven for vacuum impregnation until no bubbles are generated, ensuring that the carbon foam pores are completely filled with paraffin. Step S5: Finally, remove the impregnated sample, wipe off the excess paraffin on the surface with filter paper, and allow it to cool naturally to room temperature to obtain the carbon foam / paraffin composite phase change material.
[0023] Example 1: The foamed carbon / paraffin composite phase change material described in this example comprises: foamed carbon and paraffin filling the pores of the foamed carbon. The target carbonization temperature of the foamed carbon is 800℃. The physicochemical parameters of the foamed carbon / paraffin composite phase change material are: melting point 47.78℃, latent heat 239.61 J / g, thermal conductivity 0.36 W / m / K, and density 0.89 g / cm³. 3 .
[0024] The method for preparing the foamed carbon / paraffin composite phase change material in this embodiment is implemented according to the following steps: Step S1: Cut the melamine foam into suitable sizes, place it in the ceramic boat of the tube furnace, purge the air with nitrogen, start the tube furnace and carbonize it according to the step heating program, heat it to the target temperature of 800℃ at a rate of 0.5℃ / min, and hold it at that temperature for 1 hour. After carbonization, let it cool naturally to room temperature to obtain carbon foam. Step S2: The carbon foam is washed with deionized water and anhydrous ethanol alternately 3 to 5 times to remove surface impurities, and then placed in a constant temperature drying oven to dry for 6 hours to obtain purified carbon foam CF-800. Step S3: Place commercial paraffin with a melting point of 47°C in a constant temperature oven and heat to melt it to obtain liquid paraffin; Step S4: Immerse the purified carbon foam CF-800 obtained in step S2 into the liquid paraffin obtained in step S3, and place them together in a vacuum drying oven for vacuum impregnation until no bubbles are generated, ensuring that the carbon foam pores are completely filled with paraffin. Step S5: Finally, remove the impregnated sample, wipe off the excess paraffin on the surface with filter paper, and allow it to cool naturally to room temperature to obtain the carbon foam / paraffin composite phase change material PCM-800.
[0025] Lithium-ion batteries are embedded in the obtained foamed carbon / paraffin composite phase change material.
[0026] Example 2 differs from Example 1 in that: the target carbonization temperature of the foamed carbon is 600℃; and the physicochemical parameters of the foamed carbon / paraffin composite phase change material are: density 0.81 g / cm³. 3 The thermal conductivity is 0.56 W / m / K, and the latent heat is 218.56 J / g. Other parameters are the same as in Example 1. When the foamed carbon / paraffin composite phase change material is applied to battery thermal management, the melting point of the foamed carbon / paraffin composite phase change material needs to be controlled within the ideal temperature range of the battery, 30~50℃.
[0027] A carbon foam / paraffin composite phase change material for lithium-ion battery thermal management is disclosed. This composite phase change material is prepared by using low-cost commercial melamine foam as a template to prepare carbon foam, which is then combined with paraffin through a vacuum impregnation process. Specifically, the carbon foam is obtained by carbonizing melamine foam under nitrogen protection using a stepped heating process, and the combination of paraffin and carbon foam is achieved through vacuum impregnation. This invention solves the problems of low thermal conductivity and easy deformation and leakage in traditional pure paraffin phase change materials, as well as high cost, high density, and easy corrosion in metal-based composite phase change materials. The prepared foamed carbon / paraffin composite phase change material has low density and cost, significantly improved thermal conductivity compared to pure paraffin, and excellent thermal stability within the operating temperature range of lithium-ion batteries. Applying it to lithium-ion battery thermal management allows lithium-ion batteries to maintain their thermal stability within the phase change temperature range for a longer period, significantly outperforming traditional pure paraffin and natural air cooling solutions, providing an economical and efficient solution for battery thermal management in electric vehicles and energy storage devices.
[0028] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained: The phase change composite material of this invention is composed of phase change material and matrix material. In the process of use, it not only utilizes the latent heat of phase change of the phase change material, but also utilizes the heat transfer and leakage prevention of the matrix material. The filling of the matrix material improves the thermal conductivity of the phase change material, improves the heat transfer performance of the phase change material, and reduces the leakage risk of the phase change material.
[0029] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structures made using the contents of the present invention specification and drawings, or directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A carbon foam / paraffin composite phase change material for thermal management of lithium-ion batteries, characterized in that, The composite phase change material is a mixture of carbon foam and paraffin obtained by vacuum impregnation.
2. The carbon foam / paraffin composite phase change material according to claim 1, characterized in that, The raw material for the carbon foam is melamine foam.
3. A method for preparing the carbon foam / paraffin composite phase change material according to claim 1 or 2, characterized in that, Includes the following steps: Step S1: Cut the melamine foam into suitable sizes, place it in the ceramic boat of the tube furnace, purge the air with nitrogen, start the tube furnace and carbonize it according to the step heating program. After the temperature reaches the target temperature, hold it at that temperature for 1 hour. After carbonization is completed, let it cool naturally to room temperature to obtain carbon foam. Step S2: Wash the carbon foam from step S1 with deionized water and anhydrous ethanol alternately 3-5 times to remove surface impurities, and then dry it in a constant temperature drying oven for 6 hours to obtain purified carbon foam. Step S3: Place commercial paraffin wax in a constant temperature oven and heat it to melt it, to obtain liquid paraffin wax; Step S4: Immerse the purified carbon foam obtained in step S2 into the liquid paraffin obtained in step S3, and place them together in a vacuum drying oven for vacuum impregnation until no bubbles are generated, ensuring that the carbon foam pores are completely filled with paraffin. Step S5: Finally, remove the impregnated sample, wipe off the excess paraffin on the surface with filter paper, and allow it to cool naturally to room temperature to obtain the carbon foam / paraffin composite phase change material.
4. The method for preparing composite phase change materials according to claim 3, characterized in that, In step S3 above, the temperature of the paraffin placed in the constant temperature drying oven is at least 50°C higher than the phase transition temperature of the paraffin.
5. The method for preparing composite phase change materials according to claim 3, characterized in that, In step S4 above, the purified carbon foam is immersed in liquid paraffin and placed in a vacuum drying oven for evacuation.
6. The method for preparing composite phase change materials according to claim 3, characterized in that, In step S5 above, the sample surface is wiped with filter paper until no paraffin residue remains on the filter paper surface.
7. The application of a foamed carbon / paraffin composite phase change material obtained by the preparation method according to any one of claims 3-5 in the thermal management of lithium-ion batteries, characterized in that, The composite phase change material is processed into a through-hole heat dissipation module with the shape of a lithium-ion battery. The size of the through-hole in the heat dissipation module is determined according to the size of the lithium-ion battery. The lithium-ion battery is tightly embedded in the through-hole to form a battery heat dissipation module.