Graphene aerogels with reversible adjustable thermal resistance are used for battery thermal management.

　　1 Introduction to the results

　　Thermal management of electronic equipment under extreme temperature conditions is very important. Carbon-based materials with low thermal resistance are beneficial to cooling electronic equipment, while aerogels with high thermal resistance play a role in heat insulation. However, it is a great challenge to use the same materials to achieve heat conduction and insulation. In this paper, Professor Zhang Xueqiao, Professor Cai Weiwei and Associate Professor Zhang Yufeng of Xiamen University published a paper entitled "Graphene Aerogel with Reversible Tunable Thermal Resistance for Battery Thermal Management", and studied the synthesis of graphene aerogels by solvothermal method. High temperature annealing reduced the thermal resistance of graphene aerogels. Elastic graphene aerogel with adjustable thermal resistance makes it possible to have dual functions of heat insulation and heat conduction. The thermal resistance of graphene aerogels with 80% compressive strain is 3.3 times lower than that of the original state. In the thermal management process of lithium ion battery (LIB), the original graphene aerogel is like a thermal insulator, which can prevent the heat loss of LIB when the ambient temperature is low (-20 C), thus increasing the temperature by 9 C and the discharge capacity of LIB by 26%. On the contrary, when the working temperature is high (40°C), the compressed graphene aerogel with low thermal resistance acts as a thermal interface materials, which radiates excessive heat from LIB to prevent overheating.

　　2 Graphic reading guide

　　Figure 1. Thermal properties and characterization of GA and GA3000

　　Figure 2. Thermal and Mechanical Properties of GA3000

　　Figure 3. Structural basis of GA3000 for LIB thermal management

　　Figure 4. A/b) Schematic diagram of LIB thermal management system working in cold and hot environment. (c-g) Comparison of lib surface temperatures at -20℃ and 40℃ based on COMSOL simulation, and (f) Schematic diagram of contact interface between LIBS and ga3000. H) schematic diagram of contact interface between libs and CGA3000.

　　Figure 5. Thermal management of LIB in hot and cold environment.

　　3 summary

　　In this study, graphene aerogel was synthesized by solvothermal method, and the thermal conductivity of graphene aerogel was improved by high temperature annealing. The thermal resistance of GA3000 can be reversibly adjusted by simply changing the strain, making it a functional material suitable for thermal management system, and the temperature of lib can be adjusted according to environmental conditions. The elastic graphene aerogel with adjustable thermal resistance makes it possible to have dual functions of heat insulation and heat conduction. The research results provide a novel solution for LIB and other devices working in a wide temperature range to design an adaptive thermal management system.

　　Literature: https://doi.org/10.1039/D3TA03190J

　　Source: material analysis and application