Controllable Preparation And Thermal Properties Of Graphene Aerogel

With the rapid development of electronic science and technology and the arrival of 5G era,electronic devices are developing towards miniaturization,highly integrated and lightweight,accompanied by a sharp increase in the heat flux of electronic devices.Overheat will result in deteriorated performance or even failure of electronic devices and now become the bottleneck for further development of microelectronics.Thermal interface materials(TIMs),an important research branch of thermal management,fill in the gap between electronic devices and heat sinks to reduce the contact thermal resistance,so to dissipate the excessive heat efficiently,attracting increasingly attention.However,traditional TIMs are unable to meet the ever-increasing demands in heat dissipation for electronic devices.Graphene have been attracting intensively attention because of the high in-plane(parallel)thermal conductivity.However,low through-plane(vertical direction)thermal conductivity of graphene limits its application in TIMs.This paper intends to take advantage of the high in-plane thermal conductivity of graphene and improve its through-plane thermal conductivity by constructing three-dimensional structure.The specific research contents and conclusions in this paper are as follows:1.GA was prepared by different methods.By taking the advantages of three-dimensional graphene network,the equivalent through-plane thermal conductivity of GA was increased by 17 times by high temperature annealing.The compressive modulus of GA3000 is as low as 1.37MPa,which is beneficial to reduce the thermal contact resistance.2.The in-plane(parallel direction)and through-plane thermal conductivity of GA3000 increases simultaneously with increasing compressive strain.However,the in-plane thermal conductivity rises much faster than the through-plane thermal conductivity.The highest in-plane and through-plane thermal conductivity of GA3000 reached 95.62 W/mK and 3.30 W/mK under the 95%compressive strain,respectively.Furthermore,as TIMs,The GA3000 can effectively reduce the average and maximum temperature of a high-power LED by about 9.0 and 10.7℃,correspondingly,which is superior to the commercial thermal pad that possess higher through-plane thermal conductivity(i.e.,5 W/mK).The thermal resistance of GA3000 reaches a minimum of 0.83 cm2K/W when the compressive strain is 92%.The thermal resistance of GA3000 can be adjusted reversibly in the range of 0-80%compressive strain.3.The switching ratio of GA3000 at the compression of 80%is 3.3.The temperature and discharge capacity of LIBs worked in low temperature(-20℃)was increased by 10℃ and 26%simply by preventing the heat leakage due to the porous structure of GA3000.While the GA3000 with low thermal resistance contribute to the heat dissipating from LIBs to environment,reducing the temperature of LIBs by 17℃,preventing the lifetime and performance of LIBs are reduced caused by overheat when it works at hot environment.