Heat transport enhancement of thermal energy storage material using graphene/ceramic composites

Graphene/ceramic composites are proposed by directly depositing graphene on the insulating Al2O3 particles by chemical vapor deposition without any metal catalysts. Carbothermic reduction occurring at the Al2O3 surface is vital during the initial stage of graphene nucleation and the graphene sheet can connect with neighboring sheets to completely cover Al2O3 particles. The quality and layer number of graphene on Al2O3 can be finely tailored by changing the growth temperature and gas ratio. Graphene coated Al2O3 (G-Al2O3) composites are used as effective fillers of stearic acid (SA) to increase the thermal transport property. By the optimization of the layer number of graphene, size of Al2O3 particles and ratio of G-Al2O3/SA in a quantitative, their thermal conductivities significantly increase up to 11 folds from 0.15 to 1.65 W m−1 K−1. The great improvement is attributed to the high thermal transfer performance of graphene and excellent wettability between graphene and SA. When the G-Al2O3/SA composites with the graphene coated porous Al2O3 foam, the thermal conductivity further reaches to 2.39 W m−1 K−1, and the corresponding latent heat is 38 J g−1. It demonstrates the potential applications of graphene in thermal transport and thermal energy storage devices.