Graphene Modified Montmorillonite Based Phase Change Material for Thermal Energy Storage with Enhanced Interfacial Thermal Transfer

Thermal energy storage technology plays a crucial role in the thermal management system. Clay based organic phase change material has considerable advantages in the application of thermal energy storage due to low cost and high energy storage capacity. However, the low thermal conductivity of clay, especially poor interfacial thermal transfer, limits its thermal energy storage efficiency. Herein, stearic acid/reduced graphene oxide modified montmorillonite composites (SA/RGO-MMT) were prepared by the vacuum impregnation of stearic acid into graphene modified montmorillonite matrix, which was obtained via the in situ reduction of graphene oxide on the surface of montmorillonite. Stearic acid is assembled in the porous structures of RGO-MMT with the physical interactions. SA/RGO-MMT possesses high melting enthalpy of 159 J/g, low extent of supercooling of 1.4 oC and excellent thermal reliability after 100 thermal cycling. Energy storage and release rates of SA/RGO-MMT were significantly improved due to the enhanced interfacial thermal transfer by graphene. Therefore, SA/RGO-MMT is a promising form-stable phase change material for applications in solar heat storage fields. The strategy in this study highlights the importance of enhancing interfacial thermal transfer for the efficient thermal energy storage materials.