CaCl2·6H2O/Expanded graphite composite as form-stable phase change materials for thermal energy storage

In this study, CaCl2·6H2O/expanded graphite (EG) composite was prepared as a novel form-stable composite phase change material (PCM) through vacuum impregnation method. CaCl2·6H2O used as the PCM was dispersed by surfactant and then, was absorbed into the porous structure of the EG. The surfactant was used to enhance the bonding energy between CaCl2·6H2O and EG, which fulfilled the composites with good sealing performance and limited the leakage of the inside CaCl2·6H2O. Differential scanning calorimetry and thermal gravimetric analysis show that all the composite PCMs possess good thermal energy storage behavior and thermal stability. Thermal conductivity measurement displays that the conductivities of the samples have been significantly improved due to the highly thermal conductive EG. The thermal conductivity of the sample including 50 mass% CaCl2·6H2O (8.796 W m−1 K−1) is 14 times as that of pure CaCl2·6H2O (0.596 W m−1 K−1). Therefore, the obtained composite PCMs are promising for thermal energy storage applications.