Palmitic acid/expanded graphite/CuS composite phase change materials toward efficient thermal storage and photothermal conversion.

In this study, an expanded graphite (EG) with nano-CuS (EG/CuS) support material with a special morphology was prepared, with EG/CuS filled with different ratios of palmitic acid (PA). Finally, a PA/EG/CuS composite phase change thermal storage material with photothermal conversion performance was synthesized. The superb chemical and thermal stability of PA/EG/CuS was demonstrated by characterization and analysis of the experiments. EG, a multi-layer structured material, provides rich binding sites for PA and nano-CuS and constructs rich thermal conductivity paths, which effectively improves the thermal conductivity of PA/EG/CuS. It is noted that the maximum thermal conductivity of PA/EG/CuS reached 0.372 W m K and the maximum phase change thermal storage capacity reached 260.4 kJ kg, which proved the excellent thermal storage properties of PA/EG/CuS. In addition, PA/EG/CuS exhibits excellent photothermal conversion performance, and the experimental results demonstrated that the best photothermal conversion efficiency of PA/EG/CuS reached 81.4%. The PA/EG/CuS developed in this study provides a promising method for fabricating excellent conductive and low leakage composite phase change materials for solar energy utilization and energy storage.