Constructing heat conduction path and flexible support skeleton for PEG-based phase change composites through salt template method

Abstract

Phase change materials (PCMs) have been widely applied to various occasions for their merit of constant temperature during energy storage process. However, the risks of leakage, low thermal conductivity, and brittleness severely limit the applications of PCMs. In this work, the shape-stabilized phase change composites (PCCs) with high thermal conductivity and heat storage density were fabricated by vacuum impregnation of natural rubber (NR)-expanded graphite (EG) skeleton material in polyethylene glycol (PEG) above phase change temperature, and the NR-EG skeleton was prepared by salt template method. In detail, the obtained NR-EG85@PEG exhibits high thermal conductivity of 1.05 W/(m·K) and high phase change enthalpy of 144.11 J/g. Benefiting from high thermal conductivity and enthalpy, the PCCs show remarkably rapid energy storage and thermoelectric conversion efficiency to drive windmill. In addition, the PCCs exhibit excellent reusability and flexibility in which the enthalpy shows negligible reduction after 500 thermal cycles and the porous skeleton of NR-EG can be compressed and recover under high pressure. The results indicate that the NR-EG85@PEG PCC displays huge application prospects in the field of industrial waste heat recovery.