Enhanced thermal conductivity of composite phase change materials based on carbon modified expanded perlite

Phase change materials (PCMs) have attracted growing attention in clean energy storage fields. To improve the thermal conductivity of porous mineral-based composite PCMs (c-PCMs), pretreatment via in-situ carbonization is proposed to fill the pore structure with thermally conductive carbon. After vacuum impregnation, high-performance c-PCMs are obtained, comprising carbon-modified expanded perlite (EPC) and polyethylene glycol (PEG). The modified micro-pores optimize the heat transfer characteristic behaviors in c-PCMs and improve the adsorption stability of PEG. Thus, the load capacity of PEG reaches approximately 73.90 wt% in EPC/PEG c-PCMs, providing excellent chemical and structural stability among perlite matrix, carbon modifier and PEG PCMs. The thermal conductivity of the EPC/PEG c-PCMs is 0.521 W/(m·K), which is almost 1.3 times that of the pristine PEG. These performances indicate that the EPC/PEG c-PCMs could be used as an environmentally friendly material for external wall heat-insulation application. •The micro-pores and carbon skeleton were developed in expanded perlite modified by sucrose after a carbonation process.•Low-cost, high thermal conductivity, shape-stable c-PCMs were composed of modified expanded perlite and polyethylene glycol.•The mass fraction of PEG in PEG/EPC c-PCMs was 73.90% approximately.•The as-prepared c-PCMs exhibited excellent thermal energy storage performance.