Nano additives-enhanced PEG /AlN composites with high cycle stability to improve thermal and heat storage properties

The low thermal conductivity and easy leakage of phase change materials are the shortcomings that hinder their further application for thermal energy storage. It is crucial how to properly match skeleton materials and phases to improve heat transfer in order to solve the above problem. Here, we systematically investigate the effects of nano additives on the phase change and thermal properties of bionic hierarchical porous aluminum nitride-polyethylene glycol (PEG/AlN) composites. Alumina (Al2O3) nanoparticles were found to have the largest enhancement effect for the thermal conductivity of PEG (84% for 4 wt% addition) compared to silica, titanium dioxide, and boron nitride. For these additives, the thermal conductivity and stability of the nano additives-enhanced PEG increase with the increase of their mass fraction. After 100 heating/cooling cycles, the thermal response curve shows that the Al2O3-enhanced PEG can maintain the phase transition behavior, and the measured phase transition temperature agrees well with the differential scanning calorimeter results. The thermal conductivity of the PEG/AlN enhanced with 4 wt% Al2O3 is 20.41 W/m·K, and the melting point and phase change enthalpy are 55.93 °C and 81.05 J/g. In addition to the great improvement in thermal response, the heat storage rate also increases by 36.10%.