Synthesis of form-stabilized Al/Al2O3 composite phase change materials for high-temperature thermal energy storage

Phase change thermal storage represents a valid solution to the problem of renewable energy indirection. Metals have a high heat storage density and high thermal conductivity, making them a promising material for high-temperature phase change materials, yet limited in application by corrosion. As a solution, a boiling and cold pressing with subsequent calcination method was proposed for the development of shape-stabilized PCMs with Al as a phase change material and Al₂O₃ as the matrix. A three-step preparation process was involved: (1) Generation of precursor shell layer on the surface of Al micropowder by boiling water treatment. This step was crucial for leakage prevention. (2) Stabilization and composite formation of the phase change material by cold pressing. In this step, we carefully studied the effect of pressure on the structural strength of composite phase change materials (PCCMs) and finally concluded that 10 MPa was the optimal cold pressure. (3) Formation of structurally stable PCCM was finalized by thermal oxidation treatment. The phase transition temperature and latent heat of phase transition of PCCM were 653°C and 68 J/g, respectively. Importantly, these phase transition properties remained consistent over 100 thermal cycles, indicating a good cycling property. These results inform the application of metallic Al in high-temperature thermal storage.