Modified preparation of Al2O3@Al microencapsulated phase change material with high durability for high-temperature thermal energy storage over 650 °C

Latent heat storage using phase change materials (PCMs) with high melting points above 600 degrees C can mitigate the fluctuation in renewable energy supply and recover energy from industrial waste heat. Microencapsulated PCMs (MEPCMs) expand the possibilities of heat utilization owing to the presence of a thermally and chemically stable coating on the PCMs. This study improves the durability of an Al-based MEPCM (melting point: 660 degrees C) with an Al2O3 coating. The conventional process for preparing Al-based MEPCMs, which involves a boehmite treatment in boiling water and a heat-oxidation treatment at high temperature, was modified by adding Al(OH)(3) before the boehmite treatment to precipitate Al(OH)(3) on the surfaces of the Al particles after the boehmite treatment. The precipitation treatment increased the thickness of the oxide coating, thereby enabling the proposed Al-based MEPCM to withstand 300 melting and solidification cycles. In addition, the Al-based MEPCM reported an excellent heat storage capacity of 186 J g(-1). This Al-based MEPCM with excellent durability and high heat storage capacity may be further developed for use in future thermal energy storage and management systems.