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

Abstract

Latent heat storage using phase change materials (PCMs) with high melting points above 600 °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 °C) with an Al 2 O 3 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. • Al-based microencapsulated phase change materials (MEPCMs) were developed. • The MEPCMs exhibited a high thermal storage capacity about 186 J g −1 . • The MEPCM exhibited high cyclic durability over 300 cycles. • The MEPCMs are promising for high-temperature thermal energy storage application.