Optimized Preparation of a Low-Working-Temperature Gallium Metal-Based Microencapsulated Phase Change Material

Gallium has been considered for application in the thermal management of electronic equipment because of its high heat transfer ability and heat storage density. To address the issues of metal corrosion and leakage, a microencapsulation method, through which a stable corrosion-resistant ceramic shell can be formed from the liquid metal, is proposed. In this study, an optimized fabrication method for a microencapsulated phase change material (MEPCM) consisting of liquid-state Ga droplets, possessing high durability and heat storage density, is presented. A fabrication route comprising particle formation, hydrothermal treatment, and calcination is proposed. In particular, the thickness and crystal size of the GaOOH shell are controlled by changing the pH during hydrothermal treatment to produce a highly durable shell. The morphology and microstructure, phase composition, heat storage capacity, and durability of the prepared Ga-MEPCM are investigated. In addition, treatment conditions and the shell formation mechanism are analyzed. The results show that pH 9 is the most suitable shell-forming condition, at which the thickest Ga₂O₃ shell with the smallest crystal size can be produced, which is beneficial for ensuring durability. The MEPCM achieved 200 cycles without leakage and 300 cycles without shape deformation with a high heat storage density of 369.4 J·cm^-3.