Efficient preparation of GO-modified regular spherical SiO2@CaCl2·6H2O phase change microcapsules for enhanced thermal energy storage

Hydrated salt phase change materials have great application value in passive thermoregulation fields due to their low phase change temperature. However, their practical applications are limited by problems such as leakage and phase separation, which require urgent attention. To solve these problems, in this study, a W/O emulsion system was constructed by sol-gel method, and microencapsulated composites with graphene oxide (GO) as the thermally conductive reinforcing phase, silica as the shell material, and calcium chloride hexahydrate (CaCl2·6H2O, CCH) as the core material was prepared. The regular spherical SiO2 shell layer effectively reduces the possibility of leakage of the core material. The excellent thermal conductivity of GO increases the thermal conductivity of the composites by about 41.14 % compared with that of pure CCH and maintains a latent heat of >114.1 J/g. The encapsulation of SiO2 and the introduction of GO improve the thermal cycling stability of the composites. After 150 thermal cycles, the composites still had 96.5 % (110.1 J/g) latent heat and 99.6 % (0.708 W·m−1·K−1) thermal conductivity. The GO/SiO2@CCH microencapsulated composites had good temperature regulation. This study provides a promising solution for preparing hydrated salt-based shape-stabilized composites and expands their applications in construction and other fields.