Synthesis and characterization of a novel high durability alloy microcapsule for thermal energy storage

Abstract Microcapsules can prevent leakage and increase the specific surface area of phase change materials (PCMs). Among them, metal microcapsule has great application prospects in the field of medium/high temperature thermal energy storage. However, it is easy to break after thermal cycling which seriously hinder its industrial application. To solve this problem, a novel alloy microcapsule with a void was prepared successfully with SnBi58 alloy as the core and TiO2 as the shell by “double-layer coating, sacrificial inner layer” method, which can accommodate volume expansion during heat storage, thus fundamentally solving the problem of microcapsule break caused by thermal expansion. The test results indicated that the SnBi58 microcapsules melt at 141.1°Cand crystallize at 128.1 °C. It has latent heats of 46.61 J/g and 38.20 J/g for melting and crystallization, respectively. The thermal cycle test also showed that MEPCM with a void has better thermal reliability and durability than that of MEPCM without void. In addition, due to the wall material of TiO2, the microcapsules showed good photocatalytic performance. Furthermore, “double-layer coating, sacrificial inner layer” method can be widely used to prepare other metal microcapsule and it provides a new perspective for metal microencapsulation.