Optimization strategies of microencapsulated phase change materials for thermal energy storage

Phase change materials (PCMs) have attracted much attention for their ability to store and release sizeable latent heat via the isothermal phase transition process. However, pure PCMs have the disadvantages of leakage and low thermal conductivity. Encapsulation technology has become a research hotspot, which can play an active role in improving these problems. Although the heat storage performance of microencapsulated phase change materials (MEPCMs) is better than that of pure PCMs, the disadvantages of high supercooling, poor mechanical durability still needs to be improved. There are some reviews on the encapsulation of PCMs or the practical application of MEPCMs. Still, few reviews focus integrally on thermal storage performance optimization strategies and the preparation of MEPCMs. We introduce the encapsulation methods of PCMs including physical, chemical, and physical-chemical methods, and present the advantages and disadvantages of these methods. Increasing thermal conductivity, reducing supercooling, and enhancing mechanical durability are vital to improve the performance of MEPCMs. These measures include modifying the shell materials, changing the core-shell structure and core-shell ratio, adding nucleating agents, etc. We hope that this review will serve as a useful guide and contribute to the preparation and performance optimization of MEPCMs.