Recent developments in solid-solid phase change materials for thermal energy storage applications

Phase change materials (PCM) have been widely used in thermal energy storage fields. As a kind of important PCMs, solid-solid PCMs possess unique advantages of low subcooling, low volume expansion, good thermal stability, suitable latent heat, and thermal conductivity, and have attracted great attention in recent years. In this review, the application and preparation method of solid-solid PCMs were introduced. The preparation methods mainly consist chemical grafting, block polymerization and cross-linking polymerization. In terms of performance improvement, the enthalpy, thermal conductivity, mechanical properties, and thermal stability of PCMs were comprehensively illustrated. The research advances of solid-solid PCMs were mainly summarized in several application fields, including lithium-ion battery thermal management, solar energy storage, building energy conservation and other thermal storage fields. Finally, the current challenges and probable recommendations of solid-solid PCMs for thermal energy storage was put forward. Although some properties of solid-solid PCMs still need further research, they have good prospects for future thermal energy storage applications. This review provides latest progress and ideas for the design, preparation, and application research of new solid-solid PCMs.