LAUSR

Phase‐change materials (PCMs) offer tremendous potential to store thermal energy during reversible phase transitions for state‐of‐the‐art applications. The practicality of these materials is adversely restricted by volume expansion, phase segregation, and leakage problems associated with conventional solid‐liquid PCMs. Solid–solid PCMs, as promising alternatives to solid–liquid PCMs, are gaining much attention toward practical thermal‐energy storage (TES) owing to their inimitable advantages such as solid‐state processing, negligible volume change during phase transition, no contamination, and long cyclic life. Herein, the aim is to provide a holistic analysis of solid–solid PCMs suitable for thermal‐energy harvesting, storage, and utilization. The developing strategies of solid–solid PCMs are presented and then the structure–property relationship is discussed, followed by potential applications. Finally, an outlook discussion with momentous challenges and future directions is presented. Hopefully, this review will provide a guideline to the scientific community to develop high‐performance solid–solid PCMs for advanced TES applications.