Phase-change thermal energy storage: Materials, thermophysics and emerging applications

Phase change materials (PCMs) can reversibly store and release considerable thermal energy through nearly isothermal and isometric phase state transitions, thus have attracted broad attention in energy decarbonization, passive thermal management, and emerging fields such as medicine and intelligent robots. However, critical challenges at material, device, and system levels remain to be addressed. These include the development of pure or composite PCMs with superior thermophysical properties, the design of effective latent heat storage devices, and the optimization of system integration. This review provides a comprehensive overview of phase change thermal storage, beginning with the mechanisms underlying the regulation of PCMs’ thermophysical properties. We summarize recent advances in the physical and chemical modification of PCMs by molecular engineering, multi-component doping, and rational design of composite microstructure and morphology to improve thermodynamic and heat-transfer performance. We then highlight advanced latent heat storage device design using passive and active strategies for increasing both energy and power density, and outline PCM-integrated systems across multifunctional applications including energy harvesting and storage, thermal management, medical treatment, intelligent machine, and catalysis. Finally, we discuss future research directions towards next-generation PCMs, high-performance devices and intelligent system integration.