A review of modification strategies and applications for hydrated salts: Insights from energy storage materials encapsulation technology

As the demand for thermal energy storage continues to rise, hydrated salts have emerged as a highly promising thermochemical material, thanks to their high energy storage density, cost-effectiveness, appropriate phase-change temperatures, and material availability. However, hydrated salts have yet to cross the gap from laboratory research to large-scale application due to various inherent defects such as supercooling, phase separation, and poor thermal cycling stability. This review innovatively provides a comprehensive and systematic analysis of hydrated salts as an emerging energy storage material, covering their entire lifecycle from classification and thermophysical properties to energy storage mechanisms, modification strategies, and application potential. First, hydrated salts are systematically classified based on their chemical composition, and representative thermophysical parameters are summarized in detail. Subsequently, the energy storage mechanisms of hydrated salts are elaborated from both macroscopic and microscopic perspectives. To address the inherent defects of hydrated salts, we review existing solutions, integrate encapsulation technologies with existing modifications, and innovatively propose a comprehensive modification framework, aiming to optimize modification effects while minimizing the loss of energy storage performance. Finally, the current primary application directions of hydrated salts are summarized and their potential underexplored in waste heat recovery from power plants, agricultural insulation systems, and seawater desalination is prospectively highlighted. By integrating fundamental research with practical applications, this review serves as a comprehensive reference for researchers new to hydrated salts and offers innovative insights for advancing their modification, large-scale development, and commercialization.