Deep Eutectic Solvents: Physicochemical Properties and Challenges in Applications as Phase Change Materials in Thermal Energy Storage

Deep eutectic solvents (DESs) have emerged as versatile and highly tunable solvents for a variety of applications. This review explores properties of different DES-based phase change materials (PCMs), highlighting their potential and challenges for latent heat thermal energy storage (LHTES). Key challenges such as supercooling, thermal stability, thermal conductivity, and thermophysical properties such as melting temperature, heat of fusion, heat capacities, viscosities, and densities of DESs are discussed along with strategies to improve their thermophysical properties. By reviewing recent advances, this study aims to provide a comprehensive understanding of DESs as next-generation PCMs for renewable energy applications. This work is also a source of curated, extensive data sets for future research directions in the field of LHTES systems and related applications.