Review of Recent Developments in Thermochemical Energy Storage Materials and Systems

Thermochemical energy storage (TES) is emerging as a transformative solution for enhancing thermal energy management in buildings and industrial applications. Unlike conventional sensible and latent heat storage, TES systems store energy through reversible chemical reactions, offering significantly higher energy densities and minimal standby losses. This review provides a comprehensive overview of recent developments in TES materials and system configurations, including both closed-cycle systems (e.g., chemical heat pumps, adsorption/absorption cycles) and open-cycle systems integrated with solar thermal collectors. Advances in material engineering—particularly in salt hydrates, composite sorbents, and nanostructured materials—have led to improvements in cyclic stability, regeneration temperature, and thermal efficiency. The paper also highlights innovative reactor designs such as fixed-bed, fluidized-bed, and plate-fin heat exchangers, alongside smart control and additive manufacturing approaches. Key technical challenges, including reaction kinetics, long-term stability, and heat/mass transfer complexity, are discussed to identify future research needs. This review aims to support the development of high-performance, scalable TES systems for sustainable and flexible energy infrastructure.