Traditional Mg(OH)2/MgO systems suffer increased heat losses from evaporation-condensation

limiting storage efficiency to about 70%. To address these limitations

this study proposes an innovative pressure self-balancing thermochemical cascaded storage system. A numerical model is developed to simulate the coupled operation of thermochemical storage and high-pressure hot water storage for cascaded thermal energy storage. Energy conversion configurations are systematically optimized through parametric studies. The results demonstrate that compared with traditional Mg(OH)2/MgO thermochemical storage systems

the proposed system

when integrated with high-pressure hot water storage

achieves a maximum increase in thermal energy storage efficiency of 28.17%. By utilizing thermochemical reactions for high-grade heat storage and release

the system’s exergy efficiency improves from 58.35% to 82.88%. These findings provide valuable guidance for the design and optimization of medium- and low-temperature thermal energy storage systems.