Al–Ce Co-modified for enhanced long-cycle performance of CaCO3-Based thermochemical energy storage materials

Ca-looping-driven thermochemical energy storage (TCES) materials are highly promising options for next-generation concentrated solar power (CSP) applications. However, the heat storage performance of pure Ca-based materials largely deteriorates after repeated cycles, reducing the operational lifespan of CSP plants. To improve the cycling stability of TCES materials, a sol–gel-based strategy is developed that introduces Al and Ce into CaCO 3 powders. After 50 cycles, the conversion rates of CaCO 3 -based composites exceed 80 % and the heat storage densities reach 1600 kJ/kg, with the composite with a Ca:Al:Ce molar ratio of 100:10:2.5 exhibiting exceptional stability. This high performance is attributed to oxygen vacancies generated by Ce 3+ and the porous structure preserved by Al 3+ throughout the cycling process. Furthermore, the adsorption energies of the CaO-based composites (pertaining to the (002) plane) are calculated using density functional theory. The results showed that the N-10 M ratio can decrease the adsorption energy of CaO for CO 2 from −1.5006 to −1.6718 eV and shorten the bond length between C CO2 and O CaO from 1.41 to 1.38 Å. Furthermore, PDOS curves of C and O on N-10 exhibit a significant shift toward lower energy regions. These results demonstrate that the addition of Al and Ce can enhance the CO 2 -capture capacity. Alongside presenting a new doping strategy, this study elucidates the microscopic physical mechanism by which Al and Ce improve the properties of CaO-based materials, offering valuable guidance for developing high-performance TCES materials for CSP applications.