Study of co-promotion mechanism of Zr-Mn co-doped CaO-based composite for solar thermochemical energy storage

Ca-based materials are considered to be promising energy storage materials for the 3rd generation concentrated solar power (CSP) plants due to their high energy storage density , high operating temperature , and low energy loss . However, the poor cyclic stability, low solar absorption capability, and slow reaction kinetics of conventional Ca-based materials seriously limit large-scale applications. Here, we successfully synthesized a Zr-Mn co-doped CaO-based composite, achieving good cyclic stability, enhanced solar absorption capability, and fast carbonation reaction kinetics simultaneously. The energy storage performance of 20Ca-0.5Zr-0.5Mn was evaluated at a high carbonation reaction temperature of 850 °C. Results showed that the performance decay of 20Ca-0.5Zr-0.5Mn was only 10.11 % over 30 cycles. By co-doping Zr and Mn elements, the carbonation reaction kinetics of CaO-based composites were promoted because of increased basicity and oxygen vacancies . Compared with pure CaO, the average solar absorptance of 20Ca-0.5Zr-0.5Mn was enhanced by about 376 %. Therefore, the proposed Zr-Mn co-doped CaO-based composite indicates the bright applied prospect in CSP plants for solar energy storage .