High-temperature energy storage is very important for solar power systems with advanced thermal cycles. Manganese oxides are considerable materials for high temperature thermochemical energy storage (800-1000℃) due to the merits of low-cost and non-toxic. However, pure Mn2O3/Mn3O4 redox couple suffers low re-oxidation rate and poor cycling stability. Fe-doped Mn2O3 is expected to improve the reaction characteristics, by using a sol-gel synthesis method. The reversibility and cyclic stability are significantly enhanced by the adoption of Fe, verified by over 10 TGA experimental cycles. As to crystallographic analysis, tetragonal spinel and phases cubic spinel were detected in the reduced materials. Jacobsite (MnFe2O4) is regarded as the vital for the promotion, while (Mn0.8Fe0.2)2O3 exhibits good adaptability under different oxygen partial pressure. Lab-scaled honeycomb materials were investigated for over 100 reduction-oxidation cycles, with an average reaction ratio of 87.9%, which indicates an excellent cyclic stability of iron doped manganese oxides for solar thermochemical energy storage.
Keywords thermochemical energy storage, metal oxides, reversible reaction