Mn-based oxides modified with MnSiO3 for thermochemical energy storage

Affordable and durable metal oxide thermochemical energy storage (TCES) materials possess the capability to meet the large-scale energy storage requirements of next-generation concentrated solar power (CSP) plants. Iron-doped manganese oxide has garnered increasing attention owing to its non-toxicity, low cost, and high energy capacity at temperatures exceeding 800 degrees C. However, the challenge of sintering at high temperatures has posed difficulties in maintaining the excellent performance of thermal storage materials over long-term cycles. This study introduces the surface modifier MnSiO3 into Mn-based oxide (Mn0.8Fe0.2)(2)O-3 to inhibit grain agglomeration. The effects of preparation methods and silicon precursors on the properties of synthesized MnSiO3 are investigated. The sample doped with 1 wt% MnSiO3 demonstrates excellent conversion rate during cycling and retains 94.9 % of its heat storage capacity after 1000 redox cycles. Characterization techniques indicate that MnSiO3 adhered uniformly to the surface of Mn-Fe oxides without forming any new phase even after 1000 redox cycles. By performing density functional theory (DFT) calculations, the higher formation energy and migration barrier for Mn vacancies are determined, thereby confirming the anti-sintering effect of MnSiO3 at high temperature. And the interaction between the surface modifiers and Mn-Fe oxides is analyzed, providing a deeper understanding of the long-term stable adhesion mechanism at their interface. This study guides performance improvement and modification design for Mn-based metal oxides while also laying a solid foundation for the large-scale practical application of cost-effective and high-temperature thermochemical energy storage materials.