Analysis of solid-state reaction in the performance of doped calcium manganites for thermal storage

Solid-state reaction is a potentially cost-effective route to obtain perovskite-type materials suitable for thermochemical energy storage (TCES). This work analyses the influence of the synthesis conditions on a doped calcium manganite, CaCr0.1Mn0.9O3-delta, since it has been identified as a promising material for TCES. The macrostructure shows noticeable dependence with mixing time of precursors. The perovskite, with general chemical formula ABO(3), possesses secondary phases for all the synthesis conditions explored, as confirmed by X-ray diffraction analysis. The dopant effect of chromium on the crystallographic lattice is studied by the Rietvel refinement method from the comparison with CaMnO3-delta compound structure. Customized non-isothermal and isothermal experiments are performed via thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). From these experiments, an oxidation temperature of around 900 degrees C; energy storage density higher than 150 J/g; reaction reversibility and stable cycling performance are obtained, facts that reflect a high potential for application in concentrating solar power plants.