Ruddlesden‐Popper‐type perovskite Sr3Fe2O7−δ for enhanced thermochemical energy storage

Abstract Perovskite has been considered a promising thermochemical energy storage material. Such materials can perform redox reactions reversibly under the control of oxygen partial pressure over a wide range of temperatures. Layered perovskites have been poorly studied as energy storage material, although their oxygen species exhibit good oxidation activity. In this work, Ruddlesden‐Popper‐type quasi‐2D perovskite Sr3Fe2O7‐δ and 3D perovskite SrFeO3‐δ were prepared for the testing of thermochemical energy storage properties. It was shown that the degree of reduction reaction for Sr3Fe2O7‐δ was much greater than that of SrFeO3‐δ, with change of non‐stoichiometry up to 0.79. The combined effect of thermodynamic parameters for samples on heat storage behavior was studied by Van't Hoff method. The reduction entropy of Sr3Fe2O7‐δ is much higher than that of SrFeO3‐δ, which explains the large promotion in the reaction degree of SrFeO3‐δ. The total reduction enthalpy of Sr3Fe2O7‐δ is about 2.8 times that of SrFeO3‐δ, with both reduction enthalpy and reaction entropy affecting the heat storage capacity. Sr3Fe2O7‐δ also has an attractive spectral absorption of 96.92% in the range of 300–2500 nm, which makes it advantageous in volumetric solar collector. Overall, Sr3Fe2O7‐δ offers improved performance in terms of thermochemical energy storage compared to SrFeO3‐δ.