Ruddlesden‐Popper‐type perovskite Sr₃Fe₂O_7−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 Sr₃Fe₂O_7‐δ and 3D perovskite SrFeO_3‐δ were prepared for the testing of thermochemical energy storage properties. It was shown that the degree of reduction reaction for Sr₃Fe₂O_7‐δ was much greater than that of SrFeO_3‐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 Sr₃Fe₂O_7‐δ is much higher than that of SrFeO_3‐δ, which explains the large promotion in the reaction degree of SrFeO_3‐δ. The total reduction enthalpy of Sr₃Fe₂O_7‐δ is about 2.8 times that of SrFeO_3‐δ, with both reduction enthalpy and reaction entropy affecting the heat storage capacity. Sr₃Fe₂O_7‐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, Sr₃Fe₂O_7‐δ offers improved performance in terms of thermochemical energy storage compared to SrFeO_3‐δ. image