Medium-Entropy perovskites Sr(FeαTiβCoγMnζ)O3- as promising cathodes for intermediate temperature solid oxide fuel cell

Medium-entropy perovskites Sr(FeαTiβCoγMnζ)O3-δ (SFTCM) are investigated as potential cathodes for intermediate temperature solid oxide fuel cell (IT-SOFC). The effects of entropy on crystal structure, thermal expansion coefficients (TEC), electrical conductivity, oxygen surface exchange and bulk diffusion coefficients, electrochemical performance, and long-term stability of SFTCM are systematically investigated. High entropy facilitates the diffusion of oxygen ions but hinders the transmission of electrons. The SFTCM with higher entropy shows a lower TEC, displays suppressed strontium surface segregation, and delivers more stable polarization resistance. Although the catalytic activity towards oxygen reduction reaction was slightly reduced, the maximum power density of the LSGM-supported (250 μm) single cell with SrFe0.25Ti0.25Co0.25Mn0.25O3-δ cathode can still reach 0.85 W cm−2 at 800 °C. All these results suggest that the medium-entropy SFTCM perovskites can be promising cathodes materials for IT-SOFC.