Cost-Effective（Sr,Ca）FeO₃-Based Cathodes: Structural Stability and Electrochemical Performance =

Abstract

Solid oxide fuel cells （SOFCs） Solid oxide fuel cells （SOFCs） are promising next- generation energy conversion systems owing to their high efficiency and fuel flexibility. Although La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ （LSCF） has been widely used as a cathode material due to its high conductivity and oxygen reduction activity, its reliance on costly and resource-limited elements such as La and Co motivates the development of alternative cathodes. In this study, low-cost La- and Co-free （Sr,Ca）FeO₃-based perovskite cathodes were designed to improve the structural instability and low electronic conductivity of CaFeO₃. Sr²⁺ was introduced to enhance structural stability, while B-site transition metal doping was employed to improve conductivity and catalytic activity. A machine learning-based prediction model was used to screen the effects of dopants on ionic and electronic conductivity, and selected candidates were synthesized and experimentally validated. The phase structure, surface chemical states, electronic conductivity, and ionic conductivity were evaluated using XRD, XPS, four-probe measurements, and O₂ permeation tests, respectively. This study suggests that （Sr,Ca）FeO₃-based perovskites can serve as promising low-cost cathode candidates for next-generation SOFCs.