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Summary High‐temperature solid oxide fuel cells (HT‐SOFCs) generally operate at 800°C to 1000°C and intermediate temperature SOFCs (IT‐SOFCs) at 600°C to 800°C. Reducing the SOFCs operational from high to ITs results in many issues mainly at the cathode site. One of the shortcomings that have been addressed is high polarization losses associated with oxygen reduction reaction (ORR) and degradation of La1−xSrxCo1−yFeyO3−δ (LSCF) cathode materials. Strontium (Sr) has been discovered to segregate and inhibit the surface‐active site for the ORR under specified conditions (temperature, relative humidity, and suppressing activity). It enriched the surface, formed Sr‐rich secondary phases, and eventually changes the composition and the structure of the perovskite surfaces. Therefore, this review aims to summarize the occurrences of Sr segregation at the LSCF cathode surfaces as a function of operating conditions and their effects on the material performance. In addition, the characterization techniques utilized to investigate the Sr segregation, and strategies for Sr segregation mitigation are also discussed.

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Proton-conducting ceramics based on perovskite-type oxides have been significantly applied in a wide range of electrochemical devices such as fuel cells, hydrogen sensors, and steam electrolysers. One of the emerging applications of these ceramic proton conductors is as an electrolyte component in a solid oxide fuel cell (SOFC), where the proton is mobilized from the anode to the cathode side via these conductors. The proton (hydrogen ion) diffusion mechanisms and activation energies (Ea) in these materials are heavily influenced by their composition, stoichiometry, and crystal structure. Hence, this review presents and discusses the mechanism of hydrogen ion movement for proton-conducting solid oxide fuel cells or known as proton ceramic fuel cells (PCFCs), based on experimental and modelling data, including the vehicular and the Grotthuss mechanisms. This review will provide a brief understanding of the connection between experimental and modelling evidence for proton mechanisms in perovskite electrolyte materials.