Investigation of the Functional Characteristics of Pr1–xSrxFe1–γCoγO3–δ Perovskite Cathodes for Reversible Solid Oxide Fuel Cells

Abstract

A systematic investigation was conducted on perovskite-type cathode materials of the composition Pr1–хSrхFe1–γCoγO3–δ, synthesized via self-propagating high-temperature synthesis, with the aim of optimizing their performance in reversible solid oxide fuel cells (RSOFCs). Particular attention was given to the influence of Sr and Co substitution on thermal expansion, electrical conductivity, and polarization resistance under operating conditions. Detailed analyses using dilatometry, four-probe conductivity measurements, and electrochemical impedance spectroscopy revealed that moderate strontium substitution (x = 0.2–0.3) provides the most favorable balance between enhanced oxygen vacancy concentration, optimized lattice parameters, and structural stability. These factors jointly promote higher conductivity while maintaining low polarization resistance. The incorporation of cobalt was shown to boost electronic transport, although excessive Co levels (e.g., y = 0.5) resulted in increased thermal expansion and interfacial resistance due to phase interactions with the electrolyte. Among the studied compositions, PSFC-2020, PSFC-3020, and PSFC-4020 demonstrated superior electrochemical performance, with conductivities up to ~186 S·cm–1 and polarization resistances as low as 1.9 Ω·cm2 at 850 °C. The findings confirm the potential of Pr–Sr–Fe–Co perovskites as highperformance cathode candidates for advanced RSOFCs systems, combining favorable thermomechanical compatibility, efficient charge transport, and long-term durability.