B-SITE SUBSTITUTION EFFECTS (Fe, Mn, Ni) ON THE STRUCTURAL, ELECTRONIC, AND ELECTROCHEMICAL PROPERTIES OF La₀.₇Sr₀.₃BO₃ PEROVSKITES FOR INTERMEDIATE-TEMPERATURE SOFC CATHODES

Abstract

The shift toward low-emission energy technologies is increasing interest in intermediate-temperature solid oxide fuel cells (IT-SOFCs), where cathode performance is crucial for system efficiency and durability. The perovskite compound La₀.₇Sr₀.₃BO₃ (B = Fe, Mn, Ni) is promising as a cathode material due to its flexible crystal structure and mixed ionic–electronic conductivity (MIEC) properties. This article comparatively reviews three main systems: La₀.₇Sr₀.₃FeO₃, La₀.₇Sr₀.₃MnO₃, and La₀.₇Sr₀.₃NiO₃ based on their crystal structure, metal ion valence, oxygen vacancy concentration, conductivity, oxygen reduction reaction (ORR) activity, and thermal and chemical stability. The analysis results indicate a trade-off between electrochemical activity and stability: the Fe system has high stability but moderate activity, the Mn system offers a balance of both, while the Ni system shows the highest activity but is susceptible to high-temperature degradation. Optimization of the composition and oxygen vacancy (δ ≈ 0.10–0.18) can improve the conductivity without compromising crystal stability. This study emphasizes the importance of composition engineering, surface modification, and composite cathode fabrication to produce more efficient and durable next-generation IT-SOFC perovskite cathodes.