Rapid synthesis and performance analysis of La _0.8 Sr _0.2 MnO ₃ cathodes and La _0.85 Sr _0.15 Ga _0.85 Mg _0.15 O ₃ electrolytes for IT-SOFCs

Abstract La–Sr–Mn–O (LSM) and La–Sr–Ga–Mg–O (LSGM) perovskite-like oxide ceramics have been extensively studied owing to their attractive electrochemical properties and thermal stability, making them promising materials for intermediate-temperature (IT) solid oxide fuel cells (SOFCs). In this work, we report a cost-effective and scalable synthesis methodology for LSM (cathode) and LSGM (electrolyte) powders using an original fast solution combustion (FSC)-based procedure, followed by a comprehensive evaluation of their electrochemical behavior in symmetric LSM/LSGM/LSM cells by electrochemical impedance spectroscopy (EIS) in the 600 °C–800 °C range. EIS results revealed a substantial decrease in the cathodic polarization resistance ( R p ) with increasing temperature, reaching ∼2.6 Ω·cm 2 at 800 °C. Arrhenius analysis yielded an activation energy of approximately 1.15 eV for the oxygen-reduction reaction, which is consistent with the typical range reported for LSM-based cathodes. Impedance analysis indicated that the electrochemical response is mainly limited by surface oxygen exchange processes on LSM, whereas interfacial resistance at the LSM/LSGM contact may also contribute to the overall polarization losses. Overall, the proposed synthesis route enabled the preparation of structurally appropriate LSM and LSGM materials with properties suitable for IT-SOFC operation. These results provide relevant insights into the interplay between synthesis, microstructure, transport properties, and interfacial phenomena in LSM/LSGM systems, supporting the future development of optimized IT-SOFC components based on these compounds.