Achieving long-term stability in large-area solid oxide fuel cell through microstructural engineering of La0.6Sr0.4CoO3-δ cathode

Perovskite-based ceramics, such as strontium-doped lanthanum cobaltite (La0.6Sr0.4CoO3-delta, LSC), are widely recognized for their efficiency as cathode materials in solid oxide fuel cells (SOFCs) due to their high electrocatalytic activity toward the oxygen reduction reaction (ORR). However, LSC cathodes often suffer from significant degradation during both the fabrication process and long-term operation of SOFCs. In this study, we applied microstructural tailoring to LSC cathodes in large-area (12 x 12 cm2) SOFCs to enhance long-term performance and stability. We systematically investigated the effects of sintering temperature and particle size on LSC microstructure, assessing their influence on SOFC performance at 750 degrees C and a high current density of 1 A cm-2 over 1000 h. Severe degradation (3.6 %/1000 h) was observed in LSC cathodes sintered at lower temperatures (850 degrees C), primarily due to a loss of cathode/electrolyte interface stability after the sintering Conversely, LSC cathodes with a particle size of 0.5 mu m exhibited a much lower degradation rate of 1.6 %/1000 h, attributed to enhanced interface stability and reduced elemental migration during the long-term operation. High-resolution TEM-EDS analysis identified cation migration and secondary phase formation at the interfaces as key degradation mechanisms under accelerated operating conditions. This study demonstrates that optimizing microstructure and fabrication parameters can significantly improve the long-term performance and stability of SOFCs.