Performance Enhancement of LSM Cathode of SOFCs through Sequential Infiltration of Ag and Ceria

In this study, the effect of sequential infiltration and catalyst loading of metallic and ceramic catalysts on the performance and stability of La_0.8Sr_0.2MnO₃ (LSM) cathode of solid oxide fuel cell was investigated. Small loading of catalytic silver nanoparticles along with ceria catalytic nanoparticles were sequentially infiltrated into the porous structure of LSM cathode and the electrochemical performance of the cells was evaluated at intermediate temperature range of 600-800°C. Cathode performance was investigated by electrochemical impedance spectroscopy (EIS) and Chrono potentiometery technique at dc bias of 200 mA/cm² on cathode half cells. The results indicate that electrochemical performance of dually infiltrated cathode is significantly improved compared with those of LSM cathodes separately infiltrated with Ag and ceria. The results show that while individual infiltration of Ag and Ceria decreased the electrode polarization resistance of the cell by %56 and %79, respectively, dual infiltration of Ag and Ceria with equal total loading of catalyst decreased the polarization resistance of the electrode by %98 at open circuit potential and 700°C. Scanning electron microscopy (SEM) studies showed the random distribution of discrete nano catalysts in the vicinity of cathode/electrolyte interface which proves effectiveness of the infiltration technique for performance enhancement of cathode electrodes. Long term stability of cathode was also investigated and a stable performance was observed for dually infiltrated cathode which can be attributed to well distribution of catalyst nanoparticles.