Study of the rate limiting steps and degradation of a GDC impregnated La0. 6Sr0. 4Co0. 8Fe0. 2O3-δ cathode

摘要: In this work, a Solid Oxide Fuel Cell (SOFC) cathode surface modification by nanoparticle impregnation was carried out. La0. 6Sr0. 4Co0. 8Fe0. 2O3-δ (LSCF) ceramic cathodes impregnated with Ce0. 8Gd0. 2O3-δ(GDC) nanoparticles were characterized with scanning (SEM) and transmission (TEM) electron microscopy. The electrochemical response as a function of temperature, oxygen partial pressure (pO2)(10-4< pO2< 1 atm) and time was evaluated by electrochemical impedance spectroscopy (EIS). We obtained reproducible and homogeneous impregnations, which reduce the total cathodes polarization resistance more than 20% in the temperature range between 400ºC and 800ºC and during 500 h at 700ºC. The impregnated cathode was found to be electrochemically limited by the same processes as the nonimpregnated cathode, namely gas diffusion, ion bulk diffusion and dissociative adsorption. The …