Chemical Degradation of the La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Sm0.2O2−δ Interface during Sintering and Cell Operation

A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process tested in operating fuel conditions exhibited strong degradation performance over time. Study the cathode–electrolyte interface after testing showed, on one hand, diffusion lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to La- phase. On other Ce Sm diffused perovskite phase cathode. The grain boundaries appear be preferred pathways cation diffusion. Furthermore, strontium enrichment was clearly observed both layer at with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich corresponded SrCO3. These different phenomena led chemical materials interfaces, explaining decrease electrochemical performance.