Performance and stability of SrCo0.9Nb0.1O3-δ-(La0.60Sr0.40)0.95(Co0.20Fe0.80)O3-δ bilayer cathode for intermediate-temperature solid oxide fuel cells

Developing low-polarization and stable cathodes is key to the success of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Here we report a study on the electrochemical performance and stability of a commercial (La0.60Sr0.40)(0.95)(Co0.20Fe0.80)O3-delta (LSCF) cathode overcoated by a SrCo0.0Nb0.1O3-delta (SCN10) nanoscaled layer. At the optimal 20 wt% loading, the SCN10-LSCF bilayer cathode exhibits an 89.4% reduction in polarization resistance over the pristine LSCF at 650 degrees C. Over a 6,000-h testing at 650 degrees C, the SCN10-LSCF bilayer cathode also shows a similar stability to but much lower resistance than the pristine LSCF. A combined microscopic and spectroscopic post-test analysis unveils that SCN10-overcoat remains nanosized, well crystallized and uniformly distributed. An elongated, sporadically distributed phase was found and identified as SrCO3 in the SCN10 layer, which may contribute to the degradation of SCN10-LSCF cathode.