Performance of a La0.6Sr0.4Co0.8Fe0.2O3–Ce0.8Gd0.2O1.9–Ag cathode for ceria electrolyte SOFCs

Performance of an La0.6Sr0.4Co0.8Fe0.2O3–CGO–Ag cathode (where CGO is Ce0.8Gd0.2O1.9) on a Ce0.8Sm0.2O1.9 electrolyte was studied by the three-probe AC impedance method at the steady state of various DC bias currents. The electrode consisted of a porous layer of La0.6Sr0.4Co0.8Fe0.2O3–CGO (30 wt.%) and a layer of Ag particles coated on the surface. The Ag coating was used to improve the oxygen exchange reaction activity. As a result, an interface conductivity greater than 1 S/cm2 was obtained at 600 °C with a low activation energy. The dependence of the AC impedance on the frequency was analyzed in order to clarify the reaction steps in the oxygen reduction mechanism.