Oxygen transport in La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Ge0.2O2−x composite cathode for IT-SOFCs

The oxygen transport properties and the performance of the composite La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Ge0.2O2−x, a potential IT-SOFC cathode material, were investigated. Using the isotopic exchange depth profiling (IEDP) technique with secondary ion mass spectroscopy (SIMS), the oxygen tracer diffusion coefficient, D* and the surface exchange coefficient k were measured. The measured D* values of the composite material were higher than that of the non-composite LSCF diffusion coefficient values, while the k values were similar to the non-composite material at all temperatures. The area-specific resistance of the porous composite cathode was measured by impedance spectroscopy. A performance improvement was observed below 650 °C when compared to a non-composite LSCF cathode. This improvement was mainly attributed to the improvement in the oxygen tracer diffusion coefficient of the LSCF/CGO composite.