La0.6Sr0.4CoO3-δ(LSC) Thin Film Electrodes with Very Fast Oxygen Reduction Kinetics Prepared by a Sol-Gel Route

La0.6Sr0.4CoO3-δ(LSC) thin film electrodes of about 80 nm thickness were prepared via a sol-gel route on yttria-stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) solid electrolytes. Impedance measurements on microelectrodes fabricated from these films revealed very low polarization resistances for electrochemical oxygen exchange at intermediate temperatures (500–600 ºC). Prerequisite for the very fast oxygen reduction kinetics was a limitation of the preparation (annealing) temperature to 600 ºC. Already after ca.15 minutes annealing of the sol-gel prepared layer at this temperature, electrodes were electrochemically highly active despite low crystallinity (almost XRD amorphous). LSC electrodes on GDC showed much higher polarization resistances. However, this originated from an additional interfacial resistance rather than from kinetically slow LSC surfaces.