AC Impedance Characterisation of a La0.8Sr0.2Co0.2Fe0.8O3-δ Electrode

The electrochemical characteristics of a La0.8Sr0.2Co0.2Fe0.8O3-delta electrode, synthesised using the spray-drying technique and deposited via screen printing on a double layer Ce0.8Gd0.2O2-delta/ZrO2(8 mol% Y2O3) electrolyte, were studied using AC impedance spectroscopy. It was found that depending on temperature (600 to 850 degrees C) and oxygen partial pressure PO2 (0.7 to 100 kPa) the impedance characteristics of the electrode are determined by up to three different processes, which were identified as ionic conduction in the electrode bulk, interfacial charge transfer and gas phase diffusion, respectively, on the basis of the temperature and oxygen partial pressure dependence of the polarisation conductance associated with the individual processes and the related pseudocapacitance values.