Tuning Electrochemical Properties and Thermal Stability of YSZ Mesoporous Thin Films for SOFC Applications

Dense and mesoporous 4% mol Yttria stabilized zirconia thin films were deposited on amorphous silica substrates. The effects of the temperature on the mesostructure were analyzed by applying different thermal treatments to the samples within the range of solid oxide fuel cell (SOFC) operation conditions. Electrochemical impedance spectroscopy measurements rendered evidence of a single mechanism, consistent with grain boundary-surface oxide ion conduction. Our results show that the presence of the highly accessible porosity improves the superficial ionic conductivity, reducing the activation energy of the overall process. Density functional theory calculations on the (110) surface were performed to estimate the associated energy barriers. Our results suggest that ionic transport along the surface of accessible pores connected to the atmosphere could account for the observed reduction in activation energy. Therefore, we expect that the incorporation of a mesoporous thin film between the electrolyte and the electrode materials will enhance the interfacial electrochemical processes, thereby improving the SOFC performance.