Effects of H 2 O and CO 2 on Electrochemical Behaviors of BSCF Cathode for Proton Conducting IT-SOFC

Abstract

© The Author(s) 2016. Published by ECS. All rights reserved. Proton conducting intermediate temperature (400–700◦C) solid oxide fuel cells (IT-SOFC) have attracted great interest recently. However, for SOFC operation at intermediate temperature, cathode is often considered to be the main factor limiting the overall cell performance. In this study, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), which is one of the most active cathode materials and shows significant hydration effect suggesting possible proton conductivity, was investigated as the cathode for proton conducting IT-SOFC at temperature down to ∼450◦C. The stability and compatibility of BSCF cathode with BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb), one of the leading proton conducting electrolyte materials, were studied at intermediate temperature in various atmospheres. In addition, experiments were carried out to understand the electrochemical behaviors of BSCF as a mixed proton, oxide ion and electron conducting cathode using BSCF/BZCYYb/BSCF symmetrical cells in simulated air containing different concentrations of water vapor (H2O) and carbon dioxide (CO2), especially at lower temperature of ∼450◦C. The results are analyzed from the underlying oxygen electrode reaction mechanism point of view, and the direction for future research to further improve the cathode for proton conducting IT-SOFC is pointed out.