Electrochemical Performance of SrFeO3-? for Application as a Symmetric Electrode in Solid Oxide Fuel Cells

SrFeO3-o has been earlier reported to exhibit a large area-specific resistance even though it possesses high mixed ionic- electronic conductivity both in oxidizing and reducing conditions. The present study clarifies this aspect and investigates the defect chemistry and electrochemical performance correlations in SrFeO3-o for the possible use as a symmetric electrode in solid oxide fuel cells. A conventional solid-state reaction method is adopted for powder synthesis. Structural characterization indicates an orthorhombic perovskite phase formation with a o of 0.21. High dc electrical conductivities of -114.9 and 0.26 S center dot cm-1 are observed at 800 degrees C in air and reducing conditions, respectively. The area-specific resistance (ASR) for the SrFeO3-o electrode is measured in a symmetrical half-cell configuration under various gas environments. At 800 degrees C, SrFeO3-o offered low ASRs of 0.082, 0.055, and 0.122 omega center dot cm2 in air, oxygen, and 3% H2O/H2, respectively. Although the ASR possesses excellent temporal stability in an oxidizing atmosphere, it increases to 0.42 omega center dot cm2 after 100 h in reducing conditions owing to the brownmillerite phase formation. The redox cycling performance is also affected with the ASR rising from 0.13 to 0.24 omega center dot cm2 at 800 degrees C in 3% H2O/H2 after 20 cycles. A maximum power density of 202 mW center dot cm-2 is achieved from the electrolyte-supported symmetric single cell based on the SrFeO3-o electrodes at 800 degrees C. The results demonstrate the viability of using a SrFeO3-o-based electrode for symmetrical solid oxide fuel cells.