Electrochemical properties of A-site deficient SOFC cathodes under Cr poisoning conditions

Under solid oxide fuel cells (SOFCs) operating atmosphere, volatile Cr species are generated over the chromia scale of chromia-forming alloy interconnects, poisoning the cathodes and causing the rapid degradation of the fuel cell performance. In this study, the influence of the cathode composition and A-site deficiency of Perovskite ABO3 cathodes on their tolerance to Cr poisoning was investigated in detail through the electrochemical polarization and electrochemical impedance spectroscopy (EIS) analysis. Results showed that 5 mol% La-site deficient cathodes, La0.75Sr0.2BO3−δ (B = Mn, Fe), presented a good performance in resistance to Cr poisoning and electrocatalytic activity to oxygen reduction reaction in the presence of alloy interconnects under a constant current density of 0.2 A cm−2 in oxygen at 1073 K. B-site atom of Perovskite ABO3 cathodes has a strong influence on the mechanism of Cr deposition and cathodes performance, while proper A-site deficiency can greatly improve the cathodes electrochemical performance and slow down Cr deposition.