Mechanism of SO2 Poisoning on the Electrochemical Activity of LSCF and LSM Electrodes

Abstract

Sulfur in the air stream is one of the major contaminants affecting the performance stability of cathodes of solid oxide fuel cell (SOFCs) such as La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and La0.8Sr0.2MnO3 (LSM) perovskite oxide. In this paper, the effects of operating temperatures and SO2 concentrations on the electrochemical performance of LSCF and LSM cathodes are investigated. Sulfur poisoning effect is more pronounced at lower temperatures for LSM and LSCF cathodes, i.e., 700 oC. Sulfur deposition occurs inside the LSCF electrodes according to TOF-SIMS result and is most pronounced on the surface of LSCF at 700 oC, forming primarily SrSO4. For LSM, sulfur deposition is more obvious on the interface of LSM/YSZ at 800 oC by Nano-SIMS result. The reaction mechanism between sulfur dioxide and LSCF and LSM electrodes is then discussed.