Investigations on sulfur poisoning mechanisms of a solid oxide fuel cell with niobium-doped ferrate perovskite anode

As anodes for solid oxide fuel cells (SOFCs), one of the significant advantages for perovskite alternatives over conventional Ni-based cermets is the high tolerance to sulfur poisoning. However, there are some controversies on sulfur poisoning mechanisms of perovskite anode cells and many related works are not systematic and convincible enough. Herein, with 200 ppm H₂S–H₂ fed to anode chamber, we find that (La_0.8Sr_0.2)_0.95MnO_3-δ/(Sc₂O₃)_0.1(CeO₂)_0.01(ZrO₂)_0.89 (LSM/ScSZ) cathode undergoes a severe deactivation using Ceramabond 552 sealant, while La_0.8Sr_0.2Fe_0.9Nb_0.1O_3-δ (LSFNb) anode keeps activating. Adopting annealing-quenching treatment to simulate in-situ conditions, transmission electron microscopy studies reveal that ∼5 nm hexagonal FeS nanoparticles and ultrathin sulfur species layer are dynamically-formed on LSFNb surface upon exposure to 200 ppm H₂S–H₂ since they disappear after the subsequent annealing in H₂. Finally, sulfur poisoning stages of the cells and the corresponding mechanisms are discussed systematically. Our work offers a new dimension for understanding sulfur poisoning behaviors of whole cells and sulfur poisoning and promotion effects on LSFNb perovskite anode.