Influence of H2S Poisoning on Anode Layer of SOFC

The influence of sulfur compounds on Ni-YSZ anode of SOFC cell has investigated by measuring cell voltage under a constant current density for Ni-YSZ anode / YSZ electrolyte / (La,Sr) MnO3 cathode cell. Two-step degradation of cell voltage was observed by supplying H2S contained fuel. The first-step degradation of cell voltage was recovered completely by switched to sulfur-free fuel, while the cell voltage wasn't recovered completely once the cell voltage went down under 0V. After the cell with irreversible degradation was cooled down under pure N2 atmosphere, it was analyzed by FE-SEM, EDX and Raman Spectroscopy. The results of these analyses of cross-section of the cell revealed nickel sulfides formation by supplying H2S contained fuel. It is supposed that melted nickel sulfides diffused in the anode and electrolyte layer. The irreversible cell poisoning might be caused by these nickel sulfides.