Accelerated anode failure of a high temperature planar SOFC operated with reduced moisture and increased PH_3 concentrations in coal syngas

摘要

Electrolyte supported SOFCs with Ni-YSZ/Ni-GDC bi-layer anodes were operated at 800 ℃ and 900 ℃ with 8% H_2O and 10-20 ppm of PH^syngas to reduce steam-related interference accelerate degradation. Cell power output degraded rapidly within the first 12 h, with even faster degradation at 900 ℃. Nickel phosphide phases detected in the anode include Ni_3P, Ni_(12)P_5 and Ni_5P_2, while CePO_4 formed in the catalyst layer. Irrespective of the electrolyte component used, phosphorus penetrated to the anode-electrolyte interface in electrically loaded cells, as well as with Ni-GDC cells in coupon tests. In contaminated bi-layer anodes, phosphorus appeared to concentrate away from the surface, suggesting oxidation of PH_3 when steam rich environments were present.