Sn-doped Ni/YSZ anode catalysts with enhanced carbon deposition resistance for an intermediate temperature SOFC

Solid oxide fuel cells (SOFCs), capable of operating in an intermediate temperature range with a high power density, are fabricated using Sn-doped Ni/YSZ as an anode catalyst with a functional layer between the anode and electrolyte. The cell shows a high power density of 0.41 W cm−2 at 650 °C when operated using humidified methane fuel. A comparison of this cell with a single cell prepared without Sn shows that the long-term stability is greatly improved; the Sn-doped Ni/YSZ cell operates for 137 h, whereas the Ni/YSZ cell ceases operation within 27 h. A minimal level of Sn-doping yields the best cell performance; higher levels of Sn-doping results in occupation of most catalytic active sites, causing poorer performance. In the case that carbon deposited on the Sn-doped Ni/YSZ surface during operation is removed, the long-term stability of the cell is further improved, and the cell operates stably for 300 h without degradation. The quantity and distribution of Sn on the anode surface remains nearly unchanged over the course of operation.