Ni–Fe + SDC composite as anode material for intermediate temperature solid oxide fuel cell

Composite materials of Sm0.2Ce0.8O1.9 (SDC) with various Ni–Fe alloys were synthesized and evaluated as the anode for intermediate temperature solid oxide fuel cell. The performance of single cells consisting of the Ni–Fe + SDC anode, SDC buffer layer, La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM) electrolyte, and SrCo0.8Fe0.2O3 − δ (SCF) cathode were measured in the temperature range of 600–800 °C with wet H2 as fuel. It was found that the anodic overpotentials of the different Fe–Ni compositions at 800 °C were in the following order: Ni0.8Fe0.2 < Ni0.75Fe0.25 < Ni < Ni0.7Fe0.3 < Ni0.9Fe0.1 < Ni0.95Fe0.05 < Ni0.33Fe0.67. The single cell with the Ni0.8Fe0.2 + SDC anode exhibited a maximum power density of 1.43 W cm−2 at 800 °C and 0.62 W cm−2 at 700 °C. The polarization resistance of the Ni0.8Fe0.2 + SDC anode was as low as 0.105 Ω cm2 at 800 °C under open circuit condition. A stable performance with essentially negligible increase in anode overpotential was observed during about 160 h operation of the cell with the Ni0.8Fe0.2 + SDC anode at 800 °C with a fixed current density of 1875 mA cm−2. The possible mechanism responsible for the improved electrochemical properties of the composite anodes with the Ni0.8Fe0.2 and Ni075Fe0.25 alloys was discussed.