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. © 2007 Elsevier B.V. All rights reserved.