Gel-cast NiO–SDC composites as anodes for solid oxide fuel cells

NiO–SDC(Ce0.8Sm0.2O1.9) composites were synthesized using gel-casting technique with nitrate precursors. The composite oxides were formed after the gels were fired at 350 °C in flowing air. No reaction between NiO and CeO2 occurs as analyzed using X-ray diffraction (XRD). The average particle size was about 50 nm and specific surface area was 10 m2 g−1, when the powder was fired at 900 °C for 2 h. NiO–SDC cermets were prepared by firing the composites at 1350 °C. The electrical conductivities and porosities of the cermets were measured, for example, 360 S cm−1 at 600 °C for a cermet with 30% porosity, 35 vol.% Ni, and 35 vol.% SDC. And the electrochemical performance of Ni–SDC cermet as an anode was investigated using a fuel cell with 25-μm thick SDC electrolyte and Sm0.5Sr0.5CoO3-SDC cathode. Maximum power density was 618 mW cm−2 and 491 mW cm−2 at 650 and 600 °C, respectively, inferring high catalytic activity of the Ni–SDC anode. Impedance measurements on the fuel cell at open circuit showed that the interfacial polarization resistance of the Ni–SDC anode was negligible compared to the resistance of cathode and electrolyte.