A direct carbon fuel cell with a molten antimony anode

The direct utilization of carbonaceous fuels is examined in a solid oxide fuel cell (SOFC) with a molten Sb anode at 973 K. It is demonstrated that the anode operates by oxidation of metallic Sb at the electrolyte interface, with the resulting Sb2O3 being reduced by the fuel in a separate step. Although the Nernst Potential for the Sb-Sb2O3 mixture is only 0.75 V, the electrode resistance associated with molten Sb is very low, approximately 0.06 Omega cm(2), so that power densities greater than 350 mW cm(-2) were achieved with an electrolyte-supported cell made from Sc-stabilized zirconia (ScSZ). Temperature programmed reaction measurements of Sb2O3 with sugar char, rice starch, carbon black, and graphite showed that the Sb2O3 is readily reduced by a range of carbonaceous solids at typical SOFC operating conditions. Finally, stable operation with a power density of 300 mW cm(-2) at a potential of 0.5 V is demonstrated for operation on sugar char.