All-solid-state direct carbon fuel cells with thin yttrium-stabilized-zirconia electrolyte supported on nickel and iron bimetal-based anodes

Solid oxide fuel cells (SOFCs) with thin yttrium-stabilized-zirconia (YSZ) electrolyte supported on composite anode of nickel-iron bimetal and YSZ are prepared and operated directly on Fe-loaded activated carbon fuel, without any liquid medium or purging gas. The composition of the anode is represented as Ni 1- x Fe x O δ ( x  = 0, 0.05, 0.1, 0.2, 0.3)-YSZ. Experiment result shows that such kind of all-solid-state direct carbon solid oxide fuel cells (DC-SOFCs) perform well at 800 °C, giving maximum output power densities in the range of 425–529 mW cm −2 . Similar to the case of a SOFC operated on hydrogen fuel , a small amount of Fe addition into the Ni-based anode can improve the performance of a DC-SOFC and the optimum composition is x  = 0.1. A DC-SOFC with Ni 0.9 Fe 0.1 O δ -YSZ anode, loaded with 2.5 g Fe-loaded activated carbon fuel, is steadily operated at a constant current density of 0.1 A cm −2 for 15 h at 800 °C. The anodes and the DC-SOFCs are characterized through XRD , AC impedance spectroscopy , and SEM measurements. The superior performance of the Fe-added anode is analyzed accordingly.