Effects of interface roughness on a liquid-Sb-anode solid oxide fuel cell

Liquid Sb anodes are examined at 1073 K in solid-oxide fuel cells with single-crystal yttria-stabilized zirconia (YSZ) electrolytes. Two types of cells with different anode-electrolyte interface morphologies are operated in “battery” mode, with dry Ar flow in the anode chamber, to characterize the effects of the interface roughness on the electrochemical oxidation of the metals with oxygen ions. When the effects of the electrolyte surface morphology are minimized by using an extremely smooth (Ra = 0.69 nm) anode-electrolyte interface, the intrinsic exchange current density is found to be 1.5 mA cm−2 by fitting the Tafel equation. When the surface roughness is increased to Ra = 540 nm, the effective contact area of the liquid Sb anode increases by 33% compared to the smooth cell. The product Sb2O3 can increase the effective reaction boundary by acting as an oxygen ion conductor. However, the accumulation of Sb2O3 at the interface weakens the effect of the surface morphology.