Improved electrochemical oxidation kinetics of La0.5Ba0.5FeO3-δ anode for solid oxide fuel cells with fluorine doping

Sluggish anode kinetics and serious carbon deposition are two major obstacles to developing hydrocarbon fueled solid oxide fuel cells. A highly active and stable perovskite La0.5Ba0.5FeO3-delta anode material is studied in this work. The oxygen surface exchange and charge transfer steps are the rate-determining steps of the anode process, and the former is accelerated with fluorine doping on the anion sites due to the lowering of metal-oxygen bond energy. The oxygen surface exchange coefficients of La0.5Ba0.5FeO3-delta and La0.5Ba0.5FeO2.9-delta F0.1 at 850 degrees C are 1.4 x 10-4 and 2.8 x 10-4 cm s-1, respectively. A single cell supported by a 300 mu m-thick La0.8Sr0.2Ga0.8Mg0.2O3-delta electrolyte layer with La0.5Ba0.5FeO3-delta anode shows maximum power densities of 1446 and 691 mW cm-2 at 850 degrees C with wet hydrogen and methane fuels, respectively, which increase to 1860 and 809 mW cm-2 respectively when La0.5Ba0.5FeO2.9-delta F0.1 is used as the anode. The cell exhibits a short-term durability of 40 h using wet methane as fuel without carbon deposition on the anode.