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

Abstract

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 La 0.5 Ba 0.5 FeO 3-δ 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 La 0.5 Ba 0.5 FeO 3-δ and La 0.5 Ba 0.5 FeO 2.9-δ F 0.1 at 850 °C are 1.4 × 10 −4 and 2.8 × 10 −4 cm s −1 , respectively. A single cell supported by a 300 μm-thick La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ electrolyte layer with La 0.5 Ba 0.5 FeO 3-δ anode shows maximum power densities of 1446 and 691 mW cm −2 at 850 °C with wet hydrogen and methane fuels, respectively, which increase to 1860 and 809 mW cm −2 respectively when La 0.5 Ba 0.5 FeO 2.9-δ F 0.1 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. • La 0.5 Ba 0.5 FeO 3-δ perovskite is developed as an anode material of SOFCs. • The oxygen surface exchange on the anode is accelerated through F anion doping. • La 0.5 Ba 0.5 FeO 2.9-δ F 0.1 anode shows high activity and stability with CH 4 fuel.