Highly active and stable tin-doped perovskite-type oxides as cathode materials for solid oxide fuel cells

Abstract

The development of cathode materials with low-cost, high electrocatalytic activity and better electrochemical performance is critical for the widespread commercial applications of solid oxide fuel cells. Herein, we report a series of cobalt-free LaBaFe2-xSnxO6-δ (x=0–0.2) cathode materials and provide a systematic investigation on their physical and electrochemical properties. Compared with the parent material, the LaBaFe2-xSnxO6-δ materials exhibit a suitable thermal expansion coefficient, high oxygen reduction reaction electrocatalytic activity, better electrochemical performance and long-term stability. Among all the components, the LaBaFe1.85Sn0.15O6-δ cathode obtains the lowest polarization resistance and the largest power densities with the values of 0.073 Ω cm2 and 514 mW cm−2 at 800 °C, respectively, while maintaining excellent stability without observable degradation for 100 h. In addition, the electrochemical impedance spectra combining with the corresponding distribution of relaxation times analysis results indicate that there are three determining steps limited the whole oxygen reduction reaction processes. The present results imply that the LaBaFe1.85Sn0.15O6-δ sample has great potential to be an attractive cathode material for solid oxide fuel cells.