A Stable and Efficient Cathode for Fluorine-Containing Proton-Conducting Solid Oxide Fuel Cells.

ABSTRACT

Substitution of anions such as F- and Cl- can effectively improve the stability of proton-conducting electrolytes at no expense to proton conduction. However, during operation, F- and Cl- in electrolytes can transfer to the cathodes, which reduces the stability of the electrolytes. In this work, F- -doped Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-δ [Ba0.5 Sr0.5 Co0.8 Fe0.2 O2.9-δ F0.1 (F-BSCF)] was prepared as a potential cathode for proton-conducting solid oxide fuel cells with BaCe0.8 Sm0.2 F0.1 O2.85 electrolyte. The incorporation of F- in the cathode depressed F- diffusion from the electrolyte and improved the stability of button cells. Temperature-changing X-ray photoelectron spectroscopy and electronic conductivity relaxation results demonstrated that the incorporation of F- enhanced the oxygen incorporation kinetics at intermediate temperatures and improved the cathode catalytic performance. Moreover, a button cell prepared with this novel cathode was stable for 270 h at a current density of 300 mA cm-2 and 700 °C, which was much superior than those containing a BSCF cathode.