Electrochemical performance of mixed ionic–electronic conducting oxides as anodes for solid oxide fuel cell
Abstract Mixed ionic–electronic conducting (MIEC) oxides, SrFeCo 0.5 O x , SrCo 0.8 Fe 0.2 O 3− δ and La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3− δ have been synthesized and prepared on yttria-stabilized zirconia as anodes for solid oxide fuel cells. Power output measurements show that the anodes composed of such kinds of oxides exhibit modest electrochemical activities to both H 2 and CH 4 fuels, giving maximum power densities of around 0.1 W/cm 2 at 950°C. Polarization and AC impedance measurements found that large activation overpotentials and ohmic resistance drops were the main causes for the relative inferior performance to the Ni-YSZ anode. While interlayered with an Ni-YSZ anode, a significant improvement in the electrochemical performance was observed. In particular, for the SrFeCo 0.5 O x oxide interlayered Ni-YSZ anode, the maximum power output reaches 0.25 W/cm 2 on CH 4 , exceeding those of both SrFeCo 0.5 O x and the Ni-YSZ, as anodes alone. A synergetic effect of SrFeCo 0.5 O x and the Ni-YSZ has been observed. Future work is needed to examine the long-term stability of MIEC oxide electrodes under a very reducing environment.