Electrochemical performance of mixed ionic-electronic conducting oxides asanodes for solid oxide fuel cell

Mixed ionic-electronic conducting (MIEC) oxides, SrFeCo0.5Ox, SrCo0.8Fe0.2O 3-delta and La0.6Sr0.4Fe0.8Co0.2O3-delta 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 e xhibit modest electrochemical activities to both H-2 and CH4 fuels, giving maximum power densities of around 0.1 W/cm(2) at 950 degrees C. Polarizatio n and AC impedance measurements found that large activation overpotentials and ohmic resistance drops were the main causes for the relative inferior p erformance 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 SrFeCo0.5Ox oxide interlayered Ni-YSZ anode, the maxim um power output reaches 0.25 W/cm2 on CH,, exceeding those of both SrFeCo0. 5Ox and the Ni-YSZ, as anodes alone. A synergetic effect of SrFeCo0.5Ox and the Ni-YSZ has been observed. Future work is needed to examine the long-te rm stability of MIEC oxide electrodes under a very reducing environment. (C ) 1999 Elsevier Science B.V. All rights reserved.