Sr2Fe1.5Mo0.5O6-delta - Sm0.2Ce0.8O1.9 Composite Anodes for Intermediate-Temperature Solid Oxide Fuel Cells

Sr2Fe1.5Mo0.5O6-delta (SFM) perovskite is carefully investigated as an anode material for solid oxide fuel cells with LaGaO3-based electrolytes. Its electronic conductivity under anodic atmosphere is measured with four-probe method while its ionic conductivity is determined with oxygen permeation measurement. Samaria doped ceria (SDC) is incorporated into SFM electrode to improve the anodic performance. A strong relation is observed between SDC addition and polarization losses, suggesting that the internal SFM-SDC contacts are active for H-2 oxidation. The best electrode performance is achieved for the composite with 30 wt% SDC addition, resulting in an interfacial polarization resistance of 0.258 Omega cm(2) at 700 degrees C for La0.8Sr0.2Ga0.8Mg0.2O3-delta supported single cells. Electrochemical impedance spectroscopy analysis indicates that the high performance of SFM-SDC composite anodes is likely due to the high ionic conductivity and electro-catalytic activity of SDC by promoting the ionic exchange processes. Redox cycle treatment shows that SDC addition can even improve the redox tolerance of SFM anodes. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.020206jes] All rights reserved.