Sr₂Fe_1.5Mo_0.5O_6−δ- Sm_0.2Ce_0.8O_1.9Composite Anodes for Intermediate-Temperature Solid Oxide Fuel Cells

Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) perovskite is carefully investigated as an anode material for solid oxide fuel cells with LaGaO 3 -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 Ω cm 2 at 700°C for La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3−δ 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.