- Qi, H; Thomas, T; Li, W; Li, W; Xia, F; Zhang, N; Sabolsky, EM; Zondlo, J; Hart, R; Liu, X
- High performance anode materials with suitable thermal and chemical expansions are highly desirable for solid oxide fuel cells. In this work, we report a promising anode material La0.5Sr1.5Fe1.5Mo0.5O6-δ (LSFM) synthesized in nitrogen at 1050 °C. Its phase stability, mechanical behavior, redox stability, and electrochemical performance were studied. The electrical conductivity of LSFM reaches 23 S cm-1 in 5% H2-95% N2 at 800 °C with excellent reversibility over three redox cycles. After lanthanum doping, the coefficient of thermal expansion (CTE) is reduced from 17.12 × 10-6 K-1 (SF1.5M) to 15.01 × 10-6 K-1 (LSFM), and this value can be lowered further with a higher lanthanum content. Dilatometry testing at 800 °C shows that the chemical expansion behavior of LSFM is highly reversible during the oxidation-reduction cycling. These results indicate that the thermal and chemical expansion of the crystal lattice can be reduced by a stronger metal-oxygen (M-O) bond strength, leading to an improvement in redox reversibility. The polarization resistance of the LSFM symmetrical cell at 800 °C in humidified hydrogen is 0.16 ω cm2, and the active region is ∼4.5 μm. The half-tear-drop-shaped impedance spectroscopy indicates an oxygen bulk diffusion and surface reaction colimited process. The maximum power density of the LSFM single cell reaches 1156 mW cm-2 at 800 °C within humidified H2. The new ceramic material LSFM is a promising anode for high performance solid oxide fuel cells.
- June 24, 2019
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