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Reduced Thermal Expansion and Enhanced Redox Reversibility of La0.5Sr1.5Fe1.5Mo0.5O6-delta Anode Material for Solid Oxide Fuel Cells
Journal article   Peer reviewed

Reduced Thermal Expansion and Enhanced Redox Reversibility of La0.5Sr1.5Fe1.5Mo0.5O6-delta Anode Material for Solid Oxide Fuel Cells

He Qi, Tony Thomas, Wenyuan Li, Wei Li, Fang Xia, Nan Zhang, Edward M. Sabolsky, John Zondlo, Richard Hart and Xingbo Liu
ACS applied energy materials, Vol.2(6), pp.4244-4254
06/24/2019
DOI: https://doi.org/10.1021/acsaem.9b00494
Web of Science ID: WOS:000473116600036

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Abstract

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-delta (LSFM) synthesized in nitrogen at 1050 degrees 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% H-2-95% N-2 at 800 degrees C with excellent reversibility over three redox cycles. After lanthanum doping, the coefficient of thermal expansion (CTE) is reduced from 17.12 x 10(-6) K-1 (SF1.5M) to 15.01 x 10(-6) K-1 (LSFM), and this value can be lowered further with a higher lanthanum content. Dilatometry testing at 800 degrees 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 degrees C in humidified hydrogen is 0.16 Omega cm(2), and the active region is similar to 4.5 mu m. 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 degrees C within humidified H-2. The new ceramic material LSFM is a promising anode for high performance solid oxide fuel cells.

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