Structure and properties of MgMxCr2-xO4 (M = Li, Mg, Ti, Fe, Cu, Ga) spinels for electrode supports in solid oxide fuel cells
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Novel electrode scaffold materials based on chromium-rich spinets, such as MgMxCr2-xO4, = Li, Mg, Ti, Fe, Cu, Ga) have been investigated for solid oxide fuel cell (SOFC) applications, in terms of conductivity and chemical stability when operated in fuel environments. Cation distributions were obtained by Rietveld refinement from X-ray diffraction data (XRD), with cation site preference considered in agreement with literature, and correlated with electrical properties determined experimentally. The substitutions with cations such as Li and Cu on B site improved the conductivity of the materials in air, while introducing Fe and Ga in the structure led to a decrease in conductivity in air. However, Fe had a positive contribution under reducing conditions, generating a change in the conductivity mechanism from p-type in air, to n-type. Conductivity measurements indicated that MgFexCr2-xO4 spinets exhibit faster reduction kinetics, in comparison with other substituted cations at the B site which is desirable in fuel cell application, for a reasonably fast response of a cell or a stack to reach its full functional potential. MgFeCrO4 showed fast reduction kinetics, with increase of the conductivity in reducing conditions from 0.014 S cm-1 to 0.4 S cm-1 and equilibration time for reaching the maximum conductivity value of 10 hours, under dry 5% H2/Ar at 850 degrees °C.
Stefan , E , Connor , P A , Azad , A K & Irvine , J T S 2014 , ' Structure and properties of MgM x Cr 2-x O 4 (M = Li, Mg, Ti, Fe, Cu, Ga) spinels for electrode supports in solid oxide fuel cells ' Journal of Materials Chemistry A , vol 2 , no. 42 , pp. 18106-18114 . DOI: 10.1039/c4ta03633f
Journal of Materials Chemistry A
© 2015 the Authors. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1039/C4TA03633F
DescriptionThe authors thank the Office of Naval Research, USA, grant code N00014-11-1-0247, the Engineering and Physical Sciences Research Council, UK, grant platform EP/E064248/1 and the European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cell and Hydrogen Joint Technology initiative under grant agreement no. [FCH JU-GA 278257]10 for financial support.
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