Manganese Doped Lanthanum-Strontium Chromite Fuel Electrode for Solid Oxide Fuel Cell and Oxygen Transport Membrane Systems

Wednesday, 27 May 2015
Salon C (Hilton Chicago)
S. Gupta and P. Singh (University of Connecticut)
La0.75Sr0.25Cr1-xMnxO3 perovskite family, a mixed ionic electronic conductor has promising attributes to function as fuel electrode and electrolyte membrane in high temperature electrochemical devices including solid oxide fuel cell as well as oxygen transport membrane systems. In this study, role of oxygen partial pressure on the sintering behavior of (La0.75Sr0.25)0.95Cr0.7Mn0.3O3 is investigated at 1400°C (simulating device fabrication condition). Unlike conventional chromite, results show a decrease in the density during exposure to reducing atmospheres. Chronology of microstructural development is presented along with mechanisms for the role of exposure conditions on the compound formation. Electrochemical impedance spectroscopy is performed on LSCM73+8YSZ//8YSZ//LSCM73+8YSZ symmetrical cells under constant bias for 80h at ~950°C (simulating device operating condition) in both oxidizing (air) and reducing atmosphere (Ar-3%H2-3%H2O). Stable and higher performance is obtained in oxidizing atmosphere when compared to reducing atmosphere. Sr-segregation on the LSCM73 surface is attributed to the lower performance in reducing gas atmosphere. Bulk, surface and the electrode/electrolyte interfaces are examined during post-test characterization of the tested cells. No electrode delamination as well as no interface layer or compound formation is identified in the bulk and/or interface in both oxidizing and reducing atmosphere.