Substantial Oxygen Flux in Dual-Phase Membrane of Ceria and Pure Electronic Conductor by Tailoring the Surface

The oxygen permeation flux of dual-phase membranes, Ce0.9Gd0.1O2-delta-La0.7Sr0.3MnO3 +/-delta (GDC/LSM), has been systematically studied as a function of their LSM content, thickness, and coating material. The electronic percolation threshold of this GDC/LSM membrane occurs at about 20 vol % LSM. The coated LSM20 (80 vol % GDC, 20 vol % LSM) dual-phase membrane exhibits a maximum oxygen flux of 2.2 mL. cm(-2).min(-1) at 850 degrees C, indicating that to enhance the oxygen permeation flux, the LSM content should be adjusted to the minimum value at which electronic percolation is maintained. The oxygen ion conductivity of the dual-phase membrane is reliably calculated from oxygen flux data by considering the effects of surface oxygen exchange. Thermal cycling tests confirm the mechanical stability of the membrane. Furthermore, a dual-phase membrane prepared here with a cobalt-free coating remains chemically stable in a CO2 atmosphere at a lower temperature (800 degrees C) than has previously been achieved.