Oxygen permeation in thin, dense Ce0.9Gd0.1O 1.95- membranes II. experimental determination

Thin (∼30 m), dense Ce0.9Gd0.1O1.95- (CGO10) membranes (5 5 cm2+) supported on a porous NiO/YSZ substrate were fabricated by tape casting, wet powder spraying and lamination. A La 0.58Sr0.4Co0.2Fe0.8O 3-δ/Ce0.9Gd0.1O1.95- (LSCF/CGO10) composite cathode was applied by screen printing. Oxygen permeation measurements and electrochemical characterisation of the cells were performed as a function of temperature with air and varying hydrogen/steam mixtures flowing in the feed and permeate compartments, respectively.

The oxygen flux was found to reach 10 N mL min-1 cm-2 at ∼1100 K and to exceed 16 N mL min-1 cm-2 at 1175 K. The measured oxygen flux was in good agreement with theoretical predictions from a model that takes into account the bulk transport properties of Ce0.9Gd 0.1O1.95-, the anode and cathode polarisation resistances, and the gas conversion and gas diffusion losses in the permeate compartment.

The performance of the membrane was also investigated under varying CH 4 and H2O gas mixtures at 1106 K. The oxygen flux increased with decreasing steam to carbon ratio and was found to exceed 10 N mL min-1 cm-2 of O2 for steam to carbon ratios below 4:3. Post-test analysis of the tested membrane did not reveal any significant microstructural degradation of the CGO10 membrane or the anode-support. © 2011 The Electrochemical Society.