Co/Fe oxide and Ce0.8Gd0.2O2-δ composite interlayer for solid oxide electrolysis cell

Abstract

A composite interlayer comprised of gadolinia doped ceria (GDC) and Co/Fe oxide was prepared and investigated for solid oxide electrolysis cell with yttrium stabilized zirconia (YSZ) electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) anode. The interlayer was constructed of a base layer of GDC and a top layer of discrete Co3O4/FeCo2O4 particles. The presence of the GDC layer drastically alleviated the undesired reactions between LSCF and YSZ, and the presence of Co/Fe oxide led to further performance improvement. At 800°C and 45% humidity, the cell with 70% Co/Fe-GDC interlayer achieved 0.98A/cm2 at 1.18V, 14% higher than the cell without Co/Fe oxide. Electrochemical impedance spectroscopy (EIS) revealed that with higher Co/Fe content, both the ohmic resistance and the polarization resistance of the cell were reduced. It is suggested that Co/Fe oxide can react with the Sr species segregated from LSCF and Sr1-x(Co,Fe)O3-δ, a compound with high catalytic activity and electronic conductivity. The Sr-capturing ability of Co/Fe oxide in combination with the Sr-blocking ability of GDC layer can effectively suppress the undesired reaction between LSCF and YSZ, and consequently improve the cell performance.