Chromium poisoning and degradation at LaNi0.6Fe0.4O3 cathode with LaNi0.6Fe0.4O3–Gd0.2Ce0.8O2 functional layer for SOFC under open circuit condition

Abstract

We fabricate symmetrical cells adopting LaNi0.6Fe0.4O3–δ (LNF) cathode with LNF–Gd0.2Ce0.8O2 (GDC) functional layer on scandia-stabilized zirconia electrolyte by screen printing. Degradation of cathode performances by Cr poisoning is studied. Specific polarization resistance (Rp) increases with time to power of 1/4 and 1/3 in LNF cathode with and without functional layer under exposure of Cr vapors at 750 °C for 900 and 500 h, respectively. Electrochemical impedance spectra illustrate LNF exhibits greater Rp than that of LNF with functional layer under exposure of Cr vapors due to strong Cr deposition at LNF/ scandia stabilized zirconia (ScSZ) interface. No significant degradation in performance has been observed after 900 h of operating under the same condition due to very little Cr deposition at LNF-GDC/ScSZ interface, suggesting little poisoning effect for O2 reduction on LNF cathode with functional layer. These demonstrate LNF cathode with functional layer has high resistance towards Cr deposition and high tolerance towards Cr poisoning.