Operando Studies of Redox Resilience in ALT Enhanced NiO-YSZ SOFC Anodes

Abstract

This work explores the effects of aluminum titanate (ALT) as a dopant in standard NiO-YSZ SOFC anodes on cell resilience under reduction and oxidation (redox) cycling. Cells operated galvanostatically (50% Imax) at 800°C for the duration of a single redox cycle with hydrogen exposure lasting for 20 minutes prior to electrochemical oxidation. Observable reduction and oxidation of the Ni anode was monitored using operando vibrational Raman spectroscopy and electrochemical potential measurements, while electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements were performed to determine cell condition and performance following each redox cycle. Repeated electrochemical redox cycling led to irreversible cell degradation for both ALT doped and standard anodes, but ALT conferred significantly more resilience to the doped anodes. Increased stability of Ni catalyst microstructure resulting from ALT addition was shown to slow degradation rates and increase average cell tolerance to redox cycles by a factor of two.